Multilevel Selection and the Theory of Evolution by Ciprian Jeler

Author:Ciprian Jeler
Language: eng
Format: epub, pdf
Publisher: Springer International Publishing, Cham

2 Interactors on a Train

On a train ride in 1986, Elisabeth Lloyd finally convinced Stephen Jay Gould that he had been wrong about species selection. They were riding back to Harvard University from a trip to visit Elisabeth Vrba at Yale. Vrba and Gould were active in debates about evolutionary theory, and had co-authored two papers, one of which had been accepted for publication in March, earlier that same year, about species selection (Gould and Vrba 1982; Vrba and Gould 1986). 1 In that paper, they proposed criteria for distinguishing selection acting at the species level from processes that could generate a sorting pattern between species caused by selection at lower levels. Lloyd was sure that the criteria they adopted to distinguish between these two processes were too restrictive, and had been trying to convince Gould that he was making a mistake since she had taken a course on problems in evolution he had taught with Lewontin at Harvard in 1983. 2 Lloyd spelled out her arguments challenging Gould and Vrba in a draft of a dissertation chapter on group selection, which was to become chapter six in her book, The Structure and Confirmation of Evolutionary Theory (1988). Upon reading the draft in 1986, Gould suggested that they send a copy to Vrba via overnight mail, and travel to Yale to discuss it with her together. The meeting did not go well. Vrba was less than impressed with Lloyd’s arguments, and insisted that her writing was terrible. As the train left on the return trip to Harvard, Lloyd recalls (personal communication, 2017) being certain that the encounter had destroyed any chance of convincing Gould he had been wrong.

Gould had changed his mind about species selection before. In 1972, along with Niles Eldredge, Gould had proposed that the fossil record indicated evolutionary change in populations was not usually a steady process, but rather typically occurred in relatively rapid periods of transformation, followed by periods of relative stasis. They named their theory ‘punctuated equilibrium’, and in 1977, proposed these patterns could be explained by the selection of species, analogously to organismic selection, as Steven Stanley (1975) had argued (Gould and Eldredge 1977). By 1982, Gould became convinced that this approach to species selection was too permissive; it could not distinguish between cases where selection acted at the level of the species from cases where selection acted at lower levels to produce similar patterns. Gould credited Vrba’s 1980 “effect hypothesis” as especially persuasive on this point. To formulate this hypothesis, Vrba relied on a distinction introduced by George C. Williams, who famously challenged group selection in 1966. Williams argued that traits that had been engineered by selection to perform a specific function that increased fitness were adaptations, and ought to be distinguished from traits that merely had a fitness effect, but no engineering history shaping them to perform that role (Williams 1966, pp. 8–9). If a causal account of selection was to be found at the level of the species, then a species level adaptation appeared to be required.

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