Becoming Human

One hundred years ago today an amateur scientist named Charles Dawson announced his discovery in 1908 of an ancient skull,  immediately dubbed “ Piltdown man”, in a gravel pit near the town of Piltdown, England . Thus began an infamous but ultimately instructive series of events in the annals of science.

We humans have the largest brain relative to body weight, compared to all other animals.  On average the human brain is three times the size that of our nearest primate relative, the chimpanzee.  Why is this so? In a think piece in last week’s edition of the journal Science, Michael Balter summarizes some of the hypotheses.

The importance of genetic research in helping us understand diversity among our ancestors is playing an ever more important part. Last week a paper in the journal Science Express cast new light on a previously dimly glimpsed people referred to as the Denisovans.

A Nature paper in early August announced the finding of  dramatic fossils and refocused attention on the significance of fossils found decades ago.  The team led by Meave Leakey said bones found at Koobi Foora near the shores of Lake Turkana resembled those found forty years ago near this same location.

Philip V. Tobias, a world renowned paleoanthropologist, equally at home in the field or in his office preparing descriptions, has died at 87. He succeeded Raymond Dart as department head at the University of the Witwatersrand in Johannesburg, South Africa. In his long and fulfilling career he worked with the Leakeys at Olduvai Gorge and fought apartheid at home.

This is the title of a paper appearing last week in the journal Nature.  A careful examination of fossilized tooth enamel and a plaque from this intriguing (and controversial) taxon discovered at a site called Malapa in South Africa in 2008, provides a detailed insight to the diet of one species of hominin at a particular place and time.

Researchers investigating thin layers of limestone deposited on ancient cave paintings suggest in a paper published in Science last week two intriguing possibilities: the famous cave paintings in France and Spain may be as much as 15,000 years older than previously established; Neanderthals may have been cave painters as well as were the anatomically modern humans who replaced them.

Recent years have seen the decoding of the human genome, then that of our closest human relative, now extinct, Neanderthals (Homo neanderthalensis). The Chimpanzee genome has been analyzed and now is the turn of the often overlooked sister species to Chimpanzees, the Bonobos.

“It’s a lovely little foot” declared Don Johanson, upon learning of a  new fossil find in Ethiopia. Johannes Haile-Selassie and others announced in the March 28 issue of the journal Nature the recovery of a partial foot from the Burtele area of  Ethiopia. Eight of the normally 17 bones of the hominin foot were found eroding from sandstone dated to 3.4 million years ago.

Adaptations, large and small, are occurring at a regular rate in all species and demonstrate how evolution by natural selection works.    The changing shape and strength of the beaks of finches in the Galapagos; the darkening color of moth wings in England as the Industrial Revolution took hold; and the recent loss of sound produced by crickets rubbing their wings together in Hawaii are compelling examples of adaptations.