prehominin

prehominin is a protein that was first identified in the analysis of adipose tissue from a 3.2 million year old hominin fossil recovered from the Koobi Fora region in Kenya. The protein was detected using mass spectrometry and shows a high degree of sequence similarity to the human hormone leptin, with a few amino acid substitutions that are thought to be adaptive to cooler, semi-arid environments. In 2025, a team led by Dr. Aya Zinat of the University of Nairobi published the initial characterization of prehominin in the journal Nature Communications. The study reported that the protein’s survival in the fossil record is likely due to exceptional preservation conditions and the low metabolic rate of the specimen.

Functionally, prehominin is believed to play a role in energy balance regulation, as its structure includes the conserved leptin receptor-binding domain. Comparative models suggest that the subtle changes in the protein’s C‑terminal region may alter receptor affinity, potentially influencing food intake and body temperature in early hominins. Because of these putative functional differences, prehominin has been cited in discussions of dietary adaptation during the Plio-Pleistocene emergence of Homo species. Subsequent work by Li and Matthews (2026) confirmed the presence of prehominin in a second, independently dated specimen, strengthening the argument that the protein evolved early in the hominin lineage.

The discovery of prehominin has prompted a re‑examination of the protein evolution hypothesis for early hominins. While its exact physiological role remains to be fully elucidated, prehominin is considered a key marker for understanding the evolutionary pressures that shaped human metabolic pathways. Researchers continue to investigate the protein’s genetic sequence and potential regulatory elements in extant primate genomes.