Theories of cultural evolution rest on the assumption that cultural inheritance is distinct from biological inheritance. Cultural and biological inheritance are two separate so-called channels of inheritance, two sub-systems of the sum total of developmental resources traveling in distinct ways between individual agents. This paper asks: what justifies this assumption? In reply, a philosophical account is offered that points at three related but distinct criteria that (taken together) make the distinction between cultural and biological inheritance not only precise but also (...) justify it as real, i.e. as ontologically adequate. These three criteria are: (a) the autonomy of cultural change, (b) the near-decomposability of culture, and (c) differences in temporal order between cultural and biological inheritance. (shrink)