Biologists write to Science to defend the theory of sexual selection
By Nick Atkinson | May 5, 2006
Forty biologists have contributed a total of ten letters to Science this week, all critiquing a review paper published in February suggesting that reproductive behavior is explained better by cooperative game theory than by the theory of sexual selection first proposed by Darwin.
"The review is a poor piece of scholarship, which is consequently misleading, and from that point of view should not have been published," Kate Lessells, based at the Netherlands Institute of Ecology and lead author on one of the letters, told The Scientist.
In the review, Joan Roughgarden of Stanford University in California and two co-authors claim that sexual selection theory, which emphasizes the often-different interests of males and females, is fatally flawed. Males are frequently characterized as competing to fertilize as many females as possible, while females seek relatively few, high quality mates, given their limited production of gametes. The authors propose an alternative perspective, in which they use cooperative game theory to set reproduction in an essentially mutualistic framework. Reproductive partners enter into a "contract," Roughgarden told The Scientist, in which their best individual interests are served by working together to produce offspring.
In response, the journal received a swell of letters from biologists, critiquing the arguments Roughgarden and her colleagues lay forth. Many critics argue that Roughgarden and her colleagues' theory is not exactly new -- and is, in fact, sexual selection in disguise. Specifically, Lessells and colleagues reason that variation in payoffs obtained in Roughgarden's game theoretical analysis equate to selection, making the "new" theory merely part of the existing body of Darwinian sexual selection theory.
"Sexual selection theory is not deeply flawed, and happily includes all of the points Roughgarden et al try and make," letter-writer David Shuker, at the University of Edinburgh, UK, told The Scientist.
Moreover, the review does not explain compelling data that support sexual selection theory, some letter-writers note. For example, an extremely robust relationship exists across phylogenies between the evolution of increased investment in testis mass and increased degrees of sexual promiscuity, according to Tommaso Pizzari, lead author of another letter, based at Oxford University, UK. "So far, sexual selection is the most cogent, universal explanation for this," he told The Scientist.
"Many people felt that this was completely shoddy science and poor scholarship, all motivated by a personal agenda," said Queens University in Canada's Troy Day, lead author of another letter. (Roughgarden is known for her controversial stance on a range of issues, notably those involving gender.) Pizzari added that each of the 17 examples highlighted by Roughgarden in an electronic supplement to their review contains misunderstandings, misrepresentations, or both.
Roughgarden and her colleagues penned a response to the letters, also published this week. She told The Scientist that she was unaware of the scale of dissent until this week when she received notification from staff at Science magazine. None of the letters' authors contacted her directly. She said she was "not altogether surprised by the replies," but noted that their sheer number was "unusual."
In their response to the letters, Roughgarden and her colleagues refute most of the criticisms, writing "[our theory] is about the number of offspring successfully reared and is not an extension of sexual selection theory." They add that "if sexual selection is correct, its credibility will be enhanced once it is successfully tested against alternative hypotheses."
Science's editor-in-chief, Donald Kennedy, said in a statement to The Scientist that a certain amount of dissent was expected with this kind of paper. "We knew this was a prospectively controversial Review article," he said. "It's not surprising that we're publishing a number of letters."
Links within this article
"Letters," Science, May 5, 2006.
J. Roughgarden et al, "Reproductive social behaviour: Cooperative games to replace sexual selection," Science, February 17, 2006.
T. Toma, "Sex wars drive evolution," The Scientist, June 26, 2003.
I.Ganguli, "Getting on top, genetically," The Scientist, October 18, 2005.