I agree with you here @vinny... there is an instinctual fear of the 'other' and that extends especially to a preference to those 'like me'... yet this doesn't mean that its right or good... in fact, its contrary... such preference for those who share my identity traits is what limits us, eg free trade, sharing of opinions, sharing of scientific data etc...
I don't agree with your analogy though... its simplistic. If you need to save only one you would be more likely to save the one that is nearest and poses the least risk of life to yourself. you can then team with the first saved to save the second. This is a survival trait that is also instinctual.
