Back-scratching

After a three year study Back-scratching: Do what is best for your mates and screw the rest:
"For me the take-home lessons are: 

• Loyalty is strong. Rotation policies are good, unless those people being rotated in have existing loyalties. This means there is a trade-off for regulators; staff with more industry experience are also likely to come with stronger prior alliances and hence be more prone to back-scratching. In politics it means voting in a different political party brings with it the alliances of that party.

• Bureaucracy can work. The array of procedures emerging in our large organisations could simply be the result of seeking internal fairness over favouritism. But back-scratching can still arise even with minimal amounts of discretion.

• Social norms are strong. In organisations or groups where some people are observed ‘doing the right thing for the group’, this quickly becomes the norm. Whereas where favouritism is observed, the group descends into counterproductive back-scratching.

• Be loyal, but not too loyal. If your alliance partner fails to come through with favours when expected it pays to look for someone else whose back needs scratching." and "And if you look deep enough there is an evolutionary foundation for this behaviour. As Joshua Green explains: 

• Morality evolved to enable cooperation, but this conclusion comes with an important caveat. Biologically speaking, humans were designed for cooperation, but only with some people. Our moral brains evolved for cooperation within groups, and perhaps only within the context of personal relationships. Out moral brains did not evolve for cooperation between groups (at least not all groups). How do we know this? Because universal cooperation is inconsistent with the principles of natural selection. I wish it were otherwise, but there's no escaping this conclusion

  This. Fundamentally. Is why corrupt back-scratching is so hard to eradicate, and why it will continue to be the main game in politics." The part attributed to Joshua Greene seems to from a review of Joshua Green book by Thomas Nagel