© University of Missouri
Researchers have discovered a 1.42-million-year-old hand fossil that possesses the styloid process, a vital anatomical feature that allows the hand to lock into the wrist bones, giving humans the ability to make and use complex tools.
Researchers have discovered a 1.42-million-year-old hand fossil that possesses the styloid process, a vital anatomical feature that allows the hand to lock into the wrist bones, giving humans the ability to make and use complex tools.
A critical trait that distinguishes modern humans from all other species alive today is the ability to make complex tools. It's not just the extraordinarily powerful human brain, but also the human hand, that gives humans this unique ability. In contrast, apes - humans' closest living relatives - lack a powerful and precise enough grip to create and use complex tools effectively.
A key anatomical feature of the modern human hand is the third metacarpal, a bone in the palm that connects the middle finger to the wrist.
"There's a little projection of bone in the third metacarpal known as a "styloid process" that we need for tools," said study lead author Carol Ward, an anatomist and paleoanthropologist at the University of Missouri.
"This tiny bit of bone in the palm of the hand helps the metacarpal lock into the wrist, helping the thumb and fingers apply greater amounts of pressure to the wrist and palm. It's part of a whole complex of features that allows us the dexterity and strength to make and use complex tools."
Until now, this styloid process was found only in modern humans, Neanderthals and other archaic humans. Scientists were unsure when this bone first appeared during the course of human evolution. (The human lineage, the genus Homo, first evolved about 2.5 million years ago in Africa.)
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