Fifty years after her discovery, in Ethiopia, on November 24, 1974, Lucy remains iconic among prehuman fossils. When American Paleontologist Donald Johanson and Tom Gray, the student who accompanied him, saw a few bone fragments protruding from an arid hillside in the Afar region, they quickly realized that they had found the paleontologists' Holy Grail: A specimen representing 40% of a single individual's skeleton, something that was unheard of for such an ancient period – around 3.2 million years ago.

In the same year, a lower jaw, which would be associated with the same species, was unearthed in Tanzania. In 1975, 200 fossils, representing 17 probably related individuals, were unearthed in Afar. Others followed, including the fossil of a 3-year-old, found in the Dikika area of Afar, in 2000. Named Selam, she would be wrongly described as "Lucy's baby" – indeed, she had been born some 100,000 years before Lucy.

This abundance of fossils led the American scientists Johanson and Tim White, along with a Frenchman, Yves Coppens (1934-2022), the co-director of the Afar expedition, to propose a species name for Lucy and her relatives in 1978: Australopithecus afarensis, whose members had been dated to a period rangng from around 3.8 to 3 million years ago – which made it the oldest potential human ancestor.

Fifty years on, what is the status of this australopithecine species – standing 1.10 meters tall and weighing less than 30 kilograms – in our phylogenetic tree? For Johanson, Au. afarensis "remains the most likely ancestor and one of the most important species in human evolutionary history." That was how he concluded an article, co-authored with his Ethiopian colleague Yohannes Haile-Selassie, which was published in November's edition of the magazine Scientific American (and in its French version, Pour la science, "For science"), to mark the anniversary of the discovery.

'Our great-aunt'

In in, the two researchers also review the many new species descrbied as hominins – those found in the human family tree after its separation from that of chimpanzees – that have come to light over the last half-century.

First of all, there are the oldest species: Sahelanthropus tchadensis (Chad), alias Toumaï, and Orrorin tugenensis (Kenya), dated back to 7 and 6 million years old respectively, which are already bipeds. There is also Au. anamensis. This species has sometimes been described as a close ancestor of Lucy, and it has recently been found that two species probably coexisted. Moreover, there are all of its contemporaries, who have become increasingly numerous (Au. bahrelghazali, alias Abel, Au. deyiremeda and Kenyanthropus platyops).

You have 66.23% of this article left to read. The rest is for subscribers only.