Leading article: What happened to our profusion of cousins?

Yet more evidence of the profusion of human ancestry has dealt another blow to the notion of a single "missing link" between modern Homo sapiens and our ape-like forebears.

We may have known for some time that, as recently as a few tens of thousands of years ago, we lived alongside Homo neanderthalensis and Homo floresiensis. But three new fossils found in Kenya and dating back nearly two million years now prove that probably for all of human existence there were several different "Homo" species living at the same time.

The question, then, is why only we survived. Did we breed our evolutionary cousins out of existence, or exterminate them, or simply out-compete them? Whatever the answer, it is time to let go of the iconic image of the "march of progress", with 15 proto-humans in a neat line from ancient ape to one of us. Reality – as is so often the case – is rather messier.