Saturday 13 April 2013

How a Kuhnian missed a crisis (on Ghiselin)

According to George C. Williams (1975, Sex and Evolution. Princeton University Press, p. v) there has been a crisis simmering in evolutionary biology ever since the recognition of the paradox (anomaly) that sexual reproduction is the prevalent mode of reproduction in higher animals and plants although, all else equal, asexual mutants should gain an  immediate,  twofold reproductive advantage.
   From my student days,  perusing the primary literature in order to grasp the scientific issues, I only remembered that Michael T. Ghiselin (1974, The Economy of Nature and the Evolution of Sex. Univ. California Press) introduced his book with chapters on the history and philosophy of science showing that he was a dyed-in-the-wool Kuhnian. Therefore, on rereading his book with a historical interest recently, my expectation was that he would also have seen the paradox of sex and perceived a crisis.
   Alas, Ghiselin (1974) marched through the eras with such a wide gait, that he stepped over this major problem of his time.
His discussion remains engaged against teleology, vitalism, and naive reasoning for the good of the species of earlier periods. As William D. Hamilton (1975, reprinted in 1996, Narrow roads of gene land, vol 1, Oxford Univ. Press, p. 359) says:
He seems to see less a recent acceleration in evolutionary biology leading up to the present interest than a 100-year hiatus of thought.
   Although Williams (1975) and Maynard Smith (1978, The Evolution of Sex. Cambridge Univ. Press) published after Ghiselin (1974) the problem has been studied in peer reviewed journals since the late 1960s. Therefore, Ghiselin should have known it and John Maynard Smith (1975, Evolution of sex. Nature 254:221) regarded his book as infuriating because it simply does not do to ignore the difficulty and to appeal to nature as a witness.
   Later Ghiselin recognized the problem and admitted that he had evaded the twofold cost of sex by a kind of gerrymandering--asking why sex exists, not what was wrong with a theory that made it seem paradoxical (Ghiselin 1988,  p.17, in The evolution of sex: an examination of current ideas. Ed. by R.E. Michod & B.R. Levin. Sinauer Associates). Ironically, Felsenstein denied the crisis in the same volume (see here) and Williams concluded:
“Felsenstein is inclined to belittle the crisis that arises from these considerations. I believe that Ghiselin's recognition of the crisis is more likely to lead to important new understanding.  (Williams 1988,  p. 293, in The evolution of sex: an examination of current ideas. Ed. by R.E. Michod & B.R. Levin. Sinauer Associates)  
   That's an odd collection of papers. Given the above lack of consensus among its contributors, Richard Michod and Bruce Levin (1988 in The evolution of sex: an examination of current ideas. Ed. by R.E. Michod & B.R. Levin. Sinauer Associates) nevertheless introduced the anthology by stating:
A survey of evolutionary biologists would doubtless come up with a consensus that the elucidation of the selective pressures responsible for the origin and maintenance of sex is a big (maybe the biggest) unsolved problem in evolutionary biology. [...] While there may well be agreement about the importance of the problem of the evolution of sex, there is no consensus about where the solution lies. (p. vii) 
As Williams and others point out, the costs of sex are explicit and borne by individual organisms, while the postulated benefits of sex have been vague and not readily modeled. The crises involving the question of sex can be seen clearly in this contrast between the costs and benefits of sex. (p. 2)