Herto skulls (Homo sapiens idaltu)
Some new fossils from Herto in Ethiopia, are the oldest known modern
human fossils, at 160,000 yrs. The
discoverers have assigned them to a new subspecies, Homo sapiens
idaltu, and say that they are anatomically and chronologically intermediate
between older archaic humans and more recent fully modern humans. Their
age and anatomy is cited as strong evidence for the emergence of modern
humans from Africa, and against the multiregional theory which argues that
modern humans evolved in many places around the world.
Three skulls were found:
The conclusion of the authors is that the Herto skulls "sample a population that
is on the verge of anatomical modernity but not yet fully modern". They
therefore assigned it to a new subspecies idaltu ('elder' in the
local Afar language):
- BOU-VP-16/1 is an almost complete adult cranium (shown at right). It is large and robust,
with a cranial capacity estimated at 1450 cubic centimetres, larger than most
modern humans. The skull is long and high in lateral view, and
White et al. (2003) list a number of features in which it is near or beyond the
limit of modern humans (the occipital angle, mastoid height, palate breadth). Viewed from
above, its length exceeds any from a sample of over 3000 modern humans,
but one width measurement is below the modern human average. The brow ridge is
not prominent and is within the modern human range.
- BOU-VP-16/2 consists of portions of another adult cranium which appears
to have been even larger than the previous specimen.
- BOU-VP-16/5 consists of most of a skullcase from a child, probably about
6 or 7 years of age judging by its teeth.
"Because the Herto hominids are morphologically just beyond the range of
variation seen in AMHS [anatomically modern Homo sapiens], and
because they differ from all other known fossil hominids, we recognize
them here as Homo sapiens idaltu, a new palaeosubspecies of
Stringer (2003), however, in a commentary article, suggests that the skulls may
not be distinctive enough to warrant a new subspecies name.
Both anatomically and chronologically, the Herto skulls seem intermediate
between earlier and more primitive skulls such as Bodo and
Kabwe ('Homo rhodesiensis')
and the first completely modern human skulls which are first found from about
115,000 years ago.
The authors' final conclusion is that "When considered with the evidence
from other sites, this shows that modern human morphology emerged in
Africa long before the Neanderthals vanished from Eurasia." Because of this,
these finds have been generally seen as a setback for the Multiregional model of human
evolution (which argues that modern humans evolved in geographically
widespread areas of the world) and strong support for the competing
Out Of Africa model (which argues that modern humans evolved in Africa and
spread out from there, displacing any preexisting populations).
Answers in Genesis argues, quite reasonably, that these fossils are so similar to modern humans that they don't constitute any problem for creationists - or, at least, to their own position. Reasons To Believe, an old-earth creationist ministry founded by Hugh Ross, takes the more surprising position that these fossils are of soulless animals that merely look like humans, and has accused AIG of "factual errors and distortions", to which AIG has responded energetically. RTB's position seems untenable to me: it's hard to see how anyone can credibly claim that fossils so remarkably similar to modern humans are animals. RTB appears to have a strategy that by definition excludes any possibility of transitional fossils: if scientists put a fossil in anything other than Homo sapiens sapiens, it is "not a modern human" and hence is an animal (no matter how trivial the differences); if they do put it in H. sapiens sapiens, of course, it's also not evidence for human evolution. Heads I win, tails you lose.
Clark J.D., Beyene Y., WoldeGabriel G., Hart W., Renne P., Gilbert H. et al. (2003): Stratigraphic, chronological and behavioural contexts of Pleistocene Homo
sapiens from Middle Awash, Ethiopia. Nature, 423:747-52.
Stringer C.B. (2003): Out of Ethiopia. Nature, 423:692-4.
White T.D., Asfaw B., DeGusta D., Gilbert H., Richards G.D., Suwa G. et al. (2003): Pleistocene Homo sapiens from Middle Awash, Ethiopia. Nature, 423:742-7.
Oldest human skulls
found (Jonathan Amos, BBC)
from oldest modern humans (Richard Stenger, CNN)
African Legacy: Fossils plug
gap in human origins (Bruce Bower, Science News)
This page is part of the Fossil Hominids FAQ at the talk.origins Archive.
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