Hands, it could be argued, were humans’ first useful tool. After all, the construction of all other tools would be impossible without them. While it’s true that apes and even raccoons have hand-like appendages, no other animal possesses the same dexterity and anatomical features that humans do. Even today, the origins of the modern human hand remain unknown. However, a recent discovery from a University of Missouri team may shed some light on how we got to where we are now. They found a new hand bone from a human ancestor who roamed East Africa about 1.42 million years ago, suggesting that this hand evolution occurred far earlier than expected. The bone belonged to Homo Erectus, one of the earlier human species.

“This bone is the third metacarpal in the hand, which connects to the middle finger. It was discovered at the ‘Kaitio’ site in West Turkana, Kenya,” said Carol Ward, professor of pathology and anatomical sciences at MU. The discovery was made by a West Turkana Paleo Project team, led by Ward’s colleague and co-author Fredrick Manthi of the National Museums of Kenya. “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, Neandertals and other archaic humans.”

The new hand bone was found not far from sites where the earliest Acheulian tools have appeared. These tools are shaped stone tools that include stone hand axes believed to be more than 1.6 million years old. The ability to make such tools indicates that the early humans at these sites were probably capable of other complex tasks.

The styloid process helps the hand bone lock into the wrist bones. This allows for greater amounts of pressure to be applied to the wrist and hand from a grasping thumb and fingers. In apes, the lack of the styloid process makes making and using tools much more difficult, and could also increase the risk of early-onset arthritis.

“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,” Ward said. “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. 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.”

These findings are important for better understanding how the human hand emerged over the course of evolution. Specifically, it shows how this ancient ancestor was able to use tools earlier than originally thought. Scientists still don’t have all the answers, but this latest discovery brings them one step closer.