When early Homo met Australopithecus and Paranthropus

If you could stroll through Ethiopia’s Afar Region about 2.6 million years ago, you wouldn’t just bump into “Lucy’s” kin. You might also pass a sturdy-jawed Australopithecus stranger, a nimble early Homo. Moreover, if you headed far enough, you would meet their Paranthropus cousins. The new fossils described in a paper published in Nature suggest that eastern Africa in this period was no one-species show. It was a lively evolutionary neighborhood.

A team led by Brian Villmoare of the University of Nevada Las Vegas, with colleagues from Arizona State University, the University of Arkansas, and Ethiopian institutions, has unearthed teeth from three distinct sedimentary layers in the Ledi-Geraru area. Using precise volcanic ash dating, the fossils were slotted into a narrow but crucial window: between 2.78 and 2.59 million years ago. This is a chapter of prehistory that has long frustrated paleoanthropologists because of how rarely it’s preserved.

Why is that span so important? It’s the moment just after Australopithecus afarensis (the species that gave us the famous Lucy) disappears from the fossil record, and right when our own genus, Homo, and the more robust-jawed Paranthropus make their debut. Until now, the Afar’s story for that time was skeletal, with big evolutionary events inferred but not well recorded in the bones and teeth left behind.

The new finds fill some of those gaps. From the oldest layer, the team recovered a premolar with the distinctive shape and proportions seen in early Homo. In the middle layer came an unexpected Australopithecus, not afarensis, and not the later A. garhi, but something morphologically distinct. The youngest layer produced molars matching early Homo again, with crown shapes and cusp patterns that wouldn’t look out of place alongside fossils from 2.3-million-year-old sites.

Taken together, these discoveries mean that by 2.6 million years ago, at least three non-robust hominin lineages, early Homo, A. garhi, and the newly recognized Ledi-Geraru Australopithecus, were all sharing the Afar Region. Add in Paranthropus from other East African sites of the same age, and the tally reaches four contemporaneous species.

The ecological backdrop matters beyond the numbers game. Previous work in Ledi-Geraru has shown a shift toward more open, arid landscapes around this time. It had been tempting to link such environmental changes directly to the rise of Homo, imagining our ancestors alone as adaptable enough to thrive in drier habitats. But these new fossils complicate that story. Clearly, Australopithecus was still around, and doing well enough to hold its ground alongside early humans.

That raises many questions. Were these species carving out separate ecological niches, specializing in different diets or foraging strategies? Or did they overlap heavily, with survival hinging on subtle differences in behavior or social structure? The absence of Paranthropus in the Afar at this time, despite their presence to the south, adds another wrinkle. Could late-surviving Australopithecus here have blocked their expansion, competing for similar foods?

For now, the teeth don’t tell us everything. They are, after all, fragments of a much bigger evolutionary picture. But their shapes, sizes, and wear patterns have already overturned the idea that A. afarensis’s exit left a straightforward path for Homo. Instead, the Afar of 2.6 million years ago was a crossroads where multiple evolutionary experiments in “being human” ran in parallel.

As co-author Kaye Reed of Arizona State University puts it, the find “shows that evolution was exploring several variations on the hominin theme at the same time.” In other words, our family tree back then was more of a tangled bush than a single trunk. And the Ledi-Geraru sediments are helping to tease apart its branches, layer by layer.

If you want to learn more, the original article titled "New discoveries of Australopithecus and Homo from Ledi-Geraru, Ethiopia" on Nature at https://www.nature.com/articles/s41586-025-09390-4