Oldest Known Human DNA Reveals A Mysterious Branch of Humanity

A mysterious human thighbone has been unearthed in the Sima de los Huesos, or "Pit of Bones," an underground cave in the Atapuerca Mountains in northern Spain. The bone is apparently 400,000 years old, and belongs to a previously unknown type of early human.

Traces of two types of early hominid are known to exist in the DNA of modern humans, the result of our ancestors inbreeding with earlier varieties of humans.

Neanderthal DNA makes up 1 to 4 percent of modern Eurasian genomes, and Denisovan DNA makes up 4 to 6 percent of modern New Guinean and Bougainville Islander.

This ancient bone from Spain is neither of these early types. It seems not Neanderthal, but some sort of human that perhaps shared a early common ancestor with the humans that later became Denisovans.

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