[Stratos]

Well one can always twist and turn a word but to some degree you´re correct; if I help someone he or she is more likely to help me in the future so it isn´t completely selfless. As for the animal kingdom many animals help their buddies and their family when they´re in need of help. Much of the animals reality is about survival and to spread their genes. Spreading your own genes is the best but if your siblings, who have a similar genome, get to spread theirs it´s the second best and thus helping them to survive might benefit perhaps not alway the individual personally but still their family. And this is only the biological side.
Helping poor people in your society might decrease crime and thus the risk of crime happening to you decreases. So yes you do gain by helping people sometimes even if it still just the feeling that you have done something good. What comes around goes around, as they say.