Tooth Analysis Reveals Ancient Diets

The food preferences of two early human ancestors and another competing species have been elucidated by mass spectrometric analysis of their tooth enamel (Nature, DOI: 10.1038/nature11349). An international team led by Vincent Balter of École Normale Supérieure in Lyon, France, analyzed calcium, strontium, and barium isotopes in fossilized molars. The researchers discovered that two species of Australopithecus, a bipedal ancestor of the Homo lineage, and a concurrent competitor, Paranthropus, had much more diverse diets than their successors. Although all three hominins ranged over a similar-sized territory, Australopithecus ate a variety of both plants and meats before dying out 2 million years ago. On the other hand, the isotopic ratios from subsequent Homo ancestors show that modern human forebears had a predilection for meat—for example, low Ba/Ca levels are characteristic in carnivores, whereas higher Ba/Ca levels are characteristic in herbivores. The competing Paranthropus species preferred a more plant-based diet, the researchers note, which may have “contributed to its demise because it was unable to adapt to the changing environmental conditions that took place approximately 1 million years ago.”