Any discussion of evolution must assume something about heredity, so ideas about evolution and notions of heredity are intimately linked. From the outline of our views given in the previous chapter, it will be clear that we believe that something is wrong with the assumptions about heredity that underlie a lot of present-day evolutionary thinking. In this chapter, therefore, we are going to take a closer look at the hereditary basis of behaviour, focusing on its genetic basis. What does it mean to say that genes determine behaviour? What is the difference between this assertion and the claim that patterns of behaviour have a genetic basis? To what extent do heritable differences in behaviour reflect genetic differences?

Often the easiest and most fruitful way of thinking about the evolution of behaviour is to have some actual animal behaviour in mind, so in this and most subsequent chapters we are going to ground our discussion on some observations of real animals in their natural habitat. This time we take ourselves at sunrise to an old olive orchard in the Judaean hills near Jerusalem.