genetics of altruism: Is blood really thicker than water?

It isn't that often that a scientific controversy is featured in the New Yorker, but in 2012 an article titled "Kin and Kind" (http://www.newyorker.com/magazine/2012/03/05/kin-kind) describing a tempest over a biological theory appeared in its pages.

The tempest was provoked by an article in the Aug. 26, 2010 issue of Nature. Written by Harvard mathematicians Martin A. Nowak and Corina E. Tarnita and Harvard biologist Edward O. Wilson, it questioned the validity of the theory of inclusive fitness.

Inclusive fitness theory, proposed by British biologist W. D. Hamilton in 1964, expanded Darwin's definition of "fitness" -- an organism's success in passing on its genes -- to include the genes of its relatives. This expansion made altruism in the service of kin a competitive strategy.

The Nature article, titled "The Evolution of Eusociality," asserted that inclusive fitness theory, which has been a cornerstone of evolutionary biology for the past 50 years, had produced only "meagre" results and that mathematical models based on standard natural selection theory provide a "simpler and superior approach."

This provoked a prolonged argument among evolutionary biologists that is still not resolved. But in the March 31 issue of PLOS Biology David C. Queller, PhD, a well-known evolutionary biologist at Washington University in St. Louis, suggests a way out of the impasse.

Queller, the Spencer T. Olin Professor in the Department of Biology, and his co-authors Stephen Rong, who graduated from Washington University with a bachelor's degree in math and is now a graduate student at Brown University, and Xiaoyun Liao, a former research assistant at Rice University with expertise in mathematical modeling, adopted the model the Harvard writers had proposed as an alternative to inclusive fitness and tested it to see whether it supported the claims the authors made in the Nature paper.

It didn't. "They had a modeling strategy that should work and should be fine, but they weren't careful enough when they made claims about their models' novel results," Queller said. But he also argued that the two mathematical models are essentially equivalent in that they ultimately predict the same results.

Inclusive fitness and social insects

Inclusive fitness was originally developed to explain eusociality, a extreme form of altruism found in social insects, where non-reproducing colony members give up their right to reproduce and devote their lives to caring for the offspring of a single reproducing member.

Hamilton's inclusive fitness theory was invented to solve this paradox, which vexed even Darwin. Hamilton calculated that sterile castes could evolve if altruistic sterility sufficiently benefited relatives also carrying the altruistic gene.

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genetics of altruism: Is blood really thicker than water?