Cut marks on 1.6-million-year-old bones reveal early humans moved and processed meat in Kenya

A new study from northern Kenya adds fresh detail to how early humans found, processed, and consumed meat about 1.6 million years ago. The findings suggest these hominins were not random scavengers picking over abandoned carcasses. Instead, they followed repeated food-gathering behaviors across different habitats, showing planning and flexibility in how they used animal resources.

The research, published in the journal Proceedings of the National Academy of Sciences, focused on animal fossils from FwJj 80, a site in the Koobi Fora Formation. This area is one of the most important regions for studying early human evolution because it preserves fossils of hominins, animals, and ancient environments from the Plio-Pleistocene.

Researchers analyzed more than 1,000 fossil bones, mostly from antelopes and other grazing animals. Using magnification, they studied tiny marks left on the bones. Cut marks made by stone tools and percussion marks from hammerstones showed clear signs of butchery. Tooth marks from carnivores appeared far less often, suggesting predators played only a limited role in modifying these remains.

Many of the clearest cut marks appeared on the shafts of leg bones, where large amounts of meat would have been attached. This pattern suggests early Homo reached carcasses before carnivores stripped them. The animals were not already reduced to scraps when humans arrived.

The team also found many broken long bones with impact marks linked to marrow extraction. Bone marrow offered a dense source of fat and calories, which would have been especially useful for hominins with growing energy demands. Access to meat and marrow has long been considered an important factor in the evolution of larger brains in the genus Homo.

The composition of the fossil collection also tells an important story. Leg bones were much more common than skulls, ribs, and vertebrae. If animals had been butchered and eaten where they died, a more complete skeleton would be expected. Instead, the evidence suggests early humans selected nutrient-rich limbs and transported them elsewhere.

Researchers believe these hominins likely moved the best cuts of meat away from dangerous kill sites into safer places, possibly near rivers or sheltered vegetation. This behavior reduced the risk of conflict with large predators while allowing more careful processing of food.

FwJj 80 comes from the KBS Member of the Koobi Fora Formation, dated to about 1.87 to 1.56 million years ago. Although the region has yielded important hominin fossils, earlier layers from the KBS Member have produced fewer well-preserved animal assemblages for detailed study. This makes FwJj 80 especially important because researchers could examine butchery patterns, marrow extraction, and transport decisions in a way not previously possible for this time period.

The results closely match patterns already documented in younger deposits from Koobi Fora’s Okote Member, dated between about 1.56 and 1.38 million years ago. Similar evidence of early carcass access, limb transport, and marrow extraction appears in both layers, showing continuity in behavior over long stretches of time.

The team also compared FwJj 80 with two older East African sites, FLK Zinj in Tanzania, dated to around 1.84 million years ago, and Kanjera South in Kenya, about 2 million years old. Across these sites, early humans repeatedly followed similar strategies despite environmental differences.

At the time, Koobi Fora included open grasslands as well as wetter floodplain areas with dense vegetation. The persistence of these food-related behaviors across shifting landscapes suggests early Homo maintained a stable but flexible foraging strategy.

This repeated access to high-quality animal foods likely supported major changes in human evolution. Reliable calories from meat and marrow would have helped meet the metabolic demands of larger brains. Food transport and shared processing areas may also have encouraged more organized group behavior, adding another piece to the story of how early humans adapted and expanded across ancient African landscapes.