For the vast majority of the species' time on earth, human social evolution occurred in a world of little tribes which competed with each other for resources - co-operation within the group to achieve success in group competition.
From this origin arose the finest things about humans - advanced social skills, language, consciousness etc. And obviously a lot of the bad things arose from this origin as well - xenophobia, war etc.
In general our ever-growing cognitive skills have been able to rise above the instincts we inherited from the little tribes of our fore-folk. This is illustrated by the very existence of cities and states where strangers co-exist relatively peacefully, and by the onward march of ever increasing population.
However the "us vs them" instinct which helped tribes to grow and prosper in subhuman times has not gone away, and is not even deeply buried in our psyches. It is explicit and manifest in the cities and the states themselves, in the international institutions which acknowledge the rights of nations, in sport and in everyday life, and human relations everywhere on every level. It is an integral part of human nature, as instinctive as sweating.
However, we are now at an epochal moment in evolution when the "us" is becoming sufficiently large and integrated that there is no more "them". Infinitely fine networks of economics, communication and environment are enmeshing the lives of all together.
Beyond this moment the purpose of the "us vs them" instinct is no longer valid. The automatic desire to strive and achieve and own and control more than our neighboring communities no longer confers an advantage on our offspring - in fact it endangers them. We - "us" - cannot continue to profit at the expense of "them" because "they" are not there anymore. "They" are now "us".
Is it possible for human cognitive capacities to once again overcome ancient instincts, as has happened in the past? Fear of strangers was surmounted to create the city, acceptance of leadership by strangers allowed us to create the nation. But all of these earlier steps left some other "us" to be "them".
Humans are highly adaptable and I don't discount the possibility we can rise above this basic need for us-ness and them-ness. But its also fair to say this next step is altogether greater and different from earlier ones.
More likely I think is that we will identify something else to be "them"- and it's most likely to be extraterrestrial life. The discovery of Gliese 581c caused bookies to drop their odds of finding "them" from 1000-1 to 100-1. We are on a roll and things will only accelerate from here.
When extraterrestrial life is found the implications for ontology, teleology and religion generally are incalculable. Whatever differences people may perceive between themselves on religious, racial or other grounds will vanish to irrelevance in the face of life on another planet, let alone intelligent life.
With extraterrestrial life we will have another "other", a "them" for our "us". Our instincts (which evolution created, not us) will kick in once again and we will do what we have traditionally done with "first contacts" - hide behind a rock and see what we can make of them.
Then maybe all of us can sneak up on them!
