Hand Bone Evolution Showcased in Recovered Fossil Posits Theories Regarding Human Origins
A fossil recovered by researchers is leading to theories regarding the evolutionary gap of the development of early humans.
An international team of scientists discovered the bone at a site in Kenya and estimated it to be approxinately 1.42 million years old, according to a news release from the University of Missouri-Columbia.
The bone, from a human species known as Homo erectus, features a clue that could answer questions regarding how scientists think early humans were able to use and utilize tools through changes in the bone structure of their hands.
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The bone that was found is a metacarpal and displays a styloid process, which helps the hand bone lock into the wrist bones. This allows for the hand to express greater pressure over objects as the additional pressure is borne by the wrist. The styloid process is unique to humans.
The perceived date of the bone fossil found leads researchers to believe that changes to the human hand occurred far earlier-- previous estimates were about 600,000 years off-- initially thought. Researchers also stated that the new bone structure could have taken place around the time of Homo erectussensu lato.
"The styloid process reflects an increased dexterity that allowed early human species to use powerful yet precise grips when manipulating objects," Prof Ward, professor of pathology and anatomical sciences at the University of Missouri, Columbia, told the BBC.
"This was something that their predecessors couldn't do as well due to the lack of this styloid process and its associated anatomy," she added.
Ward added that this development is one of the defining features that allowed early humans to create and use primitive tools.
"With this discovery, we are closing the gap on the evolutionary history of the human hand. This may not be the first appearance of the modern human hand, but we believe that it is close to the origin, given that we do not see this anatomy in any human fossils older than 1.8 million years," she said.
The bone was found at the Kaitio site in West Turkana in the same region where other ancient artifacts including tools have been found and dated to around 1.6 million years ago.
"Our specialized, dexterous hands have been with us for most of the evolutionary history of our genus, Homo. They are -- and have been for almost 1.5 million years -- fundamental to our survival," Ward said.
