The day we started using our thumbs

When exactly did human-like manual dexterity arise? When did we start using our thumbs? Which species of hominid was the first to demonstrate this ability? These questions are key to our evolution as a species.

The day we start using our thumbs, we distance ourselves from other species.
The day we start using our thumbs, we distance ourselves from other species.
Thumbs up for millions of years

A team tried to answer these questions. They analyzed the biomechanics and efficiency of the thumb in various fossil human species. They used the virtual modeling of their muscles to gain new perspectives. They wanted to know when these skills came about and what they mean for the development of human culture. The results are collected in an article entitled Biomechanics of the human thumb and the development of dexterity. It is published by the magazine Current biology. They suggest that a fundamental aspect of the human thumb’s opposition first appeared about 2 million years ago.

“Increased manual dexterity is the result of efficient thumb opposition. It gave us an impressive adaptive advantage over our ancestors, ”explains Katerina Harvati. It belongs to the Eberhard Karls University in Tübingen. “It is a critical element in the development of a complex culture over the past 2 million years. It shapes our biocultural development, ”he adds.

How has the development of thumb dexterity been studied so far? Comparison of the skeletal anatomy of modern humans with that of earlier hominin species. The similarities between the two could be taken as evidence of their capabilities.

There isn't that much difference between human and chimpanzee thumbs.
There isn’t that much difference between human and chimpanzee thumbs.
Analyze muscles

The Harvati-led team took a completely new perspective. “Our methodology integrates the latest virtual muscle modeling with three-dimensional analysis of bone shape and size.” It is explained by the lead study author and expert in manual biomechanics, Alexandros Karakostis. “This process involves a thorough 3-D study of the areas of the bones into which the muscles will be inserted.”

The efficiency and dexterity of the thumb was already remarkable among hominids in South Africa 2 million years ago. That was when the day came when we started using our thumbs … and we changed history. It remains to be understood why our close relatives stayed as they were.

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