Chapter 18.6, Problem 1CSC

We might be able to more easily distinguish between the African replacement and multiregional origin hypotheses (and to answer a host of other unanswered questions about the origin and early evolution of H. sapiens) if we had access to DNA sequences from the earliest representatives of our genus. Is it possible that researchers will one day extract useable DNA from, say. early H. erectus? Perhaps, but the odds of success are not great. H. erectus fossils are up to 1.8 million years old, but the oldest ancient genome so far obtained is from a 700,000-year-old fossil horse. What’s more, the fossil horse was found in northern Canada, where the cold climate is excellent for preserving DNA. H. erectus. however, inhabited warmer regions where DNA degrades more quickly. Nonetheless, some evolutionary biologists hold out hope that useable DNA might be found in early H. erectus bones that fossilized in an environment conducive to preservation, perhaps in a deep cave or in oxygen-depleted underwater sediments. Could DNA survive for more than a million years under the right conditions? Current evidence says no, but then it wasn’t too long ago that recovering Neanderthal DNA seemed like an impossible dream.