Irrefutable evidence of a connection between colour and aggression

Despite appearances to the contrary, all domestic dogs belong to a single species. Nevertheless, they vary greatly in temperament and intelligence. Many years ago, it was suggested that the case may be similar among humans. Haldane JBS. (1956) The argument from animals to men: an examination of its validity for anthropology, J R Anthropol Inst G B Irel. 1956;86(2):1–14.