Some 135 years ago a certain Mrs Laps, a respectable lower-middle-class lady with conventional opinions on life in general and particular views on the importance of decent behaviour, had organized a pleasant evening with her friends at her home in Amsterdam. She and her invited lady guests were chatting very cosily when her son, a schoolteacher, yielded to the temptations of displaying some advanced thinking. He challenged one of the ladies present to say what she ‘really’ was. After some beating about the bush he informed her that the real answer was that she was a ‘mammal’. This striking solution to a fundamental question ruined the entire evening: a respectable lady was not an animal, let alone a mammal (Douwes Dekker [1862] 1907). In this anecdote the well-known Dutch author Douwes Dekker presents us with an image of the devastating potential of that process which might be described as ‘the biologising of our philosophy of life’ (Bulhof 1988; De Negentiende Eeuw 1993). The publication of The Origin of Species by Charles Darwin in 1859 signified the intrusion of all that was green and growing into the domain of ideology and philosophy. The anecdote does much to capture this moment but at the same time illustrates some of the difficulties involved in analysing the reception of Darwin in The Netherlands, for in Dekker’s little story Darwin’s name was not mentioned. In all honesty, Dekker was to confess later in life he had never read him. As so often is the case in public life it was easier to hold distinctive views of the burning issue of the day if one was not overburdened with knowledge. Evolutionary theory was no exception to this rule. Nevertheless, it is still interesting to try to recreate the process by which Darwin was to gain such rapid acceptance in The Netherlands and explain why his work encountered no serious opposition. Essentially this was achieved by the softening, even sometimes the elimination, of the more disturbing elements of the theory. The evolution of Darwinism was thus subject to its own process of natural selection. The most striking result of this was that by the end of the 19th century it was to come to mean precisely the opposite of what it had originally meant.