Newly Discovered Oldest Human Fossils Push Our Origin Back By 100,000 Years

A reconstruction of the skull belonging to the earliest example of our own species, Homo sapiens. Philipp Gunz/MPI EVA Leipzig/License: CC-BY-SA 2.0

Josh Davis 07 Jun 2017, 18:00

The earliest fossils belonging to our own species, Homo sapiens, have been uncovered in the arid mountains of Morocco. Discovered in a cave full of stone tools and other animal bones, the human remains push the origin of humans back by a stunning 100,000 years.

The findings are reported in two studies published in Nature, and could alter how we think our species evolved. Comprehensive dating puts the extensive remains – which represent three adults, an adolescent, and a child – at around 300,000 years old. This is much earlier than the previous oldest human remains discovered in Ethiopia that date to roughly 200,000 years old.

“This is much older than anything else in Africa that we could relate to our species,” said team lead Jean-Jacques Hublin of the Max Plank Institute to IFLScience. “In light of this new date – at 300,000 years old – it convinced us that this material that we present is the very root of our species. The oldest Homo sapiens ever found in Africa.”

The team dated the bones by using the vast collection of flint tools found alongside the fossil remains. They employed a technique known as thermoluminescence to measure the level of accumulation of radiation in the artifacts to establish an accurate age of the objects. The researchers attempted to extract genetic material from the bones, but found that the fossils were too old and the environment too dry to yield any results.

A jaw bone from the oldest Homo sapien fossils ever discovered. Jean-Jacques Hublin/MPI EVA Leipzig

We know from genetic evidence that all humans alive on this planet owe their origins to Africa, where our species first evolved. But rather than a single origin of our species somewhere in East Africa, the discovery of the fossils in Morocco instead lend support to the pan-African emergence of Homo sapiens. “If there is a Garden of Eden, it is Africa,” said Hublin.

It suggests that the lineage that gave rise to humans evolved in pockets all across the continent, which were periodically linked together as ecosystems changed, allowing for the mixture of genes and the spread of technological innovations. Any beneficial mutation would then spread from one population to another, and would have been magnified by positive selection in each group.

The site in which the fossils were discovered at Jebel Irhoud, Morocco. Shannon McPherron/MPI EVA Leipzig/License: CC-BY-SA 2.0

It is important to remember that some 300,000 years ago, the continent of Africa did not look like it does today. The cave in which the fossils were found would have sat in the middle of a grassland dotted with small stands of trees, as gazelles, zebras, and wildebeests grazed, while lions and early Homo sapiens stalked them. The Sahara did not yet exist, meaning that our species was free to migrate vast distances, connecting populations that in modern times are now separated.

The authors are quick to point out that while the individuals these fossils represent would have blended into a crowd of people alive today, they were not modern humans as we tend to think of the term. Their brains were not as well developed and they did not have the intelligence that we associate with our own species.

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Some of the Middle Stone Age tools from Jebel Irhoud. Credit: Mohammed Kamal, MPI EVA Leipzig (License: CC-BY-SA 2.0)

 

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