In 2010, the study’s toe bone first turned up at Denisova Cave, where excellent fossil preservation conditions had allowed for the genetic mapping of the then-surprising Denisovan finger bone found in 2008. Gene tests showed the toe belonged to a Neanderthal, and Prüfer and colleagues began calculating its full genetic map.
The results show that it belonged to a woman whose closely matched chromosomes suggest that her parents were closely related, perhaps half-siblings or an uncle and niece (or aunt and nephew).
Over time, such inbreeding has been shown to be bad for the genetic fitness of most species, including people, throughout the animal world.
(Only 96 genes responsible for making proteins in cells are different between modern humans and Neanderthals. Intriguingly, some of the gene differences involve ones involved in both immune responses and the development of brain cells in people.)