About 3.2 million years ago, Lucy, our famous ancestor Australopithecus afarensissurveyed what is now Ethiopia. Since the discovery of its skeleton in 1974 by Donald Johanson and his team, it has become an essential symbol of paleoanthropology. However, Lucy was not alone. Recent discoveries reveal that at least four other proto-human species shared his era. Who were they, and did they interact with Lucy and her ilk?
An unexpected coexistence in a changing continent
For almost a million years, Australopithecus afarensis flourished in East Africa and covered a vast expanse of 2,350 kilometers from northern Tanzania to north-central Ethiopia. Well adapted to various habitats, these hominids combined bipedal walking and arboreal life.
For a long time, researchers thought thatA. afarensis was the only hominid species in this region during the Middle Pliocene (3 to 4 million years ago). However, the discovery in 1995 of a jaw fragment in Chad, attributed to Australopithecus bahrelghazaliupset this certainty. 3.5 million years old, this fossil, found more than 2,400 kilometers from the sites ofA. afarensisproves that at least one other archaic human species lived in Africa at the same time. Although their geographic distance may have prevented any direct interaction, this discovery paved the way for the identification of other hominids contemporary with Lucy.
A diverse neighborhood around Lucy
In Ethiopia, just 30 miles from the site where Lucy was discovered, a team led by Yohannes Haile-Selassie has unearthed distinct fossils ofA. afarensis attributed to a new species: I say Australopithecus. Dated to 3.5 to 3.3 million years ago, these fossils are distinguished by robust teeth that suggest a different diet from Lucy's. This dietary divergence could reflect ecological specialization, avoiding direct competition between the two species.
At the same Woranso-Mille site, researchers also discovered a partial fossil known as Burtele's foot. Dated 3.4 to 3.3 million years ago, this foot has an opposable big toe, an ideal adaptation for climbing trees. Although this individual is not related to A. afarensisit has not yet been assigned to a specific species, which adds an additional enigma to the diversity of Middle Pliocene hominids.
Kenyanthropus platyops : a flat-faced hominid
In 1999, on the shores of Lake Turkana in Kenya, Meave Leakey and his team discovered the fossils of Kenyanthropus platyops. Dated between 3.3 and 3.2 million years ago, this hominid had a flat skull and teeth different from those of Lucy. Some researchers think it could be a regional variant ofA. afarensis while others argue that it is a distinct genre.
The lifestyle of K. platyops was similar to Lucy's: they lived in a grassy savannah environment near lakes where they probably sought to escape the same predators. This ecological proximity raises questions about how these species coexisted and occupied different niches in similar landscapes.
Interactions or isolation?
Whether Lucy and her contemporaries met or even genetically interbred remains a mystery. Current evidence shows that hominids lived in social groups similar to modern primates. A famous footprint in Laetoli, Tanzania, shows three australopithecines walking side by side, confirming their sociability.
However, paleoanthropologists have yet to find fossils that suggest hybridizations between species. Rebecca Ackermann, a biological anthropologist, explains that dental variations in A. afarensis could be compatible with hybridization, but the fossils are too old to contain usable DNA. The study of ancient proteins, such as those in dental enamel, could one day offer clues to possible crossbreeding.
A world still largely unknown
Despite decades of research and hundreds of fossils discovered, Lucy's world remains largely mysterious. We now know that it shared its time with other hominids: A. bahrelghazali, A. I don't saythe bearer of Burtele's foot and K. platyops. However, the nature of their interactions, their competition for resources and their role in human evolution are still far from being fully understood.
As biological anthropologist Jeremy DeSilva points out, these discoveries open up new crucial questions: “ How these hominids related to each other, how they interacted, how they filled niches in the landscape, and the degree of interbreeding that may have occurred are open and important questions.. »
The story of Lucy and her neighbors reminds us that human evolution is a complex story, marked by coexistence, adaptation and sometimes disappearance. Each new fossil discovered adds a piece to the puzzle that brings us one step closer to understanding our origins.
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