Adaptive recursion is a term borrowed from computer sci-ence. A recursive algorithm is a program that runs a newversion of itself, by calling itself as it runs. Such recursioncan be used, for instance, when searching down a directorytree, or, in the case of adaptive algorithms, to optimize anoutcome (Smithies et al. 2004). There are obvious parallelsbetween adaptive algorithms and biological adaptation.Adaptive recursion in computing involves a repeated pro-cess, the repeat being dependent upon on the preceding re-peat in a particular way. In biological adaptation the“adaptive recursion” is the cycle from gene sequences totheir unfolding as functional phenotypes that then interactwith the environment leading to gene frequency change innatural populations, and so back to a different starting set ofgene sequences. The programme then repeats in a mannerthat is dependent on the previous iteration. In computing it isimportant to avoid an infinite loop. In biology however therecursion is potentially infinite, only terminated on extinc-tion.