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

Dawkins uses this clutch size argument (originally proposed by David Lack) to explain territorial behaviour and dominance hierarchies. Using red grouse as an example, he describes how they fight over territories early in the season but how, after a while, the losers seem to accept that they have failed and do not fight anymore. Only territory owners breed, despite the fact that non-territory owners are capable of breeding themselves. Why then do the non-territory owners not continually try to expel a territory owner in a desperate attempt to reproduce? The selfish gene theory explains this behaviour by saying that if the odds of an outcast’s succeeding to a territory are greater by waiting than the odds of his gaining one by fighting, then it would pay him as a selfish individual to wait in the hope that somebody will die, rather than waste what little energy he has in futile fighting. Similarly, a seal that leaves the harem-holders unmolested to mate is not doing it for the good of the group; he is biding his time, waiting for a more opportune moment.

Battle of the generations

Parental investment is defined as "any investment by the parent in an individual offspring that increases the offspring’s chance of surviving (and hence reproducing) at the cost of the parent’s ability to invest in other offspring." Other things being equal, a mother should invest most of her resources selfishly in herself because she bears 100 of her genes while her children only bear 50 of them. However, things not equal – her children are younger and more helpless and so would benefit more from each unit of investment than she would.

Furthermore, there is no genetic reason for a mother to have favourites because her relatedness to all of her children is same: a half. Therefore, her optimal strategy is to invest equally in the largest number of children that she can rear to the age when they have children of their own. However, some individuals are better life insurance risks than others are. For example, an under-sized runt bears just as many of his mother’s genes as his healthier siblings but his life expectancy is less. Therefore, a mother may either decide to refuse to feed him because it would be a waste of the resources that could otherwise have gone to a child who stood a greater chance of going on to reproduce themselves.

This is from the parent’s point of view. On genetic grounds alone, a mother should have no favourites and if she does show favouritism, it should be based on differences in other factors such as life expectancy. However, children will try to get their mother to invest in him more than in any particular sibling because he is twice as closely related to himself as he is to any brother or sister. Thus, if you and your brother are the same age and both are in a position to benefit equally from a pint of mother’s milk, you "should" try to grab more than your fair share. However, this behaviour only occurs up to a point. In other words, if you are competing with your brother for a morsel of food, and he is much younger than you are, then he would benefit more from the food than you would. Therefore it would pay your genes to let him have it when the resulting net benefit to him is half the cost of the for-going it yourself.

Therefore, a conflict between the parents and the young arises due to their differing optimal conditions. A child will pretend to be hungrier than it is in order to receive more food than its fair share as it will benefit its genes to become stronger. Parents on the other hand must be alert to this cheating and deceiving, and must try not to be fooled as it does not benefit its genes to have favourites. But this is not as easy as it seems. If a parent ignores a child’s screams of hunger, thinking it to be an attempt at deception, but the child in not lying and consequently dies, the parent will have lost some of its precious genes. This is where the battle lies and what will finally emerge is a compromise between the ideal situation desired by the child and that desired by the parent.

Battle of the sexes

A similar battle as described between the generations arises between the sexes. Each parent has 50 genetic shareholding in a child but if one parent can get away with investing less than his or her fair share of costly resources in each child, he will be better off since he will have more to spend on other