How do altruistic behaviors arise through kin selection?

Question

A) The Altruistic is taken care of by other members of the population

B) Altruistic behaviors lower stress in population which increase the survivability and reproduction of all the members of the population

C) No answer is correct. Animals that perform altruistic acts have higher direct fitness than those what are not altruistic

D) By his/her actions, the altruistic increases the likelihood that some of its alleles will be passed on the next generation

Answer 1

D) By his/her actions, the altruistic increases the likelihood that some of its alleles will be passed on the next generation

Answer 2

The correct answer here is D) By his/her actions, the altruistic increases the likelihood that some of its alleles will be passed on the next generation.

As for an explanation, the evolution of altruistic behaviors is an interesting problem. You might wonder, how can a trait that reduces the fitness of an individual directly (for the good of others) possibly be selected for?

The answer is INDIRECT fitness. By performing altruistic behaviors for other individuals in the population that you are genetically related to (brothers, sisters, cousins), you actually increase your indirect fitness because you increase the chances of your siblings to reproduce. Since they share some of the same alleles you do, your overall fitness increases as long as the altruistic behavior is beneficial enough to outweigh the direct fitness cost.