Homo habilis is the earliest named human. But is it even human?

A close up of a reconstructed skull, missing its lower jaw, against a black background.

For 60 years, the earliest known human species has also been one of the most mysterious. Homo habilis was added to our family tree in 1964. But it's long been unclear exactly what the ancient species, which lived between about 2.4 million and 1.65 million years ago, looked like.

That's because, until recently, only three very incomplete fossilized skeletons had been unearthed.