Footprints offer clues about daily hominid life

Impressions show watering hole was a popular gathering spot for human ancestors, many other animals

ST. LOUIS — A good 1.5 million years before spring break or the America’s Cup, guys liked to cluster by the water. Male hominids living in East Africa that long ago hung out in groups by a large lake that also attracted a variety of animals, researchers reported March 27 at the annual meeting of the American Association of Physical Anthropologists. The evidence: footprints, and lots of them.

A team led by Brian Richmond of the American Museum of Natural History in New York City first excavated 1.5-million-year-old hominid footprints near Kenya’s Lake Turkana in 2007. Last year, the researchers discovered 20 more comparably ancient footprint sites in the same area. Most foot impressions belonged to antelopes, pigs, hippos and waterbirds, such as pelicans. But sets of footprints from groups of hominids, probably some species of the genus Homo, turned up surprisingly frequently, Richmond said. Each site contains tracks of two or more individuals.

Only the hominids, unlike the other animals, traveled east to west and west to east, perhaps skirting the edge of what was once a substantial lake, he suggested. Hippo tracks run perpendicular to those of hominids, possibly marking the larger animals’ lake visits and departures.

The hominid prints at all 20 sites appear to be those of tall males. If that’s the case, adult males must have been involved in some sort of cooperative activity, Richmond suggested. But whether they were hunting or doing something else remains a mystery.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

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