This paper first appeared in the March Issue of the 'Skeptical Adversaria' (the Newsletter of ASKE, the Association for Skeptical Enquiry), 2009, p1.
An article that appeared in a recent issue of the Journal of the Royal Society of Medicine will, I am sure, appeal to ASKE members and other readers of this newsletter.
The article (see note 1) by dermatologists at the University of Norwich, explores a common claim and belief, supported by anecdotal evidence, that has defied orthodox scientific explanation and therefore should be deemed 'extraordinary'. The authors review early hypotheses (from over 100 years ago) that assume the authenticity of the phenomenon and are based on physical mechanisms that only those with specialist knowledge would be fully able to understand and evaluate.
The authors find that there is no support for these hypotheses and, accordingly, they reject them. Instead they favour two simpler explanations that would certainly account for the phenomenon. An intelligent layperson would have been able to offer the first of these and probably make a guess at the second.
Many people will be acquainted with someone claiming either to have observed the above phenomenon or to know a person who has, namely that someone had such a terrible shock that his or her hair turned white overnight.
The paper's authors refer to well-known historical examples, including Sir Thomas Moore and Marie Antoinette, both on the eve of their executions.
Early documented examples are very dramatic, as in the case of a Benagali sepoy who was surrounded and stripped by hostile soldiers and whose jet-black hair turned white in 30 minutes!
Even setting this unusual example aside, it seems that there is a problem accounting for how hair follicles could collectively become de-pigmented in such a short space of time. Does the reader have any suggestions that would not require this process?
One hypothesis is that the victim normally dyes his or her hair but is unable to or (through being in a state of shock) neglects to do so. The dye could also be washed out. This might explain the examples given earlier, though we have to assume that the victims did indeed use artificial hair colouring. (In the case of the sepoy one could suggest that any hair colouring was washed out by sweat during his ordeal.)
The second hypothesis is that the victim has mixed white and pigmented hair and has an episode of alopecia (hair loss), which can occur rapidly (e.g. in reaction to shock) and may selectively affect pigmented hair.
Obviously we need direct evidence from case examples to support these claims. Despite this, we have here a good example of the implicit application of Occam's Razor in the analysis of a common preconception, which may turn out to be largely a myth.
Skellett, A.-M., Millington, G.W.M. & Levell, N.J. (2008) Sudden whitening of the hair: An historical fiction? Journal of the Royal Society of Medicine, 101, 574-576.