In the late twentieth century, television provided more immediate ways of representing the processes of evolution, while the press increasingly seized on debates arising from their human implications. Progress remained an important theme, although the image of a linear ascent to humanity was usually qualified by recognition of diversity. The air of unity promoted in the synthesis era evaporated as biologists explored new and disturbing implications of the selection mechanism, including sociobiology and the notion of the ‘selfish gene.’ Studies of primates were used to throw light on human behaviour. Along with new challenges to the plausibility of the Darwinian theory, the resulting controversies were played out in a blaze of publicity. Darwinism also had to be modified to take account of growing evidence for discontinuities in the ascent of life, including mass extinctions. Creationists presented these ‘Darwin wars’ as evidence that evolutionism was losing its credibility even within science.