It was more than 14 million years ago that ancient apes departed Africa and began radiating throughout Europe and Asia, according to scientists. So why don't we see apes in Europe today?
Researchers in Spain argue that a variety of great apes went extinct in Europe about 7 million years ago because the qualities that allowed them to spread throughout the Old World were the same that sealed their fate.
In a paper published Wednesday in the journal PLOS One, researchers say an analysis of the enamel on ancient ape molars shows that dietary specialization among different species left them unable to adapt to a rapidly cooling environment at the close of the Miocene epoch.
"Overall, our analysis supports the view that the same dietary specialization that enabled Western Eurasian hominoids to face progressive climatic deterioration was the main factor ultimately leading to their extinction when more drastic paleoenvironmental changes took place," wrote lead author Daniel DeMiguel, a researcher at the Institut Català de Paleontologia Miquel Crusafont in Barcelona, and his colleagues.
Researchers examined microscopic pits and scrapes on the enamel of ancient ape molars to determine whether they ate dense foods, like nuts and hard-shelled fruits, or leaves, grasses and soft fruits.
DeMiguel and his colleagues concluded that leaves and stems were not a primary diet of any of the various species of ape in Europe or western Asia, as previously believed.
Instead, the authors argue that while the apes ate hard-shelled fruits and seeds when they first entered Europe and Asia, they later diversified, eating soft fruits as well as hard foods.
Researchers say this diversification was probably the result of a changing environment and competition over millions of years, as the different species settled into specific areas.
As the Miocene epoch drew to a close, however, even larger climactic and environmental changes occurred: Subtropical plants were replaced by seasonal deciduous trees.
Unable to adapt to a diet of leaves, the European apes eventually disappeared, the authors argue.
"The extinction of hominoids in Europe was ultimately related to an increase in environmental uniformity and the resulting loss of suitable habitats," the authors wrote.