In all cells, from yeast to human, a mitochondrion's main job is to produce the energy that powers cells. This takes the form of a chemical called ATP.
In the case of modern humans, the mitochondria do this quite efficiently under ideal conditions, making 36 ATP molecules with the energy stored in a single molecule of glucose sugar.
Mutations that sap this efficiency would generate heat instead, which is a potentially useful trick for Neanderthals who are known to have had adaptations to cold weather, according to Chinnery.
However, a warmer and less climatically stable habitat could have spelled trouble for Neanderthals with such mutations.
Perhaps the Neanderthals' mitochondrial DNA adapted them to the cold, and they couldn't cope when the climate started to change, hypothesized [Patrick] Chinnery.The authors are quick to point out that all we have is one Neandertal sequence so it is simply not known how wide-spread the mutations are. The article also doesn't say which Neandertal was sequenced. As it turns out, it is the type specimen from the Neander Valley, discovered in 1856 by Fulrott. The authors also point out that more sequences are coming soon. It is an intriguing hypothesis but unless similar selection can be found in modern day cold-adapted populations, it remains extremely provisional. I would also be curious to see whether or not the Levantine Neandertals have positive selection for this adaptation.
Why doesn't Yahoo news in the United States pick up on any of these stories?