What is an explanation for human altruism?
Three ideas have been put forward: it helps your immediate family, you may derive some benefit later on, and/or it may increase your social standing/status.
Altruism probably has its roots in our deep evolutionary past. Kin type altruism is when we help our immediate relatives out and by so doing, help to keep our genetic lineage going. A clear and immediate benefits.
Altruism toward non-kin relatives is harder to explain, but one idea is that if you are nice to someone now, they may reciprocate at some time in the future. A sort of I'll scratch your back now, if you scratch mine later idea.
I third type of altruism toward non-kin is thought to occur, as it increases an individuals social standing and status in a given society.