Sunday, September 19, 2010

Quintessence of Dust

Australopithecus afarensis (reconstruction).
Source: Wikimedia Commons.

     Last month in Nature, a team of scientists published findings on the use of stone tools securely dated to 3.4 million years ago.  The evidence is indirect, in the form of cut marks on bones that could only have been made by stone tools.  Apart from the age of the findings, which are the oldest known showing tool use, the other point of interest is that whatever tools made the marks were not held by human beings.  They were made and used by Australopithecus afarensis, a pre-human ancestor species.

     Australopithecus is a genus of primates that comprises several species.  While there is not yet consensus on which species of Australopithecus ultimately evolved into modern humans, afarensis appears to be the last common ancestor of all the hominids.  Until the discovery last month, we could not say for sure that they made tools.  We already knew they walked on two feet (see the famous Laetoli footprints), but tool use was unproven.  However, we know that chimpanzees today make tools from plant stems, and the autralopithecines already had slightly larger brains than chimps.  Brain size is a crude measure, but it is interesting that while the chimpanzee brain is about 300 cubic centimeters the afarensis brain was about 400 cubic centimeters.  For comparison, modern humans have brains of about 1350 cubic centimeters, but we are significantly larger than afarensis.  In any case, Australopithecus afarensis may have been the first species on Earth to make stone tools.

     It is irresistible to wonder whether they realized they were the most advanced creatures on Earth at that time.  Lawyers object to speculation in court, but this is not court.  How much did they think?  How much did they reason?  Would they have had their own poets?  Their own Shakespeare?  Their own Hamlet?  “What a piece of work is [afarensis]! how noble in reason! how infinite in faculty! … And yet, to me, what is this quintessence of dust?”  Perhaps not exactly like that.  Still, we should encounter our ancestors with a mixture of wonder at their technology, which was supreme at the time, and humility for our own advances.  After all, are we not merely human?

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