Understanding what our ancestors ate millions of years ago means diving into the heart of human evolution. The diet of early hominids indeed played a key role in brain development, the acquisition of bipedalism and our modern biological adaptations. A recent study carried out by a team of researchers from the Max Planck Institute offers us a fascinating insight into the diet of australopithecines, a group of hominids which could be at the origin of our own genus, Homo.
Who were the australopithecines?
THE australopithèqueswhich lived in Africa around 2 to 4 million years ago, occupy an essential place in our evolutionary history. These hominids were distinguished by a fascinating combination of both human and apelike traits. Their partially bipedal posture allowed them to walk upright short distances, but they also retained adaptations for arboreal life, such as long arms and sturdy hands for climbing trees. Their brains, although smaller than those of modern humans (around 400 to 500 cm³), also already showed signs of evolving towards increased cognitive abilities.
Australopithecines lived in diverse environments, ranging from dense forests to open savannahs, and they likely evolved great adaptability to exploit diverse food resources. These traits combined make them a key step in the gender transition Homowhich will give rise to our own species.
The fossils studied in this research come from the the Sterkfontein cavein South Africa, a site rich in paleontological discoveries. The teeth analyzed date from 3.3 million yearsat a period when australopithecines cohabited with other mammals in a wooded savannah environment. Their diet has long remained the subject of debate, due to lack of direct evidence. However, this new study provides precise answers about their eating habits.
Analyzing tooth isotopes
To reconstruct the diet of australopithecines, the researchers relied on an innovative isotope analysis method. This technique makes it possible to study the proportions of nitrogen and carbon isotopes present in fossil tooth enamel.
Nitrogen isotopes, particularly nitrogen-15, play a crucial role in this process. In fact, herbivores store more nitrogen-15 in their bodies than the plants they consume, while carnivores, by consuming herbivores, accumulate even more nitrogen-15. Thus, the proportions of this isotope make it possible to determine whether an animal was herbivorous, carnivorous or omnivorous.
The results of the study paint the picture of a complex and varied diet. Contrary to popular belief, australopithecines consumed little or no meat. Their diet was dominated by C3 plantssuch as fruits, leaves and seeds from wooded areas. The researchers also identified the occasional presence of C4 plants, adapted to warmer and drier climates, such as certain grasses.
-Another intriguing aspect of this study is the Australopithecine diet variability. Nitrogen isotopes show high diversity between individuals, which could reflect seasonal variations or geographic differences. For example, some australopithecines appear to have consumed legumes, which have particularly low levels of nitrogen-15. Others may have incorporated invertebrates, such as termites, an accessible protein source in the savannah.
These results show that, although they were essentially vegetarians, australopithecines were opportunistic and adapted their diet to available resources. This dietary flexibility may have been a major evolutionary asset that allowed them to survive in changing environments.
Implications for human evolution
The diet of our ancestors is a central subject for understanding human evolution. For a long time, it was believed that the introduction of meat into the diet was the main driving force behind the development of the brain and bipedalism. However, this study qualifies this idea. Australopithecines, despite their vegetarian diet, survived and thrived for millions of years.
It is possible that changes in diet, notably the gradual addition of meat, occurred later in our lineage, with the emergence of the genus Homo. These dietary adaptations would then have made it possible to support the increasing energy needs linked to the increase in brain size.
This research also highlights the importance of dietary diversity in human evolution. Australopithecines were not limited to a single food source; they exploited a wide variety of resources, from plants to insects. This ability to adapt to environmental conditions may be one of the factors that allowed our ancestors to expand into diverse habitats across Africa and beyond.
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