Oldest-known Homo sapiens fossils reveal the 'root of our species'
Published Wednesday, June 7, 2017 1:00PM EDT
Last Updated Wednesday, June 7, 2017 8:47PM EDT
Newly-discovered fossils have shattered the notion that early humans emerged from a "Garden of Eden" region in east Africa 200,000 years ago, by strongly suggesting that our ancestors had already spread across the continent and taken major steps in their evolution some 100,000 years earlier.
The findings are based on the several early Homo sapiens remains from 300,000 years ago, which were found at the site of a pre-historic hunting encampment in Morocco, in North Africa. Among the remains were several skull fragments, as well as an assortment of animal remains, cooking fire traces and tools from the Middle Stone Age, which all pre-date the era when Homo sapiens supposedly emerged from a "Garden of Eden" region in modern-day Ethiopia.
"This material represents the very root of our species – the oldest Homo sapiens ever found in Africa or elsewhere," Jean-Jacques Hublin, of the Max Planck Institute for Evolutionary Anthropology, told reporters during a conference call. Hublin co-authored one of two papers on the findings, which are published in the latest edition of the journal Nature.
Both papers dispute the notion that Homo sapiens spread during a period of rapid evolution some 200,000 years ago.
Hublin says it's more likely Homo sapiens evolved gradually through mutation and intermingling between nomadic groups that roamed Africa during a wetter, greener era for the continent 300,000 years ago.
"There is no Garden of Eden in Africa, or if there is a Garden of Eden, it's Africa," he said.
Beauty before brains
Hublin's paper analyzes various skull fragments discovered at the site in Morocco, which are thought to have belonged to three adults, an adolescent and an eight-year-old child.
He says these early Homo sapiens exhibit a combination of modern and primitive characteristics, which suggests that humans evolved "face first, and brain after." For instance, the brain cases of the early Homo sapiens skulls are more elongated than that of a modern human, suggesting that Homo sapiens' brains still hadn't fully evolved. But, while their brains were different, Hublin says their faces would have been "indistinguishable" from a modern human.
"The face of these people, which is a short, flat and retracted face… is the face of people you could cross in the street today," Hublin said.
He added that while these early Homo sapiens' brains were shaped differently from ours, they were starting to develop larger cerebellums – a development that would be key to their eventual rise to dominance on Earth.
The previously oldest-known Homo sapiens fossil, which was found in Ethiopia, is estimated to be approximately 195,000 years old.
The remains were found in a layer of sediment unearthed in 2004, at a site called Jebel Irhoud, 100 kilometres west of Marrakech. The archeological site was originally discovered in the 1960s, when bones found there were thought to be approximately 40,000 years old. However, subsequent visits to the site suggest those original bones many have been much older.
Shannon McPherron, who co-authored the second paper on tools at the Morocco site, says the spot was once a cave where early Homo sapiens would stop to repair their hunting weapons and butcher their kills.
The second paper examines a variety of flint stone flakes found at the site, which likely came from a flint source 25-30 kilometres away. McPherron says flint was useful for making "high-quality tools" such as spears, which allowed Homo sapiens to hunt without getting too close to their prey. He added that Homo sapiens at the site had obvious expertise with making fires, based on traces in the sediment.
McPherron says, at the time when these Homo sapiens lived, the now-arid Maghreb and Sahara deserts would have been lush, green regions teeming with such creatures as gazelle, zebra and lions. The gazelle would have been the early Homo sapiens' prey.
McPherron and his team dated the flint used in the tools to approximately 300,000 years ago, when such materials would have been common among Middle Stone Age Homo sapiens.
Both McPherron and Hublin said they have categorized the fossils at the site as Homo sapiens, despite their differences from modern humans, because they show clear signs of being part of a line of evolutionary progress.
"Evolution exists, and so there is no reason why a representative for our species living 300,000 years ago would be just like us," Hublin said.