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.