As a general rule, the larger a social group of primates, the more time its members spend grooming one another. The m...

shunhe on May 30, 2020

Hi @filozinni,

Thanks for the question! So let’s take a look at what this stimulus is telling us. Generally, as social group of primates get larger, the more time the members spending grooming each other in order to maintain social cohesion. Early human groups were quite large (and so needed social cohesion), but humans didn’t spend much time grooming one another. Therein lies the paradox that we need to resolve: humans had this social cohesion, but didn’t groom each other, and so we need to find something that might explain how they had this social cohesion without grooming. As long as we have that in mind, that’s good enough for anticipating what the right answer choice might look like, so we can dive into the answer choices.

Sure enough, (B) gives us what we need. It tells us that early humans didn’t need to groom each other to maintain social cohesion, because they developed languages. This helps explain both why humans didn’t need to groom each other (they developed language) and why they could maintain social cohesion (again, because of the language). And so this other factor helps resolve the paradox above.

Choices (A) and (C) are quite similar in that both of them help explain why humans didn’t need to groom each other as much. (A) tells us that humans were more likely to groom themselves; (C) tells us that humans don’t have as much hair, and so don’t need to groom as much. But this only helps address one part of the paradox, why humans didn’t groom each other as much. The question of how they managed to maintain social cohesion (which the passage tells us they did) is still a mystery, and so (A) and (C) don’t fully resolve the paradox in the way that (B) does.

Hope this helps! Feel free to ask any other questions that you might have.

filozinni on June 3, 2020

Thank you so much Shunhe!