dhw: Like Tony, I'm not sure what to make of this, but I agree that the personification of evolution is a fudge. I'm grateful to David for the article and for putting it on the inventive mechanism thread. In the context of my hypothesis, it's the cells themselves that have to work on a developmental programme. If they fail to embrace the cheats, they will not survive.-Thank you for the compliment.The article demonstrates to me the great difficulty in understanding the advent of multicellularity.