Australopithecus Didn’t Regularly Eat Meat, New Study Shows | Sci.News

Australopithecus had a variable but plant-based diet, according to an analysis of stable isotope data from seven hominin specimens dating back 3.5 million years from Sterkfontein in South Africa.

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

“When animals digest food, biochemical reactions favor the light isotope of nitrogen (¹⁴N).”

“Consequently, the degradation products that are produced in their body contain high proportions of ¹⁴N.”

“The excretion of these light nitrogen compounds in urine, feces, or sweat increases the ratio of heavy nitrogen (¹⁵N) to this light nitrogen the body in comparison to the food it eats.”

“This means that herbivores have a higher nitrogen isotope ratio than the plants they consume, while carnivores in turn have a higher nitrogen isotope ratio than their prey.”

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

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

However, in fossil material, these measurements have previously been limited to samples that are only a few tens of thousands of years old due to the degradation of organic material over time

In the new study, Dr. Lüdecke and colleagues used a novel technique to measure nitrogen isotopes ratios in fossilized tooth enamel that is millions of years old.

They found that the nitrogen isotope ratios in the tooth enamel of Australopithecus varied, but were consistently low, similar to those of herbivores, and much lower than those of contemporary carnivores.

They conclude that the diet of these hominins was variable but consisted largely or exclusively of plant-based food.

Therefore, Australopithecus did not regularly hunt large mammals like, for example, Neanderthals did a few million years later.

While the researchers cannot completely rule out the possibility of occasional consumption of animal protein sources like eggs or termites, the evidence indicates a diet that was predominantly vegetarian.

“Our method opens up exciting possibilities for understanding human evolution, and it has the potential to answer crucial questions, for example, when did our ancestors begin to incorporate meat in their diet? And was the onset of meat consumption linked to an increase in brain volume?” said Dr. Alfredo Martínez-García, a researcher at the Max Planck institute for Chemistry.

“This work represents a huge step in extending our ability to better understand diets and trophic level of all animals back into the scale of millions of years.”

“The research provides clear evidence that its diet did not contain significant amounts of meat.”

“We are honored that the pioneering application of this new method was spearheaded at Sterkfontein, a site that continues to make fundamental contributions to science even 89 years after the first hominin fossils were discovered there by Robert Broom,” said Professor Dominic Stratford, Director of Research at the Sterkfontein Caves.

The study was published in the journal Science.

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Tina Lüdecke et al. 2025. Australopithecus at Sterkfontein did not consume substantial mammalian meat. Science 387 (6731): 309-314; doi: 10.1126/science.adq7315