Tit-for-Tat defeated!

[swestrup]

For the first time since Axelrod first investigated strategies for solving an iterated prisoners dilemma, somone has produced a strategy (called Southampton) which beats Tit-for-Tat. The secret was to use a fixed set of initial responses so that agents using the Southampton strategy could identify themselves. Then one of the agents would sacrifice itself to provide maximum benefit to the other agent. In the end, a few of the submitted southampton agents scored at the very top of the list, beating Tit-for-tat, while all the rest ended up on the bottom.  You are free to draw your own conclusions as to what this means in terms of cooperation within societies.

More info here.