Hopes that aging might be defeated by identifying and interfering with culpable genes, have run into an obstacle. Paul Nelson and Joanna Masel of the University of Arizona in Tucson have shown that, while competition between cells within one organism should seemingly just remove ones that work less well, the need for cells to co-operate with other cells can also select ones which do not themselves work as well, but co-operate better. This is at odds with the idea that aging is simply be due to a weakness in removing genes that only affect mortality late in life, and suggests ageing is a fundamental feature of multicellular life.