Our direct ancestor in Africa, chaparro and robust

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The Homo erectus, the first human ancestor that spanned the Old World from its emergence in Africa two million years ago, it has been considered so far as a slender and stylized. This physical configuration has been related to their ability to travel long distances. However, a new study conducted by paleantropólogos Spanish suggests that, in reality, our direct ancestor was far from having the look of a champion marathoner. On the contrary, it was a hominid compact, squat and robust .

Reconstruction of the skeleton of the Turkana boy – Markus Bastir. License CC-BY-NC-ND 4.0.

The team of the Consejo Superior de Investigaciones Científicas (CSIC) and the National Research Centre on Human Evolution (CENIEH) have reconstructed in 3D the shape of the rib cage of the famous Turkana boy , a skeleton of a juvenile Homo erectus found in 1984 in Kenya, where he lived 1.5 million years ago.

“Surprisingly, the Turkana boy had a chest deeper, and wider and shorter than that of modern humans”, tells Markus Bastir, of the National Museum of Natural Sciences, MNCN-CSIC. “This suggests that H. erectus had a construction body more robust than is generally supposed, because until now had the body shape of this species is as slender or slim, which was associated with their ability to travel long distances,” he adds.

therefore, it seems that the slender shape of the human body modern, with a thorax and a pelvis narrow, it evolved more recently than was previously thought. “Instead of appearing so early on with the emergence of H. erectus, some two million years ago, would have appeared with our species, H. sapiens,” concludes Daniel García Martínez, of the CENIEH.

Large lung capacity

studies on how the Turkana boy was walking and running have been limited largely to the legs and pelvis. However, for the endurance race, their capabilities in respiratory would also have been relevant. “Until now, this aspect was not investigated in detail, because they evaluate the movement of the chest and the respiratory capacity on the basis of fossils of the ribs and vertebrae are fragmented it is difficult with conventional methods,” explains Bastir. “Now, thanks to the introduction of imaging techniques and virtual reconstruction of increasingly sophisticated, this study has finally been possible,” he adds.

Comparison of the boxes of the chest of a modern human, an erectus and a neanderthal – M. Bastir

The research, published in the journal Nature Ecology and Evolution, has reconstructed the rib cage virtual 3D young Turkana, so that the team has been able to predict its shape chest adult. “In addition, the shape of your rib cage is compared to that of modern humans and that of an individual neanderthal, to investigate the motion of your breathing by using the virtual animation”, indicated García Martínez..

This study also addresses the fact that the shape of our body modern can be linked with a kinematic respiratory optimized for running long distance, as well as other resistance activities. “The H. erectus perhaps it was not the broker’s slim and athletic long-distance that we imagine”, says Bastir. “In fact, this is consistent with some estimates of body weight, suggesting that this species was more heavy than was first thought. This ancestor iconic probably seemed a little less to us of what we portray them over the years.”

Adaptation to the environment

The evolution of body shape reflects an adaptation to the environment. Modern humans have a body relatively tall and slender, which contrasts with the body shape of the neanderthals, a lower and stunted.

scientists have traditionally meant that the body shape modern originated with the first representatives of H. erectus in the context of climatic changes related to the recession in the tropical forest, african, about two million years ago.

The bodies of modern, tall and slender, could be evolutionarily advantageous in the dry climate of savannah that east Africa was beginning to acquire. This is due to that this slender body would have helped to avoid the overheating of the body, at the same time, that would have served to run long distances over open ground.

According to this conception, the fossils attributed to H. erectus suggested up to now this species already had a few legs longer and arms shorter than their ancestors Australopithecus, which had a running biped, fairly efficient, but that also possessed the ability to climb trees.

Some features of modernity that we observe today in the human species, could be seen in the Turkana boy, that it is the fossil of H. erectus most complete found to date. Now, this new study adds to this conception by showing that Homo erectus had a body more compact and robust than previously thought.

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