two species of primates fill diverse ecological niches around the world, humans and rhesus macaques, and that what distinguishes both of these ‘weed species', as he calls them, from all other primates is the presence of 5-HTTLPR short allele in some individuals. It seems unlikely that that which might afford these two species such an adaptive advantage would only be ‘vulnerability genes' that predispose carriers to depression in the face of contextual stress.
