An article published in the journal Scientific Reports ages the fossilized sediment tracks found a few years ago on a Cretan beach near the village of Trachilos. The scientists, an international team led by researchers from the University of Tübingen (Germany), have used geophysical and paleontological methods to date these footprints, which represent the oldest direct evidence we have of the existence of a human-like foot used for walking. .
“The tracks are almost 2.5 million years older than the tracks attributed to Australopithecus afarensis (Lucy) from Laetoli in Tanzania,” explains Uwe Kirscher, one of the authors. This puts the Trachilos footprints the same age as the fossils of the Kenyan Orrorin tugenensis , which walks upright. Findings related to this biped include femurs, but there are no foot bones or footprints.
This was the foot of our ancestors
The dating of the Cretan footprints therefore sheds new light on the early evolution of human wandering more than six million years ago. “The oldest human foot used to walk upright had a ball, with a strong parallel big toe and successively shorter lateral toes,” explains Per Ahlberg, a professor at Uppsala University and a co-author of the study. “The foot had a shorter sole than Australopithecus. An arch had not yet been pronounced and the heel was narrower ”.
Six million years ago, Crete was connected to the Greek mainland through the Peloponnese. According to Professor Madelaine Böhme, ” We cannot rule out a connection between the producer of the tracks and the possible pre-human Graecopithecus freybergi .” Several years ago, Böhme’s team identified that previously unknown prehuman species in what is now Europe in a 7.2-million-year-old site of fossil deposits in Athens, just 250 kilometers away.
In addition, the study confirms recent research and the theses of Böhme’s team, according to which six million years ago the European continent was separated from East Africa by a relatively brief expansion of the Sahara. Geochemical analysis of the six-million-year-old Cretan beach deposits suggests that dust from the North African desert was carried there by the wind. By dating mineral grains the size of dust, the team reached an age of between 500 and 900 million years. These time periods are typical for North African desert dust, the authors note.
Recent research in paleoanthropology also suggested that the African monkey Sahelanthropus could be ruled out as bipedal, and that Orrorin tugenensis , which originated in Kenya and lived 6.1 to 5.8 million years ago, is the oldest prehuman in Africa, Böhme explains. . Thus, short-term desertification and the geographic distribution of early human predecessors may be more closely related than previously thought.
On the one hand, a phase of desertification 6.25 million years ago in Mesopotamia could have started a migration of European mammals, possibly including apes, to Africa. On the other hand, the closure of the second phase of the continents by the Sahara 6 million years ago could have allowed a separate development of the prehuman African Orrorin tugenensis in parallel with a European prehuman. According to this principle, called “desert oscillation” by Böhme, the successive short-term desertifications in Mesopotamia and the Sahara caused a migration of mammals from Eurasia to Africa.
Referencia: Kirscher et al. 2021 Age constraints for the Trachilos footprints from Crete. Scientific Reports, DOI: http://doi.org/10.1038/s41598-021-98618-0
Text: University of Tübingen
