HUMAN EVOLUTION

The First of Our Genus

~2.8 million years ago

Phanerozoic · Cenozoic · Neogene · Pliocene

Half a lower jaw, picked up on an Ethiopian hillside, carries the teeth of later Homo on a chin line still shaped like an Australopithecus. At 2.8 million years it is the oldest fossil anyone assigns to Homo, and the first Oldowan tools follow it by about two hundred thousand years. Newer finds from the same area show Homo again at 2.6 million years and, beside it at 2.63, an Australopithecus that has not yet been matched to any named species.

Why it matters

The picture that emerges is not a relay race. In the Afar, before 2.5 million years ago, our genus shared the ground with another upright lineage that was not on its way to becoming us. The origin of Homo is a branch inside a crowd, and the crowd is the part we keep forgetting.

Dating & uncertaintyDisputed

The jaw, catalogued LD 350-1, was published in 2015 and challenged in the same journal within months: correct the comparative measurements, its critics argued, and the specimen can no longer be assigned to Homo with any certainty. Nothing since has settled the question, and a single jaw is a thin foundation for the origin of a genus.

Sources

1. Villmoare et al. (2015), Science · Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia
2. Villmoare et al. (2026), Nature · New discoveries of Australopithecus and Homo from Ledi-Geraru, Ethiopia
3. Braun et al. (2019), PNAS · Earliest known Oldowan artifacts at >2.58 Ma from Ledi-Geraru, Ethiopia, highlight early technological diversity
4. Hawks et al. (2015), Science · Comment on “Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia”

Earth history as one day

23:59:0653.3 s before midnight

if Earth’s 4.54 billion years were compressed into a single day