The idea that Darwin rejected Lamarck’s ideas of use and disuse and the inheritance of acquired traits emerged in the late nineteenth century as biologists debated the mechanisms by which evolution occurs.  In characterizing “pure Darwinism,” critics and enthusiasts alike sought to purge Darwinism of any reliance on the idea that changes acquired in the as the result of the use or disuse of organs could be passed along to the next generation via heredity.  But Darwin himself was a strong believer in the idea.  Through the successive editions of the Origin of Species he represented the inheritance of acquired characters as an important supplement to natural selection. In his Variation of Animals and Plants under Domestication, he not only gave examples of the inherited effects of use and disuse, but he was also pleased to propose how his “Provisional Hypothesis of Pangenesis” could successfully explain the phenomenon.  August Weismann’s attacks on the inheritance of acquired characters, beginning in the 1880s, were the primary impetus for the idea’s decline in popularity among biological theorists – and ultimately for the widespread forgetting of the fact that this was an idea that Darwin himself explicitly endorsed.

Coordination is a central feature of economic life. If we do not coordinate our activities, we are destined to waste our time and effort. However, often the way we coordinate has distributional consequences – some people receive more benefits than others. Such situations establish what Ullman Margalit (1977) call “norms of partiality” where the convention created to solve a problem bestows privileges on one set of people. If you are on the short end of the convention, you may be upset. We investigate the creation and evolution of conventions of behavior in these situations using our “intergenerational games” framework or games in which a sequence of non-overlapping “generations” of players play a stage game for a finite number of periods and are then replaced by other agents, who continue the game in their role for an identical length of time. Players in generation t can offer advice to their successors in generation t + 1. What we find is that word-of-mouth social learning (in the form of advice from laboratory “parents” to laboratory “children”) can be a strong force in the creation of social conventions.

The ability of conscious human subjects to modify their behavior and adapt their institutions to changing circumstances has never been in question. Lamarck and Darwin innovated by making natural species the outcomes of adaptation to environmental pressures: thus, not only human institutions, but natural kinds, fell under the heading of choice and change. This plasticity raised the question of heritability, or the persistence of somatic learning across generations. Attempts to formulate a physical basis for inheritance through the second half of the nineteenth century relied on analogies drawn from technology and culture and, in return, suggested new ways of describing and explaining cultural facts. Neo-Lamarckianism in France spurred the creation of analogies involving biology, chemistry, psychology, and aesthetics, as a protest against the reduction of inheritance to features of the gene.

This chapter reads the late nineteenth-century genres of American naturalism and regionalism through the prism of climate, and finds that their authors depict characters whose characteristics are shaped by their responses to their ambient environments, including climate, and by the inherited effects of their ancestors’ adaptations to theirs. It argues that their thinking about climate was informed by the popular Lamarckian science of their post-Darwinian evolutionary era, by the climate theory of the historian Hippolyte Taine, and by turn-of-the-century geography. In the decades during which Frank Norris, Charles Chesnutt, Edith Wharton, and Hamlin Garland were at work on questions of determinism and/or a “determined indeterminacy,” climatic, genetic, medico-psychiatric, and sociological models of identity vied for authority. The writers drew their representations of the making of Americans from these competing claims.

This concluding chapter revisits the four main themes of the book and ties them into important theories and ideas that emerged after 1750.