We started walking upright 7 million years ago.What benefits has it brought us?|Mail

This study provides new evidence that the earliest hominids already had bipeds, an important feature of our ancestors.

We started walking upright 7 million years ago.What benefit did it give us?

The study provides new evidence that the first known hominid was already bipedal, a key characteristic of our ancestors.

Last April, the first half marathon in which human and robot athletes took part took place in Beijing.Among the conditions required for the machines to participate was that they had to bipedally, as we do.The result was remarkable: the first of these humanoids reached a time of 2 hours and 40 minutes, far from the best participants of our species.For reference, the world record for this distance is 56 minutes and 42 seconds.

"Even if we don't know because we do it without thinking, our ability to move is very difficult. It's just a challenge to maintain balance. The distribution of mass, inertia, the small size offered by the two legs, the stress of the terrain, obstacles, slippery ground are all at play," said Unai Zabala, a personstudy in Robotics Groups and Autonoit System.the children of the people at the University of the Basque Country.robots.

This example is enough to illustrate the complexity of one of the defining traits of our species.Because walking upright is something only we and our hominid ancestors do.This form of locomotion appeared seven million years ago in Sahelanthropus tchadensis, the oldest known hominid.This ancestor was discovered in 2001 in the Djurab desert, in Chad, and while some researchers thought he walked upright, others doubted it.Now, a study published in the journal Science Advances confirms that this is the case."Sahelanthropus tchadensis was essentially a bipedal ape with a brain the size of a chimpanzee and probably spent most of its time in trees, searching for food and safety. Despite its superficial appearance, it was adapted for bipedal posture and locomotion on the ground," says Scott Williams, associate professor in the Department of Anthropology at New York University.

When paleontologists at the University of Poitiers found the remains of this primitive hominid in the heart of Africa, their research focused on the skull.Both their orientation and the position of the occipital foramen, where the spine attaches, suggested they could walk upright, but not all experts agreed.Two decades later, the femur and two anterior ulna were analyzed.In this latest study, the fossils have now been re-examined to confirm that Sahelanthropus could indeed walk.

What they found was that although they were about the same size as apes, they were closer to hominids in size.In addition, these bones show three main features for standing: a strong femur, which helps the legs to move forward, making walking easier;the muscles in the gluteus - these are recreated in 3D surgery - which help to keep the hips stable, making it possible to stand, walk and run;and the femur, which is adapted for stabilization.In conclusion, those hominids from seven million years ago had shorter legs than ours, but they were different from those of chimpanzees and bonobos."These features may represent some of the earliest adaptations to bipedalism in the hominid lineage, albeit with ease of locomotion on trees," they say.

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"Walking on two legs gave our ancestors certain characteristics important for our evolution.Vulnerability to the son is less, and it allows you to go in the sun hour without suffering from sunlight.These are not the only advantages of a geographical straight line and greater ease when crossing a body of water, for example.

The expert says bipedalism was also important for more complex reasons."Primates living in trees carry their young without difficulty, but when we grow into clams, we start using both hands regularly at the same time. Being able to walk on the ground effortlessly and holding a tree with our hand was a very useful feature for our ancestors in creating and using tools, which is closely related to symbolic thought and language," he concludes.

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