November 17, 2009
Category: Truth and Reconciliation in Group Selection
We have reached the end of the T&R series. In a truth and reconciliation process, truth is required for reconciliation. There must be a consensus on what happened, even if all wrongs cannot be righted. I have had my say on what happened during the group selection controversy. Anyone who wishes to challenge my account is welcome to do so. This period in the history of evolutionary thought deserves the same kind of scholarship that is lavished upon Darwin and his contemporaries. The more scholars the merrier. Much of what I have reported in the T&R series is drawn from my book with Elliott Sober, Unto Others, which was published in 1998 and has largely withstood the test of time. I'd like to think that Samir Okasha, author of the highly respected Evolution and the Levels of Selection (2006), agrees with my account. If not, I hope he will speak up.
Once a consensus is reached on what happened, scientific inquiry can proceed in a more unified fashion than before. I end this series with a summary of what a fully reconciled field of sociobiology will look like. For a more detailed account, please consult my 2007 article co-authored with E.O. Wilson titled "Rethinking the Theoretical Foundation of Sociobiology".
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Posted by David Sloan Wilson at 4:48 PM • 6 Comments • 0 TrackBacks
November 13, 2009
Category: Truth and Reconciliation in Group Selection
August 22, 2009. I am at the annual meeting of the European Society for Evolutionary Biology (ESEB) in Turin, Italy. Twelve hundred evolutionists have gathered to strut their stuff and party over a five-day period. I'm here to speak at a symposium on levels of selection that is being held on the first day. 
The symposium is one of six held concurrently and all of them are preceded by a plenary talk in a room large enough to accommodate everyone.
The plenary speaker is Hanna Kokko, a theoretical biologist from Finland who has risen to the top of her field. I just turned 60 and Hanna seems awfully young to be giving plenary talks, but anyone who worries about women in science should see her lead the huge audience through her theoretical models on diverse ecological and evolutionary topics.
Hanna's first two examples illustrate the fact that evolution at a local scale can be maladaptive at a larger scale and can even lead to extinction. In the first example, a species of fish in which the females are asexual but still need to mate with males of a sexual species for their eggs to develop outcompetes the sexual species and therefore drives itself locally extinct. In the second example, an endangered bird species on a small island evolves large territory sizes, reducing its population size and increasing its chances of extinction. If local evolution favors traits that are so detrimental over the long term, how can more sustainable traits evolve? When Hanna mentions group selection as a possibility, she shows this image of a man so panicked that he's about to jump out the window (thanks to Hanna for providing me the image).
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Posted by David Sloan Wilson at 1:01 PM • 4 Comments • 0 TrackBacks
November 11, 2009
Category: Truth and Reconciliation in Group Selection
John Maynard Smith and Eors Szathmary boldly expanded the symbiotic cell theory of Lynn Margulis to include other major transitions. They were a bit timid in their discussion of human evolution, however, restricting themselves to the genetic basis of language. Now it appears likely that human evolution was a full-fledged major transition. The reason that we are so unique among primates is because our ancestors became the primate equivalent of a single organism or a social insect colony.
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Posted by David Sloan Wilson at 11:23 PM • 17 Comments • 0 TrackBacks
November 9, 2009
Category: Truth and Reconciliation in Group Selection
Just as Brutus was a close companion to Caesar but proved to be his undoing, evolutionary theory seemed to provide a rock-solid foundation for individualism-- until Lynn Margulis came along.
Lynn is famous so you might already know her story. In the 1970's she proposed the radical theory that nucleated (eukaryotic) cells evolved not by small mutational steps from bacterial (prokaryotic) cells, but as symbiotic communities of bacteria that became so integrated that the group became a higher-level organism. She was fiercely opposed but carried the day, an accomplishment so great that she was admitted into the National Academy of Sciences in 1983.
The concept of organism as group was generalized in the 1990's by John Maynard Smith and Eors Szathmary in two books titled The Major Transitions of Evolution and The Origins of Life: From the Birth of Life to the Origins of Language. Their theory was multilevel selection theory with a twist. The evolution of group-level adaptations requires a process of group-level selection and is undermined by selection within groups. Now for the twist: The balance between levels of selection is not static but can itself evolve. When between-group selection sufficiently dominates within-group selection, the group becomes a super-organism and the lower-level organisms acquire the status of organs. The evolution of nucleated cells was just one of many major transitions, preceded by the evolution of the first cells and possibly even the origin of life itself as groups of cooperating molecular interactions, and followed by the evolution of multicellular organisms, social insect colonies, and--as we shall see--human social groups.
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Posted by David Sloan Wilson at 6:09 PM • 27 Comments • 0 TrackBacks
November 7, 2009
Category: Truth and Reconciliation in Group Selection
In T&R XIV I showed that prejudice against group selection is impervious to evidence from laboratory experiments. It is also impervious to evidence from the wild.
I will focus on one of many examples that can be provided. In 1995, Robert Heinsohn and Craig Packer published an important paper on territorial defense in lions in the journal Science. As good experimental field biologists, they had played recordings of lions from neighboring territories to observe how females of the focal territory responded. They discovered that the same individuals consistently arrived first at the scene while others consistently lagged behind. There seemed to be bravehearts and cowardly lions within the same pride.
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Posted by David Sloan Wilson at 5:18 PM • 110 Comments • 0 TrackBacks
November 5, 2009
Category: Truth and Reconciliation in Group Selection
The newest issue of Science Magazine includes a lovely demonstration of multilevel selection by Omar Tonsi Eldakar, my former graduate student, who is currently at the University of Arizona's Center for Insect Science.
Readers who have been following my "Truth and Reconciliation for Group Selection" series will be well prepared to appreciate the import of the Science article. Group selection requires variation among groups. Variation among groups is eroded by dispersal. Therefore, group selection can only take place in groups that are highly isolated from each other. That is part of the reasoning the led to the conclusion that group selection can only take place under highly restrictive conditions.
But wait. This argument assumes that dispersal is random. What if dispersal is conditional? What if individuals stay in groups when they are sufficiently cooperative but leave when they become overrun by selfish individuals? In this case, dispersal might increase variation among groups, improving the conditions for group selection. John Pepper and Athena Aktipis (featured in T&R XII) are two theorists who have studied this "walk away" process in agent-based simulation models.
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Posted by David Sloan Wilson at 1:21 PM • 32 Comments • 0 TrackBacks
Category: Truth and Reconciliation in Group Selection
In the storybook portrayal of science, theories are tested by experiments, which are conducted in laboratories so that the conditions can be rigorously controlled.
How would group selection be tested in the laboratory? Let's begin with the thousands of selection experiments that have already been conducted in the laboratory at the individual level. A population of animals, such as fruit flies or chickens, is measured for a particular trait, such as bristle number or egg productivity. Individuals that score high or low (depending upon the desired direction of selection) for the trait are selected to breed the next generation. If the average value of the trait in the offspring generation shifts in the direction of selection, then the trait is heritable and there has been a response to selection. Over many generations, artificial selection can cause organisms to become completely different from their ancestors, as our domesticated plants and animals attest.
Group selection can be studied in the laboratory by a simple extension of the protocol outlined above. A population of groups is created, a particular trait is measured for the groups, and the highest (or lowest) scoring groups are used to breed the next generation. If the average value of the trait in the offspring generation shifts in the direction of selection, then group selection is proven to be efficacious, at least under the conditions of the laboratory experiment.
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Posted by David Sloan Wilson at 10:09 AM • 17 Comments • 0 TrackBacks
November 4, 2009
Category: Truth and Reconciliation in Group Selection
Pity people who become icons. Once they represent an important idea in the minds of others, they can't change their iconic status, even when they change their own minds.
Such was the fate of William D. Hamilton, the legendary founder of inclusive fitness theory, which was dubbed kin selection by John Maynard Smith (see T&R VIII). Hamilton became world famous for explaining how altruism can evolve according to the rule br - c >0, where b is the benefit that the altruist gives a recipient, c is the cost to the altruist, and r is the chance that the recipient shares the same altruistic gene through a common ancestor. At least that was the original interpretation of r; eventually it morphed into something different, as we shall see.
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Posted by David Sloan Wilson at 9:28 AM • 5 Comments • 0 TrackBacks
November 3, 2009
Category: Truth and Reconciliation in Group Selection
Meet Athena Aktipis--evolutionist, mother of two, and salsa dance instructor in her spare time. Perhaps it was the dancer in Athena that caused her to teach multilevel selection by having the students get up and move.
Each student is given a wooden stick with an A (for Altruistic) or S (for Selfish) written on one end. Information on the blackboard tells them that altruists give three fitness units to their partners at a cost of one fitness unit to themselves. Selfish individuals receive without giving. Then they are instructed to move around the room and find a partner at random without revealing their identities. At the count of three, they reveal who they are and write their gains and losses on a 3x5 card. After repeating the process of pair formation and social interaction several times, the students total their score and take their seats for a few minutes of instruction.
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Posted by David Sloan Wilson at 3:33 PM • 20 Comments • 0 TrackBacks
I am an evolutionist who studies all aspects of humanity in addition to the biological world, as I relate in my book Evolution for Everyone: How Darwin's Theory Can Change the Way We Think About Our Lives.
In addition to my academic research, I manage a number of programs and
websites for expanding evolution beyond the biological sciences in
higher education(
