 Jablonka and Lamb use the characteristic differences between typical modes of social inheritance in animals and humans to illuminate the impact our own symbolic transmission systems have on human cultural evolution (see also Deacon 1997). Although they argue that there can be non-linguistic symbolic systems (2005, 224), language exemplifies nicely the way in which systems of symbols contain elements that can be recombined in countless ways to yield a vast array of different meaningful messages. Repositories of symbolically stored information, such as books, can also be searched, annotated, edited and so forth, in ways that add to their power and versatility. This manner of thinking opens up a number of challenging issues. The question of the degree to which symbolic systems resemble other inheritance systems is an illuminating one. Consider, by way of example, Stegmann’s (2004) discussion of the sense in which the genetic code is ‘arbitrary’. One quickly realises that any attempt to say precisely what makes some inheritance system a symbolic system, and any attempt to differentiate between types of symbolic systems (linguistic, non-linguistic and so forth), will be exceptionally philosophically demanding.