Chapter Chapter-by-Chapter Anaylsis of The Selfish Gene (1989 edition) - Study Guide by Richard Dawkins

not noticed the flock and so the "spotter" could crouch low and hope not to be seen by the predator. However, this will not do much good if the rest of the flock are being conspicuous because they will attract the predators attention to the area and then every member of the flock, including the "spotter" are in danger. Therefore, from a purely selfish point of view it is in the spotter’s interests to warn the rest of the flock so that they too hide from the predator.

Other animals demonstrate apparently suicidal altruism, such as the stotting Thomson’s gazelle. However, even this behaviour can be explained by the selfish gene theory. Zahavi argues that the stotting is not, in fact, intended as a warning for other gazelles but instead is directed at the predator. What the gazelle is actually doing by stotting is letting the predator know that he is a fit and healthy gazelle and that the predator would be better off chasing another gazelle from the herd that is not so fit. Therefore, this behaviour is far from altruistic!

Social insects also demonstrate astonishing feats of co-operation and apparent altruism but on closer inspection, one can see that they are initiated by gene selfishness. The workers are sterile and therefore their only means of propagating their genes into the next generation is to help the queen to produce more brothers and sisters. They do this by sacrificing themselves when they attack intruders; they provide the reproductive members with food and they help care for the brood.

In some social colonies, altruism can be explained by the unusual system of sex determination which results in the relatedness between full sisters being ¾ and not ½ as it would be for normal sexual animals. Therefore, a hymenopteran female is more closely related to her full sisters than she is to her offspring of any sex and so it would be genetically beneficial for them to farm their mother as an efficient sister- making machine! Thus, worker sterility evolved because workers could use their mother as a more efficient manufacturer of copies of their own genes than they would be themselves.

Apparent reciprocal altruism has been seen to occur between members of different species as well, where relatedness cannot be used as an explanation. For example, ants "milk" aphids for the plant juice that they have stored in their abdomen and in return receive protection from their enemies. This occurs because the different species have different "skills" to offer the partnership. Aphids have the right sort of mouthparts for pumping up plant sap, but sucking mouthparts are no good for self-defence. Ants are no good at sucking sap from plants, but they are good fighters. Therefore, ant genes for cultivating and protecting aphids have been favoured in ant gene pools and similarly, aphid genes for co-operating with the ants have been favoured in aphid gene pools, thus becoming an ESS.

The exchange of favours between the ant and the aphid can be seen to take place simultaneously. But reciprocal altruism has also been seen to occur when there is a delay between the giving of the favour and its repayment. Examples include the removal of disease-infected ticks from the top of a bird’s head where it is unable to remove it itself and the cleaning symbiosis between the wrasse and the grouper. This delayed reciprocal altruism can evolve in species that are capable of recognising and remembering each other as individuals. However, there is the threat of cheating because an individual can benefit from exploiting the co-operative efforts of others. If the same individuals interact over a long period of time it is possible for reciprocity to become evolutionary stable, as subsequent interactions would lead selection to discriminate against the cheater. The Prisoner’s Dilemma model is used to demonstrate this and it is described in the chapter "Nice guys finish first".

Memes: the new replicators

This chapter focuses in on man in particular. Dawkins believes that there are good reasons for supposing our species is unique, namely "culture". He believes that there is such a thing as cultural transmission, analogous to the genetic transmission we have been discussing above; and it is through this cultural transmission that things such as language, fashions, ceremonies, customs, arts, and technology have evolved.