To appear in Heams et al. (eds.), Handbook of Evolutionary Biology (provis. Title), Springer.

Please do not quote without permission. This is not the final version

fittest in a harsh and savage environment was considered to be a factor in the improvement of the race: it suppressed the weak and maintained only the best seed (Spencer 1864). This conception of a violent and progressive evolution was often associated with a host of other beliefs. Varying according to the author, we come across the idea that there is a hierarchy of social class as well as of race; the western races (in particular their upper classes) are the supreme result of the process of evolution, and are thus superior to other races. One also finds the idea that new technologies, advances in medicine, and state policies that support the disadvantaged in society prevent selection from playing its role of racial and social purifier. It is thought that an excellent way of resolving these problems is to take political measures (laissez-faire), or social or medical measures (of the eugenics variety) to give a selection2. boost to evolution, and re-establish in an 'artificial' manner the beneficial effects of A great many versions of Social Darwinism are based on the notion of race and the idea that it can evolve in a positive or negative sense: it can improve or deteriorate. In the best case, one might use this collection of beliefs as a basis for one’s good intention to improve one's race through knowledge about heredity and evolution (Spencer). In the worst case, one will consider one's own race qualitatively better than others and seek to purify it and to impose supremacy (Bruecher 1936); the political consequences of this kind of ideology (extermination by force of individuals who do not conform or those of 'inferior' race) are sadly known in the form of the German Nazism of the Second World War.

The presentation of Social Darwinism just provided is very summary and does not attempt to describe the details of the positions defended by different thinkers in this movement, all the more given that there is often debate about which authors were really part of this current of thought. For example, Herbert Spencer (1864) is commonly considered a Social Darwinist because he advocated a policy of laissez-faire based on his conviction that governmental measures to help the poor and the weak favoured the survival of mal-adapted human specimens. But Spencer would certainly not have accepted a cult of force or the Nazi derivations of his position. On the contrary, he was convinced that the process of evolution was headed towards a situation where military societies gave way slowly to industrial civilisation, where the struggle for survival became less brutal and altruistic sentiments 1879)3. replaced egoistic motivation (Spencer The last point explains why Spencer has directly inspired some thinkers from another current of thought, which we could call ‘Pro-social Darwinism’, where this means the defence of a socio-political ideal of equality, mutual aid and collaboration. In fact, Darwinian thought has not only inspired eugenists, or been used as nationalist propaganda, or by ideologues who seek to justify the superiority of their race and their cult of force. One also finds it among left- wing thinkers. In France, for example, Emile Gauthier, the left-wing anarchist of the 1880s, used Darwin’s ideas to defend his political ideals. Instead of the survival of the fittest, his slogan was aid for existence (Gauthier 1880). In the same vein, the liberal republican Alfred Fouillé was inspired by the socialising passages in Spencer’s writings to sing the praises of 1880)4. altruism and cooperation (Fouillé There is nothing bizarre in the idea of using Darwinian concepts to support social and egalitarian measures, since Darwin himself thought that cooperation between individuals was an adaptive strategy in many environments. In fact, he saw very well that the reproductive success of members of a group could be noticeably improved if cohesion, cooperation and

2