Altruism and Evolution: A New Theory
Support the queen at all costs! That is the prime directive in an ant colony, the mission to which all its members are committed, even though it means sacrificing their own reproductive capacities. This kind of hierarchical social organization—in which the individual exists radically for sake of the collective—is called eusociality. Eusociality, which is also observed among bees and other species, has long been thought difficult to explain in terms of standard evolutionary theory. After all, the purpose of biological life is to reproduce itself. Why would ants, for example, give up their own ability to have children to help the queen with her own offspring? How can natural selection account for this kind of extreme altruism?
For decades, scientists have believed eusociality was a family affair—that is, that members of a eusocial collective shared so much DNA that they treated each other like close relatives. Proponents of “inclusive fitness theory,” also called “kin selection,” contend that eusocial organisms depend on the survival of family members to pass on their genes. The puzzling altruism of eusociality has therefore been understood as something of a deviation from standard natural selection.
Photo: Stephanie Mitchell
From left: Martin Nowak, Corina Tarnita, and E.O. Wilson
But a stunning paper published in the August 26 issue of the science journal Nature dramatically challenges these once-settled conclusions. Harvard evolutionary biologists E.O. Wilson, Martin Nowak, and Corina Tarnita contend that eusociality can, in fact, be explained within the bounds of ordinary natural selection theory—a finding with profound implications for the study of basic evolution.
“We provide a mathematical proof that shows that inclusive fitness theory needs many specific assumptions,” Nowak says. “It is not an extension of natural selection, but a subset of natural selection. Moreover, we show that inclusive fitness theory is not needed to explain eusociality, or, in fact, any other phenomenon that arises in evolutionary biology.”
Nowak, Harvard professor of mathematics and biology and leader of the university's Program for Evolutionary Dynamics at Harvard, argues that erroneous mathematics behind inclusive fitness theory has “led to much confusion in the field” of evolutionary biology. Though their paper was received with controversy among scientists, Nowak hopes that the new framework that he and his colleagues propose “will help to clarify the issues and lead to a clear understanding of the evolution of social behavior.” If Nowak and his team are correct, biologists will have to explore new theories of how eusocial behavior emerges among species.
Nowak’s work on this project is part of the $10.5 million Foundational Questions in Evolutionary Biology initiative JTF established in 2009 in commemoration of Charles Darwin’s “double anniversary” year—that is, the 200th anniversary of Darwin’s birth, and the 150th year since the publication of his landmark On the Origin of Species.
“Exploring these kinds of Big Questions in biology can do as much for our understanding of ‘deeper’ or ‘ultimate’ reality as work in cosmology and physics does,” says Paul Wason, who directs JTF’s life sciences programming. “For this is a universe capable of bringing forth and supporting life. For the living world, natural selection is one of the most basic of processes, so the study of its effects and limits represent some of the most important topics in biology.”
Converging on the Web
Simon Conway Morris is one of the world’s top biologists and a leading scholar of evolutionary convergence, the idea that all life evolves toward similar adaptations, using very different routes. With grant support from the Foundation, the Cambridge University paleobiologist recently launched Map of Life, a comprehensive Web resource for students, academics, and other readers curious to learn more about convergence. Not only is this website intended to be as informative as possible about convergence, it also aims to remind both scientists and the public that while the fact of evolution is beyond dispute, the apparently surprising fact that many features in the biological world evolved again and again suggests that the pathways of evolution are more constrained than is generally thought to be the case. As the Map of Life site explains, “Through the surprisingly ubiquitous process of convergent evolution, organisms as distantly related as moths and birds, ciliates, and worms, when inhabiting similar environments, have developed similar features as adaptive solutions to life there. This suggests that evolutionary outcomes can be much more predictable than generally thought, and raises interesting questions about how patterns of convergence arise.” Through this engagingly interactive and scientifically rich Internet site, Conway Morris and his Cambridge-based team are eager to raise the profile of convergence in public discussions about evolution.
"Convergence suggests, at least to some persons, that evolution is not a completely random, patternless process and that if you could rerun the history of life it would not be unrecognizably different each time," says Andrew Rick-Miller, a senior program officer at the Foundation. "For Sir John’s interest in big questions about purpose and meaning, including the possibility you could discern them in biological systems, the prevalence of convergence is potentially very fruitful."