Human Ancestors Put Best Foot Forward 1.5M Years Ago

Feb. 27 -- THURSDAY, Feb. 26 (HealthDay News) -- Anthropologists have uncovered a trail of ancient footprints in northern Kenya believed to represent the oldest evidence to date of an essentially modern, human-like foot.

The footprints date back at least 1.5 million years, according to a report in the Feb. 27 issue of Science.

"Finding footprints in the early stage of human evolution is very rare. They're very fragile and they don't often preserve," explained study co-author John W.K. Harris, a professor of anthropology at Rutgers University in New Brunswick, N.J. "This is only the second finding in 30 years."

"This is not the first time that a footprint has been found that has shouted to us through time, but it certainly is one of the most important," added Jeffrey T. Laitman, distinguished professor and director of anatomy and functional morphology and of gross anatomy at Mount Sinai School of Medicine in New York City. Laitman was not involved with the study.

The features of the footprints indicate that they belonged to the hominid Homo ergaster, or early Homo erectus. These are the oldest footprints that can be linked to mankind's genus, Homo, according to an accompanying perspective article in the journal. This creature had the longer legs and shorter arms of modern man, rather than the longer arms and shorter legs of the more ape-like ancestors.

According to fossil records, the ability to walk on two feet -- called bipedalism -- seems to have emerged about 6 million years ago. But it's unclear when the more human form of bipedalism evolved.

Thirty years ago, in 1978, British archaeologist/anthropologist Mary Leakey discovered 3.75-million-year-old footprints at the Laetoli archaeological site in Tanzania.

But these prints seem to have belonged to a less "modern" bipedal creature, still with the big toe separated from the rest of the toes and with the more ape-like long arms with shorter legs.

And any skeletons of mankind's more modern-proportioned ancestors tend to have lacked foot bones.