The researchers examined 173 teeth from 11 species of hominins, which include human ancestors and extinct relatives. What the tale of the teeth reveals is this: About 3.5 million years ago, our ancestors started switching from the ape diet — leaves and fruit — to grasses and grass-like sedges. In the terminology, they switched from C3 plants to C4 plants. Around 4 million years ago, our ancestors ate about 90 percent fruit and leaves, a diet nearly identical to that of chimps. But 1.4 million years ago, grasses made up around 55 percent of some Homo diets. This switch may mirror changes that were going on in the local environment. Around 10 million years ago, NPR reports, Africa’s forests began thinning into grassy savannas. Over millions of years, animals that lived there, including hominins, adapted, switching to a diet predominantly composed of grass. Some dietary questions remain, NPR reports: Now, one thing this carbon isotope technique can’t tell is whether Australopithecus just grazed like a bunch of antelope, or whether they ate the antelope that did the grazing. The carbon signal from the C4 plants gets taken up in animal (or insect) tissue and passed on to whoever eats that tissue (thus, when we eat chicken, we’re pretty much eating corn). Read more: blogs.smithsonianmag/smartnews/2013/06/human-ancestors-grazed-on-grass/#ixzz2YueATQqb Follow us: @SmithsonianMag on Twitter
Posted on: Sat, 13 Jul 2013 08:36:29 +0000