Science

Fossil skull reveals new overlap between ancient human species

Fossil skull reveals new overl...
The Homo erectus skullcap known as DNH 134 is causing a rethink of the human evolution timeline
The Homo erectus skullcap known as DNH 134 is causing a rethink of the human evolution timeline
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The Homo erectus skullcap known as DNH 134 is causing a rethink of the human evolution timeline
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The Homo erectus skullcap known as DNH 134 is causing a rethink of the human evolution timeline
Fossils being sorted at Drimolen cave, north of Johannesburg in South Africa
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Fossils being sorted at Drimolen cave, north of Johannesburg in South Africa
The Homo erectus skullcap DNH 134 is between 2.05 and 1.95 million years old, making it the oldest known fossil from the species
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The Homo erectus skullcap DNH 134 is between 2.05 and 1.95 million years old, making it the oldest known fossil from the species
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The human family tree is being shuffled around again. A new study suggests that Homo erectus existed 100,000 to 200,000 years earlier than previously thought, meaning they lived alongside species they were once thought to have descended from.

The currently accepted version of the Homo erectus chapter of the human story says that the species arose about 1.8 to 1.9 million years ago. They were more human-like than the Australopithecines that came before them – Homo erectus was tall and slender, with longer legs, shorter arms and an upright stance. It’s also thought to have been the first hominin to master fire, hunt in groups, and care for injured group members.

But most importantly, Homo erectus is often credited as being the first hominin to venture out of Africa, where it gave rise to various other Homo species such as Neanderthals, Denisovans, and eventually modern humans.

That’s the neat version, anyway. In reality details are constantly being updated, and the family tree regularly redrawn. So it’s not entirely surprising that the new find shakes up the timeline a bit.

In Drimolen cave, north of Johannesburg, South Africa, archaeologists found 150 fragments of a skull over five years of excavation. Dubbed DNH 134, the fossil was eventually determined to belong to Homo erectus, and was found to be between 2.04 and 1.95 million years old.

Fossils being sorted at Drimolen cave, north of Johannesburg in South Africa
Fossils being sorted at Drimolen cave, north of Johannesburg in South Africa

“The Homo erectus skull we found, likely aged between two and three years old when it died, shows its brain was only slightly smaller than other examples of adult Homo erectus,” says Andy Herries, lead researcher on the study. “It samples a part of human evolutionary history when our ancestors were walking fully upright, making stone tools, starting to emigrate out of Africa, but before they had developed large brains.”

In the big picture 100,000 years is only a small adjustment, but it does bring up some heavier implications. For one, the team says that this older fossil is evidence that Homo erectus did evolve in Africa – other studies have suggested it may have emerged in Asia, after other earlier species migrated out of Africa.

It also means that Homo erectus lived alongside other species from which it was believed to have evolved, pouring cold water on that theory.

“We can now say Homo erectus shared the landscape with two other types of humans in South Africa, Paranthropus and Australopithecus,” says Herries. “This suggests that one of these other human species, Australopithecus sediba, may not have been the direct ancestor of Homo erectus, or us, as previously hypothesized.”

The Homo erectus skullcap DNH 134 is between 2.05 and 1.95 million years old, making it the oldest known fossil from the species
The Homo erectus skullcap DNH 134 is between 2.05 and 1.95 million years old, making it the oldest known fossil from the species

Homo erectus was already known to be one of the longest-surviving hominins, having walked the Earth for well over a million years. This new study stretches that window back further, and another recent discovery suggests they survived until as recently as 108,000 years ago in Indonesia.

If these finds are correct, this particularly hardy ancestor could have lived for closer to two million years. In that time it would have shared the planet with more archaic hominins like the Australopithecines, and its own descendants like Neanderthals, Denisovans, and us.

The research was published in the journal Science.

Sources: La Trobe University, University of Johannesburg via Phys.org

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