 Issues relating to evolvability are sometimes framed in terms of systems of information transfer. On this view, if offspring are to resemble parents, developmental information must be transmitted from one generation to the next. The question is what forms of information transmission system do this job. This mode of framing the issue is contentious, for it is not always clear how we are to understand the concept of information, and what it means for some causal contributor to development to count as an information-bearer, rather than some other kind of developmental participant, such as an information-reader, say, or a background condition for information transfer (see Oyama 2000 and Griffiths 2001 for discussion of these issues). This general way of thinking about inheritance has, however, been influential in characterising so-called ‘major evolutionary transitions’ (Maynard Smith and Szathmary 1995). Key transitions in the history of life are said to include the development of DNA-based inheritance, the emergence of chromosomes, the advent of the ‘genetic code’, and events such as the arrival of sociality and language. Maynard Smith and Szathmary propose that we can think of these events as modifications to the mechanisms of inter-generational information transmission.