X-Men: Days Of Future Past - 10 Questions Singer Failed To Answer

9. How Has Wolverine Got Grey Hair?!

Wolverine has a healing factor that means he can lie at the bottom of a lake for some time drowned without ever actually dying, which makes him the prime candidate for travelling back in time, and there is explicit mention that he will look basically the same when he arrives in his old body because of his mutation, which all makes sense. But how the hell does he have white hair at his temples? Surely his mutation would expressly forbid his genes from going bad and changing the colour of his hair? There is some medical research available that suggests that changing hair colour can be pinned down to lower bone density in older age, which is clearly not an issue for old metal skeleton here, and it's unlikely that the ropey suggestion that stress causes premature whitening is accountable either. Obviously there's some narrative value in having him appear a little bit older to imply the passage of time, but that was never a problem in X-Men Origins, when he barely aged over 50 years, and it seems like a contradiction to have Wolverine's mortality even hinted at.