Academic journal article Mankind Quarterly

An Update on Human Evolution

Academic journal article Mankind Quarterly

An Update on Human Evolution

Article excerpt

An Update on Human Evolution Brain Dance: New Discoveries about Human Origins and Brain Evolution Dean Falk Revised and Expanded Edition, University Press of Florida 2004

This updated version of a popular book seeks to trace human evolution from pre-hominoid ancestors through to Homo sapiens, with prime reference to that supremely human characteristic, the human brain. It is useful to students coming to grips with palaeontology for the first time, or the curious, intelligent layman. It also contains up-to-date observations on the Out-of-Africa debate.

Dean Falk, a professor of anthropology at Florida State University, begins by pointing out that at the time of the first (1992) edition of her text, "most paleontologists agreed that the first African Homo to appear was Homo habilis, and that this species gave rise to Homo erectus who in turn gave rise to Homo sapiens. Furthermore, at that time workers believed that the transition between Homo habilis and Homo erectus had occurred rapidly (some thought between 1.8 and 1.6 million years ago) and exclusively in Africa." However, since then, she observes, "the picture has become murkier."

Classifying Hominin Fossils

This is because, as more fossil evidence becomes available, paleontologists have been virtually overwhelmed by the variety. Remains that were originally grouped together as Homo habilis have been split into categories such as Homo habilis sensu styncto and Homo rudolfensis, and yet others reclassified as Australopithecines. In short, while classification is a vital step toward what may one day be a fairly accurate picture of hominoid and hominid evolution, the evidence is as yet too scanty to allow us to construct with any degree of certainty what happened among evolving and increasingly advanced varieties of intelligent primates over the past two or three million years.

Paleontologists can be divided into "splitters and lumpers," those who tend to be affected by what Russ Tuttle has described as "splitomania," regarding almost every new fossil as representative of a different species, and those who are overly keen to see differences as purely idiosyncratic, and who therefore tend to lump a wide range of fossils into the same group. The latter argue that fossils that appear to be more or less contemporaneous should be regarded as belonging to the same species, and play down the possibility that different species of hominins might have been residing on the earth at the same time, even on the same continent. Yet there is sufficient evidence that different species of hominins did in fact inhabit the earth at various times. It is generally accepted that different species of Australopithecines lived in Africa at the same time, and more recently we have the evidence of Homo florensi, seemingly akin to Homo erectus, surviving in an age when essentially modern men had already populated many parts of the Old World.

Falk's book is not only interestingly written, but attempts to introduce the reader to the wide variety of terminological inventions that we find in the literature. Terminology is a necessary step toward scientific classification but it is not itself bedrock science. The guesswork involved in much terminology is illustrated by the fact that is has recently been suggested that Homo habilis should have been classified as an Australopithicine rather than as Homo.

Falk is acutely aware of the danger of classificatory excess, and asks: "can two fossils that are identical (not to mention contemporaneous) reasonably be assigned to two separate species? I do not think so," while at the same time warning that in cladistic analysis, a family tree is only as good as the traits the researcher selects when seeking to construct it.

The Evolution of the Human Brain

But the main purpose of Falk's book is to summarize what we now know about the growth of the human brain. It is now established that chimpanzees are the closest surviving relatives of Homo, and much work has been done to compare the workings of the chimpanzee brain with that of modern humans, in the hope that this may provide clues to the evolutionary history of the human brain. …

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