Kin Recognition - Theoretical Background

Theoretical Background

Hamilton's theory of inclusive fitness and the related theory of kin selection were formalized in the 1960s and 1970s in an attempt to explain the conditions surrounding the evolution of social behaviours. Hamilton's early papers, as well as giving a mathematical account of the selection pressure, also included wide ranging discussion about possible implications and behavioural manifestations. In one area, Hamilton discusses potential roles of cue-based mechanisms mediating altruism versus the possibility of 'positive powers' of kin discrimination:

The selective advantage which makes behaviour conditional in the right sense on the discrimination of factors which correlate with the relationship of the individual concerned is therefore obvious. It may be, for instance, that in respect of a certain social action performed towards neighbours indiscriminately, an individual is only just breaking even in terms of inclusive fitness. If he could learn to recognise those of his neighbours who really were close relatives and could devote his beneficial actions to them alone an advantage to inclusive fitness would at once appear. Thus a mutation causing such discriminatory behaviour itself benefits inclusive fitness and would be selected. In fact, the individual may not need to perform any discrimination so sophisticated as we suggest here; a difference in the generosity of his behaviour according to whether the situations evoking it were encountered near to, or far from, his own home might occasion an advantage of a similar kind.” (1996, 51)

This possibility served as the main impetus for a generation of researchers to start looking for evidence of any 'positive powers' of kin discrimination. Later however, Hamilton had developed his thinking to consider that such discriminatory behaviour was unlikely to play a role in mediating social behaviours:

But once again, we do not expect anything describable as an innate kin recognition adaptation, used for social behaviour other than mating, for the reasons already given in the hypothetical case of the trees.(Hamilton 1987, 425)

The implication that inclusive fitness theory can be met by mediating mechanisms of cooperative behaviour that are context and location-based has been clarified by recent work by West et al.:

In his original papers on inclusive fitness theory, Hamilton pointed out a sufficiently high relatedness to favour altruistic behaviours could accrue in two ways — kin discrimination or limited dispersal (Hamilton, 1964, 1971, 1972, 1975). There is a huge theoretical literature on the possible role of limited dispersal reviewed by Platt & Bever (2009) and West et al. (2002a), as well as experimental evolution tests of these models (Diggle et al., 2007; Griffin et al., 2004; Kümmerli et al., 2009 ). However, despite this, it is still sometimes claimed that kin selection requires kin discrimination (Oates & Wilson, 2001; Silk, 2002 ). Furthermore, a large number of authors appear to have implicitly or explicitly assumed that kin discrimination is the only mechanism by which altruistic behaviours can be directed towards relatives... here is a huge industry of papers reinventing limited dispersal as an explanation for cooperation. The mistakes in these areas seem to stem from the incorrect assumption that kin selection or indirect fitness benefits require kin discrimination (misconception 5), despite the fact that Hamilton pointed out the potential role of limited dispersal in his earliest papers on inclusive fitness theory (Hamilton, 1964; Hamilton, 1971; Hamilton, 1972; Hamilton, 1975). (West et al. 2010, p. 243 and supplement)

For a recent review of the debates around kin recognition and their role in the wider debates about how to interpret inclusive fitness theory, including its compatibility with ethnographic data on human kinship, see Holland (2004).