Inclusive Fitness Psychology 3107 Introduction Darwin was troubled

Inclusive Fitness Psychology 3107

Introduction Darwin was troubled by the preponderance of behaviour that seemed to be of no benefit to the actor Examples n n Sterile insect castes Bee stings Alarm calling Reproductive restraint

Reproductive restraint Birds can produce many more eggs than they actually do! Wynne-Edwards beleied that selection also acted on the species level to stop massive overpopulation

Reproductive Restraint? Lack argued that animals are doing what is best for the INDIVIDUAL Big clutch means possible exhaustion, death LIFETIME fitness, not just this season

Lack Well, if clutch size depends on the environment, then clutch size should vary with quality of resources

Hamilton figured it out Hamilton’s Response was theoretical Look at behaviour from the gene’s point of view Inclusive fitness = direct fitness + effect on fitness of others

Hamilton C < rb Or r > c / b Remember, r is relatedness, c is cost b is benefit Would you give your life for a brother? No, but maybe 2 brothers, or 8 cousins Two uncles and one mother….

Mechanism For this to work there must be some sort of proximate mechanism Easy for mother/father and child How about everyone else? ‘Green Beard’ hypothesis n n Allele produces some phenotype Also allows for recognition Tough for a single gene….

The elusive mechanism Proximity n n n Families Little dispersal So if close by, you are related Example: n n n Leaf eating ants Far nests more hostile Different plants more hostile

More on mechanism Those crazy ants n n Split colony and put on different plants Hostile, but non injurious! Gene environment interaction baby! Vervet monkeys n n n 2 year olds scream Mother comes Others watch the mother!

Mechanisms, pheremones and bees Greenberg looked at bee relatedness and allowing bees in or not Probably genetically determined odour

Conclusions Group selection is silly Individual selection is cool Gene level selection is VERY cool Hamilton is a genius Don’t over use this Gives us some insight into some nasty human behaviour