A group of 773,000-year-old hominin fossils from Morocco may shed new light on when our species branched off from the ancestors of Neanderthals and Denisovans.
A team of anthropologists recently examined a collection of fossil hominin jawbones, teeth, and vertebrae that belong to hominins who probably lived very close in time to our species’ last common ancestor with Neanderthals and Denisovans. They reveal a little more about a murky but important moment in our evolutionary history.
From predators’ quarry to rock quarry
Archaeologists unearthed the 773,000-year-old bones just southwest of Casablanca in a cave aptly named Grotte à Hominidés. They’re just fragments of what used to be hominins: an adult’s lower jawbone, plus the partial lower jaw from another adult and a very young child, along with a handful of teeth and vertebrae. A hominin femur from the same layer of sediment in the cave has clear gnaw marks from sharp carnivore teeth, offering a chilling clue about how the bones got there.
The layer of sediment in which the fossils lay spanned a few thousand years on either side of a long-ago flip in the polarity of Earth’s magnetic field (periodically our planet just… does that), which happened around 773,000 years ago. It’s a slice of time not quite narrow enough to say whether the three jawbones’ owners might have known each other but narrow enough to put them all at a crucial point in the story of human evolution.
Around 1.8 million years ago, a species called Homo erectus emerged in Africa and spread around most of the world (sorry, Americas and Australia). And around a million years ago, populations of Homo erectus living in different places started to evolve along their own paths. Potentially with a few species in between, this process likely gave rise to species like Homo floresiensis and Homo luzonensis in the islands of Southeast Asia.