George C. Williams (biologist) should only be used where it is really necessary", and, that, when it is necessary, selection among genes or individuals would in general be the preferable explanation for it. He elaborated this view in later books and papers, which contributed to the development of a gene-centered view of evolution; Richard Dawkins built on Williams' ideas in this area in the book "The Selfish Gene". Williams was also well known for his work on the evolution of sex, and was an advocate of evolutionary medicine. In later books, including "Natural Selection: Domains, Levels and Challenges", Williams softened his views on group
The Selfish Gene "nature", providing an excuse for behavior with bad consequences for future human society. Dawkins' major concluding theme, that humanity is finally gaining power over the "selfish replicators" by virtue of their intelligence, is criticized also by primatologist Frans de Waal, who refers to it as an example of a "veneer theory" (the idea that morality is not fundamental, but is laid over a brutal foundation). Dawkins claims he merely describes how things are under evolution, and makes no moral arguments. On BBC-2 TV, Dawkins pointed to evidence for a "Tit-for-Tat" strategy (shown to be successful in game theory) as the