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Using cutting-edge technology, CU paleoanthropologist helps unravel what humans’ ancient predecessors actually ate, helps show ‘how we became us’

Those who eat like “cavemen” or follow a “Paleo Diet” will get “Neanderthin,” some weight-loss books contend. The premise is that people should eat like their ancient forebears, avoiding carbs and favoring lean meat and vegetables.

But this broth lacks something: Scientists are still figuring out what early hominins actually ate. And while the picture is not complete, it is more complex than previously thought.

Matt Sponheimer, associate professor of anthropology at the University of Colorado, has helped increase human understanding of what ancient hominins ate. Research on ancient hominin diet, he notes, is the study of “how we became us.”

As hominins migrated throughout ancient Africa, some began using tools, which could suggest that our relatives were hunting and eating meat.

But, “If you look at stone tools, you’re going to over-emphasize animal foods,” Sponheimer says. “We have good reason to believe that most ancient diets were plant-based.”

This view differs from what emerged after the 1924 discovery of Australopithecus africanus, an extinct hominin, in South Africa. Australopithecus, which had human characteristics, was found on the edge of the Kalahari Desert “in an area no living ape could survive,” Sponheimer says.

The hostile environment and the presence of tools at some hominin sites led to the inference of ancient hominins as hunters. As one writer famously proclaimed: “Not in innocence, and not in Asia, was mankind born.”

Not so fast, Sponheimer suggests. “When we find stone tools, there are often multiple hominins around, and so who was using them?” Scientists don’t know.

Further, the earliest evidence of tool usage is 2.5 million years ago, but there are millions of years of hominin evolution prior to that. Tools might also have been used for non-hunting purposes or for occasional hunting. By themselves, stone tools are not rock-solid proof of highly carnivorous hominin diets.

Hominin anatomy gives other dietary clues. Paranthropus boisei, for instance, had huge jaws, big teeth, and massive muscles of mastication. This led to the idea that Paranthropus boisei ate hard foods like nuts and seeds along with low-nutrient, high-fiber foods—stuff that required a lot of chewing.

However, steadily growing volume of data indicates that hominin anatomy tells us what they were able to eat, not necessarily what they did eat. For instance, this year, Sponheimer was part of a team of researchers that foundParanthropus boisei, nicknamed “Nutcracker Man,” probably didn’t eat nuts. Instead, the hominin predominantly ate tropical grasses or sedges.

“Nutcracker Man’s” diet was almost the same as that of ancient zebras, pigs, warthogs and hippos, the National Science Foundation, which sponsored the research, reported.

Sponheimer, who churns out colorful phrases as routinely as important journal articles, put it this way: “Frankly, we didn’t expect to find the primate equivalent of a cow dangling from a remote twig of our family tree.”

Headline writers riffed on that theme. As Discover magazine wrote, “Our ancient cousin ‘Nutracker Man’ actually ate like a cow.”

In a paper published in Science this October, Sponheimer and other researchers added more depth to the picture. The team found that hominin diets varied by where they lived.Paranthropus groups in eastern Africa probably ate grasses or sedges, while those in South Africa probably ate harder food like nuts and seeds.

These results stem from analysis of dental microwear and carbon isotopes and were surprising, given that �ʲ������Գٳ���DZ�ܲ�’&�Բ�����;anatomy did not vary much.

“Frankly, I don’t believe anyone would have predicted such strong regional differences,” Sponheimer told a CU editor. “But this is one of the fun things about science—nature frequently reminds us that there is much we don’t yet understand.”

“The bottom line is that our old answers about hominid diets are no longer sufficient, and we really need to start looking in directions that would have been considered crazy even a decade ago,” he added.

“We also see much more evidence of dietary variability among our hominid kin than was previously appreciated. Consequently, the whole notion of hominid diet is really problematic, as different species may well have consumed fundamentally different things.”