From New Scientist magazine:
In simulations with groups ranging from 4 to 256 invididuals, the team found that altruism could evolve. The benefits that cooperation conferred on a group outweighed its costs to individuals – but only in groups of less than about 10…. so how could cooperative behavior have evolved and spread in these groups?
The answer lies in the fact that strong reciprocity is not simply a matter of cooperation; it also requires punishment of those who fail to toe the line. When the team added punishment to their models, they found it made a huge difference…. This time, competition between groups led to the emergence of cooperation in groups of up to 50 individuals.
It’s interesting to note here how science is supporting the idea that altruistic cooperation is only naturally possible in family-sized units. These experiments also explain why the government is so comfortable using coercion to force the social “altruism” it desires. The article went on to explain how cooperation between even larger groups was possible if not only the “anti-social” were punished, but those who fail to punish the “anti-social” were punished as well.
This helps explain the vehemence with which the tax cheerleaders, secular supremacists, feminist groups and other collectivist, pro-government forces attack not only those who overtly oppose them, but also those who fail to adequately submit to their hive mentality.