1.4 Million-Year-Old Hand Fossil Discovered: Bone Gave Human Ancestors Ability To Make Tools
Researchers have found a 1.4 million-year-old bone in East Africa which they say is the earliest known evidence of a human-like hand. The bone, which is believed to have belonged to the early human species Homo erectus, allows humans to make and use tools. Carol Ward, a professor of pathology and anatomical sciences at University of Missouri, calls "fundamental to our survival."
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"This bone is the third metacarpal in the hand, which connects to the middle finger," said Ward, who led a study on the bone. "What makes this bone so distinct is that the presence of a styloid process, or projection of bone, at the end that connects to the wrist. Until now, this styloid process has been found only in us, Neanderthals and other archaic humans."
By locking the hand bone into the wrist bones, the styloid process allows the thumb and finger to exert pressure on the wrist and hand. Without the styloid process, apes and nonhuman primates are hampered in their ability to make and use tools.
"The styloid process reflects an increased dexterity that allowed early human species to use powerful yet precise grips when manipulating objects. This was something that their predecessors couldn't do as well due to the lack of this styloid process and its associated anatomy," said Ward. "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."
Ward told LiveScience that 1.4 million years ago, which the hand bone dates back to, early members of Homo existed along with late-surviving Australopithecus members. The two were "close relatives of humans that don't seem to have this adaptation," Ward said, so it "raises the question of how important our hands were in the success of our lineage and the extinction of their lineage (Australopithecus)."
Ward and her team discovered the bone in West Turkana, Kenya, an archeology-rich area where the earliest Acheulean tools have been discovered. The Acheulean tools are stone tools like hand axes which are over 1.6 million years old. They may have been used for scraping hides, digging and cutting animal hides.
The study was published this week in Proceedings of the National Academy of Science.
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