Researchers studying the fossilized hands of 2-million-year-old hominins concluded that human fingers back then had the same range of motion as our fingers today. The “dexterity” partially offered by the human finger allowed us to overwhelm all other species on Earth.
Until now, the ancient origins of the human thumb and dexterity have always been closely locked archaeological mysteries. By 3D modeling the range of motion of muscles in old, fossilized fingers, a team of German researchers concluded that about 2 million years ago, our ancient human ancestors first developed this key tool for survival.
Human finger: All the better to tighten!
The new study was published in the journal Current biology by a team of paleoanthropologists from the University of Tübingen. Researchers have digitized the fossil bones of hominin fossil fingers, including those of homo sapiens (new), in a project full of complications.
The main problem facing the research team was that the fossils did not preserve the muscles and that meant relying on the risky approach known as “speculation”.
To help them accurately analyze ancient human fingers, the team first analyzed hand bone samples from two early modern humans and four Neanderthals who have lived and died for the past 100,000 years.
Summary of the analytical stages of the study: (A) Preparation of the model and assumption of the ability to generate human muscle strength or the chimpanzee (m. Opponens pollicis). (B) Biomechanical efficiency is calculated as the torque generated by m. Oposens pollicis at the TMC joint of the thumb. (C) 3D geometric morphometric analysis of proportional bone projection on the site of attachment of the metacarpal muscle. (© 2021 Harvati, Karakostis and Haeufle / Current biology )
An article in Science Mag says German scientists then analyzed the hands of “the diminutive who lives in the cave H. naledi who lived about 250,000 to 300,000 years ago, ”and also those of a sister genre,“ Australopithecine. ”
Using 3D technology, the researchers rebuilt the ancient hands and then “digitally” added a key muscle known as ” Opposite thumb ”Which is attached to the base of the palm and allows the thumb to flex inward.
Australopithecus sediba’s right hand. (Image by Peter Schmid, courtesy of Lee R. Berger and the University of the Witwatersrand./ CC BY-SA 3.0 )
How the human finger has become the power tool of evolution
After building their dynamic 3D models of ancient hands, the researchers applied increasing force to the model. It was observed that with a more applied force “better and more precise adhesions” were obtained.
This, according to the authors, would have helped to “keep a needle and thread fixed or to move a hammer”. In conclusion, the scientists said that all tested members of our genus, Homo, it had “practically the same grip force as the thumb” and that it matches the power measured in the thumbs of modern humans and chimpanzees.
During their experiment, the team analyzed the movements of the thumb in two specimens of hominin found at the Swartkrans site in South Africa. Dating about 2 million years ago and of an unknown genus, the authors said that these fossils of Swartkrans represent “the oldest known human fingers in the fossil record.”
The study finds that compared to these two Swartkrans fossils “ Australopithecine he had much weaker thumbs. “And although they may have exhibited instrument-related behaviors, they have not yet developed a human-like level of efficiency, according to the authors.
What this means is that the human finger, as it is today, evolved about 2 million years ago in Man kind and that it was the thumb that accelerated the ability of ancient people to make more complicated stone tools and weapons, which in turn helped us surpass all other groups of hominins.
This ancient man gives us the “thumb up” for a good reason, because the latest study shows that the human thumb is what separates Homo sapiens from the summers we left behind as we evolved into “uber-humans. ”. ( Floors / Adobe Stock)
An excellent research project, but the questions remain. . .
Dr Tracy Kivell, a professor at the School of Anthropology and Conservation at Kent University in the UK, said CNN that a lot of “assumptions” are made in these types of studies, because “muscles are not kept in the fossil record.” But accepting that a certain degree of speculation was involved in the research, she said that the authors of the new paper “did an excellent job of dealing with all the complexities involved in this type of research.”
However, there is another voice urging “caution” towards the conclusions of the new study for another reason. Dr. Evie Vereecke is an anthropologist and anatomist at the Belgian University KU Leuven and, while openly praising the authors’ “approach”, she said. Science Mag findings should be treated with caution. She said, “We [evolutionary scientists] know that “dexterity” is not due to just one muscle. ”
In other words, dexterity has a massive mental component, which was not taken into account in the 3D modeling of the German research team. Therefore, it is not yet known how “capable” people have applied “super-thumbs” in projects that require complex prediction and prediction of results.
The full study is available with open access from Elsevier, Current Biology, DOI: https://doi.org/10.1016/j.cub.2020.12.041
Image above: The researchers used 3D modeling software to reconstruct the ancient hands and then added them to the model’s critical human muscle. Source: © 2021 Harvati, Karakostis and Haeufle / Current biology
By Ashley Cowie