These are the questions bro-ologists seek to answer—the quandaries they parse as they pick through footage of bros in the wild and captivity. 

Perhaps the most interesting of man's tribes, bros have a culture all their own, complete with a self-governed moral code and social hierarchy. They are not an extant offshoot of the human race, but if one were to study them as such, you'd quickly see a great variety of sub-species within the bro community.