Which concept describes helping relatives to increase the overall genetic propagation?

• A. Reciprocal altruism
• B. Inclusive fitness
• C. Proximate
• D. Ultimate

Answer: (B)

Inclusive fitness explains how helping relatives can boost genetic propagation. It combines direct benefits from your own offspring with indirect benefits from aiding relatives who share your genes. Since relatives carry a portion of your DNA, helping them reproduce increases the number of your genes in future generations, even if you don’t reproduce as much yourself. This idea is often summarized by the idea that an organism’s genetic success depends on both its own offspring (direct fitness) and the success of relatives who share common genes (indirect fitness).

For example, helping a sister raise more offspring can be favored by evolution because sisters share about half of their genes with you; the extra offspring they produce can pass on many of the same genes you carry. This is the core idea behind inclusive fitness and Hamilton's rule, which describes when altruistic behavior toward relatives is favored by natural selection.

Reciprocal altruism, by contrast, centers on mutual exchanges with non-relatives rather than shared genes. Proximate and ultimate refer to levels of explanation (mechanisms vs. evolutionary purpose), not to the concept of gene propagation itself.