familial relationships 1

inclusive fitness

the ability of an individual organism to pass on its genes to the next generation, taking into account the shared genes passed on by close relatives

Direct fitness = genes passed onto own offspring

indirect fitness = genes passed on by helping close kin who share some genes

animal e.g. yellow- bellied marmots, more likely to alarm call if their own offspring is also out of the burrow

human e.g. males spending lots of money to advertise their resources

animal e.g. soldier ants, don't reproduce: invest in siblings ( more closely related to siblings then they would be to offspring due to inbreeding)

human e.g. looking after distant relatives for free, strangers usually charge.
smith et al. (1997) the higher the relatedness the more money inherited

Kin Selection

Hamilton's rule r x B >C

we will behave altruistically towards individuals who share more of our genes e.g. will hold a door open for a stranger (not costly) but wouldn't donate and organ (costly). more likely to for someone sharing our genes as we want our genes to survive.

Parental investment

time and effort an individual puts into rearing offspring - differs depending on number of offspring

slow life history - more investment fewer offspring

fast life history - less investment in lots of offspring, hoping some survive

parent/ offspring conflict

depends on environmental and social pressures e.g. less offspring as modern medicine improves - fewer children required to ensure successful survival of genes

both parent and offspring is wanting to maximise their own inclusive fitness

parents seek to gain as many offspring as possible, each offspring seeks as much parental care as possible = sibling conflict

conflict greatest when child weaned

parents encourage offspring to be more cooperative then they want to be : punish conflict and praise cooperation.