Bocherens and his colleagues analyzed Neanderthal and animal remains from two excavation sites in Belgium. They also looked at the diet of modern humans from the same time period, 45,000–40,000 years ago. The animals included mammoths, woolly rhinoceroses, wild horses, reindeer, European bison, cave hyenas, bears, lions and wolves.
Isotope analysis of the collagen (component of connective tissue) in the various bones demonstrated that the Neanderthals' diet differed markedly from that of other predatory animals living at the same time.
Photos: What Did Prehistoric Humans Eat?
"Previously, it was assumed that the Neanderthals utilized the same food sources as their animal neighbors," Bocherens said. "However, our results show that all predators occupy a very specific niche, preferring smaller prey as a rule, such as reindeer, wild horses or steppe bison, while the Neanderthals primarily specialized on the large plant-eaters such as mammoths and woolly rhinoceroses."
Anthropologists have found weapons, like spears, associated with Neanderthals, who must have had a very organized, group approach to hunt such large prey.