1. If living in large groups has costs and benefits, under what conditions would natural selection favor group living?

2. Why might individuals give up defending territories if the density of their population increases?

3. Explain the costs and benefits that might influence the optimal flock size in birds.

4. Why should natural selection not favor spiteful behavior?

5. How could helping a relative improve the helper’s fitness?

6. In the kin selection explanation for the evolution of altruism, why is the benefit to the recipient weighted by its coefficient of relatedness to the donor?

7. Why are selfish behaviors less favored when the donor and recipient are related to each other?

8. Compare the coefficient of relatedness between brothers and sisters in diploid organisms with haplodiploid organisms.

9. How does a haplodiploid sex-determination system favor the evolution of eusociality?

10. What evidence is there that a haplodiploid sex-determination system is not required for the evolution of eusociality?