An interesting article in today's New York Times
summarises a paper in the current issue of The Journal of Human
Evolution concerning discoveries of stone tools in Ethiopia which are
so small and simple that they were probably among the first 'generation'
to be made by man's ancestors and useful only for cutting meat away from
bone. These sorts of bones had been found previously in a site not far
away but the more recent specimens were found alongside scraped animal
bones and were thus more specifically datable -- to about 2.6 million
years ago.
While this discovery probably dates our predecessor's discovery of tools
fairly accurately for the first time it doesn't solve further questions
that are asked about our ancestry. What came first: A larger brain that
enabled tool-making? or tool-making which encouraged meat-eating,
with the consequence of a richer diet necessary for brain
development?
In my view, the answer is the first because the chimpanzee (which had
broken off from our predecessors' evolutionary line 3 million years
previously) also became a meat eater quite independently in the rain
forest without developing a significantly larger brain (that is, frontal
lobes). Nor did our predecessors need a larger brain for the purpose of
meat-eating when we were forced into the savannah by a cooler climate. If
anything, hunting small grazing animals would have been easier for our
ancestors than the chimps' problem of catching monkeys or pigs in the
forest. Initially, grazing animals would have had no fear of the new
bipedal species that appeared among them.
But our ancestors would have been exposed to considerable danger from
predators in the savannah so the really selective pressure would have
been on the enlargement of the frontal lobes in order to be able to think
of strategies of defence rather than immediate panic. It is this control
of emotions which is one of the prime attributes of our frontal lobes.
However, it is likely that this extra capacity gave a chance for the
discovery of the making of stone tools -- something which the chimps
never arrived at. Furthermore, once scraping tools had been invented then
our predecessors could quickly dismember an animal and carry relatively
small portions away instead of whole bodies. This would have been of
considerable survival advantage -- compared with, say, tigers, leopards
or baboons who have to struggle when carrying a prey away from the site
of slaughter to a safer place for consumption.
Another consideration is that all innovation requires a lot of
concentrated thought and this, in turn, requires time. Our predecessors
would not have had time enough during the day to think about anything if
they were predominantly a vegetarian. Meat-eating concentrates the value
of food about tenfold and allows free-time in which the frontal lobes
could be given scope to maximise their selection advantage, however
slight it was initially.
We have about 12,000 genes responsible for brain development in common
with the chimps. Allowing for body mass, our rear cortex is very similar
in size to that of the chimanzee and probably not a great deal different
in its abilities (mainly the processing of our perceptions). But we have
an additional 90-odd brain genes and it is probably these, and these
only, which are mainly responsible for our frontal lobes, giving us that
extra degree of curiosity, of emotional control, of creativity (e.g.of
embellishing our bodies with ornaments and colourings which enhanced our
status), which made all the difference between merely surviving as just
another hunter-gatherer species 100,000 years ago, and actually
initiating the trading of materials with neighbouring groups and so
starting the economic system we have today. Our modern high-tech society
is an amazing result for such an apparently small initial investment by
no more than a few dozen genes!
Keith Hudson
<<<<
NEW CLUE ON WHICH CAME FIRST: TOOLS OR BETTER DIETS
John Noble Wilford
On a hillside in the badlands of Ethiopia, an ancestral home of the human
family, an international team of scientists has uncovered the earliest
known stone tools to be found mixed with fragments of fossilized animal
bones. The scientists think the material, almost 2.6 million years old,
is the strongest evidence yet that the primal technology was used to
butcher animal carcasses for meat and marrow.
The discovery could go a long way toward resolving a debate in
paleoanthropology which came first, a significant advance in the brain
that enabled human ancestors to make tools, or the toolmaking ability
that led to an enriched diet and then an evolutionary change in the
brain?
"I believe the use of stone tools came first and the larger brain
came later with a more substantial meat diet," Dr. Sileshi Semaw,
the leader of the discovery team, said last week by telephone.
The findings are described in the current issue of The Journal of Human
Evolution. Dr. Semaw, principal author of the report, is a
paleoanthropologist who is a research associate at the Center for
Research Into the Anthropological Foundations of Technology at Indiana
University.
The age of the stone tools was no surprise, the researchers said. Working
in the same region a decade ago, Dr. Semaw found similar cobbles flaked
for use in scraping and cutting at sites of about the same age. The
cobbles were hailed as the earliest known artifacts created by distant
human relatives, known as hominids.
Nor was it startling to find animal bones with cut marks, presumably made
by the sharp edges of butchering tools. Similar fossilized bones with
stone-tool cut marks had been excavated at a site 50 miles away, but
without any associated artifacts. Never before, the researchers said, had
stone artifacts and animal bones been found together at a single site
from this early time in human evolution.
In the journal report, Dr. Semaw's group said the discovery near the bank
of a branch of the Gona River, in the Afar region of Ethiopia, had
provided "the oldest known archaeologically documented associations
between artifacts and broken faunal elements," or animal
bones.
Another member of the team, Dr. Michael J. Rogers of Southern Connecticut
State University in New Haven, said in an interview that the stone tools
and the animal bones, probably from ancestors of wildebeests and zebras,
had been unquestionably associated with each other.
"What's important," Dr. Rogers said, "is that this
suggests that early stone-tool use was responsible for much of the
expansion of hominid diet from mostly plants to more meat and
marrow."
Dr. Rogers, a paleoanthropologist, came upon the most revealing site
three years ago while searching the arid hills for fossils or artifacts.
Several sharp flakes of rock caught his eye. They were no more than an
inch or two long, he said, and they were different from any other rock on
the surface. They looked as if they had recently eroded out of the
hill.
"We got a little bit excited," Dr. Rogers said, and soon he and
colleagues began excavating and uncovered some of the cobbles from which
the flakes had been broken. Then they began finding bones, including rib
and limb fragments. At another site a few yards away, discovered by Dr.
Jay Quade of the University of Arizona, the excavators found several
bones with distinct cut marks.
The quality of the tool workmanship impressed the researchers. "The
flakes are amazingly well struck and look much the same as tools made a
million years later," Dr. Rogers said.
No hominid fossil bones have been found at the sites, so it is impossible
to tell who the toolmakers were. The researchers said that they were
probably members of the 2.5-million-year-old species named
Australopithecus garhi, which lived in Ethiopia and was identified in
1999 by Dr. Tim D. White of the University of California at
Berkeley.
Dr. White said the new research provided more evidence that "a
dietary and technological threshold had been crossed" by 2.6 million
years ago
New York Times -- 21 October 2003
>>>>
Keith Hudson, Bath, England,
<www.evolutionary-economics.org>,
<www.handlo.com>,
<www.property-portraits.co.uk>
