Extinct ancestor wasn't so finicky.

Many anthropologists assume that from around 3 million to 1 million years ago, the human evolutionary family consisted of two sharply contrasting lineages. The genus Homo adapted flexibly to new environments and ate a variety of foods, heralding the rise of people. In contrast, a big-jawed and relatively small-brained hominid known as Paranthropus consumed mainly nuts and other hard foods, causing it to die out as these resources became scarce in African habitats.

Paranthropus exhibited at least as much dietary and behavioral flexibility as ancient Homo did, contend Bernard Wood of George Washington University in Washington, D.C., and David Strait of New York College of Osteopathic Medicine in Old Westbury. Both lineages ate from a broad menu, but Paranthropus added more hard foods to its diet over time, while Homo acquired a stronger taste for meat, the scientists propose in the February Journal of Human Evolution.

This revisionist view of hominid evolution is partly based on analyses of diet-sensitive chemical elements, such as strontium and calcium, extracted from fossils. The findings indicate that Paranthropus consumed plants and possibly meat, as well as seeds, nuts, and tubers, Wood says. Fossils of hands suggest that Paranthropus could have made stone tools, as ancient Homo species did, he adds. Such implements would have enabled the hominids to crush or grind foods for easier consumption.

Moreover, only three Paranthropus species evolved over a roughly 2-million-year span. That relatively low number for a hominid lineage underscores the likelihood that each Paranthropus species exploited diverse dietary resources and survived for hundreds of thousands of years or more, Wood says.--B.B.