 Also indicative of the difference between altruistic behaviour and behaviour that benefit both self and others is the fact that in the latter case, though not the former, the beneficiary may be a member of a different species, without altering the evolutionary dynamics of the behaviour. Indeed, there are numerous examples where the self-interested activities of one organism produce an incidental benefit for a non-conspecific; such behaviours are sometimes called ‘mutualistic’, though again, this is not the only way that the latter term has been used (West et al. 2007). By contrast, in the case of altruism, it makes an enormous difference whether the beneficiary and the donor are con-specifics or not; for if not, then kin selection can play no role, and it is quite unclear how the altruistic behaviour can evolve. Unsurprisingly, virtually all the bona fide examples of biological altruism in the living world involve donors and recipients that are con-specifics. (Cases of so-called ‘reciprocal altruism’ are sometimes thought to be exceptions to this generalization; but see section 4 below.)