The sequencing of the complete Neanderthals genome was one of the highlights of last year, not just because of the technical achievement involved, but because it confirmed something extraordinary about our own ancestry. It showed that everyone outside of Africa can trace around 1-4% of their genes to Neanderthals. Our ancestors must have bred with Neanderthals on their way out of Africa.

Then, later in the year, the same team revealed another ancient genome. This one belonged to a group of people called Denisovans, known only from a single finger bone and a tooth. They too had left genetic heirlooms in modern people. Around 5-7% of the genes of Melanesians (people from Papua New Guinea, Fiji and other Pacific islands) came from the Denisovans.

In this week’s issue of New Scientist, I’ve got a feature that explores our patchwork origins. I looked at what these ancient genomes mean for our understanding of human evolution. I also considered some intriguing questions like whether other Denisovan fossils have already been found, whether this human pattern is applicable to other animal species, how much you can tell from modern genomes alone, and whether we’ll ever ...