A chimp who displays feelings of affection toward the other members of its social group is more likely to be defended...

Emil-Kunkin on May 29 at 11:19PM

Hi, in this argument, the author is drawing on what happens in chimp and human societies and then arguing that affection plays the same role. In chimp society, chimps who show affection to others are more likely to be defended by others. In human societies people are more likely to defend people who they have affection for. These are two different things. For chimps we know that those who show affection get defended, but in human society people who receive affection get defended.

The author is relying on the premise that those who show affection also receive it. So, if we negate B by saying that affection is NOT reciprocated in chimp society, that would clearly undermine the argument by negating the assumption that the author relied on.