‘Lucy’ was not alone: ​​some footprints show the passage of a hitherto unknown hominid

  • The analysis of footprints found in Laetoli, in Tanzania, points to the existence of another species of hominids that also walked on two legs

  • The finding sheds light on the origins of bipedalism; one of the main evolutionary differences between our species from other primates

In the 1970s, a excavation at the archaeological site of Laetoli, in Tanzania, found a set of footprints forged about 3.6 million years ago on a soil covered with volcanic ash. The first analysis of these footprints concluded that a part of these belonged to an ‘Australopithecus afarensis’, the same species as the famous ‘Lucy’ skeleton, and the other part could be the trail of a bear. Fifty years later a new study concludes that these traces belonged to a hitherto unknown hominid that, furthermore, it may have been one of the first members of our species to walked on two legs.

The study, published this Wednesday in the prestigious journal ‘Nature’, raises a new and detailed analysis of the mysterious Laetoli footprints. The team led by researcher Ellison Mcnutt returned to the archaeological site, scanned the terrain with laser technology and created a 3D copy of the footprints. Next, these footsteps were compared with that of other known hominids but also with that of other animals such as chimpanzees and bears. In the case of bears, in addition, a curious experiment was devised to get a bear cub to stand up on a plate of fresh mud in order to study its footprint in great detail. After this meticulous analysis, the team concluded that the enigmatic Laetoli footprints they are the trail of a hominid.

But what do we know about the walker who ventured over the Tanzanian ashes 3.6 million ago and left his mark on the ground? Well, as argued by the researchers responsible for this analysis, everything indicates that it is a hitherto unknown hominid who, along with ‘Lucy’s cousins’, was one of the first to stand on two legs. But unlike what had been found so far about our ancestors, the analysis of the Laetoli footprints shows that this mysterious had a somewhat unusual gait. When he walked he stepped with his right foot on the left side of his body and vice versa. Almost like “a dancer or a supermodel of prehistory”, joke independent experts consulted by this newspaper.

Origin of human gaits

The fact that these footprints point to a hitherto unknown hominid, far from closing the debate, opens a whole new range of unknowns among experts. “Where the article ends the discussion begins“, Explain Laura Martín-French, a researcher at the Catalan Institute of Human Paleoecology and Social Evolution (IPHES) and a scientist associated with the National Center for Research on Human Evolution (CENIEH). The first question that will have to be cleared up, explains the scientist, is whether beyond these traces there is any fossil remains to confirm identity of this mysterious hominid (and confirm if, indeed, we are dealing with a new species). Another of the burning topics will be to study how the panorama changes the fact that, according to this finding, there was two species sharing ecological niche and what kind of interaction would there be between them.

The unusual footprints of the mysterious Laetoli hominid are also further proof that our species’ gait passed one “evolutionary trials“, explains the researcher Carlos Lorenzo, expert in human evolution from the Rovira i Virgili University (URV). “In the origins of bipedalism, not everyone was walking perfectly. Many evolutionary trials are needed to refine the distance between the steps, the effectiveness of the tread or the anatomy of the body to walk without losing your balance“, explains the scientist, who, questioned by this newspaper, applauds the” impeccable method “of the study of ‘Nature’ on the footprints of Laetoli.

According to the experts, the fact that our species got on two legs changed everything. “Bipedalism implied an anatomical restructuring, from the spine to the skull. But it also meant a change in material culture, because by leaving the hands free, it allows them to be used to manipulate instruments”, comments Martín-Francés. Yes indeed. As the researcher explains, bipedalism also had its dark side. Especially for childbirth. “Unlike other animals, the human baby to pass through the birth canal has to change position and do a kind of torsion, which implies that it is born with the bones of the skull much more immature than other species”, illustrates the expert.

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“The bipedalism is the golden question of human evolution because it is one of the main characteristics that differentiates our species from other primates “, comments Lorenzo. Investigating this question, explains the expert, is still one more return to the eternal questions of How did we get here and why we are the way we are.


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