Comment by t1E9mE7JTRjf

I remember reading about tribes in Indonesia who when someone got too old/slow, they'd kill them. They were living on the edge of existence, and either everyone was on form, or the group didn't survive. In that context, it was presented as a caring act for the group. A bit different context to the original thread, but an example of why a group may do what outwardly seems a little surprising.