A 7 million-year-old practice set our ancestors on the course to humanity, new study finds

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Researchers looked at a femur and two ulna bones from Sahelanthropus tchadensis, one of the earliest known human ancestors, and found signs that they walked on two feet — also known as bipedalism, according to a new study published Wednesday in Nature.

“Our oldest known representatives practiced bipedalism (on the ground and in the trees),” said study author Franck Guy, a research associate at the Université de Poitiers in France. The remains of the ancient creatures show that bipedalism emerged shortly after chimpanzees and human ancestors diverged in their evolutionary track, he added.

There is even more to be found in these fossils. Their characteristics show that, according to the study, Sahelanthropus tchadensis also retained the ability to skillfully climb trees.

These ancestors were hominids, or species more closely related to humans than chimpanzees, and they mark an early stage in our evolutionary divergence, said Daniel Lieberman, a professor of human evolutionary biology and paleoanthropologist at Harvard University. Lieberman was not involved in the investigation.

Bipedalism in these ancestors is not exactly a surprise. The arm and leg bones analyzed in this study were found in Chad in 2001 next to a nearly complete skull, the study said. However, it’s unclear if they came from the same person, said study author Guillaume Daver, an assistant professor of paleontology at the Université de Poitiers.

The skull showed a downward-pointing spot where the head and spinal cord meet — a feature that would make it much more difficult to walk on all fours, Lieberman said.

The new analysis of the limbs from that find provides further evidence that hominins traveled on two legs when they roamed the Earth about 7 million years ago, he added.

“It’s a glimpse of what has put human lineage down a different evolutionary path than our monkey cousins,” Lieberman said. While the recent findings support what early studies suggested, fossils from this time are rare, so any discovery is an important piece of evidence, he added.

And the new study “makes it quite unlikely that the common ancestor we share with the chimpanzees looked like a chimpanzee,” Guy said.

Bipedalism has fueled the fire

Bipedalism was extremely important to our evolution, but it didn’t make sense to our ancestors, Lieberman said.

Walking on two legs makes an animal slower, more unstable and more at risk for back pain, which doesn’t help it survive, he added.

“There must have been a very big advantage,” said Lieberman. Scientists have a hypothesis about what that might be.

Our common ancestor with monkeys looked a lot like a chimpanzee, and we know they need a lot of energy to walk — twice as much as humans if you adjust for body size, Lieberman said.

Site "overlooked for over 90 years"  was home to some of Britain's earliest humans, study finds

As the evolutionary paths of humans and chimpanzees diverged, Earth’s climate changed and rainforests in Africa disintegrated, so our ancestors had to travel farther to get food, he said. The hypothesis is that walking on two legs gave them more energy to travel.

“What really put us on this different evolutionary path is that we were bipedal, or we walked on two legs,” Lieberman said. “It helps us really understand the origins of humanity.”

There are many things that define us as humans, such as language, tools and fire, he said. And in the 1870s, Charles Darwin — without any evidence we have now — suspected that walking on two legs was the spark that started it all, Lieberman said.

And we can now see that bipedalism was a big differentiator from monkeys, helping free up our hands to develop tools, Lieberman said.

“We have agreed with Darwin,” he said. “That’s pretty cool.”

The Valley Voice
The Valley Voicehttp://thevalleyvoice.org
Christopher Brito is a social media producer and trending writer for The Valley Voice, with a focus on sports and stories related to race and culture.

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