What is inclusive fitness and how does it relate to the evolution of altruism?

How does inclusive fitness relate to selection acting on different levels of biological organization?What is inclusive fitness and how does it relate to the evolution of altruism?Inclusive fitness is a concept invented to explain the apparent paradox of how some eusocial insects (such as ants and bees) have worker castes that do not reproduce. Individual fitness is of course calculated on how many offsprings one have that survive to adulthood and reproduce. Inclusive fitness is calculated on how many relatives one raises to adulthood. It was thought that since bees and ants are more closely related to their sisters than to their own offspring (3/4 vs. 1/2), they benefit more by raising sisters rather than their own young. Inclusive fitness therefore was thought to be an answer to one of the greatest puzzles in nature of the evolution of individuals that did not reproduce. Intoxicated by the apparent success of inclusive fitness theory, the discipline of sociobiology was born in the late 1970's and it attempted to explain all sorts of seemingly altruistic behavior in all sorts of animals. Sociobiology provoked a lot of negative reactions and rebuttals from many scientists, who pointed out that it was simply bad, overreaching science.



Since then, there have been numerous research efforts on eusocial insects, and the results are summarized in the paper below. A quote:



"The altruism of insect workers has puzzled researchers for decades. Inclusive fitness theory suggests that high relatedness has been key in promoting such altruism. Recent theory, however, indicates that the intermediate levels of relatedness found within insect societies are too low to directly cause the extreme altruism observed in many species. Instead, recent results show that workers are frequently coerced into acting altruistically. Hence, the altruism seen in many modern-day insect societies is not voluntary but enforced."



The workers therefore did not voluntarily give up reproduction, but they were merely slaves of the queen mothers. Since bees and ants are often thought of as superorganisms. The workers are therefore analogous to the body cells of, say, a cow. The body cells, blood cells, liver cells, heart cells etc. play no role in reprouduction and yet they are vital to the survival of the cow. Reproduction is left to the testes and ovaries of the cow, just as the drones and queens are the specialists that take care of reproduction in an insect colony. Viewed in this light, it is therefore no surprise that eusociality evolved, even in termites in which there is no inclusive fitness advantage for the workers. All that it needs for eusociality to occur is for the queen to evolve ways to enslave its daughters.



http://www.santafe.edu/~bowles/Dominance鈥?/a>