Discovery of Human Hand Bone Closes Evolution Gap

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handUntil a recent discovery, a gap has existed in human evolution. The distinctive hand anatomy of humans is what allows them to make and use tools of which apes and other nonhuman primates are incapable. The question for scientists has always been “At what point in time did these features first appear during human evolution?” Now, a researcher from the University of Missouri, along with her team of colleagues, made a discovery of a human hand bone from a human ancestor in East Africa from about 1.42 million years ago. Carol Ward, professor of pathology and anatomical sciences, discovered a human hand bone that has a styloid process.  The bone is believed to have belonged to the early human species, Homo erectus and it is the earliest evidence of a human-like hand with this modern anatomical feature.

An article on the topic was featured in Science Daily News, explaining that it is the third metacarpal which runs across the palm and links the middle finger to the wrist that is significant. Scientists had never understood how the tools that had been found dating back to this period could have been used when our human ancestors had weak wrists and were not strong enough to grip them with enough power to effectively use them. This finding explains how human hands developed during the period between 1.7 million years ago and 800,000 years ago, leading scientists to believe that humans who eventually developed the third metacarpal were at an advantage over those who did not.

Until the discovery of this well-preserved bone, evidence of the styloid process that connects to the wrist had only been found in modern humans, Neandertals and other archaic humans. By helping the hand bone lock into the wrist bone, the styloid allows for greater pressure to be applied to the wrist and hand. The bone was discovered near sites where ancient Acheulian tools have been found, including stone hand axes. This evidence closes the gap on the evolutionary history of the human hand, according to Ward. The findings were originally published in Proceedings of the National Academy of Sciences, (PNAS), the official science journal of the United States National Academy of Sciences.

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