800,000-Year-Old Footprints Found in Desert

Researchers digging in the desert of southeast Eritrea have uncovered what could be the first footprints that are clearly attributed to Homo erectus, a species of hominid widely considered to be a direct ancestor to modern humans.

Estimated to feature a size 12 foot size, the fossilized footprints were possibly made by tall individuals some 800,000 years ago in sandy sediments along the shores of what was once a large lake surrounded by grasslands.

Today the Aalad-Amo site where the H. erectus's prints were excavated by a team of the National Museum of Eritrea and Rome's La Sapienza University is occupied by the semi arid Danakil desert.

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"The prints are preserved on a hardened sandy sediment that was partly flooded. So far we have been able to bring to light a portion of 85 square feet," Alfredo Coppa, the anthropologist from Rome's Sapienza University who led the dig, told Discovery News.

Coppa explained the slab of stone features footprints which move from north to south and possibly belong to several individuals. They may have been stalking an antelope-like animal whose prints were also recognized in the trackway.

"Homo erectus was the only hominid species that inhabited the area at that time. Indeed, these could be the first clearly recognizable H. erectus's footprints," Coppa said.

The large-brained H. erectus is very important to the study of human evolutionary history. The species emerged 1.8 million years ago and went extinct in Africa around 800,000-700,000 years ago. It spread from eastern Africa to the Middle East and Asia, where it may have survived up to 50,000 years ago.

Appearing very similar to those of modern man, the fingerprints from Eritrea may provide important clues on how H. erectus's gait evolved until Homo sapiens, a species physically close to modern humans, came about around 200,000 years ago.

"The prints show toe details, a marked longitudinal arch and an abducted toe, all features distinctive of human feet," Coppa said.

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He noted that footprints can offer a series of insights -- such as information on the body mass, gait and even social behavior if they belong to several individuals -- that skeletal and skull remains can't provide.

But fossilized human prints are extremely rare. In Africa only three footprint sites were discovered. One, found in Laetoli, Tanzania, is 3.7 million years old and represents the earliest direct evidence of hominin bipedalism. The prints were made by Australopithecus afarensis, an hominin that lived between 3.9 and 2.9 million years ago and whose best known specimen is the famous Lucy.

Other two sites in Kenya, at Ileret and Koobi Fora, are dated to 1.5-1.4 million years ago and display prints of different homind species.

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"It is very likely the area around Ileret and Koobi Fora was populated by H. erectus, although also Homo habilis and perhaps members of the Paranthropus genus lived there. On the contrary, the area where our footprints were unearthed was inhabited only by H. erectus, thus the importance of the finding," Coppa said.

He noted that until now no footprint could have been traced back to 800,000 years ago, during the transition between early and mid-Pleistocene.

"Further research is certainly needed and more excavations must be carried out in the area. During the last campaign we also found the fossilized fragmented remains of five or six different Homo erectus specimens," Coppa said.