Rethinking the roots of altruism

F or decades, researchers working to understand how altruistic behavior evolved have relied on a concept known as inclusive fitness, which holds that organisms receive an evolutionary benefit - and are able to pass on their genes - through cooperative behavior. Now Harvard scientists say the theory is mathematically flawed and unnecessarily complicates the story of altruism's evolution. In a new study, Martin Nowak , a professor of mathematics and of biology, E.O. Wilson , the Pellegrino University Professor Emeritus , and Benjamin Allen , a research associate in mathematical biology and an assistant professor at Emmanuel College, find that not only is inclusive fitness impossible to calculate in most cases, but also that it often leads to incorrect conclusions. "Our main goal is to develop a rigorous mathematical theory of evolution," Nowak said. "Inclusive fitness is an antiquated concept. Its flaws and limitations are not understood by the majority of people who use it. Once these limitations are clear, the door is open for a meaningful interaction between empiricists and theoreticians working in this area of sociobiology to construct new models and ask precise questions." A classic example of altruism, Nowak said, would be one animal opting to forgo reproduction to help care for a sibling's offspring. Because of that assistance, the sibling may eventually have more offspring than otherwise. The problem for proponents of inclusive fitness, Nowak said, is how to calculate the benefit for the sibling and the cost for the altruist. "There are two ways you can pass on your genes," Nowak explained. "You can have your own children, or you can help your sibling reproduce. Once we have this insight, the question is how to make it precise?