Rubin: What happens is, you have a Neanderthal buried in the back of the cave and then you come back thirty, forty thousand years later and it's basically served as this very rich nutrient source for all kinds of things that happened to be wandering through that cave; primarily microbes that are basically living on it.
Narrator: Rubin says they sequenced a small fragment of a 38,000 year old Neanderthal bone after removing contamination and grinding it up into a fine powder.
Rubin: Eventually, it becomes a needle in a haystack problem in that most of the sequence you have is from the organisms that have been feeding on the Neanderthal and not the Neanderthal, but we have very powerful magnets that allow us to sift through all of that hay and find out sequences that are similar to human.
Narrator: For Science Today, I'm Larissa Branin.