Styloid Process Found on Hand Bone Pushes Human Use of Tools Back

Styloid Process Found

The earliest fossil evidence of tool use by human ancestors, a third metacarpal bone with a curved bit at the end — the styloid process — was found in East Africa, according to anthropologists, and it pushes the earliest human use of tools back over a half a million years. The third metacarpal bone, some 1.42 million years old, comes from an ancestor of modern humans, Australopithecus anamensis, according to scientists at the University of Arkansas at Fayetteville.

The styloid process is such a small part of the third metacarpal bones of hands, yet is is an important part, when it comes to using tools with both precision and dexterity. Apes and other nonhuman primates don’t have the styloid process.

According to anthropology Professor J. Michael Playcan, one problem with determining the earliest date at which human ancestors became tool users is that “hand bones are difficult to find.” That has made it difficult for anthropologists to determine exactly how long ago modern human hands developed the structural hand changes necessary for our ancestors to became adept at using tools.

Kenya was where the third metacarpal bone was unearthed. The styloid process is prominent on the fossil. It’s crucial to utilizing tools, and previously, the earliest example of an ancestor of humans with this curved projection of the third metacarpal bone was 800,000 years ago.

Playcan suggests that the structural changes necessary, like the development of the styloid process, occurred much earlier. According to Playcan, scientists “need to find even earlier bones” to discover just how long ago the “structural features of the hand appeared” necessary for our ancestors to be adept at using tools.

Also, a researcher from the University of Missouri, Carol Ward, a professor of pathology and anatomical sciences, and an international team of anthropologists and fellow scientists participated in discovering the small but important bone.

According to Fredrick Manthi of the National Museums of Kenya, a colleague of Ward’s and a coauthor of the study on the find, the styloid process on the third metacarpal bone. The third metacarpal bone connects to the middle finger, and the styloid process on it connects to the wrist and makes grasping objects easier. The styloid process has only been found previously in Neanderthals, other human ancestors, and modern humans.

Considering that the hand bone was found near stone hand axes that date to over 1.6 million years ago, human ancestors undoubtedly had developed the styloid process much earlier. But, until even older bones are discovered, the third metacarpal bone found in Kenya that dates back 1.42 million years is the oldest known evidence that indicates tool use in the ancestors of modern-day humans.You can read the study in the journal Proceedings of the National Academy of Sciences.

Written by: Douglas Cobb

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