The sex lives of our distant ancestors were not only "rampant", but involved extensive interbreeding with neanderthals, denisovans and a "mysterious archaic population".
The ancient genomes, one from a Neanderthal and one from a different archaic human group, the Denisovans, were presented on 18 November at a meeting at the Royal Society in London. They suggest that interbreeding went on between the members of several ancient human-like groups living in Europe and Asia more than 30,000 years ago, including an as-yet unknown human ancestor from Asia. “What it begins to suggest is that we’re looking at a ‘Lord of the Rings’-type world — that there were many hominid populations,” says Mark Thomas, an evolutionary geneticist at University College London who was at the meeting but was not involved in the work.
Nature reports that scientists are abuzz with conjecture about the "mystery" group—“We don’t have the faintest idea,” said London Natural History Museum paleoanthropologist Chris Stringer—but it's aliens, obviously.