In a recent meta-analysis improved social reasoning and attitudes towards outgroups was linked to

I believe the answer is: watching animals interact at the zoo.

When we watch animals interact at the zoo, could easily a similar social structure just like what we see in human (especially if we observe primates)

In primates social structure, we could see that they possess a hierarchy where one alpha primate decide the course of action that taken by group, and would make protective attempt if the group is in danger. As a return, the alpha primate would obtain the most resource compared to the follower.