 Charles Darwin told us the basic law of evolution. Individuals that convert resources into offspring better will dominate the next generation with their copies. The product of that kind of evolution are individuals that maximally exploit resources with no respect to anything. So ruthless exploiters will evolve. After population density has increased competition becomes inevitable and now individuals that maximize exploitation of resources under competition will produce most offspring and therefore ruthless competitors will evolve. Now if such ruthless exploiters that have evolved have access to technology they will over exploit resources. Garrett Hardin coined the term the tragedy of the Cummins. This is a really apocalyptic vision. Whenever people have free access to a public resource the resource will be overused and collapse. Many examples proved Hardin right from overfishing to destroying the global climate by a ruthless overuse of fossil energy. Now the public good game tests such situations experimentally. You ask each player of the game to provide one euro anonymously. Here three did and you double the three euros and redistribute the money to all of them which means the single defector has the highest game so not contributing to the public good pays off. Here you see an example of such a game. Here are groups of six students each playing eight rounds of a game and you see initial cooperation collapses quickly. However if this game is interacting with another game for which you need reputation you might enhance your contributions to the public good just to increase your reputation. Now what can this other game be? Give and you shall receive is the message of indirect reciprocity. A observes that B helps C and A helps B. A helps B because B has built a reputation for helping. Does that work? We studied with 80 Swiss students who were asked to give from their own money to a student of whom they knew only the history of giving and refusing help. And as you can see only those receivers received money that had a positive reputation gained in this game. Those was a negative didn't get anything. Here we continue now we have again groups of six students each now playing alternating games of indirect reciprocity and public goods, solid blue circles. And you see now in this interacting situation the contributions to the public good are at a high level until we told them that from now on there will be only rounds of the public goods game and as you have seen contributions collapsed rapidly. Which means the pending risk of having a higher reputation drove them to contribute to the public good. So they feel to be watched and this had been tested in a nice study by Melissa Bateson. He studied students that are taking tea with milk from a cafeteria machine and above the machine there were slides, there were pictures either for flowers or for faces watching alternating between weeks and as you might have seen people gave money in a honesty box at a higher rate and higher amounts and they felt observed. But the point is these eyes were ink on paper so decisions were unconscious. Now this might show that reputation might drive people to contribute and here we tested if the reputation is at stake whether 150 students were willing to invest into the global climate and we alternated rounds of the climate public goods game in which the money invested goes to rescuing the climate was indirect reciprocity rounds and we had alternating public and anonymous rounds and as you might have seen and recognized from the previous figure in those games in which the decisions were public they invested a lot more than in situations when they were anonymous. So reputations obviously matters and the previous slide which you might also remember showed a situation of our ancestors who tried to rescue a public good for their society and these investments were risky and the investments were public and I guess that those which stayed away were socially punished later on. So I think and this is my message that humans have evolved to guard their reputation and to pay attention to other reputation and my theme is and this is my point for the discussion group that I regard reputation as a universal currency for social interactions and I would like to have discussed whether what we found out about reputation of individuals that they really count in social interactions whether this is also true for higher units so how can reputation facilitate cooperation also among larger units groups or even states if you have ideas on that I would be glad. Thank you.