Re: Walking Small: Humanlike legs took Homo out of Africa
- From: "Peter Jason" <pj@xxxxxxxxxx>
- Date: Sat, 29 Sep 2007 08:50:32 +1000
Easier to believe is the smallness of some
African mentalities.
Back to Australopithecines?
http://news.bbc.co.uk/1/hi/world/africa/7014335.stm
Hard to believe this one, but the "back to
Africa" movement seems to
have occurred a least 1.77 million years
ago if this account is
accurate. Home E and his predecessors seem
to have made it as far as
Sakartvelo (Georgia). The description makes
Piltdown Man sound like
the norm.
Science News Online
Week of Sept. 22, 2007; Vol. 172, No. 12
Walking Small: Humanlike legs took Homo out
of Africa
Bruce Bower
The earliest known human ancestors that
trekked from Africa into Asia
possessed legs, feet, and spines much like
ours, even as they sported
relatively apelike arms and small brains,
according to an analysis of
1.77-million-year-old fossils unearthed in
the central Asian nation of
Georgia.
A team led by David Lordkipanidze of the
Georgian National Museum in
Tbilisi recovered 33 lower-body bones from
at least three adults and
one teenager at a site called Dmanisi. The
researchers had previously
found four skulls and four lower jaws, as
well as simple stone tools,
in the same sediment (SN: 5/13/00, p. 308).
In several cases, skull
and lower-body remains come from the same
individual.
The researchers classify these ancient
finds as early Homo. The
fossils might be from an early form of Homo
erectus that left eastern
Africa for the Asian hinterlands, but a
definitive species identity
remains unclear, Lordkipanidze cautions. A
description of the new
finds appears in the Sept. 20 Nature.
"The Dmanisi individuals weren't the first
hominids [fossil ancestors
of humans] to leave Africa," Lordkipanidze
says. "They must have had
more-primitive ancestors that passed
through the Near East before
reaching Georgia."
An intriguing mosaic of anatomical traits
characterizes the Dmanisi
folk. Their legs and spines closely
resemble those of modern humans.
In particular, Dmanisi leg and foot bones
would have efficiently
supported long-distance walking and
running, the scientists assert.
However, the arms of Dmanisi hominids
appear more like those of
australopithecines, an earlier line of
hominids. For instance, unlike
people, the new specimens have upper arms
that are straight rather
than slightly curved, their shoulders are
relatively narrow, and their
palms are oriented forward rather than
inward.
Moreover, the Dmanisi individuals are small
compared with the oldest
known African H. erectus. That specimen, a
1.5-million-year-old
skeleton of a well-developed, roughly
10-year-old boy, stood tall at
between 151 and 169 centimeters and weighed
as much as 70 kilograms.
At Dmanisi, adults reached estimated
heights of between 145 and 166 cm
and weighed between 40 and 50 kg.
Such estimates coincide with Dmanisi brain
volumes that were one-half
to two-thirds the size of modern human
brains.
The Dmanisi fossils and early African H.
erectus remains probably
represent separate populations of a species
that evolved variations of
a common body plan as members settled
different habitats, suggests
anthropologist Daniel E. Lieberman of
Harvard University in a comment
published with the new report.
If the Dmanisi remains indeed belong to
early H. erectus, members of
that species must have returned to Africa
and evolved into a larger,
more modern-looking form by 1.5 million
years ago, remarks
anthropologist William L. Jungers of Stony
Brook (N.Y.) University
Medical Center. In his view, the Dmanisi
foot bones were built for
long-distance walking but show no
convincing sign of having supported
a fully modern running ability.
Jungers adds that the
australopithecine-like arm traits in
Dmanisi
individuals also appear in Homo
floresiensis, Indonesian ancestors
that some researchers regard as modern
humans with a developmental
disorder (SN: 11/18/06, p. 330). Jungers,
however, contends that H.
floresiensis was a separate species that
preserved some primitive
skeletal features, just as H. erectus did
at Dmanisi.
References:
Lieberman, D.E. 2007. Homing in on early
Homo. Nature 449(Sept. 20):
291-292.
Lordkipanidze, D., et al. 2007. Postcranial
evidence from early Homo
from Dmanisi, Georgia. Nature 449(Sept.
20):305-310. Abstract
available at
http://dx.doi.org/10.1038/nature06134.
Further Readings:
Bower, B. 2006. Evolution's mystery woman.
Science News 170(Nov. 18):
330-331. Available to subscribers at
http://www.sciencenews.org/articles/20061118/bob9.asp.
______. 2000. Fossils hint at who left
Africa first. Science News
157(May 13):308. Available to subscribers
at
http://www.sciencenews.org/articles/20000513/fob1.asp.
Sources:
William L. Jungers
Department of Anatomical Sciences
Stony Brook University Medical Center
Stony Brook, NY 11794-8081
Daniel E. Lieberman
Department of Anthropology
Harvard University
Cambridge, MA 02138
David Lordkipanidze
Georgian National Museum
3 Purtseladze st.
0105 Tbilisi
Georgia
http://www.sciencenews.org/articles/20070922/fob1.asp
From Science News, Vol. 172, No. 12, Sept.22, 2007, p. 179.
.
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- Walking Small: Humanlike legs took Homo out of Africa
- From: Jack Linthicum
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