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.

This chapter argues against the narrative that posits a pre-twentieth century past, where the mother and fetus were one, in contrast with the present, where the fetus is visible and autonomous. I complicate this narrative by showing that the maternal–fetal relationship was redrawn and reinterpreted multiple times in the twentieth century. The ‘fetal parasite’ era was informed by the hereditarianism of the early 1900s. The notion of a developing organism sensitive to external influences was replaced by a remarkably sheltered fetus. In contrast, concerns around the physical and psychological trauma following the Second World War supported the notion of ‘critical’ periods, responsive to external influences mediated by the mother. Yet soon thereafter, the language and imagery of an autonomous, self-sufficient fetus became prevalent amidst political battles over abortion. The notion of the autonomous fetus is linked to evolutionary biology’s 1970s concepts of the ‘selfish gene’ – with the ‘selfish’ fetus pitted against the mother in the struggle over scarce resources. By the 1990s, the rise of DOHaD and epigenetics signalled a return of the maternally mediated environment to the science of human development. While some interpreted this as a return to the pre-modern model, there is a significant difference. Here maternal experiences and surroundings have to be rendered accessible to an experimental, molecular approach and to show evidence of a quantifiable change in observed parameters.