Out of Africa, Not Once But Twice

Based on the findings, which have been accepted for publication in the Journal of Human Evolution, he concludes the first human group to have left Africa "may well have been a separate subspecies" of modern human.

Prior research could support that contention. At an Ethiopian village called Herto, archaeologists recently found fossils of individuals who were more robust than modern humans. They date to 154,000 to 160,000 years ago.

Erik Trinkaus, a professor of physical anthropology at Washington University in St. Louis, thinks the new paper "is an interesting analysis," but he told Discovery News that he hopes it will be redone with more fossils, "a better set of measurements and with the caveat that there is a huge (time) gap between his relevant samples."

Schillaci neglected one of the earliest known Southeast Asian humans in his study, noted Trinkaus.

This individual "predates the Australian fossils and is the only relevant fossil that we have between Israel and Indonesia for the relevant time period," he explained, adding that "we have no relevant fossils between 100,000 and 30,000 from the Levant [Near East] and Australia to sort out what might have been happening there."

Chris Stringer, a paleontologist at the Natural History Museum in London, however, expressed fewer reservations.

"This is a very interesting and important study that provides much food for thought," Stringer told Discovery News. "It revisits in more detail and with new approaches something which several researchers have previously noted -- certain early modern samples...seem closer to very early H. sapiens in Israel and Africa than to other early modern samples around the world."

Stinger isn't yet convinced that the Ethiopian fossils and early Australian/Indonesian individuals provide evidence of a new human subspecies. The rigors of dealing with prehistoric life might have simply resulted in sturdier bodies.