Using a very general modelling approach, Nowak and colleagues make two important and valid points (Nature 466, 1057–1062; 2010). Whether the realm of applicability of inclusive fitness models is as restricted as claimed remains to be seen, but it is in any case contained in the realm of standard models. Second, the paper makes it clear what inclusive fitness theory really is: an accounting method, not a biological mechanism.

Champions of inclusive fitness often refer to the underlying mechanism as kin selection, but this just restates the fact that the benefit a particular gene generates at a cost to its carrier must preferentially go to the gene's other carriers (kin). The real biological problem is to understand mechanisms that lead to such assortment between helper and help. For eusocial insects, Nowak et al. convincingly argue that the basic mechanism of assortment is the formation of groups owing to ecological pressures, such as the need for nest defence.

Despite the indignant response of the inclusive-fitness crowd, there can be no doubt about the fundamental tenet that, with or without the concept of inclusive fitness, in principle we have access to exactly the same amount of evolutionary knowledge. Personal modelling preferences may vary, but there is nothing magic about bookkeeping techniques.

See also: Better living through physics, Ground truth is the test that counts, Call for a return to rigour in models