Grains might have been an important part of human diets much further back in our history than previous research has suggested.
Although cupcakes and crumpets were still a long way off during the Middle Stone Age, new evidence suggests that at least some humans of that time period were eating starchy, cereal-based snacks as early as 105,000 years ago. The findings, gleaned from grass seed residue found on ancient African stone tools, are detailed online Thursday in Science.
Researchers have assumed that humans were foraging for fruits, nuts and roots long before 100,000 years ago, but cereal grains are quite a new addition to the early prehistoric gastronomic picture. "This broadens the timeline for the use of grass seeds by our species," Julio Mercader, an assistant professor at University of Calgary's Department of Archeology and author of the paper, said in a prepared statement.
Plant domestication, most scientists think, made its debut some 10,000 years ago, with grain storage cropping up about 11,000 years ago. An ancient site in Israel yielded a hearty collection of grains, which were dated to about 23,000 years ago, according to a 2004 Proceedings of the National Academy of Sciences paper. But such an early appearance of wild cereals in the human diet—as this new paper proposes—would push the assumed date of substantial grass-seed eating back more than 70,000 years.
So just what were these gatherers purportedly gnashing?
Mercader and a team from Mozambique's University of Eduardo Molande had uncovered hundreds of ancient artifacts in a limestone cave near Lake Nissa in Mozambique. Analyzing the surface of 70 of these tools, Mercader found some 2,370 granules of plant starch, which, he reasons, could not have accidentally come from growing plants in such dark reaches of the cave. And the fact that so many of the tools had a coating is evidence of at least some processing to make the seeds more edible.
"The inclusion of cereals in our diet is considered an important step in human evolution because of the technical complexity and the culinary manipulation that are required to turn grains into staples," Mercader said. Indeed, a descendent of the wild sorghum found on the tools still makes up a large portion of modern diets in sub-Saharan products including breads, porridge and even beer.
Other tidbits that these hungry humans appear to have been dining on during that period include the African false banana, pigeon peas, wild oranges, African wine palm and the African potato, the researchers concluded. These finds are "proof of an expanded and sophisticated diet much earlier than we believed," Mercader said. And grain consumption was the first step toward grains' domestication—and, eventually, cupcakes.
Image of sorghum courtesy of J. Mercader