A groundbreaking study unveils the fascinating differences in hand usage between two ancient hominins: Australopithecus sediba and Homo naledi. While Australopithecus sediba roamed the earth approximately 2 million years ago with a mix of ape-like and human-like features, Homo naledi, discovered more recently, thrived between 335,000 and 236,000 years ago, showcasing distinct bone structures that suggest varied grip styles.

Led by Dr. Samar Syeda from the American Museum of Natural History, researchers dug deep into the skeletons of these South African hominins, uncovering clues about their climbing abilities and dexterity. The focus was on nearly complete fossil hand skeletons: the two-million-year-old hand of Australopithecus sediba and a 250,000-year-old hand from Rising Star Cave.

Interestingly, neither species has been linked directly to stone tools yet, but their hand and wrist designs hint at a dexterity level far closer to humans than to modern chimpanzees or gorillas. Dr. Tracy Kivell, a noted researcher at the Max Planck Institute for Evolutionary Anthropology, points out that if stone tools were indeed used in their time, it’s likely these hominins were capable dexterous tool users.

The skeletal remains reflect features advantageous for climbing, leading to passionate debates in paleoanthropology about their actual climbing skills versus inherited traits from their climbing ancestors. To explore this, the team analyzed the internal bone structure of the fingers in both hominin groups, revealing insights into how they might have used their hands.

Remarkably, Australopithecus sediba displayed a bone structure in its finger bones similar to apes, while its thumb and pinky exhibited human-like characteristics. This suggests that it could manipulate objects due to reduced strain during the activities of climbing and grasping.

On the flip side, Homo naledi surprised researchers with a unique blend of human-like and ape-like signals in its finger bones, indicating it likely engaged its hands differently depending on the task—traits reminiscent of modern rock climbers using specific grip styles.

Moreover, the highly curved finger bones of Homo naledi provide additional evidence of its likely climbing capabilities, challenging traditional views on hominin locomotion during its era. Such insights highlight the diverse evolutionary experiments that shaped tool use and climbing adaptations among early humans.

As this research makes waves in the journal Science Advances, it reinforces the complex narrative of human evolution, revealing that it was never a straightforward journey but rather one filled with varied adaptations to ancient environments.