Early Human Ancestors Relied on Plants, Not Meat
New research shows Australopithecus primarily ate plants, with little evidence of regular meat consumption.

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New research published in Science suggests that Australopithecus, a genus of early human ancestors, primarily consumed plants, with minimal evidence of meat consumption. This study analyzed nitrogen isotope ratios in the fossilized tooth enamel of seven Australopithecus individuals who lived between 3.7 and 3.3 million years ago in southern Africa.
The findings challenge long-held assumptions about the dietary habits of early hominins, emphasizing a reliance on plant-based resources during this period of human evolution.
Australopithecus
A genus of early human ancestors that lived approximately 4 to 2 million years ago. Australopithecus is known for its bipedal locomotion and is considered a precursor to later hominin species, including Homo erectus.
Nitrogen isotopes
Atoms of nitrogen with differing numbers of neutrons. Nitrogen-15 (15N) and nitrogen-14 (14N) ratios are used to infer dietary habits, as they reflect an organism’s trophic position in the food chain.
Tooth enamel
The hardest substance in the mammalian body, tooth enamel protects teeth and can preserve chemical signatures of an individual’s diet over millions of years.
A closer look at nitrogen isotope ratios
Researchers from the Max Planck Institute for Chemistry and the University of the Witwatersrand in South Africa utilized a novel technique to measure nitrogen isotope ratios in fossilized enamel. Nitrogen isotopes (15N and 14N) provide insight into an organism's position in the food web. Herbivores exhibit lower nitrogen isotope ratios than carnivores, whose diets include animal protein.
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Subscribe for FREEThe Australopithecus samples analyzed displayed nitrogen isotope ratios similar to herbivores and significantly lower than carnivores of the same era, suggesting these hominins primarily consumed plant-based foods. While occasional consumption of animal proteins such as eggs or insects cannot be entirely ruled out, the evidence indicates that meat was not a regular dietary component.
Innovative methods reveal ancient diets
The study represents a significant advancement in dietary analysis of ancient species. Traditional nitrogen isotope analysis has been limited to organic materials no older than tens of thousands of years, but the team employed a method developed at the Max Planck Institute to analyze enamel dating back millions of years.
The analysis compared Australopithecus enamel with contemporaneous animal species, including herbivores and predators, further corroborating the plant-based diet hypothesis.
Evolutionary implications of a plant-based diet
The shift to meat consumption in human evolution has been associated with developments such as increased brain volume and tool use. However, the findings indicate that Australopithecus did not rely on large prey for sustenance, distinguishing them from later hominins like Neanderthals, who exhibited regular hunting behaviors.
The absence of significant meat consumption among Australopithecus suggests that their evolutionary adaptations, such as bipedalism and tool use, were not initially tied to a high-protein diet. Instead, the dietary flexibility and reliance on plant resources may have been crucial for survival in diverse environments.
Future research directions
The study opens new avenues for understanding the dietary evolution of hominins. The researchers plan to expand their analyses to other species and regions, aiming to pinpoint when meat consumption became a regular dietary feature.
By investigating fossilized tooth enamel from eastern and southern Africa, as well as Southeast Asia, they hope to uncover patterns linking diet with key evolutionary developments, such as brain expansion.
Reference: Lüdecke T, Leichliter JN, Stratford D, et al. Australopithecus at Sterkfontein did not consume substantial mammalian meat. Science. 2025;387(6731):309-314. doi: 10.1126/science.adq7315
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