Tiny Brains of Extinct Human Relative Had Complex Features

ImageResearchers say that the skull of Homo naledi, a hominin that lived 236,000 to 335,000 years ago, contained a brain the size of an orange that had a similar...


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Researchers say that the skull of Homo naledi, a hominin that lived 236,000 to 335,000 years ago, contained a brain the size of an orange that had a similar shape and structure with that of modern humans.CreditJohn Hawks

What makes humans so smart? For a long time the answer was simple: our big brains.

But new research into the tiny noggins of a recently discovered human relative called Homo naledi may challenge that notion. The findings, published Monday, suggest that when it comes to developing complex brains, size isn’t all that matters.

In 2013 scientists excavating a cave in South Africa found remains of Homo naledi, an extinct hominin now thought to have lived 236,000 to 335,000 years ago. Based on the cranial remains, the researchers concluded it had a small brain only about the size of an orange or your fist. Recently, they took another look at the skull fragments and found imprints left behind by the brain. The impressions suggest that despite its tiny size, Homo naledi’s brain shared a similar shape and structure with that of modern human brains, which are three times as large.

“We’ve now seen that you can package the complexity of a large brain in a tiny packet,” said Lee Berger, a paleoanthropologist at Wits University in South Africa and an author of the paper published in the journal Proceedings of the National Academy of Sciences. “Almost in one fell swoop we slayed the sacred cow that complexity in the hominid brain was directly associated with increasing brain size.”

Not every scientist agrees with their interpretation.

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Since its remains were first retrieved, Homo naledi has puzzled scientists. From head to toe the ancient hominin displays a medley of primitive, apelike features and more advanced, humanlike characteristics.

“It’s this mosaic that is unlike anything we have seen or expected,” said Dr. Berger who first discovered Homo naledi in the Dinaledi Chamber in South Africa’s Rising Star cave system. So far, researchers have found more than 2,000 fossils belonging to the human relatives which have provided a portrait of what the species once looked like.

More details about the discovery of Homo naledi

A cranial endocast of Homo naledi. The study’s authors suggest brain size alone does not explain intelligence, but that shape may have played a role as well.CreditPNAS



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