Wednesday, June 21, 2017

NEW FOSSILS DISCOVERED IN MOROCCO ARE OLDEST REMAINS OF HOMO SAPIENS



Fossils discovered in Morocco are the oldest known remains of Homo sapiens, scientists reported in early June, 2017, a finding that rewrites the story of mankind’s origins and suggests that our species evolved in multiple locations across the African continent.

“We did not evolve from a single ‘cradle of mankind’ somewhere in East Africa,” said Philipp Gunz, a paleoanthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a co-author of two new studies on the fossils, published in the journal Nature. “We evolved on the African continent.” See the full story in Nature.

Until now, the oldest known fossils of our species dated back just 195,000 years. The Moroccan fossils, by contrast, are roughly 300,000 years old. Remarkably, they indicate that early Homo sapiens had faces much like our own, although their brains differed in fundamental ways.

Today, the closest living relatives to Homo sapiens are chimpanzees and bonobos, with whom we share a common ancestor that lived over six million years ago. After the split from this ancestor, our ancient forebears evolved into many different species, known as hominins.

In 1961, miners in Morocco dug up a few pieces of a skull at a site called Jebel Irhoud. Later digs revealed a few more bones, along with flint blades. Using crude techniques, researchers estimated the remains to be 40,000 years old. In the 1980s, however, a paleoanthropologist named Jean-Jacques Hublin took a closer look at one jawbone.

The teeth bore some resemblance to those of living humans, but the shape seemed strangely primitive. “It did not make sense,” Dr. Hublin, now at the Max Planck Institute, recalled in an interview.

Since 2004, Dr. Hublin and his colleagues have been working through layers of rocks on a desert hillside at Jebel Irhoud. They have found a wealth of fossils, including skull bones from five individuals who all died around the same time. Just as important, the scientists discovered flint blades in the same sedimentary layer as the skulls. The people of Jebel Irhoud most likely made them for many purposes, putting some on wooden handles to fashion spears. Many of the flint blades showed signs of having been burned. The people at Jebel Irhoud probably lit fires to cook food, heating discarded blades buried in the ground below. This accident of history made it possible to use the flints as historical clocks.

Dr. Hublin and his colleagues used a method called thermoluminescence to calculate how much time had passed since the blades were burned. They estimated that the blades were roughly 300,000 years old. The skulls, discovered in the same rock layer, must have been the same age.

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