A recently-discovered fossil is literally giving researchers a hand when determining the evolution of humans, as the remains are of a hand bone believed to have belonged to a previously unknown human relative that would have been far taller and larger than its contemporaries.
According to NBC News and LiveScience reports, the bone was discovered at Olduvai Gorge in Tanzania, and dating has determined that it is at least 1.84 million years old. The researchers that found the fossil believe it belonged to the adult left hand of one member of an unidentified group of hominin similar to Homo erectus, the first hominin known to keep created tools.
“The hand is one of the most important anatomical features that defines humans,” explained Manuel Domínguez-Rodrigo, a paleoanthropologist at Complutense University of Madrid and the lead author of a new Nature Communications paper detailing the human-like bone.
“Our hand evolved to allow us a variety of grips and enough gripping power to allow us the widest range of manipulation observed in any primate. It is this manipulation capability that interacted with our brains to develop our intelligence,” he added, noting that the bone is about 1.4 inches long, or roughly “the same size as the equivalent bone in our hand.”
Discovery may reveal when human-like hands first emerged
Domínguez-Rodrigo believes that the discovery could reveal new clues about when hands like those currently found on modern humans first emerged in the fossil record. They also said that it likely indicates that our ancient predecessors were much larger than previously believed.
Identified as Olduvai Hominin (OH) 86, the proximal digit “represents the earliest MHL [modern human-like] hand bone in the fossil record,” the authors wrote, adding that the differences in size and shape suggest “that a hominin with a more MHL postcranium co-existed with Paranthropus boisei and Homo habilis.” The bones indicate that this species’ hands would have been dexterous enough to make and use complex tools, the research team explained.
Previous analysis of hominins appeared to inidcate that they were adapted to live in the trees, as their hands possessed curved finger bones suited for handing from branches, LiveScience noted. Modern humans are the only living higher primates with straight finger bones, and the new bone is not only straight, but contains other adaptations indicative of ground-based living.
While experts often suggest that the modern shape of the human hand evolved solely to use stone tools, recently discovered hominin fossil suggest that the story is more complicated than that. For example, the hand bones of some ancient hominin lineages can be closer to modern human hands than those of more recent lineages are, the website noted. The discovery of this fossil fill a gap in the record, helping explain when hominin hands started becoming specialized for manipulation.
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Feature Image: Researchers believe the fossil belonged to the adult left hand of one member of an unidentified group of hominin similar to Homo erectus, the first hominin known to keep created tools. (Credit: Jason Heaton)
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