1 of 9 Submitted to Biology Letters 1 2 3 Fear of shame drives cooperation 4 5 6 Jennifer Jacquetl 2., Christoph Hauert', Arne Traulsen3 and Manfred Milinski4 7 8 Department of Mathematics, University of British Columbia, 1984 Mathematics Road, 9 10 Vancouver, British Columbia, V6T 1Z2 Canada (where the