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/An Asian perspective on early human dispersal from Africa/

/by// //Robin Dennell/^1 / and Wil Roebroeks/^2

/Table of Contents/

 

1. Introduction <#1>

2. Who were the first Asians? <#2>

    Box 1: /Home erectus/ and /Homo ergaster/ <#b1>

3. /Homo ergaster /- wanderer or stay-at-home? <#3>

4. When could hominin first have left Africa? <#4>

5. Absence of evidence and evidence of absence <#5>

6. Ways forward: alternatives to Out of Africa <#6>

7. Regional imbalances and future challenges <#7>

8. "Africa" and "Asia", or "Savannahstan"? <#8>

    Box 2: Neanderthals and moderns - where were they? <#b2>

9. Hominins, not just /Homo,/ outside Africa <#9>

10. Human evolutions writ new? <#10>

11. References <#11>

12. Acknowledegments <#12>

This article is reprinted from /Nature/, 438:1099-1004, 22/29 Dec 2005

1 R. Dennell, Department of Archaeology, University of Sheffield,
Sheffield S1 4ET, United Kingdom,
E-mail r.dennell@sheffield.ac.uk

2. W. Roebroeks, Department of Archaeology, Leiden University, PO Box
9515, 2300RA Leiden, The Netherlands



/1. Introduction/

The past decade has seen the Pliocene and Pleistocene fossil hominin
record enriched by the addition of at least ten new taxa, including the
Early Pleistocene, small-brained hominins of Dmanisi, Georgia, and the
diminutive Late Pleistocene Homo floresiensis from Flores, Indonesia. At
the same time, Asia's earliest hominin presence has been extended up to
1.8 million years (Myr) ago, hundreds of thousands of years earlier than
previously envisaged. Nevertheless, the preferred explanation for the
first appearance of hominins outside Africa has remained virtually
unchanged. We show here that it is time to develop alternatives to one
of palaeoanthropology's most basic paradigms: "Out of Africa1."

A key assumption in accounts of early hominin evolution is that the
genus /Homo/ originated in Africa, and an early form, classified either
as /Homo ergaster/ or /H. erectus sensu lato/ (see Box 1 <#b1>), was the
first to leave about 1.7-1.9 million years (Myr) ago (depending upon
one's choice of dates and specimens), and then colonized southern Asia
as far as 400^o N. The identification of east Africa as the 'core' area
for the genus /Homo/ (including /H. ergaster/) as well as tool-making
seems secure to most palaeoanthropologists, and the most recent attempts
at modelling early hominin dispersals start implicitly from the
assumption that /H. ergaster/ originated in east Africa and then
dispersed across Asia (ref. 1, 2). In fact, the evidence that /H.
ergaster /originated in east Africa is less convincing than it seems.
/H. ergaster /marks such a radical departure from previous forms of
/Homo/ (such as /H. habilis/) in its height, reduced sexual dimorphism,
long limbs and modern body proportions (ref. 3) that it is hard at
present to identify its immediate ancestry in east Africa (ref. 4). Not
for nothing has it been described as a hominin "without an ancestor,
without a clear past" (ref. 5).

 

/2. Who were the first Asians?/

At present, we have very little information on where, when and which
hominins first appeared in Asia, and the expansion of /H. ergaster/
across Asia in the Early Pleistocene remains a massive assumption, even
if it is routinely treated as a historical fact. It is assumed that it
migrated out of Africa along the Nile Valley or across the southern end
of the Red Sea, but there is no archaeological or fossil hominin
evidence that hominins were in the Nile Valley in the Lower Pleistocene;
and there are no Oldowan sites in the Sinai, southern Negev, or in
southwest Arabia at the alleged point of entry to Asia. The only Asian
Early Pleistocene fossil hominin evidence comprises three incisors from
'Ubeidiya, Israel (1.4-1.0 Myr ago), attributed to /H. erectus/ /sensu
lato /(/s.l./) by default (ref. 6); the 1.7-Myr-old specimens from
Dmanisi, Georgia (ref. 7), which have recently been classified as a very
early type of /H. ergaster/(ref. 8) and/or a new taxon, /H. georgicus/
(ref. 9); and the specimens attributed to /H. erectus sensu stricto/
(/s.s/.) in Java (ref.10), 5,300 miles away and regarded by many (ref.
11-16) but not all (ref. 10, 17-20) as different from the east African
/H. ergaster/, The earliest of these is the Mojokerto cranium (ref. 2),
which now seems to have been found in context, despite previous
misgivings (ref. 22), and is dated to 1.81 +/-0,04 Myr ago (ref. 23);
the key specimens from Sangiran have been dated to about 1.6-1.7 Myr ago
(ref. 23, 24). (The Early Pleistocene mandible and teeth attributed to
/Homo/ from Longuppo (ref. 25), southern China, probably belonged to an
ape (ref. 26, 27)). This meagre list of sites is supplemented by
archaeological instances of Early Pleistocene artefacts in Asia that are
attributed to /H. erectus/ /s.l./; examples are Erq el-Ahmar, Israel,
claimed to date to the Olduvai Event (ref. 28), and the Nihewan basin,
north Chinam (ref. 29). The only reason why the earliest tool
assemblages in Asia are attributed to /H. erectus/ /s.l./, is that
palaeoanthropologists have already decided that, in effect, it was the
only hominin capable of migration out of Africa, and with sufficient
/Wanderlust/ (ref.13) to do so.

 

///Box 1: Homo erectus /and /Homo ergaster/

/H. erectus/ - or more properly, /Pithecanthropus erectus/ - was first
discovered at Trinil in Java by Eugene Dubois in 1891. In the 1930s,
further discoveries of hominin remains elsewhere in Indonesia and at
Chou-kou-tien (now Zhoukoudian) in China were seen as broadly similar,
even if initially given their own generic names (such as /Meganthropus/
and /Sinanthropus/). In 1950, Ernst Mayr reclassified all this material
as /H. erectus/, with the Trinil specimens as the type fossils.
Subsequent African specimens were also called /H. erectus/, as were much
later specimens from Europe. /H. erectus/ thus became for a while the
earliest hominin that was thought to have lived in Asia, Africa and Europe.

In the past few years, some have doubted that the east African specimens
should be placed within the same palaeospecies as the Asian ones, In the
light of discoveries at Koobi Fora, it has been suggested that the
earliest African examples should be called /H. ergaster/, after the
specimens found at Koobi Fora, including WT15000, the magnificent 1.6
Myr-old skeleton of a young boy from Nariokotome that was initially
published as /H. erectus/. Consequently, it is the African /H. ergaster/
that is now seen by some as the hominin that first colonized Asia and
formed the founding population of what later became /H. erectus/ in
China and southeast Asia. European specimens once regarded as late
examples of /H. erectus/ or 'archaic /Homo sapiens/' are now
increasingly classified under the revived taxon of /H. heidelbergensis/,
a term first used to classify the mandible from Mauer, Germany, found in
1907, To avoid ambiguity, the term /H. erectus/ is used here/ sensu
stricto/ to denote only those specimens from eastern Asia, and /H.
ergaster/ is used to denote early east African specimens of /H. erectus
sensu lato/.

 

/3. /Homo ergaster/: wanderer or stay-at-home?/

The reason why /H. ergaster/ is assumed to have been uniquely capable of
migrating out of Africa about 1.7-1.9 Myr ago into the Asian grasslands
is because of its long limbs, human-like body proportions, probable
efficient thermoregulatory mechanisms for remaining cool in hot
conditions, the ability to ingest large amounts of meat in an
environment rich in fauna but poor in plant foods for a hungry primate,
and a sufficiently large brain to deal with the challenges of a more
carnivorous niche (ref. 3) . This argument is persuasive, except for the
point that australopithecines had probably colonized all the African
savannah grasslands by 3.0-3.5 Myr ago (ref. 30), and /Australopithecus
garhi /was living in a similar environment in northeast Africa by 2.5
Myr ago (ref. 31). As savannah grasslands were extensive across southern
Asia by 3.0 Myr ago (ref. 32), there are no reasons /a priori /why
australopithecines could not also have expanded into the Asian
grasslands before /H. ergaster/.

The fossil evidence that /H. ergaster /was in Asia in the Early
Pleistocene is not only weak, but extremely ambiguous. The long-running
debate (see Box 1 <#b1>) over whether the Early Pleistocene Javan
hominins should be classified as /H. erectus s.s /(and thus different
from their east African counterparts) or incorporated with them as /H.
erectus s.l./, and/or seen as composite (ref. 33) is still unresolved.
Neither those who regard them as an integral part of /H. erectus s.l/.
(ref. 10) nor those who view them as derived from the African /H.
ergaster/ question that the core area was east Africa. Neither position
is strengthened by the recent suggestion that the Mojokerto child had an
ape-like pattern of postnatal development (ref. 34) unlike /H.
ergaster/. Another 'big unknown' is the ancestral form of the Late
Pleistocene /H. floresiensis/ (ref. 35,36), which may prove to have
roots deep in the Asian Pleistocene. The Dmanisi hominins are harder
still to assimilate within a simple model of African origin and Asian
dispersal by /H. ergaster/ or /H. erectus s.l./ The first discovery, of
the mandible, could be classified as /H. erectus/ /s.l./ (ref. 37). The
first crania were regarded as a very early form of /H. ergaster /(ref.
8), and the latest, very small-brained one (D2700) as /H. ergaster/ but
also closely related to /H. habilis s.s./ (ref. 38). Confusingly, one
mandible (D2600) has been assigned to a new taxon, /H. georgicus/ (ref.
9). These recent assessments imply that hominins dispersed from Africa
earlier than the emergence of large-bodied hominins such as the
Nariokotome individual.

 

/4. When could hominins first have left Africa?/

But how much earlier could this dispersal have been? If a hominin at the
same grade as /H. habilis/ was able to exist outside Africa, why not
others? Why not follow the logic of Wood and Collard's reasoning (ref.
39), that /H. habilis /is better classified as /A. habilis/ and suggest
that the earliest Asians were in fact australopithecine, with /A.
georgicus/ as their first known representative outside Africa? This
suggestion would open a Pandora's box: if a hominin as small-brained
(and probably as short) as those at Dmanisi could colonize southwest
Asia by 1.7 Myr ago (and with no obvious African antecedents), why not
at 2.6 Myr ago, shortly after stone tool making became part of the
hominin repertoire (ref. 40)? Or why not even earlier, by, for example,
3.0-3.5 Myr ago, when the Saharan-Arabian desert barriers did not yet
exist (ref. 32)? If /A. bahrelghazali/, 2,500 km west of the Rift
Valley, implies that by 3.5 Myr ago "hominids were distributed
throughout the woodland and savannah belt from the Atlantic Ocean across
the Sahel through eastern Africa to the Cape of Good Hope" (ref. 30),
why could they not have done the same across the grasslands of western,
southern and central Asia?

 

/5 Absence of evidence and evidence of absence/

The obvious retort to these questions is that there is no evidence that
australopithecines did migrate out of Africa. However, absence of
evidence is not enough; we need convincing evidence (so far not
forthcoming) that the absence is not the result of taphonomic
circumstance or lack of fieldwork, especially in a continent as large as
Asia. There are only a limited number of vertebrate fossil assemblages
for the Late Pliocene and Early Pleistocene of southwest Asia (a region
larger than Kenya, Ethiopia and Tanzania combined). The Late Pliocene
assemblage from Bethlehem (ref. 41) (Israel) is very small, with only 11
taxa and dominated by animals with an adult body weight of more than 60
kg and thus larger than hominins. These fossils were found in coarse
gravel (with clasts up to 0.5 m long) in a clay matrix, in which small
and fragile remains were most unlikely to be preserved. At Kvabebi (ref.
42, 43), Georgia, dated to more than 2.6 Myr ago (that is, earlier than
the earliest stone tools in Africa (ref. 40)), there are 21 mammalian
taxa indicative of a riverine and marshy environment. Two other Georgian
localities, Kocachuri and Calka, are slightly earlier than Dmanisi and
yielded small assemblages dominated by large taxa (ref.42). There are 21
taxa represented at Dmanisi, and 33 (excluding microfauna) at 'Ubeidiya.
The point here is that small assemblages, with only a few taxa that are
mainly from large animals, are most unlikely to contain hominin remains:
in southwest Asia, two of the three large and fine-grained assemblages
did yield skeletal evidence of hominins (although very little at
'Ubeidiya (ref. 6)). In central Asia, the Late Pliocene record is poor
because fossils are often found in coarse sediments (ref. 44), although
one surprising find is of the baboon (/Papio suschkini/ (ref. 45)) that
is often regarded as a commensal of /Homo (/ref./ /46). Late Pliocene
faunal assemblages from northern Pakistan and India do not contain any
hominins, and these are also unknown for the entire Early Pleistocene:
the earliest fossil hominin evidence we have is Middle Pleistocene, from
the Narmada Valley (ref. 47), long after hominins are first in evidence
to both the west and east of the Indian subcontinent. Although many
vertebrate taxa are represented in the Upper Siwaliks of India (30 in
the Tatrot and 49 in the succeeding Pinjor Stage (ref. 48), most are
larger than hominins. It is also likely that the full range of taxa is
incomplete for the Indian subcontinent, because /Megantereon/ and
/Pachycrocuta/ are not recorded in India but are present in Pakistan; in
Pakistan, there is no evidence of /Camelus/ and small primates, and in
neither country is /Homotherium/ recorded (ref. 49), although this is
present to the west at Dmanisi, to the north at Kuruksay, central Asia
(ref. 44) and to the east at Longuppo (ref. 25), south China. In
mainland southeast Asia, there is no Late Pliocene or Early Pleistocene
fossil evidence. One of the few instances for which we can be reasonably
sure that /H. erectus/ /s.l./ (and other hominins) were absent is
Longuppo (ref. 25), south China, where four primates (/Gigantopithecus/,
/Lufengpithecus/, /Macaca/ and /Procyncocephalus/) are recorded among
the 68 taxa present. The faunal assemblages from the Yushe Basin (ref.
50) and the "Hipparion fauna" of north China (ref. 50) are of comparable
quality to those from India, and the absence of hominins is equivocal.

 

/6. Ways forward: alternatives to Out of Africa 1/

If the above taphonomic review suggests that we cannot show the absence
of hominins from areas in Asia at a time before the little evidence we
have indicates their presence, we need to consider alternatives to the
current Out of Africa model. There are three issues here. The first is
when hominin(s) first left Africa - might they, for example, have left
shortly after they acquired the ability to make stone tools, the
earliest of which are currently 2.6 Myr old? Or could they have left
even earlier, about 3.0-3.5 Myr ago, when some australopithecines were
already living in the African grasslands? The second issue is whether we
yet know the full range of hominins that inhabited both Africa and Asia
in the Late Pliocene and Early Pleistocene. Even in east Africa, several
new taxa have been claimed in the past decade (for example, /A.
anamensis (ref. 51)/, /A. garhi/ (ref. 52), /Ardipithecus ramidus
/(ref./ /53) and /Kenyanthropus platyops /(ref. 54)) and doubtless more
will be found. (An indication of how little we know about Pleistocene
east Africa is that only recently has the first fossil evidence for
chimpanzee been found (ref. 55)). In Asia, the recent discoveries of /H.
georgicus/ and /H. floresiensis/ should make us very wary of assuming
that /H. erectus s.l./ was the only player on the Asian stage in the
Early Pleistocene. Third, Asia might not have been the passive recipient
of whatever migrated out of Africa but might have been a major donor to
speciation events, as well as dispersals back into Africa. Such two-way
traffic is well documented for other mammals in the Pliocene and Early
Pleistocene, such as /Equus /(ref./ /56) and bovids ref. 57), with more
taxa migrating into than out of Africa. There is no reason why hominin
migrations were always from Africa into Asia, and movements in the
opposite direction might also have occurred, as has been suggested for
the Olduvai OH9 (refs 13, 58) and Daka (ref. 4) specimens. We should
even allow for the possibility that /H. ergaster/ originated in Asia
(refs 23,59) and perhaps explain its lack of an obvious east African
ancestry as the result of immigration rather than a short (and
undocumented) process of anagenetic (/in situ/) evolution. Although
Darwin's suggestion (ref. 60) that "it is somewhat more probable that
our early progenitors lived on the African continent than elsewhere" is
widely quoted, it is worth noting his next sentence: "But it is useless
to speculate on this subject... since so remote a period the earth has
certainly undergone many great revolutions, and there has been ample
time for migration on the largest scale".

We obviously need ways of testing these alternatives. The overriding
need is for data sets from Asia that are of comparable quality to those
from Africa. Although absence can never be 'demonstrated', we can at
least put some constraints on its probability by comparing the quality
of the fossil record from the inferred core and its 'peripheries'.
Because the species we are interested in were not very abundant in their
world and hence in the fossil record, knowledge of biasing factors is a
prerequisite for the study of their past distributions. The higher the
trophic level of a species, the smaller is its abundance in the real
world and hence in the fossil record (for the whole of the Asian Late
Pliocene, we have only two records of a puma, for example, separated by
more than 3,000 miles (ref. 43)). Open, mesic-to-arid environments tend
to preserve fossils better than do forested and wetter environments
(which is probably why we have no fossil record for the gorilla and only
one observation - from open woodland - for the chimpanzee (ref. 55)).
Should faunal remains get covered in a sedimentary matrix, that matrix
obviously has to survive and be accessible, a condition that is rarely
met for Pliocene and Pleistocene sediments. The Rift Valley constitutes
a unique exception by its sheer size and the exposure of fine-grained
sediments of the relevant age, and includes many of the key African
sites, as well as Erq el-Ahmar, 'Ubeidiya and Gesher Benot Ya'aqov in
Israel.

 

/7. Regional imbalances and future challenges/

Current large-scale imbalances between regional records are often the
result of differences in research history and intensity. To some degree
the Javan and Levantine records result from research initiated during
colonial times, and the east African record similarly owes a great deal
of its incipient (and prolific) research to the consequences of its
colonial history. In contrast, most parts of Asia have experienced only
a very limited survey of Neogene exposures, in comparison with the heavy
palaeoanthropological investments made in east Africa during the past
four decades. These regional imbalances are crucial. After all, in the
early twentieth century, east Asia was thought to have been the centre
of human origins because it had the oldest fossils, and one of the
marginal areas, Africa, had not yet seen any significant fieldwork (ref.
61). Despite the imbalance in research intensity (and hence number of
sites), Asia has produced major surprises in recent years, a testimony
to its palaeoanthropological potential. As an example, recent research
in China has extended its earliest hominin presence up to 1.66 Myr ago
(ref. 29), half a million years older than envisaged only a few years
ago, with the lowest levels of the fossiliferous sequence in the Nihewan
basin not having been reached yet. The increasing evidence for Early
Pleistocene hominins in China and Java stretches the limits of current
thinking on hominin evolution, as do the finds of /H. floresiensis/ and
the Dmanisi hominin assemblage, the latter recovered from an area where
few would have expected Early Pleistocene tiny-brained hominins two
decades ago. These discoveries underscore our poor ability to discern,
let alone predict, the design on the picture we try to piece together
from the few pieces of the jigsaw that we have. Again, absence of
evidence is not enough: if we postulate that species A migrated into
area B, we need comparable data sets to infer legitimately that it was
absent before that date - we need not just the FAD (first appearance
date) of a taxon in a new area, but also its LPA (last probable absence)
(see Fig. 1). We will never have certainty about LPAs, of course: the
recently reported finds from Pakefield, southern England, show that two
centuries of intensive research of the Cromer Forest beds failed to
recover the (indeed ephemeral) traces of an early Middle Pleistocene
hominin presence there (ref. 62). That such a surprise can turn up in
one of the best-researched areas of the Old World shows that we can
never be sure about LPAs and, more importantly, underlines the necessity
of working with data sets of comparable quality in both alleged donor
and alleged recipient regions (see also Box 2 <#b2>). For Africa and
Asia, comparability is still many generations of research grants away.
Nevertheless, we could do much more to reduce the level of uncertainty
over when hominins were last absent in Asia by increasing the number and
quality of fossil assemblages immediately before their first alleged
appearance.

 

/8. "Africa" and "Asia", or "Savannahstan"?/

We also need different spatial units for investigating extinct hominin
populations. Since the time of the Greeks and the Romans, we habitually
refer to 'Africa' and 'Asia' as separate continents, each somehow
homogeneous and distinct from the other. Plants and animals (and extinct
hominins) are less respectful of our GraecoRoman heritage. The
landmasses we now call Africa and Asia are of course enormously diverse,
but they also have many plants, animals and environments in common. In
recent decades, palaeoanthropologists have rightly emphasized the
importance of savannah grasslands in hominin evolution, both as a place
where many types (including /H. ergaster/) lived in the Late Pliocene
and Early Pleistocene and as having been important in influencing
hominin brain size, post-cranial anatomy, and diet. As noted earlier,
Pliocene grasslands extended all the way from west Africa to north
China, and 'Savannahstan' might prove a more useful spatial unit for
modelling early hominin adaptations and dispersals within them than
simply an undifferentiated 'Africa' or 'Asia'. For example, the African
hominins 1.9-1.7 Myr ago at Koobi Fora (Kenya) and Ain Hanech (Algeria),
and their slightly later counterparts in Asia at 'Ubeidiya (Israel), and
Majuangou (north China) were all living in broadly comparable grassland
environments, and it makes sense to place them within the same frame of
reference. This might also highlight significant variation that is
sometimes buried under a blanket term such as 'Asia'. For example, the
hominins in the Nihewan basin, north China, and those in Java are both
clearly in east Asia, but those in Java inhabited a region that was
considerably more densely wooded. It is not the continent that matters
in studying human origins so much as the type(s) of environment with
which early hominins were associated.

 

/

	

	

 

*Figure 1.* Dispersals, cores and peripheries.

The dangers of over-reliance on first appearance dates (FADs) of when a
taxon migrated from its core area, A, into a new territory, B. Filled
green squares indicate the first appearance of a taxon, open green
squares the presence of a taxon and red circles fossil assemblages
without this taxon.

*a*. A hypothetical situation in which a taxon originated in area A, and
then migrated into territory B.

*b*. The reliability of these FADs is considerably strengthened by the
numerous well-dated instances when their last probable absences (LPAs)
can be documented. Without these, future discoveries might indicate (as
shown in *c*) that previous estimates of when a taxon first appeared
were too recent, as happened when the earliest Javan hominins were
redated from about 1.0 Myr old to 1.8 Myr old.

*d*. Even more alarmingly, future discoveries might even show that the
taxon probably originated in the area that it was supposed to have
colonized-as happened when the centre of hominin origins was relocated
from Asia to Africa in the 1960s.

/

//

///Box 2: Neanderthals and moderns - where were they?/

Highlighting the imperfections of the fossil record obviously has
implications for studies of the distribution of other species too. The
Neanderthals are by far the best-studied extinct hominins, with a rich
fossil record sampling hundreds of individuals, heavily biased towards
the western part of their range, western Europe. However, the northern,
eastern and southern limits to their distribution are poorly documented,
again because of an imbalance in research intensity. The juvenile from
Teshik-Task, Uzbekistan, is the easternmost one known, at roughly 1,300
and 2,000 miles from its nearest fossil neighbours, Shanidar in Iraq and
Kiik-Koba in the Black Sea area, respectively. The southern limit of
their distribution is unknown, and may have extended over the whole of
Arabia and the Indian subcontinent-we cannot be certain until these
regions produce the necessary fossil evidence. Distribution maps of
Neanderthals are palimpsests of range expansion and contraction,
probably hide many shifts of ranges in the rhythm of climatic
oscillations and most probably also understate their full range.
Chronological resolution is significantly better than in the earlier
Pleistocene, however, and enables us to see the occasional
'interfingering' of their range with that of anatomically modern humans
in the Near East. If the Tabun C1 hominin does indeed date to Marine
Isotope Stage (MIS) 6, Neanderthals were in the northern parts of the
Near East before anatomically modern humans were there in MIS 5, with
Neanderthals again present during MIS 4. As with Out of Africa 1, the
poor state of sampling of major parts of western and central Asia should
force us to be very humble in our inferences on the core and peripheries
in the Neanderthal world. Comparable points can be made with regard to
Out of Africa 2 (the model according to which our own species, /H.
sapiens/ (or 'anatomically modern humans') evolved in Africa by 150-200
kyr ago and then migrated outwards into Asia and Europe and eventually
replaced all indigenous populations in these regions). Current evidence
indicates that anatomically modern humans appeared in east Africa by
about 200,000 years ago (the new dates for Omo-Kibish), whereas the
earliest outside Africa are those from Israel at about 115,000 years
ago. There are no fossil hominins of the same age as Omo-Kibish from
southwest, south or central Asia, so it is an open question as to when
they first appeared in those regions: possibly at 125,000 years ago,
perhaps 200,000 years ago, or even earlier. (The only potential evidence
is the specimen from Zuttiyeh Cave, Israel, which is not particularly
diagnostic and is almost certainly considerably older than the
associated Th-U date of 154,000 years ago.) All we know about southwest
Asian hominins between 300,000 and 125,000 years ago is that
Neanderthals were present during part of MIS 6. As with Out of Africa 1,
if we cannot show when modern humans were last absent in a region, we
have no secure means of knowing from the skeletal record whether that
region was core or peripheral. Although genetic studies of modern humans
strongly imply that they originated in Africa, these studies are
notoriously vague as to when they first dispersed, or even whether the
modern genotype dispersed without any population expansion from Africa.
Current fossil evidence from Asia is clearly incapable of testing these
suggestions at present.

/ /

/9. Hominins, not just Homo, outside Africa/

We also need to focus more on hominins and not just /Homo/ when studying
early hominins outside Africa. Archaeological approaches to early lithic
assemblages in Asia are a good case here. Any stone tool assemblage in
Asia dated as older than 1.9 Myr ago (the earliest date that /Homo/ is
supposed to have left Africa) is either dismissed or (more usually)
ignored (ref. 63); undated Oldowan tools are assumed to date from after
1.9 Myr ago and not from 2.6 Myr ago (the date of their first appearance
in east Africa); and stone tool assemblages in Asia dated to the Olduvai
Event (1.77-1.95 Myr ago) and not associated with hominin remains are
automatically attributed to /Homo erectus/ /s.l./ However, there is no
reason why Oldowan assemblages in Arabia cannot be older than 1.9 Myr
old, or why the tools from Ain Hanech (ref. 64) in Algeria or Erq el
Ahmar in Israel were made by /H. erectus s.l./, not least because
similar assemblages were made in east Africa at that time (and earlier
in some cases) by /H. habilis/, /H. ergaster/ and probably /H.
rudolfensis/, /A. garhi/ and /Paranthropus/. We may be due for some big
surprises in discovering that /H. ergaster/ was not the only, or even
the first, African tool-making hominin to leave home.

 

/10. Human evolutions writ new?/

/

	

	

 

*Figure 2. *The hominin world about 1.7 Myr ago.

The circles denote radii of 1,000 miles. Blue circles indicate known
populations of /Homo/ at this time: /H. ergaster/ and various
australopithecines (including /A. (H.) habilis/ in east Africa, /H.
georgicus/ in Georgia, /H. erectus/ in Java, and /Paranthropus/ and
/Homo/ in southern Africa).

The ancestries of /H. ergaster, H. georgicus/ and /H. erectus/ are
unclear, as are their spatial extents and relationships to each other.
The yellow circles indicate areas with no fossil hominin evidence but
where stone tools were being made: north China, Algeria and Pakistan. As
shown, there is ample 'ecological space' in Asia for more hominins than
currently recorded.

/As readers othis journal (/Nature/) will be aware, Asia has produced
some surprising discoveries in the past decade, including two new
palaeospecies of /Homo/. Recent African discoveries in Chad are also
highly pertinent to those interested in early Asian hominins. The
discovery of /Sahelanthropus tchadensis /(ref. 65) shows that hominins
were already well beyond the east African Rift in the late Miocene, and
/A. bahrelghazali/ indicates that the African grasslands were probably
colonized by 3.0-3.5 Myr ago. The latter discovery raises obvious
implications for when the Asian grasslands were first colonized, and
whether large brains, modern body size and proportions, and obligate
bipedalism were essential for that process to occur. These recent finds
are not easily reconciled with the notion that hominins originated in
the Rift Valley and that /H. ergaster/ was the first and only hominin to
migrate out of Africa in the Late Pliocene/Early Pleistocene. Most
probably, we are on the threshold of a profound transformation of our
understanding of early hominin evolution that might prove as
far-reaching as the demise of the notion of Man the Hunter (ref. 66) in
the early 1960s. The process was often painful and accompanied by heated
debate, but our understanding of early hominin subsistence improved
enormously (and, indeed, some parts of the original model were
strengthened by it (ref. 67). Although there will doubtless be an
understandable reluctance to abandon Out of Africa 1, in its present
form, as a model that is widely accepted as adequate for explaining a
very small amount of data from Asia, there are benefits to be gained by
widening our range of possible hypotheses. The present model is stifling
a rigorous evaluation of how we can interpret the sparse, but recently
much improved, data upon which it rests. Useful initial steps would be
for us to be more explicit about just how few reliable observations we
have of Early Pleistocene hominins across the Old World. Other steps
would be to pay more attention to the comparability of data sets when
evaluating whether or not the absence of hominins is more than the
outcome of taphonomic circumstance or the history of fieldwork;
additionally, an emphasis on different spatial units and on hominins
other than /H. ergaster/ (including earlier ones) might prove fruitful.
Meanwhile, if we cannot demonstrate the probable absence of a hominin
(including /H. erectus/) in a region, we should reserve judgement as to
when it first appeared there. Another useful step would be to dispense
with most of the arrows indicating movement from alleged (but often
unproven) core territories into (alleged but often unproven) peripheral
ones. It might be more profitable instead to focus on populations (ref.
68) as the basic unit of study (see Fig. 2), each of which might have
its own local origins and history, and to accept that the boundaries of
each, and the relations between them, are at present unknown, because
all we have are isolated sampling points. Although these changes would
radically alter the way in which we view human evolution outside Africa,
they might prove more fruitful than continuing to envisage the earliest
evidence for hominins in Asia as the outcome of a conjectural migration,
from an unproven centre of origin and along hypothetical routes of
dispersal.

 

/11. References/

1. Anton, S. C., Leonard, W. R. and Robertson, M. L. 2002. "An
ecomorphological model of the initial hominid dispersal from Africa."
/J. Hum. Evol./ 43:773-785

2. Mithen, S. and Reed, M. 2002. "Stepping out: a computer simulation of
hominid dispersal from Africa." /J. Hum. Evol./ 43:433-462

3. Aiello, L. C. and Wells, J C. K. 2002. "Energetics and the evolution
of the genus Homo." /Annu. Rev. Anthropol/. 31:323-338

4. Asfaw, B. et al. 2002. "Remains of Homo erectus from Bouri, Middle
Awash, Ethiopia." /Nature/ 416:317-320

5. Walker, A. and Shipman, P. 1996. /The Wisdom of Bones: In Seorch of
Human Origins/. Weidenfeld and Nicholson, London

6. Belmaker, M., Tchernov, E., Condemi, S. and Bar-Yosef, O. 2002. "New
evidence for hominid presence in the Lower Pleistocene of the Southern
Levant." /J. Hum.Evol/. 43:43-56

7. Lordkipanidze, D. et al. 2005. "The earliest toothless hominin
skull." /Nature /434:717-718

8. Gabunia, L. et al. 2000. "Earliest Pleistocene hominid cranial
remains from Dmanisi, Republic of Georgia: taxonomy, geological setting,
and age." /Science/ 288:1019-1025

9. Gabunia, L., de Lumley, M.-A., Vekua, A., Lordkipanidze, D. D. and de
Lumley, H. 2002. "Decouverte d'un nouvel hominide a Dmanisi
(Transcaucasie, Georgie)." /C.R. Pahlevol./ 1:243-253

10. Anton, S. C. 2003. "Natural history of Homo erectus." /Am. J. Phys.
Anthropol./ 122, 126-17

11. Andrews, P. J. 1984. "An alternative interpretation of the
characters used to define Homo erectus." /Courier Forschunginst.
Senckenb./ 69:167-175

12. Foley, R. and Lahr, M. 2004. "Human evolution writ small." /Natur/e
431:1043-1044

13. Tattersall, I. 1997. "Out of Africa again... and again?" /Sci.Am./
276:46-53

14. Tattersall, I. and Schwartz. 2000. /J Extinct Humans, /Nevraumont,
New York

15. Wood, B. and Turner, A. 1995. "Out of Africa and into Asia."
/Nature/ 378: 239-240

16. Wood, B. and Collard, M. 1999. "The changing face of genus Homo."
/Evol. Anthropol./ 8:195-207

17. Bilsborough, A. 1999. In: /Structure and Contingency: Evolutionary
Processes in Life and Human Society/. Ed. Bintliff, J. pp. 43-101.
Leicester Univ. Press, London

18. Brauer, G. 1994. "How different are Asian and African Homo erectus?"
/Courier Forschunginst. Senckenb. /171:301-318

19. Kramer, A. 1993. "Human taxonomic diversity in the Pleistocene: Does
Homo erectus represent multiple hominid species?" /Am. J. Phys.
Anthropol./ 91:161-171

20. Rightmire, G. P. 1990. /The Evolution of Homo erectus: Comparative
Anatomical Studies of an Extinct Human Species/. Cambridge Univ. Press,
Cambridge

21. Anton, S. C. 1997. "Developmental age and taxonomic affinity of the
Mojokerto child, Java, Indonesia." /Am. J. Phys. Anthropol./ 102:497-514

22. Huffman, F., Shipman, P., Hertler, C., de Vos, J. and Aziz, F. 2005.
"Historical evidence of the 1936 Mojokerto skull discovery, East Java."
/J. Hum. Evol./ 48:321-363

23. Swisher, C. C. et al. 1994. "Age of the earliest known hominids in
Java, Indonesia." /Science/ 263:1118-1121

24. Larick, R. et al. 2001. "Early Pleistocene 40Ar/39Ar ages for Bapang
Formation hominins, Central Jawa, Indonesia." /Proc. Natl Acad. Sci.
USA/ 98:4866-4871

25. Wanpo, H. et al. 1995. "Early Homo and associated artefacts from
Asia." /Nature /378:275-278

26. Schwartz, J H. and Tattersall, I. 1996. "Whose teeth?" /Nature
/381:201-202

27. Wu, X. 2000. "Longgupo mandible belongs to ape." /Acta Anthropol.
Sin./ 19:1-10

28. Ron, H. and Levi, S. 2001. "When did hominids first leave Africa?
New high-resolution paleomagnetic evidence from the Erk-EI-Ahmar
formation, Israel." /Geology/ 29:887-890

29. Zhu, R. X. et al. 2004. "New evidence on the earliest human presence
at high northern latitudes in northeast Asia." /Nature/ 431:559-562

30. Brunet, M. et al. 1995. "The first australopithecine 2,500
kilometres west from the Rift Valley (Chad)." /Nature/ 378:273-275

31. De Heinzelin, J et al. 1999. "Environment and behaviour of
2.5-million-year-old Bouri hominids." /Science/ 284:625-629

32. Dowsett, H. et al. 1994. "Joint investigations of the Middle
Pliocene climate." I: PRISM palaeoenvironmental reconstructions. /Global
Planet. Change/ 9:169-195

33. Tyler, D. E. 2004. "An examination of the taxonomic status of the
fragmentary mandible Sangiran 5 (/Pithecanthropus dubius/), /Homo
erectus/, '/Meganthropus/', or '/Pongo/'?". /Quat. Int./ 117:125-130

34. Coqueugniot, H., Hublin, J- J, Veillon, F., Houd, F. and Jacob, T.
2004. "Early brain growth in Homo erectus and implications for cognitive
abilities." /Nature/ 431:299-302

35. Brown, P. et al. 2004. "A new small-bodied hominin from the Late
Pleistocene of Flores, Indonesia." /Nature/ 431:1055-1061

36. Morwood, M. J et al. 2005. "Further evidence for small-bodied
hominins from the Late Pleistocene of Flores, Indonesia." /Nature/
437:1012-1017

37. Gabunia, L. and Vekua, A. A. 1995. "Plio-Pleistocene hominid from
Dmanisi, East Georgia, Caucasus." /Nature /373:509-512

38. Vekua, A. et al. 2002. "A new skull from Dmanisi, Georgia."
/Science/ 297: 85-89

39. Wood, B. and Collard, M. 1999. "The human genus." /Science/ 284:65-71

40. Semaw, S. et al. 2003 "2.6-Million-year-old stone tools and
associated bones from OGS-6 and OGS-7, Gona, Afar, Ethiopia." J. Hum.
Evol. 45, 169-177

41. Hooijer, D. A. 1958. "An early Pleistocene mammalian fauna from
Bethlehem." /Bull. Br. Mus. Not. Hist. Geology/ 3:267-292

42. Vekua, A. 1995. "Die Wirbeltierfauna des Villafranchium von Dmanisi
und ihre biostratigraphische Bedeutung." /Jb.Röm.-Ger.Zent.Mus. Mainz/
42:77-180

43. Hemmer, H., Kahlke, R.-D. and Vekua, A. K. 2004. "The Old World puma
/- Puma pardoides/ (Owen, 1846) (Carnivora:Felidae) - in the Lower
Villafranchian (Upper Pliocene) of Kvabebi (East Georgia, Transcaucasia)
and its evolutionary and biogeographical significance." N.Jb.Geol.
Paläont.Abh. 233:197-231

44. Sotnikova, M. V., Dodonov, A. E. and Pen'kov, A. V. 1997. "Upper
Cenozoic bio-magnetic stratigraphy of Central Asian mammalian
localities." /Palaeogeogr. Palaeoclimatol. Palaeoecol/. 133: 243-258

45. Maschenko, E. N. 1994. "Papio (Parodolichopithecus) suschkini: a
revision of systematics, morphofunctional peculiarities of the skull and
mandible [in Russian]. /Paleoteriologiya/ 15-57

46. Bobe, R. and Behrensmeyer, A. K. 2004. "The expansion of grassland
ecosystems in Africa in relation to mammalian evolution and the origin
of the genus Homo." /Palaeogeogr. Palaeoclimatol. Palaeoecol./ 207:399-420

47. Sonkalia, A. 1995. "Skull cap of an early man from the Narmada
Valley alluvium (Pleistocene) of Central India." /Am. Anthropol./ 87:612-616

48. Nanda, A. C. 2002. "Upper Siwalik mammalian faunas of India and
associated events."/ J. Asian Earth Sci. /21:47-58

49. Dennell, R. 2004. /Early Hominin Landscapes in Northern Pakistan/.
BAR/ Archaeopress, Oxford

50. Flynn, L. J., Tedford, R. H. and Zhanxiang, Q. 1991. "Enrichment and
stability in the Pliocene mammalian fauna of North China."
/Paleobiology/ 17:246-265

51. Leakey, M. G., Feibel, C. S., McDougall, I. and Walker, A. 1995.
"New four-million-year old hominid species from Kanapoi and Allia Bay,
Kenya." /Nature/ 376:565-571

52. Asfaw, B. et al. 1999. "Australapithecus garhi: A new species of
early hominid from Ethiopia." /Science/ 284:629-635

53. White, 1. D., Suwa, G. and Asfaw, B. Australapithecus ramidus, a new
species of early hominid from Aramis, Ethiopia. Nature 371,306-312 (1994).

54. Leakey, M. G. et al. New hominin genus from eastern Africa shows
diverse Middle Pleistocene lineages. Nature 410, 433-439 (2001).

55. McBrearty, S. and Jablonski, N. G. 2005. "First fossil chimpanzee."
/Nature/ 437:105-108

56. Lindsay, E. H., Opdyke, N. D. and Johnson, N. M. 1980. "Pliocene
dispersal of the horse Equus and late Cenozoic mammalian dispersal
events." /Nature/ 287:135-138

57. Vrba, E. S. 1995. In: /Paleoclimate and Evaluation/. Eds. Vrba, E.
S., Denton, G. H., Partridge, T. C. and Burckle, L. H.. Pp. 385-424.
Yale Univ. Press, New Haven

58. Clarke, R. J. 2000. "Out of Africa and back again." /J. Anthropol./
15:185-189

59. White, T. D. 1995. In: /Paleoclimate and Evolution. /Eds Vrba, E.
S., Denton, G. H., Partridge, T. C. and Burckle, L. H. Pp. 369-385. Yale
Univ. Press, New Haven

60. Darwin, C. 1871. /The Descent at Man and Selectian in Relation to
Sex/. Murray, London

61. Dennell, R. W. 2001. In: /Studying Human Origins. Disciplinary
History and Epistemolagy/. Eds Corbey, R. and Roebroeks, W.. Pp. 45-66.
Amsterdam Univ. Press, Amsterdam

62. Parfitt, S. A. et al. 2005. "The earliest record of human activity
in northern Europe." /Nature/ 438:1008-1012

63. Dennell, R. W., Rendell, H. M. and Hailwood, E. 1988. "Early
tool-making in Asia: two-million year-old artefacts in Pakistan."
/Antiquity/ 62:98-106

64. Sahnouni, M. et al. 2002. "Further research at the Oldowan site of
Ain Hanech, North-eastern Algeria." /J. Hum. Evol./ 43:925-937

65. Brunet, M. et al. 2002. "A new hominid from the Upper Miocene of
Chad, Central Africa." /Nature/ 418:145-151

66. Lee, R. B. and DeVore, I. (eds). 1968. /Man the Hunter. /Aldine
Publishing Company, Chicago

67. Dominguez-Rodrigo, M. and Pickering, T. R. 2003. "Early hominid
hunting and scavenging: a zooarcheological review." /Evol. Anthropol./
12: 275-282

68. Howell, F. C. 1996. In: /Contemporary Issues in Human Evolution/,
eds Meikle, W. E., Howell, F. C. and Jablonski, N. G.. Pp. 1-45.
California Acad. Sciences, San Francisco

 

/12. Acknowledgments/

We thank various colleagues for comments on earlier drafts of this
paper. RD thanks the British Academy for a three-year research
professorship for his research into Asian prehistory. This work was
supported by an internationalization grant of the Netherlands
Organisation for Scientific Research. 

 

 

 

 

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