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VIVA LAMARCK: A BRIEF HISTORY OF THE INHERITANCE OF ACQUIRED
CHARACTERISTICS by Ev Cochrane

"Men who strive in their works to push back the limits of human
knowledge know well that it is not enough to discover and prove a
useful truth that was previously unknown, but that it is necessary
also to be able to propagate it and get it recognized."1 A leading
evolutionist recently observed that the great questions in
evolutionary theory remain much the same today as they were in
Darwin's time.2 Certainly this observation applies to the debate over
the inheritance of acquired characters, commonly known as Lamarckism,
after Jean Lamarck, author of the first systematic theory of
evolution. The debate over the reality of Lamarckian ideas has raged
for the better part of a century and a half and shows no signs of
abating. Indeed, as I write, the controversy has been rekindled over
the announcement of new experiments allegedly supporting the
possibility of inheritance of acquired characters. In an attempt to
understand the historical background and theoretical significance of
this controversy we will offer here a brief outline of the history of
the inheritance of acquired characters. This outline will include a
summary of Lamarck's theory of evolution; an assessment of the
validity of its rejection by Weismann and Neo-Darwinism; and a
discussion of recent developments including the modern revival of the
inheritance of acquired characters by Steele and Gorczynski. During
the course of our survey it will be found that many of the greatest
figures in the history of science have espoused a belief in the
inheritance of acquired characters, and we will attempt to discover
some of the evidence which led these scientists to adopt such a
position.

LAMARCK AND HIS THEORY OF EVOLUTION

In a discussion of Lamarck's theory of evolution, C. H. Waddington, a
distinguished contributor to the Neo-Darwinian synthesis, observed
that:
"Lamarck is the only major figure in the history of biology whose name
has become, to all intents and purposes, a term of abuse. Most
scientist's contributions are fated to be outgrown, but very few
authors have written work which, two centuries later, is still
rejected with an indignation so intense that the skeptic may suspect
something akin to an uneasy conscience."1 The virulent nature of the
debate over Lamarck's theory of evolution has made it difficult to
arrive at a fair assessment of this pioneer's rightful place in
biological thought. Until recently the history of Lamarckism has been
written by participants in the debate; i. e., by those who generally
had an axe to grind. Mayr concedes this point, offering at the same
time a parting shot at Lamarck: "As long as the battle between
Darwinism and Lamarckism was raging, it was quite impossible to
undertake an unbiased evaluation of Lamarck. For this we are now
ready, after it has been demonstrated conclusively that the various
causal explanations of evolution, usually designated as Lamarckism,
are not valid."2

In the past several decades scholars have begun to reassess Lamarck's
contribution to evolutionary thought and in the process great gains
have been made towards separating fact from fiction as regards the
development and significance of his theories. The genesis of Lamarck's
ideas on evolution can be traced to the final years of the 18th
century, during which time Lamarck was a participant in the vital
intellectual milieu which characterized Paris at the time. Through
something of an accident Lamarck had been appointed the head of the
invertebrate department of the famous Museum d'Histoire Naturelle
Institute in 1793, at the time the world's foremost center for
biological studies. Coming on the eve of his fiftieth birthday, this
appointment marked something of a departure for Lamarck, who had
earlier distinguished himself as a botanist.3

Lamarck's evolutionary views are first detectable around 1800 and were
subsequently published in systematic form in Recherches sur
l'organisation des corps vivans (1802), Philosophie Zoologique (1809),
and Histoire naturelle des animaux sans vertebres (1815-1822).
Lamarckism, inasmuch as it is understood at all by the majority of
biologists, connotes little more than a belief in the inheritance of
acquired characters. While it is true that this belief was central to
Lamarck's understanding of the evolutionary process, it is also true
that it represented only one aspect of an otherwise complete theory of
evolution. Indeed, for Lamarck the inheritance of acquired characters
was little more than a truism, obvious to all and requiring no
detailed documentation. Lamarck recognized two principal factors
behind the evolution of living forms: the first being an inherent
tendency of organic matter to reach new levels of complexity; the
second being the modifying capacity of the environment. These factors
are apparent in the following quote from Philosophie Zoologique:
"The state in which we now see all the animals is on the one hand the
product of the increasing composition of organization, which tends to
form a regular gradation, and on the other hand that of the influences
of a multitude of very different circumstances that continually tend
to destroy the regularity in the gradation of the increasing
composition of organization."1

While the former factor is well worth attention, it is Lamarck's
emphasis on environmental factors which historically has received the
most notoriety, and it is this factor which will occupy us in this
essay.2 According to Lamarck, the first steps towards modification of
form are precipitated by changes in environmental circumstances, these
changes being followed by an organism's subsequent attempt to adapt to
them. A change in environmental circumstances necessitates new needs,
which in turn lead to changes in an organism's behavior. These changes
in behavior, once established as habitual, give rise to functionally
appropriate changes in form. Lamarck's own words are as follows:
"The environment affects the shape and organization of animals, that
is to say that when the environment becomes very different, it
produces in course of time corresponding modifications in the shape
and organization of animals. It is true if this statement were to be
taken literally, I should be convicted of an error; for whatever the
environment may do, it does not work any direct modification whatever
in the shape and organization of animals. But great alterations in the
environments of animals lead to great alterations in their needs, and
these alterations in their needs necessarily lead to others in their
activities. Now if the new needs become permanent, the animals then
adopt new habits which last as long as the needs that evoked them."1

Lamarck's theory thus places a heavy emphasis on an organism's
behavior as an active agent in evolutionary development. It is an
animal's habitual behavior which ultimately determines its form, with
form following function in Lamarck's understanding. Such a view
represented a significant departure from the standard view at the
time, which supposed that an animal's divinely ordained form
predetermined its mode of life and behavior.2

Lamarck summarized his view of evolution in two laws:
"(1) The production of a new organ in an animal body results from a
new need which continues to make itself felt, and from a new movement
that this need brings about and maintains; (2) All that nature has
caused to gain or lose by the circumstances to which their race has
been exposed for a long time, and, consequently by the influence of a
predominant use or constant disuse of an organ or part, is conserved
through generation in the new individuals descending from them,
provided that these acquired changes are common to the two sexes or to
those which have produced these new individuals."3

Lamarck attempted to provide illustrations of how environmental
circumstances had influenced the form of animals but here it must be
said that his arguments were not especially persuasive, especially
when it came to explaining the acquisition of new organs. One positive
example of modification of form provided by Lamarck is worth
mentioning as it has long since been regarded as a classic example of
the inheritance of acquired characters by Darwin and many other
naturalists: namely, the modification in the location of the
flatfish's eyes.4 Here the flatfishes' habit of swimming on one side
has resulted in its eyes "migrating" to the upper side of its head.

Lamarck was more convincing when discussing the modifying effects of
disuse upon form. As an example of this type of organic change Lamarck
cited the absence of teeth in most whales, due, apparently, to their
propensity for feeding upon filtered plankton which rendered teeth
unnecessary. This feature contrasted sharply with the well-developed
teeth of related mammals, and indeed whales possess rudimentary teeth
as embryos. The rudimentary nature of the whale's teeth remains valid
today as evidence of organic evolution.5

It should be noted in passing that Lamarck recognized the existence of
other factors whereby living forms might become modified, including
the direct effects of the environment (confined primarily to plants
and lower animals), effects due to accidental variation (such as
sports), hybridization, and domestication.1 Many of these factors
would reappear in Darwin's theory of evolution a half century later.

Lamarck's observations on accidental agents of change emphasize the
fundamental difference between his conception of evolution and that of
modern biology and offer a suitable jumping off point from which to
begin our analysis. Lamarck insisted that accidental causes of
variation were subordinate in importance to those derived from force
of habit:
"One must distinguish between varieties obtained accidentally during
the development of an embryo, either in a grain, an egg, or a uterus,
from those which are formed during the course of the life of the
individual; the variety resulting from the first cause being less
conservable than that from the second."2

It is the emphasis on the accidental nature of variation, of course,
which distinguishes Darwin's theory of evolution from that of his
great predecessor, and it is this element, together with the concept
of natural selection, which survives in the modern view of the
evolutionary process, commonly termed the Neo-Darwinian synthesis.3
Indeed the modern view represents a total inversion of Lamarck's
system in that it holds that only accidental changes are
conservable-these changes being conceived as arising in the genome
alone-with those changes arising during the life of the individual
having no conservability whatsoever.

CUVIER, DARWIN, AND THE RECEPTION OF LAMARCK'S THEORY OF EVOLUTION

It is well-known that Lamarck's theory of evolution did not gain favor
with his contemporaries. Here Burkhardt has noted that: "with the
exception of a few brief and scattered comments Lamarck's evolutionary
ideas were publicly received in silence."4 Geoffroy St. Hilaire,
himself an early proponent of evolutionary views, offered the
following portrait of Lamarck's final years: "attacked on all sides,
insulted even by odious jests, Lamarck, too indignant to respond to
such cutting epigrams, submitted to the insult from them with a
sorrowful patience."5

Indeed for all practical purposes Lamarck's theory was ignored until
Darwin's Origin of Species made evolution a household word. At that
time various writers began to call attention to Lamarck's pioneering
role in evolutionary thought, foremost among these being Samuel Butler
and Ernst Haeckel.6

Why, it is necessary to ask, were Lamarck's views so offensive to the
ears of his contemporaries? Here we can only offer a few general
observations as a full answer to this question would require volumes.
That Lamarck expressed evolutionary views in a time generally
characterized by creationist views certainly did not bode well for
their acceptance. Yet this is not likely to be the sole explanation of
Lamarck's fate as other French naturalists also expressed themselves
on the possibility of organic mutability without being heaped with the
abuse that afflicted Lamarck.

In attempting to account for the failure of Lamarck's theory of
evolution Burkhardt calls attention to the empirical nature of French
science at the time of Lamarck and cites the frailty of Lamarck's
evidence: "It is often said that Lamarck's evolutionary theory was
rejected in its own day simply because people at the beginning of the
nineteenth century were unaccustomed to thinking in evolutionary
terms. Lamarck, in other words, was too far ahead of his time to be
appreciated. What seems to be more nearly the truth, at least with
respect to the French scientific community, is that Lamarck's theory
of evolution was rejected not because the idea of organic mutability
was virtually unthinkable at the time, but because Lamarck's support
of that idea was unconvincing and because, more generally, the kind of
speculative venture Lamarck had embarked upon did not correspond with
contemporary views of the kind of work a naturalist should be
doing...His arguments for evolution took the form of broad assertions
accompanied by a limited number of examples but no solid empirical
foundation."1 Lamarck's manner of presenting his evolutionary
hypotheses must bear some of the responsibility for the fate of his
ideas. A cumbersome and disjointed style of writing, a penchant for
speculation and offering grandiose interpretations of the various
natural sciences, a reliance upon outmoded understandings of chemistry
and physics, all conspired to render Lamarck's views unpalatable to
the majority of his scientific peers.2 Here again, however, it is
well-known that other pioneers in science have had cumbersome styles,
a perfect example being Darwin himself, and thus style and
presentation alone cannot account for the rejection of Lamarck's
ideas.

An important factor in the dismissal of Lamarck's theory was the
shabby treatment it received at the hands of Georges Cuvier, the
justly renowned pioneer of paleontology and comparative anatomy. The
story of Cuvier's ridiculing caricature of Lamarck's theory, delivered
as a eulogy, has been chronicled many times.3 Suffice it to observe
here that Cuvier's attack upon Lamarck's views, coming from the most
distinguished French zoologist of the time, carried a lot of weight
and temporarily banished Lamarck's ideas from serious consideration.
It is possible to trace several of the misconceptions which have
dogged Lamarck's theory directly to Cuvier's eulogy, foremost among
these being the claim that Lamarck's theory envisaged animals wishing
themselves new organs.1 The ludicrous example of the giraffe wishing
itself a longer neck continues to be repeated to this day.

It is notable that the same misconception appears in several of
Darwin's references to Lamarck, an indication, perhaps, of the
widespread influence of Cuvier's critique.2 In a letter to J. D.
Hooker, for example, Darwin begs: "Heaven forfend me from Lamarck[s]
nonsense of...'adaptations from the slow willing of animals'."3 An
additional factor in Darwin's misunderstanding of Lamarck's views-and
one which played an indeterminable but probably significant role in
their poor reception outside of France-was the lack of a suitable
translation of Lamarck's writings.4 Lamarck's Philosophie Zoologique,
for example, was first translated into English in 1914.5

Cuvierian propaganda and the language barrier aside, it is
nevertheless a fact that in his published writings and letters Darwin
typically referred to Lamarck and his theory in a derogatory manner,
denying any Lamarckian influence upon his work.6 In a letter to Lyell,
for example, Darwin refers to Lamarck's Philosophie zoologique as "a
wretched book, and one from which (I well remember my surprise) I
gained nothing."7 Darwin repeated this claim in another letter: "I got
not a fact or idea from it."8

Such statements, however, are demonstrably untrue. That Lamarck's
writings had a profound influence upon the development of Darwin's
views on evolution is obvious upon review of the formative period of
Darwin's ideas.1 It is known that Darwin encountered Lamarck's
theories while at Edinburgh (1825-1827) where he read parts of
Lamarck's Systeme des animaux sans vertebres, in which Lamarck's
evolutionary views were clearly expressed.2 This was well before the
famous voyage of the Beagle (1831-1836), and long before Darwin had
any personal inclination towards accepting the evolutionary
hypothesis. (Indeed historians have concluded that it was not until at
least 1837 that Darwin came to abandon his belief in the fixity of
species).3

Darwin's personal notebooks compiled during the period in which he
came to accept the reality of evolution (1837-1840), some twenty years
before the publication of Origin of Species, likewise attest to the
decisive influence of Lamarck. There Darwin referred to Lamarck and
his theory in the most glowing of terms:
"Lamarck was the Hutton of Geology, he had few clear facts, but so
bold and many such profound judgment that he foreseeing consequence
was endowed with what may be called the prophetic spirit in science.
The highest endowment of lofty genius."4 Prominent also in these
notebooks is the belief that habit determines structure, one of the
most distinctive features of Lamarck's theory of evolution. Thus
Darwin proclaimed: "According to my views, habits give structure,
habits precede structure, habitual instincts precede structure."5 The
same idea is expressed in another passage: "All structures either
direct effect of habit, or hereditary and combined effect of habit."6
Kohn, in a lengthy analysis of Darwin's conversion to the evolutionist
position, notes that Darwin's formative ideas on the subject were
usually, if not always, borrowed and that the "Darwinism of 1837 was
not far removed from the Lamarckism of 1809."7

Such evidence casts a new light on Darwin's derogatory remarks towards
Lamarck in his published works and letters, and suggests that Samuel
Butler was right all along in maintaining that Darwin's concern for
priority with regard to the development of the theory of evolution led
him to conceal his great debt to the French pioneer.1

As the foregoing intrigue reveals, the relationship between the
Lamarckian and Darwinian theories of evolution is far more complex
than generally acknowledged. College textbooks typically ignore
Darwin's indebtedness to Lamarck and represent the relationship
between the theories of Lamarck and Darwin as one of clearcut
progress, with Darwinism triumphing over the discarded Lamarckism.
Such an interpretation glosses over the fact that Darwin himself was a
Lamarckian-inasmuch as this term connotes a belief in the inheritance
of acquired characters. This was hardly an incidental aspect of
Darwin's thought, as is sometimes suggested; rather a belief in the
inheritance of acquired characters was integral to Darwin's
understanding of the evolutionary process.2 Indeed, from his first
notes on evolution to his final thoughts on the matter Darwin
maintained that Lamarckian inheritance was essential in explaining
many of the most difficult questions surrounding the evolution of
living organisms, including the inordinate growth of the human brain,
the loss of structures through disuse, the origin of many instincts,
etc.3 Darwin reaffirmed his "Lamarckism" in the preface to The Descent
of Man, where he complains that his critics have overlooked this
element in his writing. There Darwin reiterated that he has always
held "that great weight must be attributed to the inherited effects of
use and disuse, with respect both to the body and mind."4

It is well-known that Darwin attempted to provide a physiological
foundation for the inheritance of acquired characters via his theory
of heredity known as pangenesis, which envisaged that gemmules (a
conceptual forerunner of the gene) from the body migrated to the sex
cells to inform them of changes in the body.5 Darwin's "provisional"
hypothesis represented the first comprehensive attempt to account for
the phenomena of heredity by a common principle, and exerted a
decisive influence upon the later theories of Galton, Weismann, and de
Vries.6

THE RISE AND FALL OF LAMARCKISM

Thanks in part to the patronage of Darwin, but due mainly to the
immense influence of the evolutionary writings of Herbert Spencer,
Ernst Haeckel, Samuel Butler and others, the doctrine of the
inheritance of acquired characters enjoyed what may be called a golden
age during the period between 1860 and 1910. This period, for example,
saw the development of the American school of paleontology associated
with such influential figures as Cope, Osborn, Packard and Hyatt.1 As
Bowler points out, this American school-deemed Neo-Lamarckian by
Packard because of its heavy reliance upon the inheritance of acquired
characters as an explanatory agent in the modification of organic
forms-was as close as the Lamarckians ever came to offering an
organized community.

Paleontologists were not the only scientists to embrace Lamarckism, as
Burkhardt notes: "The idea of the inheritance of acquired characters
had great breadth of appeal in the last decades of the nineteenth
century and the early decades of the twentieth century. This appeal
cut across both national and disciplinary boundaries, and it drew
support from philosophical and social considerations as well as
scientific ones...The Lamarckian position was supported in England,
France, Germany, Austria, Switzerland, Italy, Russia, and the United
States by embryologists, paleontologists, physiologists,
bacteriologists, and plant geographers. It seemed to fit well with the
embryologist's assumption that ontogeny recapitulates phylogeny, with
the paleontologist's fossil sequences that seemed to display the
accumulated effects of use and disuse, with the physiologist's
interest in causal rather than statistical relationships, with the
bacteriologist's understanding of the bacterium's adaptation to
environmental change, and with the plant geographer's data on the
geographic variation of forms. In a more straightforward manner than
Darwinism, Lamarckism also seemed capable of explaining the
degeneration of useless organs, correlated variation, and the origin
of various kinds of instinctive behavior."2

About 1910, however, together with the continued development of a
science of genetics steeped in Mendelism and the theoretical
researches of Weismann, there began a discernable tendency to question
the theoretical necessity-if not the reality-of the inheritance of
acquired characters. The rise of Weismann's influence was particularly
apparent and was cited by numerous biologists of the period as a
primary factor in the demise of Lamarckian beliefs. L. Doncaster,
reviewing the situation at the turn of the century, attests to
Weismann's decisive role in this controversy: "Since the publication
of Weismann's theory of heredity with the great body of evidence which
has been collected on the other side, opinion has turned increasingly
towards the belief that acquired variations are not transmitted."1
Mayr observes that by 1940 Weismannism had gained nearly universal
acceptance.2 By 1930 and the development of the population genetic
programs of Fisher and Wright a new era was apparent, one which
emphasized experimental procedures and quantification of the results
through mathematics. This school generally looked down upon the sort
of indirect evidence drawn from the study of fossils and the behavior
of animals which had always provided the foundation of a belief in the
inheritance of acquired characters. It should be pointed out, however,
that there was in fact a good deal of experimental investigation of
Lamarckian inheritance. A glance at the literature of the period
reveals literally dozens of experiments in which positive evidence of
the inheritance of acquired characters was obtained.3 As Neo-Darwinism
came to dominate biology during the thirties and forties, however,
alternative explanations were offered for the experimental results
suggesting a Lamarckian interpretation, and the Lamarckian hypothesis
became increasingly ignored as a factor in evolutionary development.
Perhaps Burkhardt was right that Lamarckism began to wane not so much
from disproof, but from the death of its leading proponents and the
general belief that Lamarckian inheritance was unnecessary to explain
the processes of evolution: "Lamarckism was not falsified by
experiment so much as it was rejected as an unnecessary hypothesis."4

Bowler has offered a similar assessment of the banishment of
Lamarckism from the modern synthesis, adding that the failure of
Lamarckian theorists to come up with a viable theory of heredity
spelled their doom: "By the time the war threw European science into a
turmoil, biologists had already begun to move away from Lamarckism.
Yet the theory was never abandoned completely: Rather than refutation,
it faced a gradual loss of interest as the new science of genetics
began to show the achievements that were possible with an alternative
concept of heredity."5

SOME ISOLATED VOICES

During the period that witnessed the ultimate eclipse of Lamarckian
influence within biology several researchers stood out for their
continued defense of Lamarckian ideas. Noteworthy here are Paul
Kammerer, the tragic biologist whose incredible ability to breed
amphibians and reptiles led to a series of notorious experiments
during which many intriguing results were obtained suggestive of a
Lamarckian interpretation6; Hans Spemann, the Nobel-prize winning
embryologist whose ingenious experiments uncovered the organizer1; E.
S. Russell, a biologist whose Form and Function is still regarded as a
classic contribution to the philosophy of biology2; and F. W. Jones, a
comparative anatomist whose many books provide a wealth of evidence in
favor of Lamarckian inheritance.3

Here it is also worth noting that several of the greatest figures in
the history of psychology-many of whom were active during this
period-also expressed a belief in Lamarckian inheritance, including
Freud, Jung, Watson, McDougall, Bleuler, Pavlov and Piaget.4 The
writings of these men kept Lamarckism alive long after it had been
rejected by the majority of biologists.

Why, it may be asked, did these distinguished researchers continue to
adhere to a supposedly discredited form of inheritance? Their reasons
were numerous and can only be briefly alluded to here. Among
naturalists and psychologists alike there was a common belief that it
was impossible to explain the remarkable instincts of animals without
some direct transmission of the effects of experience. Freud summed up
this view very succinctly: "If the so-called instincts of
animals-which from the very beginning allow them to behave in their
new conditions of living as if they were old and long established
ones-if this instinctual life of animals permits of any explanation at
all, it can only be this: that they carry over into their new
existence the experience of their kind; that is to say, that they have
preserved in their minds memories of what their ancestors experienced.
In the human animal things should not be fundamentally different."5

Lamarckism appealed especially to those researchers who held that mind
and psychical factors had a role to play in evolution. While Lamarck
himself had downplayed the importance of consciousness or intelligence
in all but the highest life forms, other prominent Lamarckians such as
Butler and Russell observed that it was Lamarck's theory which first
emphasized the importance of an animal's behavior in directing its
evolution, and that it was but a small step from here towards
assigning psychical factors a significant influence in the mutability
of organic forms.1

The evidence for Lamarckism, as noted earlier, was largely
circumstantial in nature. A favorite ploy among Lamarckian writers was
to cite the intimate adaptation of an animal's form to its environment
and lifestyle, this agreement of form and function seemingly requiring
some sort of direct feedback from the animal's body to its genome. As
an example of this type of argument consider the striking adaptation
provided by the skeletal structure of the seal.

Most mammals, upon taking to the water on a temporary basis, swim by
arching their necks and throwing back their heads thereby aligning the
nostrils, eyes, and ears above the water level. To attain this
position it is necessary that the cervical region of the spine become
bent backwards producing a convex curve of the animal's cervical
column on its ventral side. Dogs customarily assume this posture
whenever they take to water; seals assume it on a permanent basis.
Upon noting the overwhelming probability that seals descended from
terrestrial mammals, Jones offers the following analysis of their
peculiar skeletal structure: "It is natural to assume that, at the
very outset of their departure from normal terrestrial life, the
ancestors of the seals produced the characteristic curvature of the
cervical region only when actively engaged in swimming. It is a
further justifiable assumption that, as aquatic life became more
habitual, this peculiarity became increasingly impressed on the
disposition of the cervical vertebrae. In the end, it became a
definite and permanent feature of the adult."2

Jones points out that the convex form of the seal's cervical region is
present in the embryo and that its hereditary nature is incontestable.
This feature of the seal's anatomy, moreover, stands in striking
contrast to the cervical regions of most mammalian embryos, which are
curved in the opposite direction (see diagram one).

It is difficult to find fault with Jones' thesis that the seal's
skeletal structure is a direct result of its aquatic lifestyle and is
to be attributed to an inheritance of acquired characters. This
explanation is perfectly logical and makes intuitive sense. What is
the alternative? That an accidental change in the genome of the seal's
terrestrial forebears caused them to acquire a uniquely curved neck,
and that this newly acquired feature preadapted them for aquatic life
and favored them in the struggle for survival? Or, granting that the
seal's aquatic lifestyle preceded any genetic changes, is it likely
that a fortuitous genetic mutation(s) occurred which established the
curvature in the cervical region as a permanent feature of the
species?3

The example of the seal's cervical vertebrae offers a vivid
illustration of the explanatory power of the Lamarckian theory of
evolution. This explanatory power, moreover, is acknowledged by most
of the participants in the debate.1 The sole difficulty with the
theory is in coming up with a viable bio-chemical explanation of
Lamarckian inheritance (more of which later). The explanatory power of
the Neo-Darwinian theory, in contrast-given the rare occasion in which
proponents of this position condescend to discuss specific examples of
organic modification of form-stretches the credulity of the reader at
every step. Mutations and selection are admittedly real phenomena; the
question is can the evolution of perfectly coordinated and apparently
purposeful structures be explained by the gradual accumulation of
accidental changes in genetic structure, particularly when these
accidental changes are envisaged as occurring at random with respect
to the needs of the evolving organism?

The fact is that given any useful character it is always possible to
postulate a Darwinian explanation provided that one accepts the
potential adaptability of accidentally wrought changes in the genome.
It is a different matter, however, if the character in question
happens not to have an adaptive value. Such non-utilitarian or neutral
characters have long troubled Darwinians since in such cases there can
be no question of selection favoring them inasmuch as they would have
no influence on survival rate or reproductive success.2 As an example
of such non-utilitarian characters we might consider the case of the
tibular facets provided by certain aborigines.

Early anthropologists called attention to the strange fact that
natives of Oriental descent customarily assumed a particular posture
when squatting. The Oriental's mode of squatting may be contrasted
with that typically assumed by Australian aborigines (see diagram
two). These respective modes of squatting, it turns out, result in
definite structural modifications of the tibia and related structures
and are heritable in the respective peoples. Jones' discussion of
these modifications, offered from the vantage point of a comparative
anatomist, is worth quoting at length: "That the well-known squatting
facets on the lower anterior border of the tibia and the upper
anterior aspect of the astragulus are caused by the extreme position
of dorsi-flexion of the ankle joint, maintained during the action of
sitting hunkered on the heels with the buttocks raised sheer of the
ground, is beyond the possibility of any dispute. No clearer case of
the intimate linking of cause and effect could be found anywhere in
nature. These peculiar articular facets are not developed in people
who do not adopt this position of rest, nor are they found in the
embryo, foetus or new-born of such people...The squatting facets on
tibia and astragalus are present in all Asiatic peoples who adopt the
hunkered position of rest, but they are absent in all people who know
the habitual use of chairs or of some other contrivance upon which to
sit. Moreover, among those peoples who do not know the use of chairs
there are various elected postures in squatting. It is well known that
the Australian aborigine squats in his own peculiar, and for us very
uncomfortable, position. He does not, as a habit, sit on his heels
with his buttocks raised clear of the ground, like an Asiatic; but he
flexes his lower limbs completely, turns the soles of his feet inwards
and backwards and rests his buttocks upon the lower part of his shanks
and his inturned feet. In conformity with this peculiar posture,
maintained for long intervals and adopted by all individuals, he has
developed perfectly definite facets on the bones of his legs and these
are obviously the outcome of his posture and are entirely different
from those of the typical Asiatic squatter...Now these things have
been known for many years (Havelock Charles published his classical
paper as long ago as 1893): they are perfectly well authenticated
facts about which there can be no possible dispute. It is quite
impossible to ignore them. What is the alternative to regarding them
as being good evidence of the inheritance of acquired characters?"1

What indeed!

WEISMANN AND THE RISE OF NEO-DARWINISM

The death-knell of Lamarckism, as we have seen, is commonly traced to
Weismann's theory of heredity. In 1959 the historian Conway Zirkle
could look back upon the developments in biology since the appearance
of Weismann's theory and offer the following assessment of his
lifelong struggle against Lamarckism: "The fact that he succeeded in
the fight insures him a permanent place in the history of science."2

Since it is Weismann's theory of heredity which is generally credited
with discrediting Lamarckian ideas, a detailed analysis of Weismann's
theory must form a prerequisite to any discussion of Lamarckism. Such
an analysis will serve two purposes: (1) it will allow us to evaluate
the theoretical basis upon which the inheritance of acquired
characters first became subject to question; and (2) it will serve as
an introduction for understanding the modern denial of Lamarckism
inasmuch as several of the fundamental assumptions of Weismann's
theory of heredity persist in the modern theory of heredity.

August Weismann (1834-1914) was truly one of the most influential
thinkers in the history of biological study. During the course of a
long and productive career Weismann was led to investigate most of the
fundamental issues in biology, from the means of evolutionary change,
to the mechanisms of heredity and development, to the biological
significance of death. Throughout his career Weismann's work was
characterized by the logical presentation of bold and sweeping
hypotheses.

It was in an essay entitled "On Heredity," delivered as a lecture at
Freiburg in 1883, that Weismann first announced his intention to hold
up to question the reality of the inheritance of acquired characters.3
Weismann offered two principal forms of argument against the
Lamarckian theory, which he repeated and refined throughout his long
career: (1) that the explanatory power of natural selection rendered a
belief in the inheritance of acquired characters superfluous; and (2)
that the facts of heredity rendered a belief in the inheritance of
acquired characters impossible from a theoretical standpoint (see the
following section). Weismann thus became the first prominent biologist
(along with Alfred Wallace, the generally forgotten co-discoverer of
the theory of natural selection) to reject the necessity of invoking
the inheritance of acquired characters to explain evolution. Weismann
coined the phrase the "all-sufficiency of natural selection" to
describe the resulting viewpoint, and historians frequently trace the
inception of Neo-Darwinism to Weismann's formulations.1

Weismann attempted to defend this position by demonstrating how
natural selection could account for the various biological phenomena
which had led Darwin and other naturalists to maintain a belief in the
inheritance of acquired characters. The loss or degeneration of organs
through disuse-such as short-sightedness in humans and degeneration in
the eyes of cave-dwelling animals-was singled out by Weismann for
analysis. (Here Darwin had written: "As it is difficult to imagine
that eyes, though useless, could be in any way injurious to animals
living in darkness, I attribute this loss wholly to disuse)."2

Here Weismann invoked his principle of panmixia-or the suspension of
natural selection-and suggested that in the absence of selection
accidental variations in the germ cells might accumulate which would
result in a degeneration of the eyes. Weismann concluded: "The greater
number of those variations which are usually attributed to the direct
influence of external conditions of life, are to be ascribed to
panmixia. For example, the great variability of most domesticated
animals essentially depends on this principle."3 Once rendered useless
an organ would become a detriment to the species insofar as it
required nutrition which might be better employed elsewhere, at which
point natural selection would intervene to account for the character's
ultimate disappearance: "The complete disappearance of a rudimentary
organ can only take place by the operation of natural selection; this
principle will lead to its elimination, inasmuch as the disappearing
structure takes the place and nutriment of other useful and important
organs."4 Weismann not only sought to discredit the favorite arguments
of the Lamarckians, he attempted to show that a Lamarckian
interpretation was precluded in numerous examples of organic
evolution. Given such phenomena as the evolution of the caste system
in social insects, where the colony is divided up amongst specialized
workers, soldiers, and nurses, Weismann asked how could the Lamarckian
principle of the inheritance of acquired characters account for such
castes when the sterile insects themselves produced no offspring?1 If
the Lamarckian principle was of no use in explaining these examples of
modification of form why was it necessary elsewhere? The only
alternative, according to Weismann, was to attribute the evolution of
these adaptations to natural selection.2

Weismann's arguments presented a formidable challenge to the
Lamarckian position, and indeed one can find the same arguments
repeated today by leaders of the modern synthesis. Soon after Weismann
published his critique, Herbert Spencer, the great English
philosopher, came to the defense of the Lamarckian position. Spencer
offered detailed responses to each of Weismann's arguments, his
discussion of the caste system in sterile insects being especially
conclusive.3 Spencer argued that the various castes in insect
colonies-far from being incompatible with the Lamarckian theory-were
in fact caused by environmental factors, such as differential feeding,
and that Weismann's assumption of a genetic basis of the castes was
not supported by the facts.4 The debate between Weismann and Spencer
was waged in the leading scientific journals of the day and continued
until the latter's death in 1903. Suffice it to observe here that
while few issues were resolved by the debate, the logical powers
displayed by the respective combatants mark it as the intellectual
pinnacle of the Lamarckian controversy.

WEISMANN'S THEORY OF THE GERM PLASM

It was in "On Heredity", significantly, that Weismann first outlined
his hypothesis of the continuity of the germ plasm. Inspired
originally, it seems, by the observation that the germ cells are
sometimes separated from the other cells early in ontogenetic
development, Weismann came to believe that this separation signalled a
qualititative difference between the two types of cells.5 Referring to
these findings Weismann wrote: "As their development shows, a marked
antithesis exists between the substance of the undying reproductive
cells and that of the perishable body cells. We cannot explain this
fact except by the supposition that each reproduction cell potentially
contains two kinds of substance, which at a variable time after the
commencement of embryonic development, separate from one another, and
finally produce two sharply contrasted groups of cells."1

Two ideas stand out in this summary statement of Weismann's position:
(1) the immortality of the germ cells; (2) a qualitative difference
between the germ cells and somatic cells. As we will see, these two
postulates remained central to Weismann's understanding of heredity
and he was to return to them again and again in his various writings
on the subject. Weismann concluded this essay on a confident note: "We
have an obvious means by which the inheritance of all transmitted
peculiarities takes place, in the continuity of the substance of the
germ cells, or germ-plasm. If, as I believe, the substance of the
germ-cells, the germ plasm, has remained in perpetual continuity from
the first origin of life, and if the germ-plasm and the substance of
the body, the somatoplasm, have always occupied different spheres, and
if changes in the latter only arise when they have been preceded by
changes in the former, then we can, up to a certain point, understand
the principle of heredity; or, at any rate, we can conceive that the
human mind may at some time be capable of understanding it."2

It is interesting to note, however, that as of 1883 Weismann still
hedged on whether the inheritance of acquired characters might play a
minimal role in evolution: "Still we cannot exclude the possibility of
such a transmission occasionally occurring, for, even if the greater
part of the effects must be attributed to natural selection, there
might be a smaller part in certain cases which depends on this
exceptional factor."3 Citing one of his own researches into the
climatic variation of the coloration of butterflies, where he had
induced dramatic changes in coloration by varying the temperature,
Weismann confessed: "Even now I cannot explain the facts otherwise
than by supposing the passive acquisition of characters produced by
the direct influence of the environment."4 Weismann returned to the
phenomena of heredity in an essay published two years later: "The
Continuity of the Germ Plasm as the Foundation of a Theory of
Heredity". Taking advantage of recent developments in cytology,
Weismann argued that the hereditary material (the germ plasm) was of a
complex material nature and that it was confined solely to the nucleus
of the germ cell (the cytoplasm serving a nutritive function).5
Weismann's researches into the embryogenesis of Hydromedusae, however,
had demonstrated that germ cells do not as a rule become separated
from the other somatic cells early in development, as he had earlier
supposed. Weismann was thus forced to abandon his belief in the
continuity of the germ cells, but he still managed to retain an
emphasis on the continuity of the hereditary substance (germ plasm).
Weismann accomplished this feat by hypothesizing that a small portion
of the nucleus remained unchanged during embryonic development until
the time of the formation of the germ cells. Weismann's discussion of
this modification of his theory is as follows: "Those instances of
early separation of sexual from somatic cells, upon which I have often
insisted as indicating the continuity of the germ-plasm, do not now
appear to be of such conclusive importance as at the time when we were
not sure about the localization of the idioplasm in the nuclei. In the
great majority of cases the germ-cells are not separated at the
beginning of embryonic development, but only in some one of the later
stages...We can only conclude that continuity is maintained, by
assuming (as I do) that a small part of the germ-plasm persists
unchanged during the division of the segmentation nucleus and remains
mixed with the idioplasm of a certain series of cells, and that the
formation of true germ-cells is brought about at a certain point in
the series by the appearance of cells in which the germ-plasm becomes
predominant."1

Apparent here is the great length to which Weismann was willing to go
to salvage his belief in the unchangeableness of the germ-plasm during
development, a belief which only makes sense with regard to his denial
of the inheritance of acquired characters. Other writers, after all,
had arrived at similar ideas of the continuity of the germ cells but
all of them allowed for the possibility that external influences could
affect the germ cells and thus effect an inheritance of acquired
characters.2

Weismann's conception of development was further distinguished by the
assumption that there was a qualitative division of the nucleus during
ontogenetic development; i.e., that as embryonic development proceeds
there results a successive diminution of the full complement of
genetic information, the net result of which was the production of
differentiated cells attributable to their qualitatively different
nuclei. Weismann was thus a vocal opponent of the hypothesis that each
cell in the body contained an identical nucleus, maintaining that it
was "impossible that this substance can have the same constitution
everywhere in the organism and during every stage of its ontogeny."3

This qualitative division of the nucleus during embryogenesis formed a
cornerstone of Weismann's theory since it reinforced his belief that
there was a fundamental difference between the germ cells and the
somatic cells, the germ cells alone containing the complete genetic
blueprint for the organism. This assumption, in turn, later led
Weismann to deduce that inasmuch as the somatic cells contained a mere
portion of the genetic material it followed that germ cells could only
be produced by other germ cells. In support of this dictum Weismann
referred to the common finding that a neutered animal is incapable of
reproducing: "The familiar fact that the excision of the reproductive
organs in all animals produces sterility proves that no other cells of
the body are able to give rise to germ cells; germ plasm cannot be
produced de novo."1

In addition to the perpetual continuity of the germ plasm, Weismann's
original theory maintained that the germ plasm was completely
impervious from external influences, whether from the body or the
environment. The only heritable characters are those acquired from
one's parents: "Only those characters which were potentially present
in the germ of the parent can be transmitted to the succeeding
generation."2 Weismann's theory of heredity is unique in the history
of biology in that it recognized no means whereby the germ cells might
be modified during ontogenetic development (aside from nutritional
influences of a minor sort, at least since the development of
multicellular organisms). Such a theory is not only incompatible with
the Lamarckian hypothesis, it is incompatible with the basic tenets of
the modern synthesis as well (the modern view, of course, relies on
accidental changes in the genetic code to provide the variation upon
which natural selection is to act).

The attentive reader will have noticed that at this point Weismann
would appear to have painted himself into a corner. If the germ plasm
is immune to any and all changes from external influences, from whence
derives the genetic variation upon which natural selection is to act?
Weismann was not unaware of the ramifications of his view: "Individual
variability forms the most important foundation of the theory of
natural selection: without it the latter could not exist, for this
alone can furnish the minute differences by the accumulation of which
new forms are said to arise in the course of generations. But how can
such hereditary individual characters exist if the changes wrought by
the action of external influences, during the life of the individual,
cannot be transmitted?"3

Weismann's answer to this all-important question stands as among the
most bizarre ever offered by a biologist: genetic variation is to be
traced to our one-celled ancestors! In Weismann's words: "The origin
of hereditary individual variability cannot indeed be found in the
higher organisms-the Metazoa and Metaphyta; but it is to be sought for
in the lowest-in the unicellular organisms. In these latter the
distinction between body-cell and germ-cell does not exist. Such
organisms are reproduced by division, and if therefore any one of them
becomes changed in the course of its life by some external influence,
and thus receives an individual character, the method of reproduction
ensures that the acquired peculiarity will be transmitted to its
descendants. If, for instance, a Protozoon, by constantly struggling
against the mechanical influence of currents in water, were to gain a
somewhat denser and more resistant protoplasm...the peculiarity in
question would be directly continued on into its two descendants, for
the latter are at first nothing more than the two halves of the
former. It therefore follows that every modification which appears in
the course of its life, every individual character, however it may
have arisen, must necessarily be directly transmitted to the two
offspring of a unicellular individual."1

As this quote illustrates, Weismann conceded that Lamarckian
inheritance governed variation at the unicellular level, and thus he
went further than any Lamarckian in attributing all genetic variation
to the inheritance of acquired characters! Weismann summarized this
train of thought as follows: "We are thus driven to the conclusion
that the ultimate origin of hereditary individual differences lies in
the direct action of external influences upon the organism. Hereditary
variability cannot however arise in this way at every stage of organic
development, as biologists have hitherto been inclined to believe. It
can only arise in the lowest unicellular organisms;
and...once...attained by these, it necessarily passed over into the
higher organisms when they first appeared. Sexual reproduction coming
into existence at the same time, the hereditary differences were
increased and multiplied, and arranged in ever-changing conditions."2

Weismann's theory of the continuity of germ plasm represented a bold
attempt to arrive at a synthesis of the facts of evolution, heredity,
and development, and it generated an extensive amount of discussion
and experimental research.3 Within a few years of its publication it
became clear that Weismann's grand theory was doomed to failure. As
Mayr observed, it was the botanists who first led the attack against
Weismann's theory: "The fact that in many kinds of plants a bud may be
produced almost anywhere which can develop into flowers, as well as
the fact that one can often reconstitute a new plant (with
flower-producing germ cells) from a single leaf or other vegetative
structure, completely refutes a strict separation of germ track and
soma track."4

Biologists, similarly, observed that Weismann's dictum that germ cells
could not be produced de novo from somatic cells was incompatible with
the facts of regeneration.5 It is well established, for example, that
organisms from many different phyla can regenerate their reproductive
organs, complete with fully functional germ cells. This ability is
common among so-called lower forms such as planaria and hydra, of
course, but as the anatomist F. W. Jones noted, it can be found among
the higher phyla as well. With reference to Weismann's famous dictum,
Jones observes: "It is owing to the persistence of his teaching that
the historical and anatomical separation of the sex cells from soma
cells is still insisted on in most recent works...It is, however,
quite certain that this basal thesis stands in need of revision. So
much are germ cells akin to the body cells that, far from their
aloofness being shown by their specialized and independent origin, we
must now admit that their appearance in development is often
suspiciously late, and that they may be developed de novo, even in
adult animals, from pre-existing soma cells. Recent experiments have
shown that when both ovaries, their capsules, portions of the
Fallopian tubes, the fat bodies and portions of the surrounding
tissues are removed from adult mice, new ovaries containing new sex
cells may be developed. These new ovaries perform their normal
function of re-establishing the oestrous cycle, even leading to normal
pregnancy; and histologically they are in every way typical of normal
ovaries...It is difficult, in the face of these facts, to give full
acceptance to the doctrines of Weismannism."1

Weismann's view of development suffered a similar fate. Although some
early experiments seemed to support Weismann's theory of a qualitative
division of the nucleus during ontogenetic development, later research
showed that this view was untenable.2 Thus, whereas Weismann had
argued that the first segmentation of the zygote gave rise to two
blastomeres with only half the information necessary to produce a
complete embryo, the classic experiment of Driesch in 1891 showed that
upon isolation each of the first two blastomeres of a sea urchin could
produce a complete embryo.3 In 1895, Zoja obtained perfect embryos
from blastomeres of the eighth and sixteenth stages. Years later the
cytologist E. B. Wilson was led to remark: "These experiments render
highly improbable the hypothesis of qualitative division in its strict
form, for they demonstrate that the earlier cleavages, at least, do
not in these cases sunder fundamentally different materials, either
nuclear or cytoplasmic, but only split the eggs up into a number of
parts, each of which is capable of producing an entire body of
diminished size, and hence must contain all of the material essential
to complete development."4

Modern concepts of heredity, in fact, proceed upon the assumption that
all of the cells in a given organism are genetically equivalent.
Robert McKinnell, a pioneer in cloning research, summarizes the modern
position as follows: "All concepts regarding control of gene
expression have the prerequisite of equivalence of genetic content of
somatic nuclei. I believe that the blastomere separation studies
available as of this writing support the view that there are probably
no fundamental differences between determinant and determinate eggs
and the molecular mechanisms underlying differentiation are likely to
be the same among all nucleated organisms."1

This finding raises an important question for all theories such as
Weismann's which seek a genetic explanation of development: if all the
cells of a given organism are genetically equivalent what determines
whether a particular cell becomes a germ cell or a somatic cell? While
a conclusive answer to this question remains elusive, it is clear that
the cytoplasm plays a fundamental role in the determination of the
fate of a particular cell. The development of germ cells, as McKinnell
points out, involves the selective introduction of non-nuclear factors
into the cell body: "The germ line and its special cytoplasm are still
being studied many years after Weismann published his now discarded
theory...Briefly, it can be shown that the early segregating
primordial germ cells are de facto germ cells not because of nuclear
peculiarities but because of special cytoplasm (at least in
Drosophilia and certain frogs) that is rich in mitochondria and stains
as RNA. Thus Weismann, who thought that germ cells were different from
somatic cells because of an undiminished genome, was wrong. The
uniqueness of germ cells must be attributed to cytoplasmic
determinants."2

To go on finding fault with Weismann's theory of the continuity of the
germ plasm seems a little like beating a dead horse. In nearly every
instance in which it has been possible to test Weismann's theory it
has been found to be in error. The germ cells' peculiar manner of
development does not reflect a superior or undiminished nucleus, nor
does it preclude their stimulation by external factors; the nucleus
does not undergo a qualitative division during embryonic development;
the cytoplasm is not devoid of genetic information, nor does it play a
passive role during differentiation; excision of the reproductive
organs does not preclude the production of germ cells; etc.

In all fairness to Weismann, several of these objections to his theory
became known during his lifetime and he immediately set about revising
his original formulations. Thus Weismann was eventually forced to
accept the fact that external influences could effect changes in the
germ cells. Here Weismann acknowledged changes due to the infection of
the genome by foreign bacilli (such as that responsible for
syphillus), as well as changes attributable to environmental stimuli
such as temperature.3 Weismann sought to accommodate this evidence by
postulating that external influences could only produce variations
that were accidental and non-adaptive in nature. This concession,
however, would appear to have obviated Weismann's earlier critique of
the theoretical impossibility of Lamarckian inheritance, as his denial
of the inheritance of acquired characters could really only be
sustained if all external influences upon the germ cells were ruled
out (as in his earlier system). Once allow the infection of the germ
cells by extraneous agents like bacilli and the door is opened to
pangene-like factors allowing for adaptive changes. Indeed Weismann
conceded that such factors were operable in plants, where plastids
routinely penetrate the cell wall and become heritable.1 Weismann
maintained, however, that such cytoplasmic factors were impossible in
animals, yet another false deduction precipitated by his unwillingness
to accept the possibility of the inheritance of acquired characters.2

Of all Weismann's revisions the most telling, perhaps, is the
abandonment of the "all-sufficiency" of natural selection as a
mechanism of evolutionary change. Now Weismann could speak of "the
obvious gaps and insufficiencies of the Darwinian theory."3 Among
other things, Weismann had come to agree with Spencer and the
Lamarckians that selection-even if supplemented by panmixia-could
never account for such phenomena as the complete reduction of organs
no longer of use.4 The problem, as Weismann acknowledged, was that in
such cases there was no satisfactory explanation why the respective
genetic variations continued in the direction of diminished size.5 To
solve this problem Weismann proposed his theory of germinal selection,
whereby a struggle is envisaged as occurring amongst the hereditary
material (now envisaged as miniature living beings called biophors)
for nutrition.6 Here the non-useful character is literally starved out
of existence.7

It is not without interest that the father of Neo-Darwinism was forced
to question the efficacy of natural selection as an explanation of
evolution. Weismann's later views, not surprisingly, are rarely cited
by modern writers, apparently because of the embarrassment caused by
Weismann's abandonment of his faith in natural selection and
attribution of vital qualities to the particles of heredity. Mayr, in
his analysis of Weismann's career, barely touches upon these later
developments, offering instead the following disclaimer: "Like all
imaginative pioneers, Weismann was quite open-minded and never
hesitated to revise his theories when he thought this was required by
new evidence. Unfortunately, his revisions, particularly those
published after 1890, were not always improvements, when seen in the
light of modern knowledge."1

ACQUIRED CHARACTERS

Weismann's original formulation of the theory of the continuity of the
germ plasm underscores the need-and inherent difficulty-of arriving at
a satisfactory definition of an acquired character. The definition of
an acquired character, like that of mutation, fitness, and many other
fundamental concepts in evolutionary theory, has evolved through time.
The historian Peter Bowler suggests that it is possible to distinguish
four kinds of acquired characters: (1) those resulting from
use-inheritance; (2) those resulting from an automatic response to the
environment, as in the production of long hair to cold weather (such
adaptations are perhaps best thought of as reflecting the
self-regulatory capacity of living forms); (3) direct environmental
influences upon the germ cells, as via temperature or radiation; (4)
mutilations.2 To this list I would add those characters resulting from
the incorporation of foreign agents, whether these agents be in the
form of viruses, organelles, symbionts, or other organic factors. The
reason for including this factor will become apparent in a following
section.

Ultimately, of course, all characters are acquired, provided one
believes in evolution and not divine creation.1 Hence all biological
characters were acquired at some point during phylogeny, no matter how
the character was generated. In Weismann's early system, for example,
all characters were acquired at some stage prior to the development of
multicellular animals via direct environmental effects.

Weismann's denial of the inheritance of acquired characters applied
strictly to multicellular life forms and was based on the assumption
that no new changes could arise in the germ-plasm once that level of
development was reached.2 A chemically induced mutation, it should be
noted, would be an acquired character according to Weismann's original
formulations. Years later, upon the discovery of radioactive and
chemical mutagens, Lamarckian critics argued that such mutations
proved Weismannism false, at least in its strict form. (And indeed it
is well-known that these mutations were originally regarded as being
incompatible with Darwin's theory of evolution).3 Leaders of the
Neo-Darwinian Synthesis, however, such as Muller, Fisher, Dobzhansky,
Simpson, and Huxley latched on to these mutagenic changes afflicting
the genome and suggested that here at last was a source of the small
genetic variations which they believed were necessary to fuel
evolution. Neo-Darwinism thus came to be associated with genetic
variation that was of an accidental, non-directed nature. Lamarckian
inheritance, in contrast, came to signify only adaptive or directed
genetic variation. While this distinction is somewhat arbitrary we
will adhere to it here since this has come to be the general sense in
which the term acquired character is understood.

An acquired character is thus any character-be it a change in
behavior, form, or function-which occurs in the life of an individual
organism. Here it may be useful to approach this issue from the
vantage point of modern information theory. To oversimplify the
situation somewhat, an organism at any given point in time can be said
to consist of a generally fixed set of characters or biological
information. An inheritance of acquired characters can be said to
occur if and when this fixed set of information is supplemented by new
information (regardless of the source) which subsequently becomes
heritable.4 An accidental change in DNA, whether resulting from
environmental mutagens or errors in transcription, would-according to
this definition-correspond to background noise rather than information
and thus would not be considered an example of Lamarckian inheritance.

WEISMANNISM AND THE MODERN SYNTHESIS

Despite the failure of Weismann's theory of heredity, vestiges of his
ideas continue to exert a formidable influence upon the formulations
of modern biologists. How else but upon Weismann's theory of the
unchangeable germ plasm can one understand the curious statement of
Mayr to the effect that the problem with Lamarckian theories of
evolution is that they "deny the complete constancy of the genetic
material that we now know to exist."1 Mayr's statement is so blatantly
false as to be laughable and indicates a lack of ability to consider
the issue of Lamarckism objectively.

Weismann's theory of a distinction between the germ cells and somatic
cells, similarly, together with its insistence upon a one-way
information flow between the germ plasm and somatic cells, has a
modern correlate, albeit in a somewhat mutated form: the so-called
central dogma of Watson and Crick. (Watson and Crick, as is
well-known, revolutionized the science of heredity when they unraveled
the heliacal structure of DNA. Since their researches it has generally
become accepted that DNA serves as the master molecule of the cell, as
the sole bearer of hereditary information).2 The central dogma, when
it was first put forward in the mid-fifties, was commonly taken to
mean that there is a one-way information flow between DNA and its
products (RNA, proteins, etc.)3 The opinion of Jacques Monod, a
Nobel-prize winning biologist, may be taken as representative of the
majority view at the time: "It is not observed, nor indeed is it
conceivable, that information is ever transferred the other way
around...)"4

If DNA is indeed the sole source of bio-chemical inheritance, and if
the central dogma is true, Lamarckian inheritance (at least as
traditionally understood) would be ruled out. In the mid-sixties
Maynard Smith summed up the significance of the central dogma for
evolutionary theorists: "The greatest virtue of the central dogma is
that it makes clear what a Lamarckian must do-he must disprove the
dogma."5

In 1970 the scientific world received a shock when Howard Temin
announced the discovery of an enzyme which enabled RNA to synthesize
its own DNA.1 Originally found in retrovirsuses known to induce cancer
tumors, this enzyme-reverse transcriptase-has since been found in many
different animals, and is believed to be a fundamental component of
normal cells. Temin's research initiated a revolution in the
understanding of the workings of the genome-the effects of which
continue to accrue today-and in 1975 he was awarded the Nobel prize.

Temin's researches confirm that there is a two-way flow of
information-at least between DNA and RNA. This finding is of decisive
importance to Lamarckism not only for its import with regard to the
sanctity of the central dogma, but because Lamarckian inheritance
depends on the genome receiving feedback from its products, and opens
up the possibility that RNA might direct the creation of DNA in line
with the needs of the evolving organism. Temin himself considered the
possibility that RNA-directed synthesis of DNA plays a fundamental
role in differentiation (the proto-virus theory).2 It is Temin's
belief that retroviruses (or retrovirus-like agents) may have evolved
to serve a functional role as intracellular messengers, conveying
genetic information between the respective cells of an organism. Temin
has also suggested, finally, that an infection of the germline by one
of these viral agents might allow for the inheritance of acquired
characters: "In extreme cases, one could imagine that a product of
protovirus evolution would infect the germ-line, become integrated
there, and thus also affect progeny organisms. Such a process could
provide part of a mechanism for inheritance of some acquired
characters."3

With the notable exception of Steele and Gorczynski, Temin's
researches have not caused biologists to reconsider the possibility of
Lamarckian inheritance. Witness the following statement of Monod, the
very man who claimed that a reverse flow of information from
RNA/proteins to DNA was inconceivable: "The old idea of acquired
characters, which had been proposed by Lamark [sic], not only has
never been verified, as you probably all know, but in fact is
completely incompatible with all of what we know of the whole
structure of transfer of information. First, the spontaneous nature of
mutation is incompatible with such an idea and second, we know that
this sequence of transfer of information is essentially irreversible.
Here, I think, I must correct a wrong idea that has been spreading for
the past three or four years. It was discovered some years ago that in
some cases, the transcription step from DNA to RNA works in the
reverse direction. That is nothing surprising. This is a very simple
step and even by the basic principle in physical chemistry of the
reversability of microscopic events, it could be predicted that such
events could occur. They do occur, indeed, but this must not be taken
to mean that information from protein could possibly go back to the
genome. I think, in spite of some hesitation even by some very
distinguished colleagues, I am ready to take any bet you like that
this is never going to turn out to be the case."1

What an amazing turnabout! Once "inconceivable", the reverse
translation of information from RNA to DNA is suddenly "nothing
surprising" and might easily have been predicted!

THE WORK OF STEELE AND GORCZYNSKI

The next major development on the Lamarckian front occurred in 1979,
with the appearance of Steele's Somatic Selection and Adaptive
Evolution. It is Steele, perhaps, who has done more than anyone else
to establish the inheritance of acquired characters on a firm genetic
basis. Steele's hypothesis, briefly, is as follows. During the course
of an organism's life mutations are constantly arising in its somatic
cells, some of which might prove beneficial to the organism and aid it
in adapting to its environment. In the case of immunological response,
for example, the body of an animal generates a specific antibody to
neutralize the invading antigen. The generation of this antibody is
believed to be a random process, i. e., mutational in nature, and it
is known that such mutated cells soon proliferate throughout the blood
(somatic selection). Invoking the ubiquitous presence of Temin's
retroviruses, Steele speculates that a virus might pick up some of the
genetic material responsible for the adaptive response (probably as
RNA rather than DNA) and transport it to the germ line, at which time
it would become incorporated into the genome and be passed on to the
animal's progeny.

The most significant aspect of Steele's hypothesis is that it is built
upon established data. Thus it is known that viruses are capable of
incorporating genetic material from somatic cells and of infecting the
germ line.2 The question is how frequently does such a process occur
in nature? Certainly it seems to be asking a lot to expect evolution
to proceed largely because of the fortuitous infection of the genome
by foreign agents such as retroviruses.3

Steele suggests, however, that it is the adaptive benefits conferred
by retroviruses that accounts for their widespread prevalence. In this
belief Steele is again extrapolating from the views of Temin, who
speculated that retroviruses-such as those responsible for certain
types of cancer-are simply the pathogenic offshoots of normal genes
which otherwise play a key role in cellular differentiation.

Steele followed the presentation of his theory with the announcement
of experiments which supported the inheritance of acquired
characters.1 These experiments, performed in collaboration with R.
Gorczynski, appeared to show that upon innoculation with foreign cell
matter rabbits could pass on an acquired immunological response to
their offspring. As the authors pointed out, similar results had
previously been obtained by other research teams.2

Subsequent attempts to repeat these experiments failed, however, for
what reason(s) is not yet clear. A major controversy ensued, yet to
fully dissapate. Suffice it to observe here that the field of
immunology is a complicated one, with a variety of interpretations
being possible.3

It is important to recognize, however, that Steele's hypothesis, while
controversial, does not represent the challenge to the modern
synthesis that the more orthodox Lamarckian theory would. This much is
clear from the various remarks of commentators on the controversy.
Bowler, for example, has observed: "Steele's ideas are not a threat to
the central dogma of molecular biology, nor do they really conflict
with the existing framework of evolution theory. Apart from the fact
that the theory requires a quasi-Darwinian mechanism within the body
to produce new genetic material, it is not intended to be more than an
addition to natural selection. If valid, the new mechanism merely
would speed up evolution by allowing a more rapid adjustment of bodily
structure to new habits adopted by the organism."4

R. Dawkins, known best for his theory of the selfish gene, perhaps the
closest modern counterpart to Weismann's theory of the continuity of
the germ plasm, notes that Steele's theory bears more resemblance to
Darwin's pangenesis hypothesis than to anything that Lamarck wrote, a
point acknowledged by Steele.5 Dawkins concludes: "The very essence of
Steele's hypothesis is that the adaptive improvement comes about
through selection of initially random variation. It is about as
Darwinian a theory as it is possible to be."6

While both Bowler and Dawkins make valid points, it is clear
nevertheless that Steele's theory marks a radical departure from
Neo-Darwinian principles. It postulates that Weismann's barrier
between the germ cells and somatic cells is routinely penetrated and
that this penetration allows for the genome's direct acquisition of
adaptive information about the environment. Such a fundamental
challenge to the Neo-Darwinian position cannot be as easily
accommodated as Bowler and Dawkins would have us believe. The bitter
controversy which has attended Steele's work is sufficient proof of
this point.

THE WORK OF CAIRNS AND HALL

As pointed out in the introduction, the past few months have witnessed
renewed discussion of the possibility of the inheritance of acquired
characters. Thus, in a recent paper submitted to the prestigious
Nature, Cairns et al., describe a series of experiments in which
bacteria displayed a remarkable ability to adapt to a variety of
substrates. Briefly, the authors raised bacteria in a medium in which
lactose served as the only energy source (lactose was chosen because
the bacterial subjects of the experiment were known to be incapable of
using this sugar as an energy source). Within a short period of time,
however, it was discovered that bacteria had indeed developed the
ability to process lactose, presumably because a mutation from Lac- to
Lac + had occurred. It was shown, moreover, that this genetic change
only occurs in the presence of lactose. The authors concluded that
bacteria apparently possess the ability to generate precisely those
"mutations" which allow them to adapt to their particular environment.
This, of course, is exactly what one would expect upon the Lamarckian
theory of evolution, in which the genome changes in accordance with
the needs of the organism.

That the adaptations of the bacteria involve the inheritance of
acquired characteristics is considered by the authors. Cairns points
out, moreover, that these experiments also cast doubt on the final
bastions of Neo-Darwinism: the spontaneousness of mutations and the
supposed impossibility of any communication between proteins and DNA
(remember Monod's statement in an earlier section). The discussion of
Cairn's et al is so important it will be quoted here at some length:
"The main purpose of this paper is to show how insecure is our belief
in the spontaneity (randomness) of most mutations. It seems to be a
doctrine that has never been properly put to the test. We describe
here a few experiments and some circumstantial evidence suggesting
that bacteria can choose which mutation they should produce. But we
realize that this is too important an issue to be settled by three or
four rather ambiguous experiments...Curiously, when we come to
consider what mechanism might be the basis for the forms of mutation
described in this paper we find that molecular biology has, in the
interim, deserted the reductionist. Now, almost anything seems
possible. In certain systems, information freely flows back from RNA
into DNA; genomic instability can be switched on under conditions of
stress, and switched off when the stress is over; and instances exist
where cells are able to generate extreme variability in localized
regions of their genome. The only major category of informational
transfer that has not been described is between proteins and the
messenger RNA (mRNA) molecules that made them. If a cell discovered
how to make that connection, it might be able to exercise some choice
over which mutations to accept and which to reject.

"Since this is the kind of versatility and adaptability we seem to be
seeing in these experiments with E. coli, it is worth considering
briefly how such a connection might be made. In a very direct way, the
cell could produce a highly variable set of mRNA molecules and then
reverse-transcribe the one that made the best protein..."1

The authors go on to discuss several biochemical possibilities whereby
proteins might be monitored, concluding that such processes "might
provide a mechanism for the inheritance of acquired characteristics."2
Note here that Cairns et al., consider the possibility that
information does indeed flow "backwards" from proteins to RNA to DNA.
This hypothesis, if confirmed, would appear to obviate once and for
all any theoretical objections to Lamarckian forms of inheritance.

Since the publication of the paper by Cairns et al., word has come of
equally revolutionary findings from yet another laboratory. In this
series of experiments, also with bacteria, Barry Hall suggests that
these microorganisms can rearrange portions of their genome in
response to a novel environment.3 Hall's findings are perhaps even
more radical than Cairns' inasmuch as they suggest that more than one
"mutation" can be directed to satisfy the needs of the bacteria.

Hall discovered that in order to adapt to an environment laced with
salicin, bacteria first responded by the excision of one gene (known
as IS103) afterwhich followed a change in another gene (bglR), the
latter known to be involved in the processing of salicin. Hall
concluded that the excision of IS103 occurred in apparent anticipation
of the subsequent change in bglR even though it conferred no adaptive
advantage by itself.4 The adaptive value of IS103, apparently, is only
apparent upon subsequent activation of bglR, the two genes together
allowing the bacteria to adapt to salicin. These results, according to
Hall, seem to indicate that gene change is susceptible to regulation
by environmental factors: "We now take for granted the notion that
gene expression is regulated, i.e., subject to modulation by
environmental conditions...We now have to examine the notion implied
by these results, that mutation, like other biological processes, is
subject to regulation by environmental factors."5

Hall's conclusion is carefully worded. The intent, apparently, is not
to unduly alarm his Neo-Darwinian audience. The import of Hall's work
is clear nevertheless. A fundamental postulate of Neo-Darwinism-that
mutations occur at random with respect to the needs of the organism
and the nature of the environment-is apparently on the verge of being
overthrown. A more threatening development for the fate of the modern
synthesis is difficult to imagine.1

It is of interest here to note that this remarkable adaptability of
bacteria has been known for some time, overlooked no doubt because it
might arouse the spectre of Lamarck from his pauper's tomb. C. H.
Waddington, for example, certainly seems to have had something similar
in mind over thirty years ago, when, in a discussion of the
possibility of Lamarckian inheritance, he observed: "Recent
developments have made it somewhat easier to envisage mechanisms by
which such effects might conceivably operate. In particular, it has
been found that in many micro-organisms, such as yeasts and bacteria,
the presence of some unusual substrate may provoke the formation of an
appropriate enzyme; and there are some reports of the synthesis of
such adaptive enzymes in higher organisms. The mechanism of the
process is still obscure, but its reality seems beyond question. Now
genes can be considered to be enzymes, or at least to be in many ways
similar to the more typical cellular enzymes...one would not, perhaps,
be too much astonished if it should be found that some metabolic
'opportunity' available in the cell might tend to induce a gene
mutation to an allele which in some way fitted it."2

Now it may seem that the world of bacteria is a long way removed from
our own. And indeed it would be premature to assume that the findings
of Cairns et al., and Hall reestablish Lamarckian inheritance as a
general principle of heredity. Much more research on a variety of
animals needs to be done before such a claim could possibly be made.
The researches of Cairns and Hall do, however, support the possibility
that Lamarckian inheritance is a real phenomenon even if questions
remain concerning the extent and importance of this phenomenon in
evolution.3

BACTERIA, SYMBIOSIS, AND THE INHERITANCE OF ACQUIRED CHARACTERS

In the reconstruction of phylogenies of genes and their products,
geneticists routinely make the assumption that one can extrapolate
from findings with regard to bacterial genetics to the genetics of
higher life forms and indeed there are solid reasons for doing so.
Hence it is worth asking the following question: if Lamarckian modes
of inheritance are operable in bacteria, as the research of Cairns et
al., and Hall seems to suggest, is there any good reason why such
processes should not occur in higher life forms as well? Is it likely
that a process which would allow a bacterium to directly adapt to its
environment would be lost by its phylogenetic heirs? Does not the
theory of natural selection imply that such a mechanism would be
subject to intense selection and in all probability be maintained? Put
another way, would an organism equipped with a system allowing for
Lamarckian inheritance be inclined to give up such a system in
exchange for one relying on accidental mistakes in the genetic code?
Surely the onus of proof must rest with the theorist who would make
such a judgement.

Most evolutionists accept that prokaryotes (those organisms which lack
a nucleus, such as bacteria) constituted the primeval ancestors of
both the Plant and Animal kingdoms and thus of all known life forms on
Earth.1 Despite this generally acknowledged relationship it is easy to
overlook the pivotal role played by microorganisms in the evolution of
life on Earth. As Margulis points out, some of the most fundamental
evolutionary steps occurred among bacteria: "All of the great
innovations in the evolution of cells occurred before the first
animals, plants, and fungi developed."2 The development of
photosynthesis and many other metabolic firsts, for example, had its
origin in bacteria. If any of these developments could be proved to
have taken place via Lamarckian inheritance this alone would be
important news.

A prime reason for the biologists' refusal to accept the inheritance
of acquired characteristics, in my opinion, can be traced to a general
failure to consider the eukaryotic genome from an evolutionary
perspective. The genome did not spring into being ready made-like
Athena from the head of Zeus. It required many eons to develop and
perfect. It stands to reason that during this time the inheritance of
acquired characters must have been a driving force in the genome's
evolution.

A decisive step in the evolution of life on Earth was the development
of the cell's various organelles, such as mitochondria and
chloroplasts. How these organelles came to be a part of the primeval
cell is a much debated question. The conventional view is that the
organelles became differentiated from the nucleus during the course of
evolution. An alternative view, one that is rapidly gaining
acceptance, is that the various organelles first became incorporated
into the bodies of ancestral eukaryotes as separate life forms (i. e.
as other bacteria), afterwhich a symbiotic relationship developed and
persisted to the point at which it is now difficult to recognize their
separate origins.

There is a good deal of evidence favoring the symbiotic origin of
organelles. It is possible to demonstrate, for example, that the
ribosomal RNA of mitochondria is more similar to the RNA of certain
bacteria than to the RNA of the cytoplasm of the host cell.1 Further
evidence consistent with the symbiotic origin of organelles is the
fact that there are numerous examples of microbial symbionts which are
transmitted independently of the nucleus. The well-known kappa
particles of paramecia, which render their hosts killers of kappa-less
paramecia, are actually Gram-negative bacteria.2 Here Margulis was led
to observe: "Most, perhaps all, nonnuclear (non-Mendelian) eukaryotic
genetic factors, many known to be inherited uniparentally, have
symbiotic or viral origins. Some examples are variegated plant
plastids, the Drosphilia sex-ratio 'gene', now known to be a
population of symbiotic bacteria, u particles in paramecia, the
genetic determinant of lysine biosynthesis in Crithidia oncopelti, y
particles in Blastocladiella, and perhaps even the B chromosomes of
maize."3

If the symbiotic theory of the origin of certain organelles is valid
it stands to reason that the various symbiotic relationships entered
into by the primordial eukaryotic organism allowed it to acquire new
characters directly, overnight as it were. The incorporation of
mitochondria-like bacteria, for example, preadapted the ancestral
eukaryote for oxidizing environments. The incorporation of
chloroplast-like bacteria, similarly, allowed the eukaryotes to secure
food by photosynthesis in the absence of other nutrients. Each of
these developments allowed the ancestral eukaryote to exploit new
environments and set the stage for the proliferation of new life
forms.

A decisive issue for us is how to explain the degree of cooperation
which developed between the two originally distinct organisms: the
host cell (i. e. the prototypical eukaryote) and bacterial symbiont.
It is inconceivable that such cooperation could persist without some
form of communication between the respective organisms, and that such
communication eventually took the form of an exchange of genetic
information may be taken for granted. Indeed research into some of the
symbiotic relationships currently existing among microorganisms has
found that upon formation of a symbiotic relationship the
participating organisms exchange genetic information.4 And this
exchange of information-whether via the agency of RNA, episomes,
plasmids, or some other unknown bio-chemical agent-permanently and
favorably affects the fate (and genetic heritage) of the respective
organisms. Here there is no denying that this exchange of information
between the symbiont and host cell involves nothing less than the
inheritance of acquired characters. Waddington concedes this point in
a discussion of the hereditary processes operating independently of
the chromosomes-via chloroplasts, mitochondria, centrosomes, and the
cortex of egg cells: "Some types of bacterial transformation, or
episomal heredity, could even be interpreted as examples of Lamarckian
phenomena."1 Stephen Gould indirectly acknowledged the same point in a
discussion of viral agents known to infect the genome: "I have heard
no evidence that any of these biochemical mechanisms leads to the
preferential incorporation of favorable genetic information. Perhaps
this is possible; perhaps it even occurs. If so, it would be an
exciting new development, and truly Lamarckian."2

SEX AND THE SINGLE BACTERIUM

A decisive step in the history of life-yet another which can be traced
to our bacterial brethren-occurred when the faculty of sex arose.
Bacterial "sex" at first seems to have involved simply the
incorporation by one microorganism of a part of another containing
several genes. According to Margulis, the number of genes transferred
during this process varies-sometimes a few genes, sometimes a large
portion of the genome may be transferred.3 Once again there is no
disputing the fact that at the moment this exchange of information
first occurred there was an inheritance of acquired characters. And,
like the information acquired through the incorporation of bacterial
symbionts, the genetic information obtained via this archaeo-sex act
was immenently, if not immediately, adaptive in nature.4

The incorporation of foreign symbionts, together with the primal sex
act, I would suggest, can serve as models for the phylogenetic
acquisition of biological information. Thus it is probable that when
the first two bacteria succeeded in exchanging genetic information it
was largely a matter of chance, and that this exchange, proving
useful, became, through further trial and error, repeated and refined
in the countless generations that followed. Eventually this exchange
of genetic information became a routine component of the bacterium's
behavioral reportoire. The ideal model for genome fitness, according
to this view, is not the perpetual isolation of the genome-as per the
theory of Weismann and Neo-Darwinism-but rather the selective
permeability of the genome to information from the outside world,
whether understood in the form of neighboring cells or neighboring
organisms.

CONCLUSION

A review of the history of evolutionary theory reveals that many of
the pioneers in its development were indefatigable supporters of the
ancient doctrine of the inheritance of acquired characters. Despite
widespread agreement regarding the explanatory power of the Lamarckian
theory it was eventually abandoned in the face of the theoretical
difficulty of accounting for directional genetic change. Recent
developments in bacterial genetics, however, offer compelling evidence
that the genome does indeed respond to the needs of the evolving
organism. This evidence constitutes prima facie evidence for the
Lamarckian theory of evolution, which, taken in conjunction with the
circumstantial evidence derived from paleontology and the study of the
behavior of animals, suggests that a return to the ideas of Lamarck
and Darwin may soon be in order. At that time and at that time only
will a realistic understanding of the evolution of living organisms
become possible.

1J. Lamarck, Philosophie zoologique (Paris, 1809), Vol. 2, p. 450. As
translated by R. Burkhardt, "Lamarck and the Politics of Science," J.
Hist. Biol. 3 (Fall 1970), p. 297.
N. Eldredge, Unfinished Synthesis (New York, 1985), p. v.
1C. H. Waddington, The Evolution of an Evolutionist (London, 1975), p.
38.
2E. Mayr, "Lamarck Revisited,"J. Hist. Biol. 5 (1972), p. 55.
3In addition to botany Lamarck had dabbled in many other sciences,
including geology, meteorology, chemistry and physics. Far from
distracting Lamarck, these forays into other sciences provided him
with several of his central insights into the nature of living forms.
Lamarck's career in botany, for example, led him to emphasize the role
of the environment as a modifying influence on the forms of animals.
Lamarck's researches into geology, similarly, made him a strong
believer in uniformitarianism, and it was as a direct result of his
attempt to refute catastrophism and the possibility of widespread
extinction-according to Burkhardt-that Lamarck was initially led to
question the mutability of species. See R. Burkhardt, The Spirit of
System: Lamarck and Evolutionary Biology (Cambridge, 1977), pp.
130-137. Lamarck's researches into meteorology, where he had
discovered that the Moon exerted some sort of influence upon the
atmosphere of the Earth-and consequently upon the fluids of living
things, comparable to its effect on tides-likewise appears to have
played a role in the theoretical prominence in Lamarck's writings of
the formative influence of vital fluids. Lamarck's intimate
acquaintance with invertebrates, such as comb jellies, where one can
actually witness the vital fluids circulating about the organism, no
doubt influenced him in this belief as well.
1Lamarck, op cit., Vol. I, p. 145.
2Lamarck's belief in an inherent tendency towards complexity has given
rise to numerous interpretations, and Lamarck's statements on this
factor are by no means unambiguous. Corsi, most recently, has stated
that: "In the texts of 1809 and 1815, the 'tendency to complication'
and the 'power of life', far from implying an intrinsic finality in
life and its properties, simply indicated the 'fact' that organic
structures grew more complex." See P. Corsi, The Age of Lamarck
(Berkeley, 1988), p. 193. Here it is interesting to note that similar
ideas have been expressed by other distinguished scientists. Peter
Medawar, for example, recently lamented that: "The main weakness of
modern evolutionary theory is its lack of a fully worked out theory of
variation, that is, of candidature for evolution, of the form in which
genetic variants are proffered for selection. We have therefore no
convincing account of evolutionary progress-of the otherwise
inexplicable tendency of organisms to adopt ever more complicated
solutions of the problems of remaining alive." Quoted in R. Dawkins,
The Extended Phenotype (San Francisco, 1982), p. 165.
1Lamarck, Philosophie zoologique (London, 1914), Vol. I, pp. 107-108.
2See Corsi, op cit., p. 100.
3Burkhardt, op cit., p. 166.
4Lamarck, op cit., Vol. I, p. 252.
5The same argument applies to the whale's rudimentary hind-legs.
1Burkhardt, op cit., pp. 179-181.
2Burkhardt, op cit, p. 179.
3It should be noted, however, that by accidental variation Darwin
meant phenotypic variation while modern biologists mean genotypic
variation.
4R. Burkhardt, "Lamarck and the Politics of Science," J. Hist. Biol. 3
(Fall 1970), p. 291.
5Burkhardt, op cit., p. 293.
>6S. Butler, Evolution, Old and New (London, 1921).
1Burkhardt, The Spirit of System, op cit., pp. 201-202, 210.
2Corsi offered the following observation on Lamarck's style and its
influence upon the fate of his theories: "The conceptual and stylistic
difficulties characteristic of Lamarck's works made it difficult to
read his transformist texts with accuracy. The story of the fate of
his ideas-and of the hypotheses variously inspired by his
theories-immediately became a tale of partial readings, of biased
emphases on different points of his thought." P. Corsi, The Age of
Lamarck (Berkeley, 1988), p. 206.
3See the extensive discussion in H. Cannon, Lamarck and Modern
Genetics (Springfield, 1959), pp. 8-31. See now also T. Appel, The
Cuvier-Geoffroy Debate (New York, 1987), pp. 168-169. On the general
reception of Lamarck's ideas Burkhardt notes that: "A scientist and
his work may be discredited by means of innuendo rather than through
open confrontation. Such mechanisms seem to have been operating in
respect to Lamarck's evolutionary ideas." R. Burkhardt, "Lamarck and
the Politics of Science," Journal of the History of Biology (Fall,
1970) Vol. 3:2, p. 284.
1A. Packard, Lamarck (New York, 1980). That the same misconception
continues to this day is evidenced by the statement of Gruber, a
biographer of Darwin, that Lamarck "believed that 'will' was an
essential part of all adaptive processes." Early Writings of Charles
Darwin (Chicago, 1980), p. 47. Nothing could be further from the truth
as Burkhardt and many other commentators have demonstrated.
2Cannon notes that the eulogy of Cuvier was published in the Edinburgh
New Philosophical Journal in 1836, the year of the return of the
Beagle, and observes of Darwin's references to Lamarck: "his
criticisms all appear to be based on the eulogy." op cit., p. 26.
3F. Darwin, ed. More Letters of Charles Darwin (New York, 1903), Vol.
I, p. 41.
4D. Kohn suggests that Darwin may have been misled here by Lyell's
translation of Lamarck's besoin "needs" as "wants" (Lyell's Principles
of Geology had contained a lengthy summary of Lamarck's theory of
evolution). See Kohn's discussion of this problem in "Theories to Work
By: Rejected Theories, Reproduction, and Darwin's Path to Natural
Selection," in Studies in History of Biology (Baltimore, 1980), Vol.
4, ed. by W. Coleman & C. Limoges, p. 167.
5Mayr, op cit., p. 56.
6Thus Grinnell observes that: "This is the pattern in all Darwin's
publications; Lamarck is either condemned or ignored." G. Grinnell,
"The Rise and Fall of Darwin's Second Theory," J. Hist. Biol. 18: 1
(Spring 1985), p. 52.
7F. Darwin, ed. The Life and Letters of Charles Darwin (New York,
1887), Vol. II, p. 199.
8Mayr, op cit., p. 90.
1Corsi has observed that while Lamarck's views were rarely faithfully
represented they nevertheless exerted a decisive influence upon the
scientific community in the years after his death: "There is no doubt
that in early and mid-nineteenth century Europe the debate on
Lamarck-however interpreted-constituted a key factor in the formation
of the broad pro-evolutionary culture that greatly influenced, and
often misdirected, the reception of Charles Darwin's Origin of
Species." See P. Corsi, The Age of Lamarck (Berkeley, 1988), p. 268.
2F. Egerton, "Darwin's Early Reading of Lamarck," in Isis, pp.
454-455. Exactly when Darwin first learned of Lamarck's theory of
evolution is still something of a mystery.
3Gruber suggests 1837 marked the year of Darwin's conversion. See
Early Writings of Charles Darwin (Chicago, 1980), p. xvii. Kohn
concurs with this judgement. See D. Kohn, op cit., p. 67.
4Grinnell, op cit., p. 53.
5Ibid., p. 63.
6Ibid., p. 69.
7See Kohn, op cit., pp. 72, 98, 131.
1S. Butler, Evolution, Old and New (London, 1879); Unconscious Memory
(London, 1880), p. 39; Luck and Cunning (London, 1887), pp. 177-178.
In 1890 Butler was led to quip of Darwin: "These facts convince me
that he was at no time a thoroughgoing Darwinian, but was throughout
an unconscious Lamarckian, though ever anxious to conceal the fact
alike from himself and from his readers." See "Deadlock in Darwinism,"
in Collected Essays (London, 1925), Vol. II., p. 14.
2See Mayr's discussion of this aspect of Darwin's thought in the
preface to C. Darwin, Origin of Species (Cambridge, 1964), pp.
xxiv-xxvii. See also E. Cochrane, Psychology, Psychologists, and
Evolution (Ames, 1982), pp. 22-30.
3In the Origin of Species, for example, Darwin observes: "I think
there can be little doubt that use in our domestic animals strengthens
and enlarges certain parts, and disuse diminishes them; and that such
modifications are inherited." Ibid., p. 134.
4C. Darwin, The Descent of Man (London, 1874), pp. iii-iv.
5C. Darwin, The Variation of Animals and Plants under Domestication
(London, 1868).
6Mayr, op cit., pp. 693-694.
1For a summary of the views of this school see P. Bowler, The Eclipse
of Darwinism (Baltimore, 1983), pp. 118-140. See also the discussion
in S. Gould, Ontogeny and Phylogeny (Cambridge, 1977), pp. 85-100.
2R. Burkhardt, "Lamarckism in Britain and the United States," in The
Evolutionary Synthesis (Cambridge, 1980), ed. by E. Mayr and W.
Provine, p. 346.
1L. Doncaster, Heredity in the Light of Recent Research (Cambridge,
1911), p. 20.
2Mayr, The Growth of Biological Thought, op cit., p. 701.
3P. Fothergill, Historical Aspects of Organic Evolution (New York,
1953), pp. 253-274.
4R. Burchardt, op cit., p. 347.
5Bowler, op cit., p. 76.
6P. Kammerer, The Inheritance of Acquired Characters (New York, 1924).
It was Kammerer's suicide in 1926, coming in the wake of the finding
that one of his prized specimens had been tampered with, that
effectively sealed the doom for Lamarckism in the eyes of many
mainstream biologists. For a poignant, albeit partisan, account of
Kammerer's experiments and their role in the Lamarckian controversy
see A. Koestler, The Case of the Midwife Toad (London, 1971).
1On Spemann see R. Rinard, "Neo-Lamarckism and Technique: Hans Spemann
and the Development of Experimental Embryology," J. Hist. Biol. 21: 1
(Spring 1988); also V. Hamburger, The Heritage of Experimental
Embryology: Hans Spemann and the Organizer (New York, 1988).
2E. S. Russell, Form and Function (London, 1916); The Interpretation
of Development and Heredity (Oxford, 1930); The Diversity of Animals
(Leiden, 1962).
3F. W. Jones, The Trends of Life (London, 1953); Design and Purpose
(London, 1941); Habit and Heritage (London, 1944).
4E. Cochrane, Psychology, Psychologists, and Evolution (Ames, 1982),
pp. 160-234. It was McDougall, in fact, who published one of the final
experiments attempting to demonstrate the inheritance of acquired
characters. Of McDougall's research the historian Fothergill observed
that it provided "one of the most elaborate biological experiments yet
devised", adding that the papers describing the results "are surely
models of their kind and must rank among the classics of scientific
literature." P. Fothergill, Historical Aspects of Organic Evolution
(New York, 1953), pp. 261-262.
5Freud, Moses and Monotheism (New York, 1939), pp. 128-129.
1E. S. Russell, The Diversity of Animals (Leiden, 1962), pp. 127-128.
2Jones, Trends of Life, p. 142.
3This is the theory of organic selection made famous by Baldwin and
the Neo-Lamarckian Osborn, later adopted and christened genetic
assimilation by Waddington.
1Even Weismann conceded this point: "I have always emphasized the fact
that it is easier to explain the transformation of species on
Lamarck's principle." A. Weismann, The Germ-Plasm (New York, 1902), p.
408. See also Mayr, The Growth of Biological Thought, p. 527.
2It was in part because of these non-utilitarian or injurious
characters that Darwin was led to develop his theory of sexual
selection. See Cochrane, op cit., p. 174. See also Bowler, op cit., p.
216.
1Jones, Habit and Heritage, pp. 49-50.
2C. Zirkle, Evolution, Marxian Biology, and the Social Scene
(Philadelphia, 1959), p. 118.
3This essay can be found in A. Weismann, Essays Upon Heredity (Oxford,
1891).
1E. Mayr, The Growth of Biological Thought (Cambridge, 1982), p. 698.
It could be argued, in fact, that the modern theory of evolution is
closer to the original formulations of Weismann than to those of
Darwin. John Maynard Smith, a leading spokesman for the Neo-Darwinian
position, acknowledges this point: "Neo-Darwinism is essentially
Weismannist; that is, it holds that heritable variation is in origin
non-adaptive, and that adaptive changes which occur during the
lifetime of individuals (for example, acclimatisation to high
altitudes) do not alter the nature of the offspring they produce. In
contrast, Darwin accepted a Lamarckian view of heredity; he thought
that the 'effects of use and disuse' could influence the nature of
offspring, and even developed his theory of pangenesis to account for
such effects...If Weismann was right, then natural selection plays an
even more fundamental role than Darwin thought; it becomes the only
process leading to genetic adaptation." J. Smith, Evolution Now
(Oxford, 1982), p. 91.
2Darwin, op cit., p. 137.
3Ibid., p. 91.
4Ibid., p. 89.
1A. Weismann, The Evolution Theory (London, 1904), Vol. 2, pp. 80-89.
Darwin had offered a similar argument in Origin of Species: "I am
surprised that no one has advanced this demonstrative case of neuter
insects, against the well-known doctrine of Lamarck." op cit., p. 242.
2Ibid., pp. 97-98. Weismann traced the various insect castes to
different genes in the queen, selection favoring the queen which
produced the most harmoniously functioning colony.
3Spencer's essays are collected in H. Spencer, Synthetic Philosophy
(London, 1898).
4Ibid., p. 662. Modern research appears to have vindicated Spencer on
this point. Thus Wilson observes: "By 1950 a modest amount of evidence
had accumulated to indicate that the female castes are determined by
environmental rather than genetic factors." See E. O. Wilson, The
Insect Societies (Cambridge, 1971), p. 148.
5Churchill traces the development of Weismann's theory to certain
ideas of Haeckel. See F. Churchill, "August Weismann and a Break from
Tradition," J. Hist. Biol. 1 (1968), p. 101-102.
1Weismann, Essays Upon Heredity, p. 74.
2Ibid., p. 105.
3Ibid., p. 101.
4Ibid., pp. 100-101.
5Ibid., p. 181. Weismann thus became one of the intellectual fathers
of the modern gene concept.
1Ibid., pp. 200-201.
2Prominent among such writers were Galton, Butler, and Hering. See,
for example, the discussion in G. Romanes, An Examination of
Weismannism (London, 1883), p. 63.
3Weismann, op cit., p. 184. Weismann was apparently led to the belief
in the qualitative division of the nucleus by the assumption that
ontogeny recapitulates phylogeny; i.e., that as the primordial
unicellular organism subsequently gave rise to the multicellular
animals, so-it would seem to follow-does the zygote give rise through
embryonic development to the various differentiated cells. Ibid., p.
186.
1A. Weismann, The Evolution Theory (London, 1904), Vol. I, p. 411.
2Weismann, Essays Upon Heredity, p. 273.
3Ibid., p. 274.
1Ibid., p. 285.
2Ibid., p. 286. Here Weismann refers to the direct effects of the
environment which, although only a minor factor in Lamarck's overall
view of evolution, was assigned a prominent role in the evolution of
protozoans in Lamarck's system as well.
3For a glimpse into the debate caused by Weismann's theory see G.
Romanes, An Examination of Weismannism (London, 1883).
4Mayr, op cit., p. 703.
5A. Weismann, Essays Upon Heredity, op cit., p. 198. Kammerer raised
this objection, among others. See the discussion in Kammerer, op cit.,
pp. 125-126.
1F. W. Jones, Man's Place Among the Mammals (London, 1929), p. 27.
2In 1888, for example, in the famous experiment of Roux, a half embryo
resulted upon the destruction of one cell of a two-celled embryo, an
apparent confirmation of Weismann's hypothesis of qualitative
division. This experiment, however, was later found to be flawed.
3Weismann, op cit., p. 199. See also Weismann's The Germ Plasm (New
York, 1902), p. 32.
4E. B. Wilson, The Cell in Development and Inheritance (New York,
1925), pp. 409-410.
1R. McKinnell, Cloning (New York, 1978), p. 8.
2Ibid., pp. 6-7.
3A. Weismann, Evolutionary Theory, op cit., p. 68. It was via the
latter factor that Weismann sought to explain the few remaining
problems seemingly requiring a belief in the inheritance of acquired
characters, such as his earlier researches with regard to
temperature-induced changes in the coloration of butterflies. Now
Weismann would argue that these induced variations only simulated
Lamarckian inheritance, involving in reality parallel changes in the
body and genome, which had been similarly and simultaneously modified.
A. Weismann, The Germ Plasm (New York, 1902), p. 401.
1Here Weismann conceded that the introduction of plastids into the
plant cell constituted an inheritance of an acquired character.
2Ibid., p. 28. See also A. Weismann, "A Reply to Prof. Vines," Nature
11 (1890), p. 323. The fact is, however, that cytoplasmic factors play
an important role in the reproduction of animals as well. To take but
one example, a key role in the spatial organization of the future
embryo is believed to be attributable to the selective infusion of
extraneous cytoplasmic material into the developing egg cell. W.
Gehring, "The Molecular Basis of Development," Scientific American
253: 4 (Oct., 1985), pp. 154-156.
3A. Weismann, The Evolutionary Theory, p. 9.
4Ibid., p. 115.
5Ibid., p. 116.
6Ibid., pp. 117-119. According to Weismann's final formulations on
evolution, this struggle among biophors accounted at once for the
origins of variation and for the eventual preservation or
disappearance of a particular character. The importance of this new
found factor is apparent in the following quote: "It is, then,
germinal selection alone which brings about the presence of a majority
of ids [chromosomes] with determinants varying in the same direction,
and personal selection has no part in the transformation of the
species." Ibid, p. 136
7Weismann's assignment of vital qualities to the nuclear determinants
seems attributable to his unwillingness to accept that nuclear factors
might be modified during development, a circumstance which could be
used to support the hypothesis of the inheritance of acquired
characters. Thus Weismann criticized those theorists like Delage who
would attribute the phenomena of heredity to chemical substances lying
in the nucleus since "chemical substances are not vital units, which
feed and reproduce, which assimilate and which bear a charm against
the assimilating power of the surrounding protoplasm. They would
necessarily be modified and displaced in the course of ontogeny."
Ibid., p. 401.
1Mayr, op cit., p. 699. Mayr's resume of Weismann's contributions, as
might be expected, is a glowing one: "One of the great biologists of
all time. He was unique among all those who worked on cytology,
development, and inheritance in the last century by being an
uncompromising selectionist...From the point of view of scientific
methodology, again, he was notable for his period in his careful,
rational analysis of every problem he encountered. When he wanted to
interpret a given phenomenon or process, he attempted to reason out
all the possible solutions. Almost invariably this included the
solution that is now considered to be the right one. Owing to the
insufficient and sometimes even faulty information available at his
time, Weismann himself sometimes chose an alternative that is now
rejected. This does not in the slightest diminish the magnitude of his
intellectual achievement. He never made a hasty decision but always
first surveyed the entire field of possible solutions. His was the
first truly comprehensive theory of genetics and his theorizing
prepared the way for the research of the entire next generation."
2Bowler, op cit., pp. 62-65. The discussion of Lamarckian forms of
evolution has suffered from the failure of the respective proponents
to keep separate the inheritance of the direct effects of the
environment from the inheritance of the indirect effects of the
environment (the classical Lamarckian inheritance, resulting from
behavioral responses to environmental contingencies). Many
Neo-Lamarckians, particularly the American school of paleontologists
represented by Cope, Osborne, and Hyatt, held that acquired characters
directly induced by the environment were of prime importance in
evolution. As an example of this phenomenon we might consider the
coloration of insects. Neo-Lamarckians held that coloration was
primarily the result of the direct influence of light, which effected
parallel changes in the body and the genome. Here the environmental
stimulus is directly induced on the evolving organism, in contrast to
classical Lamarckian inheritance which makes the animal respond
indirectly to the stimulus via the mediation of behavior. For a
discussion of recent evidence bearing on this question see C. Cullis,
"Environmentally induced DNA changes," in Evolutionary Theory:
Pathways into the Future, ed. by J. Pollard (New York, 1984), pp.
203-216.
1One other exception besides creationism might be mentioned; namely,
preformationism. This belief holds that originally ideal types
successively degenerate during phylogeny resulting in the various life
forms. Here there is no true evolution or acquired characters; rather
an unfolding of an originally complex creation (this is the original
meaning of the word evolution, by the way). Weismann's view of
development, for example, betrays the definite influence of the
preformationist position.
2"Only those new characters can be called acquired which owe their
origin to external influences." Weismann, op cit., p. 258.
3Bowler, op cit., pp. 198-200.
4A further distinction could be made between information obtained from
within the body of the organism (i.e. endogenous incorporation) and
information obtained from without the organism's body (exogenous
incorporation).
1E. Mayr, The Evolutionary Synthesis, p. 15.
2This thesis, however, a prime example of the reductionist position so
apparent in Neo-Darwinism itself, is almost certainly in need of
revision. See B. Commoner, "Failure of the Watson-Crick theory as a
chemical explanation of inheritance," Nature 220 (1968), pp. 334-340.
3While the original formulation of Crick left the door open to the
possibility that RNA might convey information to DNA, this possibility
was generally regarded as unlikely by molecular geneticists. Thus
Temin observed: "Although Crick's original formulation contained no
proscription against a 'reverse' flow of information from RNA to DNA,
organisms seemed to have no need for such a flow, and many molecular
biologists came to believe that if it were discovered, it would
violate the Central Dogma." H. Temin, "RNA-Directed DNA Synthesis,"
Scientific American 226 (1972), p. 25.
4Quoted in P. Grasse, Evolution of Living Organisms (New York, 1973),
p. 221.
5J. Smith, The Theory of Evolution (Middlesex, 1966), p. 66.
1For a discussion of this research see H. Temin, "The DNA Provirus
Hypothesis," Science 192 (June, 1976), pp. 1075-1080.
2H. Temin, "Guest Editorial," J. Natl. Cancer Institute 46 (1971), p.
iv.
3Ibid., p. vi.
1J. Monod, "On the Molecular Theory of Evolution," in Problems of
Scientific Revolution (Oxford, 1975), ed. by R. Harre, p. 20.
2See the lengthy discussion in E. J. Steele, Somatic Selection and
Adaptive Evolution (Toronto, 1979), pp. 78-81.
3Temin, asked to offer an opinion with regard to Steele's hypothesis,
commented that a major problem facing it is how the virus becomes
incorporated into the host's genome: "There is apparently no
particular specificity in where the viruses insert their passenger DNA
into the genome. This is obviously important for the hypothesis, and
it therefore poses a severe difficulty." See R. Lewin, "Lamarck Will
Not Lie Down," Science 213 (July 17, 1981), p. 317. That viruses play
a fundamental role in evolution was also expressed by N. Anderson,
"Evolutionary Significance of Virus Infection," Nature 227 (September
26, 1970), pp. 1346-1347.
1R. Gorczynski & E. Steele, "Inheritance of acquired immunological
tolerance to foreign histocompatibility antigens in mice," Proc. Natl.
Acad. Sci. USA 77 (May 1980), pp. 2871-2875; "Simultaneous yet
independent inheritance of somatically acquired tolerance to two
distinct H-2 antigenic haplotype determinants in mice," Nature 289
(Feb. 19, 1981), pp. 678-681.
2E. Steele & R. Gorczynski & J. Pollard, "The Somatic Selection of
Acquired Characters," in Evolutionary Theory: Pathways into the
Future, ed. by J. Pollard (New York, 1984), pp. 226.
3It is important to note that the experiments of Gorczynski and Steele
could be valid and Steele's theory invalid (i.e., more traditional
Lamarckian inheritance might be involved). Or, alternatively, both
could be valid but unrelated so far as these particular experimental
results are concerned.
4P. Bowler, Evolution: The History of an Idea (Berkeley, 1984), p.
321.
5R. Dawkins, The Extended Phenotype (San Francisco, 1984), p. 167.
6Ibid., p. 168.
1J. Cairns & J. Overbaugh & S. Miller, "The Origin of Mutants," Nature
335 (1988), p. 145.
2Ibid., p. 145.
3B. Hall, "Adaptive evolution that requires multiple spontaneous
mutations," Genetics 120 (December, 1988), pp. 887-897.
4Indeed Hall states that the excision of IS103 is only detected when
it creates the potential for the subsequent advantageous mutation. op
cit., p. 894
5Ibid., p. 895.
1Witness Dawkins' recent confession: "To be painfully honest, I can
think of few things that would more devastate my world view than a
demonstrated need to return to the theory of evolution that is
traditionally attributed to Lamarck. It is one of the few
contingencies for which I might offer to eat my hat." See Dawkins, op
cit., pp. 164-165.
2Waddington, The Strategy of the Genes, (New York, 1957), p. 180.
3The research of Cairns and Hall raises an important task facing
modern biologists; namely, that of arriving at a satisfactory
definition of mutation. As understood by modern geneticists, a
mutation connotes an accidental change in DNA; specifically a change
in a base coding for an amino acid or a restructuring of a chromosome.
Neo-Darwinism holds that such changes in league with selection
determine the course of evolution. The research of Cairns and Hall,
however, suggests that mutation may be a directed process, subservient
in part to the needs of the evolving organism. This is something quite
different and is exactly what Lamarckians such as myself have been
insisting upon for some time. The very phrase employed by Cairns-"that
bacteria can choose which mutations they produce"-conjurs up the
memory of Lamarck. Hence I would like to propose that some new term be
found to describe directive genetic change, mutation being inadequate
given its past history and tendency to connote accidental processes
(the term directed mutagenesis had been suggested in reference to
Cairn's results). Since the type of gene change envisaged by Cairns
and Lamarckians is the product of organismic autoregulation perhaps
the term biotation would be appropriate. Whatever the eventual term
chosen a clear distinction should be made between a genetic change
which is of a directed, adaptive nature and those changes which are
accidental in origin and non-adaptive in nature. See Cochrane, op
cit., pp. 234-248.
1L. Margulis, Symbiosis in Cell Evolution (San Francisco, 1981), p.
40.
2Ibid., p. 14.
1Ibid., p. 207. See also J. Darnell, "RNA," Scientific American 253: 4
(Oct., 1985), p. 77.
2Margulis, op cit., p. 171.
3Ibid., p. 183.
4Ibid., p. 193.
1Waddington, op cit., p. 236. The parallel with the Lamarckian view of
evolution is made complete inasmuch as there is a delay between the
incorporation of the symbionically derived information into the body
of the host cell and its eventual transfer to the nuclear genome.
2S. Gould, "Shades of Lamarck," in The Panda's Thumb (New York, 1980),
p. 80.
3Margulis, op cit., p. 27.
4Margulis observes that from a functional standpoint the incorporation
of symbionts and sexual processes are identical.

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