Just an interesting little study about a debate that I am sure will not rest here.
I have worked with chimps in the past and I do not find it very surprising that chimps would be so giving to unrelated members of their species.
But as it usually is in science, what you feel is not always what you find. Let the debates continue.

chimpanzees will do favours and a number of other things to and for related and unrelated chimps.
such as lie and practice deception, raid and kill, murder among their own tribe (goodall) and rape female members of their own tribe.

kindness has also been shown among elephants - where a member is injured the group slows or waits when the injured is unable to forage another will feed it.

altruism does not seem to be confined to us alone nor much of anything else.