Australopithecus had a varied but plant-based diet, as indicated by stable isotope data analysis from seven human specimens collected in Sterkfontein, South Africa, 3.5 million years ago.

“Tooth enamel is the hardest tissue in the mammalian body and can preserve the isotopic fingerprint of an animal’s diet for millions of years,” says geochemist Dr Tina Lüdecke from the University of the Witwatersrand. said.

“When animals digest food, a biochemical reaction involves light isotopes of nitrogen (¹⁴yeah). ”

“Therefore, the breakdown products produced in their bodies include a high proportion of ¹⁴N.”

“When these light nitrogen compounds are excreted in urine, feces, or sweat, the proportion of heavy nitrogen increases (¹⁵N) It ​​provides the body with this light nitrogen compared to the food it takes in. ”

“This means that herbivores have higher nitrogen isotope ratios than the plants they consume, and carnivores have higher nitrogen isotope ratios than their prey.”

“Therefore, the higher the ¹⁵From N ¹⁴The higher the N ratio in the tissue sample, the higher the trophic position of the organism in the food web. ”

Nitrogen isotope ratios have long been used to study the diet of hair, nails, bones, and many other organic materials in modern animals and humans.

However, in fossil materials, these measurements have until now been limited to samples only tens of thousands of years old, as the organic material degrades over time.

In the new study, Luedecke and colleagues used a new technique to measure nitrogen isotope ratios in the enamel of fossilized teeth that are millions of years old.

They found that the nitrogen isotope ratio in tooth enamel was Australopithecus Abundances varied but were consistently low, similar to herbivore populations, and much lower than modern carnivore populations.

They conclude that the diets of these hominins, although diverse, consisted largely or exclusively of plant-based foods.

Therefore, Australopithecus did not regularly hunt large mammals, as Neanderthals did millions of years later, for example.

Although researchers cannot completely rule out the possibility that they occasionally consumed animal protein sources such as eggs or termites, there is evidence that their diet was primarily vegetarian.

“Our method opens up exciting possibilities for understanding human evolution and has the potential to answer important questions, such as when did our ancestors start incorporating meat into their diets?” And was the onset of meat eating associated with an increase in brain volume?” said Dr. Alfredo Martínez García, a researcher at the Max Planck Institute for Chemistry.

“This study represents a major step in extending our ability to better understand the diets and nutrient levels of all animals to multi-million-year scales.”

“This study provides clear evidence that the diet did not include large amounts of meat.”

“A pioneering application of this new method was pioneered at the Sterkfontein site, which continues to make fundamental contributions to science 89 years after the first hominin fossils were discovered there by Robert Bloom. We are honored to have received this recognition,” said Professor Dominic Stratford, Director of the Center. Research in Sterkfontein Cave.

of study Published in a magazine science.

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Tina Ludecke others. 2025. Australopithecus In Sterkfontein, very little mammalian meat was consumed. science 387 (6731): 309-314;doi: 10.1126/science.adq7315