The shape of the hands is one of the last evolutionary mysteries of the human being. And we are one step closer to solving it

Our hands are, without a doubt, one of the wonders of biological engineering, since for a long time, the dominant evolutionary narrative has focused on how our anatomy transformed to allow precision grip and the manufacture of complex tools. However, if we look beyond the fingers and focus on the wrist, the bones tell a much older and more surprising story.

New tests. A comprehensive published study in the magazine Proceedings of the Royal Society B has put on the table quite important evidence about how our ancestors moved. And the conclusion is that the morphology of our wrist retains an undeniable echo of a common ancestor adapted to walking supported on the knuckles.

How they have done it. To reach this conclusion, the researchers have not relied on isolated conjectures, but on a large-scale anatomical analysis. The team analyzed more than 2,037 carpal boneswhich are what form the wrist, belonging to different species of primates, crossing these data with the anatomical analysis of 55 fossils of extinct hominins.

What they discovered by mapping all this morphology is that human wrist bones don’t look like those of most primates, but instead share deep structural similarities specifically with African great apes.

It’s not a coincidence, since it responds to the biomechanical adaptations necessary to support the weight of the body on the hands when they are closed. That is, although today we use our wrists for complex tasks such as typing, painting or even performing surgery, their architecture was designed for walking on the knuckles.

Cautiously. Does this mean that our ancestor walked on his knuckles with absolute certainty? In science, closed statements are dangerous, and the authors of the study themselves are cautious, since they do not present this ancient practice as an irrefutable dogma, but as the most consistent and plausible interpretation according to the anatomical evidence on the table.

Its evolution. Our body did not evolve suddenly to its current form, but rather went through different phases at different rates. Here the study shows this phenomenon in our hands, since, while the general structure of the wrist has preserved those primitive evolutionary signals shared with African apes, other parts of the hand changed later. Specifically, adaptations associated with fine, precision manipulation appeared much later in our evolutionary lineage.

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