As far I know, the hypothesis being thrown out here is that men have evolved a certain group mentality. There is the in-group (family, tribe, country, race, etc.) and the out-group (everyone else). The idea is that we have developed a sense of fairness in dealing with our in-group while pitting ourselves against anyone who is not part of that group. This is used to explain the galling inconsistencies in, say, biblical morality. On the one hand, the Jews are told "thou shalt not kill." On the other, they are told to commit genocide on the native inhabitants of the land of Canaan. This is thought to be a result of their inborn tendency to behave morally toward members of their own in-group while attempting to destroy all other groups.
This is a very hopeful hypothesis in that there are indications that the idea of an in-group has grown over time to encompass a greater number of people. When men first emerged from the ranks of older primates, the only in-group was one's own tribe. That eventually grew to include larger and larger tribes (eventually ethnicities and ethnic nations). In time again this grew to include ideological groups, such as nations that are not based on ethnicity. While the moral behavior toward one's in-group is innate, the basis of that group is not. The hope is that as cultural barriers break down, men will eventually come to see themselves as primarily part of the entire human race, rather than some smaller group, and this hypothetical genetic imperative to behave morally toward one's in-group will produce a more peaceful and ethical world.
Obviously, the hypothesis needs some work, but if it's true, it could mean great things.
