Bonobos have been observed adopting orphaned infants from neighbouring groups for the first time
Among chimpanzees, is an orphaned chimpanzee from a neighbouring community as found, it is most likely to be killed and often eaten.
This is why it is so interesting to find bonobos having done the opposite. There is little obvious gain from this behaviour, suggesting it is potentially a completely altruistic activity.
It would appear rare even in the right places, but then few groups are studied long term so we cannot know for sure. Never the less, it must be recognized that this behaviour is completely altruistic – a behaviour long thought to be a purely human trait.