Dawkins demonstrates a classic "Prisoner Dilemma AI tournament". No big surprise to us today, but at the time the revelation that Tit for Tat is one of -- if not the -- most effective strateg(y|ies) was a surprising result.
It was really surprising? That's... odd. What were they expecting?
Dawkins himself said it; they believed that "sneaky cheaters" would prosper more. This is a common intuition even today. It turns out that Tit for Tat remains a very robust strategy, despite its apparent lack of sophistication, in prisoner-dilemma trials. There was a run just a month or two back that was all the rage on Discussion on LW.
Check it out here.
Brief summary: Dawkins demonstrates a classic "Prisoner Dilemma AI tournament". No big surprise to us today, but at the time the revelation that Tit for Tat is one of -- if not *the* -- most effective strateg(y|ies) was a surprising result. He goes on to demonstrate animals employing the Tit for Tat strategy. Assumptions of generosity, with vengefulness, appear to be strongly selected for.