An international team of researchers, including Dominic Stratford from Stony Brook University and the University of the Witwatersrand in South Africa, has made a significant discovery about the diet of Australopithecus. This ancient human ancestor, which lived over three million years ago in South Africa, primarily consumed plant-based foods. The study was published in the journal Science.
The research involved analyzing tooth enamel from seven Australopithecus fossils found at the Sterkfontein Caves. This finding is important because meat consumption is believed to be a key factor in the evolution of larger brain sizes seen in later hominins. However, when early humans began eating meat remains unclear.
The research team included scientists from the Max Planck Institute for Chemistry in Germany and the University of Witwatersrand. They used stable nitrogen isotope data (15N/14N) from tooth enamel to determine Australopithecus's place in the food chain. Typically, an enrichment of 15N indicates a higher position and consumption of animal tissue.
Traditionally, bone collagen or dentin are used for nitrogen isotope analysis but decay rapidly, limiting their use to about 300,000 years. Recent advancements allow sampling of enamel—the hardest tissue that preserves isotopic fingerprints for millions of years.
Stratford explained that this new technique provided direct evidence about ancient hominin diets and helped explore when meat-eating behavior began among them. Comparisons with other animals like monkeys and big cats revealed that while Australopithecus might have occasionally eaten meat, its primary diet was plant-based.
Stratford noted that changes in behavior observed in Australopithecus may not result from increased meat consumption. It suggests regular meat eating emerged later or elsewhere geographically.
“Overall, this work provides clear evidence that Australopithecus in South Africa did not eat significant amounts of meat three million years ago," Stratford stated. "It 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.”