 Does replication play the same role in other sorts of selection that it plays in gene-based biological evolution? The reaction of the immune system to antigens is closest to the standard biological example of replication and selection (Hull et al. 2001). Certainly, immune systems arose through the same process as other functional systems. The basic structure of the human immune system is “built into our genes”, and the only genes that count in evolution are the ones that we received from our ancestors and can subsequently pass on to our progeny. In Dawkins’ (1982b: 83) terminology, the genes that code for our immune system are active, germ-line replicators. They are active because they influence their probability to be copied; they are germ-line because they can potentially have an infinity of descendants.