Researchers at the Smithsonian National Museum of Natural History have presented the earliest evidence suggesting that some of humanity’s closest evolutionary relatives may have killed and possibly eaten each other around 1.45 million years ago. The findings have been published in Scientific Reports, signaling a significant moment in the study of ancient behavior and hominin interactions. The discovery centers on a single set of remains from a relative of early humans, unearthed in Kenya, that bear 11 distinctive cut marks along the left shin. Careful analysis of 3D reconstructions of the fossil, created from tooth impressions and micro-wear patterns, shows that nine of those marks were produced during butcher-like activities using stone tools. To test this interpretation, researchers compared the fossil’s marks against a comprehensive database consisting of 898 experimentally replicated tooth and tool marks, providing a robust framework for distinguishing human-made cuts from other natural or animal-inflicted markings. A pair of additional marks were attributed to a large predator’s bite, most plausibly from a saber-toothed feline, underscoring the complexity of interactions in ancient ecosystems.
These marks are especially telling because they cluster at the location where the calf muscle attaches to the shinbone. This region is often targeted in butchery to separate a portion of meat efficiently. The pattern suggests intent and technique consistent with carving or removing edible tissue rather than incidental damage from other activities. In their assessment, the researchers note that while the presence of these marks does not conclusively prove the cannibalistic consumption of the leg by the same individual who inflicted them, the anatomical placement aligns with deliberate meat extraction and breaks with some expectations about non-anthropogenic bone damage in very old contexts.
From the available evidence, the team concludes that hominins probably engaged in cannibalistic behavior among their own lineages at least 1.45 million years ago. This interpretation contributes to a broader narrative about early human social dynamics, including competition for resources, intra-species aggression, and the potential for ritual or pragmatic meat sharing within groups. Yet the researchers also emphasize the limits of certainty. The owner of the bone remains unidentified, and it is possible the individual met a lethal end at the hands of a different species, or that the carcass later underwent other postmortem processes that could mimic or obscure original damage patterns. The evolutionary landscape at the time included multiple human species coexisting, such as Neanderthals, Denisovans, Heidelbergers, and Homo erectus, each contributing to a diverse and interwoven family tree. The current finding sits within this broader framework of coexistence, competition, and occasional cross-species interactions that characterized early human evolution.
Genomic analyses in later periods reveal traces of interbreeding among these ancient groups, including Neanderthals and Denisovans, reinforcing the view that multiple hominin lineages intersected and influenced one another in profound ways. Previous work had already shown that members of the genus Homo did not merely share the planet concurrently; they sometimes shared meals as well, with cannibalistic events inferred in various contexts. The new 1.45-million-year timeframe pushes these ideas further back, suggesting that complex social behaviors—nudging, planning, kin-based cooperation, and possibly even conflict—were emerging long before the rise of anatomically modern humans. The implications extend to how researchers think about social intelligence, resource strategies, and the ecological pressures that shaped early hominin life and diet. The story is far from finished, and future discoveries may refine or revise the interpretation as more fossil material and contextual data come to light.
Beyond the immediate bone in question, scientists acknowledge that the wider picture of early human behavior remains incomplete. A key challenge remains the attribution of specific bones to individual individuals or species, given the fragmentary fossil record and the passage of time. The study’s authors refrain from asserting that cannibalism was a universal or frequent strategy among all hominin groups of that era. They also stress that interspecies encounters were not only possible but likely part of daily life for multiple genera during stretches of shared habitats. The genomic legacies of these interactions are still visible in modern humans, where traces of ancient admixture with archaic relatives persist in the genome and help explain certain biological and phenotypic traits observed today. The evolving picture of early hominins thus blends fossil morphology, behavioral inference, and genetic echoes to build a richer understanding of how our distant relatives lived, fought, ate, and persisted in a world full of competing species and shifting resources. The dialogue between paleontology and genomics continues to illuminate the deep roots of human behavior and nutrition, offering a window into the resilience and adaptability that characterize the human lineage across millions of years.
Additional notes from the researchers indicate that ancient scientists whose work contributed to these interpretations recognized many forms of social interaction among early hominins, including cooperative hunting and scavenging, food sharing, and sometimes aggressive encounters. The long arc of discovery shows that cannibalism, when it appeared, was part of a broader spectrum of behavior that existed well before modern humans emerged. The emerging narrative also points to the ways in which carnivory, tool use, and social organization intersected at crucial moments in evolutionary history. In light of this evidence, scholars are increasingly attentive to the idea that early human life was not monolithic but a tapestry of diverse strategies adapted to distinct environments and resource pressures. The take-home message is clear: cannibalism among hominins has deep roots and was possibly more common than once believed, shaping, in subtle and overt ways, the trajectory of human evolution.