Recent research has shed light on the unique adaptations of the hands of two ancient human relatives, Homo naledi and Australopithecus sediba. Ph.D. student and lead author Samar Syeda’s new study illuminates the distinctive features of the primitive finger bones. This new research sheds light on how these early humans likely employed their hands in their locomotion and crafting tools.
Homo naledi, which lived as recently as 250,000 years ago, had strangely highly curved finger bones. That kind of curvature is highly unusual, especially when you consider that it was active at the same time as some of the very first Homo sapiens. The mechanical analysis shows that Homo naledi’s hands were the most agile and dexterous, but more adapted for climbing. Or they could have used more crimp-style grips, as today’s rock climbers do. This conclusion implies that they would have ascended rocky outcrops. Perhaps because they were forced to, these activities would have significantly contributed to their ability to survive in a hostile environment.
For example, Australopithecus sediba, which lived about two million years ago, showed less dexterity in the hands and flexibility of the foot compared to earlier hominins. Both species possessed the same ape-like features in their upper limbs that would have benefited them while climbing, and their adaptations were quite different from one another. What we learned from Australopithecus sediba is that Australopithecus sediba hands were adapted for more delicate tasks than those of Homo naledi. This important distinction highlights a key difference in the evolutionary trajectories of these two hominin taxa.
These findings provide important information regarding the internal cortical thickness of digit bones. This paints a huge picture, telling you exactly how these ancient relatives were interacting with their environment. The research results suggest that both Homo naledi and Australopithecus sediba did more with their hands than simply navigate their environments. They equally deftly put them to use for tool-making and mastication (chewing). Given the widely varied habitats they may have adapted to, as well as their enormous size, these capabilities would have been essential for locating food resources.
In other words, consciousness has reached homo naledi long before they could discover themselves. Only a few years prior—in 2010—they had discovered the new species Australopithecus sediba at the Malapa site. Their comparative study of their diverse hand structures provides insight into the evolutionary adaptations that led to the shaping of our human ancestors.