The hominin family tree is more like a complicated, tangled bramble. Homo sapiens is the only member of the genus left today, but in millennia past, the world was inhabited by multiple related Homo species – including the Neanderthals , Homo erectus, and Homo habilis , and traces of a mysterious group known as the Denisovans . In recent years, evidence has emerged that these populations did not live in isolation . Multiple overlapping human groups roamed Eurasia, occasionally fighting, trading –