According to a recently published study, early human ancestors, specifically Australopithecus africanus, primarily had a plant-based diet despite previous evidence suggesting meat consumption. The research, led by geochemist Tina Lüdecke from the Max Planck Institute for Chemistry in Germany and the University of Witwatersrand in South Africa, was published in the journal Science.
Lüdecke and her colleagues conducted isotopic analysis on fossilized teeth found in South Africa's Sterkfontein caves, a site rich in hominin fossils often referred to as the Cradle of Humankind. They studied tooth enamel samples from seven Australopithecus individuals dating between 3.3 and 3.7 million years ago. The team compared the enamel's chemical composition with that of contemporary herbivorous and carnivorous animals from the same region, including monkeys, antelopes, hyenas, jackals, and saber-toothed cats.
"The tooth enamel is the hardest substance in the body. It often conserves an isotopic fingerprint of an animal's food," said Lüdecke, as reported by N-TV. Using this isotopic fingerprint, the researchers determined that the enamel composition of Australopithecus was much more similar to herbivores than to carnivores. The finding indicates that these early human ancestors consumed a predominantly plant-based diet.
"Our data challenge the notion that meat was a crucial component of the diet of Australopithecus, despite some species having been found with stone tools and bones with cut marks," said Lüdecke, according to Exclsior.
The introduction of meat into the diet has been considered a milestone in human evolution. Some researchers hypothesize that the incorporation of animal-based foods in early hominin diets led to increased brain size, smaller gut size, and increased stature—all key events in human evolution, as noted by La Vanguardia. However, the findings of this study suggest that meat consumption may have occurred later in the evolutionary timeline than previously thought.
The research team employed a technique that allows for detailed analysis of tiny traces of nitrogen isotopes in tooth enamel, which remain stable even after millions of years. This method provides new insights into the diets of extinct species and promises to reconstruct human meat consumption more accurately than before. "This method is a milestone because the amount of preserved material in these samples is minuscule, and until now, no one had been able to analyze it," said Lüdecke.
Australopithecus, which inhabited eastern and southern Africa from approximately 4.2 million to 1.9 million years ago, had human-like traits such as upright walking but still resembled apes in other respects. They had a brain about one-third the size of modern humans and possessed long arms and curved fingers used for climbing trees. "Although their brains were smaller than ours, their relative brain size was slightly larger than that of modern chimpanzees," added Lüdecke, according to Terra.
The most famous Australopithecus specimen is Lucy, discovered in Ethiopia in 1974 and dating to about 3.2 million years ago. Lucy and her contemporaries were bipedal and walked upright, but they also had facial proportions similar to apes. The study's findings suggest that while Australopithecus may have occasionally consumed animal protein sources like eggs or termites, meat was not a substantial part of their diet.
The researchers acknowledge that their results do not entirely rule out the possibility of occasional meat consumption. "These were plant eaters, mostly," said Lüdecke, as per NPR. She noted that modern primates like chimpanzees and baboons also consume small amounts of meat or insects sporadically. Therefore, it's plausible that Australopithecus did the same, but not in quantities significant enough to impact their evolutionary development.
The study also has implications for understanding when meat consumption became a pivotal part of human evolution. Scientists have had difficulties determining when meat consumption began in the human evolutionary lineage, and the meat consumption of our ancestors is a controversial topic in the scientific community. Lüdecke and her team plan to apply their analysis method to younger and older human species from other hominin sites in eastern Africa or Southeast Asia. "Our new methodology has the potential to answer further central questions of human evolution," said Alfredo Martínez-García, a member of the research team, as reported by Archaeologie Online.
This article was written in collaboration with generative AI company Alchemiq