Ape-like hominids living more than a million years ago were not the picky eaters scientists once thought.
They ate widely, selecting grasses and tubers at times, gnawing on fruit and leaves and maybe even animals at others, according to a new study by a research team that includes University of Colorado scientists.
The discovery challenges a long-held theory that the choosy habits of 100-pound hominids called Paranthropus robustus drove them to extinction.
“This is the first study to paint a portrait of an early hominid eating its way across a varied landscape,” said Matt Sponheimer, an anthropologist at CU-Boulder.
“None of us involved in the study dreamed Paranthropus would have had such a variable diet,” he said.
Sponheimer’s team published their findings in today’s issue of Science.
A new technique for analyzing teeth, outlined in the paper, may also answer other questions about hominid behavior – from how long they nursed babies to whether young males left their communities, Sponheimer said.
Primate teeth grow for many years during an individual’s lifetime, creating microscopic layers analogous to a tree’s rings, Sponheimer said.
The types of foods the creatures eat are chemically etched into those layers.
So Sponheimer’s team used a technique called laser ablation to peel away tiny strips of Paranthropus’ teeth, and they studied the strips’ precise chemical composition to see what the creatures were eating over time.
“Lots of us have been doing work on paleo diets, but it’s always a snapshot,” he said. “The problem is, of course, that individuals are dynamic. For the first time, we can take a real dynamic look.”
Paranthropus – which stood about 4 feet and co-existed with human ancestors in the genus Homo – switched food regularly, the scientists discovered.
Previously, many assumed the creatures fed almost exclusively on tough plants. That could explain Paranthropus’ enormous jaw muscles and huge teeth, and why the hominids disappeared when Africa’s climate dried up and food availability changed.
“Thus, other biological, social or cultural differences may be needed to explain the different fates of Homo and Paranthropus,” the scientists concluded in their paper.
In a commentary piece in Science, Stanley Ambrose, an anthropologist at the University of Illinois at Urbana, said the research was “blazing a new trail.”
Staff writer Katy Human can be reached at 303-954-1910 or khuman@denverpost.com.
