Hamilton's theory

colonies can be regarded as a variation in the species as they are natural selected by the nature. This is called 'group selection'

however, in order to make group selection, we have to assume

•  there is no migration between colonies

and the weak point is 

•  Individuals are selected much higher than the groups, so group selection never counteract individual selections.

In order to improve the group selection theory that has number of considerations, Hamilton came up with 'kin selection'.

Presupporsition 

• Individuals try to make the maximim number of offspring as 0.5 or less than 0.5 of its genome are transferred into the each offsprings. 

 Hamilton’s strike of genius was to reformulate the definition of fitness as the number of an individual’s alleles in the next generation.   Or, more precisely, inclusive fitness is defined as an individual’s relative genetic representation in the gene pool in the next generation.