Altruistic behaviors can be understood, in part, by considering the coefficient of relatedness (r) between the individuals involved. Assume that an individual mammal has the option to raise its own offspring, other genetic relatives, or a combination of offspring and other genetic relatives. From a genetic point of view, which of the following represents the least successful option?

• A. Two offspring
• B. Two offspring and two first cousins
• C. Four grandchildren
• D. One sibling and three nephews
• E. Seven first cousins

Answer: (E)

Verified step by step guidance

1. Understand the concept of the coefficient of relatedness (r), which measures the probability that two individuals share a common gene inherited from a common ancestor. For example, r = 0.5 for offspring, r = 0.25 for grandchildren, r = 0.5 for siblings, r = 0.125 for first cousins, and r = 0.25 for nephews.
2. Calculate the genetic contribution for each option by multiplying the number of individuals by their respective coefficient of relatedness (r).
3. For 'Two offspring': Calculate 2 * 0.5.
4. For 'Two offspring and two first cousins': Calculate (2 * 0.5) + (2 * 0.125).
5. For 'Four grandchildren': Calculate 4 * 0.25. For 'One sibling and three nephews': Calculate (1 * 0.5) + (3 * 0.25). For 'Seven first cousins': Calculate 7 * 0.125.