'Nature' Paper Refigures the Evolution of Altruism

February 26, 2010, University of Vermont

Why do some animals sacrifice themselves for the good of their group? The battle between the theories of kin selection and group selection has raged for decades. Biologist Charles Goodnight completed the math work needed to argue that they are, really, much the same. His calculations appeared this month in the journal 'Nature.'
(PhysOrg.com) -- In 1871, Charles Darwin puzzled over the evolution of altruism. "He who was ready to sacrifice his life, as many a savage has been," he wrote in The Descent of Man, "rather than betray his comrades, would often leave no offspring to inherit his noble nature."

To this day, biologists debate about how altruistic behaviors evolve and persist. Sterile faithfully tend their queen with no chance of reproducing themselves. Vervet monkeys scream to other monkeys about approaching predators, drawing attention to themselves and risking their own safety. Bees lay down their lives to defend the hive.

"Why do they do that?" asks University of Vermont biologist Charles Goodnight. "Doesn't drive animals to behaviors that increase their own chances of survival, not those of others?"

This question underlies the decades-long debate -- sometimes rancorous -- between two camps of scientists. On one side, are those who argue in favor of "kin selection," in which individuals are altruistic to those who share their genes. In defending the hive, a self-sacrificing bee increases the chances that the genes she shares with her sisters will get passed down.

On the other side, are those who argue in favor of "group selection," (or, in its modern form, "multilevel selection") in which altruism arises from being part of a group. The self-sacrificing behavior of the bee persists and spreads across generations because the whole hive, a group, competes more successfully, leaving more offspring than others.

In the February 18 edition of the journal Nature a team of 18 scientists, including UVM's Goodnight, show that the two traditional approaches are actually mathematically equivalent.

One in the same

How can this be? In order for kin selection to be important, the related kin have to be in groups that preferentially confer altruistic behaviors on each other. In order for group selection to operate, the members of a group have to be closer kin than they are to other groups. The two ideas are close enough that they can actually be converted to each other mathematically. This understanding has been stated in technical research articles for more than 30 years, but the broader scientific community has not often recognized it.

"What we did in this paper was take the equations of a group that was very strongly kin selectionist and we worked through them and translated them back into classic equations," says Goodnight. "and they're the same."

"It is remarkable that kin selection has been widely accepted and group selection widely disparaged," says Michael Wade, a biologist at Indiana University, and the lead author on the paper, "when they are actually equivalent mathematically."

Evolution at all levels

A good bit of the fight between kin and group selection proponents is a product of history. (What fight isn't?) In the 1960's, some ideas about group selection were introduced that, in cartoon fashion, looked something like birds choosing not to reproduce for the good of their fellow birds. "There was this big rash of 'for the good of the group', naďve versions of evolution," says Goodnight.

But birds can't choose not to reproduce, nor can bacteria choose to be less virulent -- because it's good for their group. "Evolution doesn't work that way; evolution works by who leaves the most offspring," says Goodnight. Richard Dawkins and many other theorists largely dismantled this first wave of group selection ideas, and kin selection was ascendant. But in recent decades a new group-selection camp -- including Goodnight, David Sloan Wilson and others -- has emerged.

"The point is that evolution can work at many levels: the gene level, the cell level, the organismal level, the group level," Goodnight says, "and it probably works on all these levels at once."

The new paper in Nature considers the evolutionary mechanisms that would lead some parasites to have reduced virulence. From the kin selection (or individual-level selection) perspective, as presented in an earlier Nature paper by Geoff Wild at the University of Western Ontario and his colleagues, this lower virulence can be explained entirely by individual selection -- no group effect needed.

But Goodnight and his colleagues make a mathematical rebuttal, sketching out in their paper an argument for why two forms of opposing group selection -- "within-group" versus "among-group" -- are needed to explain how this seemingly disadvantageous trait nevertheless evolves in the whole parasite population.

"Those of us working on multilevel selection models have started seeing kin selection as subset of multilevel selection," Goodnight says, "The debate should no longer be whether it's individual or multilevel selection. The debate is how strong is each level of selection?" Or, as their paper concludes, "it's time to put the anachronistic debate between single-level and multilevel selection behind us."

Individual preference

Goodnight's colleague in the UVM biology department, Sara Cahan, agrees with this conclusion. But she doesn't agree with everything in Goodnight's paper -- and is more in the kin selection camp. "Charles and I really enjoy one another -- I respect Charles very highly -- but we do tend to argue a lot," she says, with a laugh. (Perhaps it's no wonder the students she and Goodnight had in their co-taught graduate seminar "Levels of Selection" called the course "Crossfire.")

"In this case of virulence, and in many cases where this argument has been battled," she says, "the trait of interest is an individual-level trait. And if it's an individual-level trait, we really need to think about it as an individual-level adaptation -- regardless of what kind of selection, group or otherwise, has acted it."

"This debate is far from over," says Charles Goodnight.

Explore further: Altruism in social insects is a family affair

More information: Paper: www.nature.com/nature/journal/ … abs/nature08809.html

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1 / 5 (9) Feb 26, 2010
What a bunch of nonsense. How did chemicals mix together and form life, then cause self sacrifice?
You evolutionists sure believe a lot of crap. All I can say to this is, "Goodnight".
1 / 5 (5) Feb 26, 2010
How many speices rescue members of a difrent species? How many spiecies rescue more than one kind of spieces other than there own kind and how many spieces have humans tryed to save Mr.Darwin? What is the evloutionary advantage to man in saving endangered critters of no social, moral, or ecnomic value to man?
5 / 5 (2) Feb 26, 2010
"You evolutionists sure believe a lot of crap"

I hear a lot of complaining about evolutionary theories. Would you like to present a better scientifically supported theory? Don't just tear down theories you don't agree with. If you think there are so many holes in it and have a better idea please enlighten the community. And you better not say what I think you're going to say.
5 / 5 (5) Feb 26, 2010
What a bunch of nonsense. How did chemicals mix together and form life, then cause self sacrifice?
You evolutionists sure believe a lot of crap. All I can say to this is, "Goodnight".

Broadhead - Please address your comments in another forum. Its quite ok with everyone if you do not believe in science, or think the world is flat or any other such nonsense, but this is a science forum. You belong in a religious forum or faith based institution, not here. Your not going to convince anyone here that the theory of evolution isn't correct.
5 / 5 (4) Feb 27, 2010
How many speices rescue members of a difrent species? How many spiecies rescue more than one kind of spieces other than there own kind and how many spieces have humans tryed to save Mr.Darwin? What is the evloutionary advantage to man in saving endangered critters of no social, moral, or ecnomic value to man?

Dolphins save human lives. Just because creatures of other species have no social, moral, or economic value to you, doesn't mean the same is true of everyone. As for how many, of each, no one knows.
5 / 5 (7) Feb 27, 2010
What a bunch of nonsense. How did chemicals mix together and form life, then cause self sacrifice?
You evolutionists sure believe a lot of crap. All I can say to this is, "Goodnight".

Yeah, the fools. Next they'll be claiming that the earth orbits the sun rather than the sun orbiting God's earth as we are clearly told Ps. 93:1, Ps. 19:1-6, Joshua 10:12-14. Crazy talk.
not rated yet Feb 27, 2010
Maybe it's the glimpse of a feeling that the ongoing marginalization of the non-human part of the local biosphere could cause massive disadvantages for its human part?

Great point and along side it is the fact that life can recognize and distinguish between other life and non-life. There is always benefit in being in proximity to other life regardless of the inherent danger.
5 / 5 (1) Feb 27, 2010
Don't just tear down theories you don't agree with.

I have been told that is is what good science is all about, falsifying theories.

No, theories are constructs of science, they are never torn down, merely changed. New science that adds dimension to theories and expands knowledge is the goal. Your definition would leave us ignorant of the world, more akin to religion.
not rated yet Feb 27, 2010
Um...I'm sorry, but what exactly is the difference between kin and group selection? They sound the same to me, particularly if the group in question stays together over several generations (i.e, basically becomes kin). What am I missing, here?
not rated yet Feb 27, 2010
It seems that the definition of 'science' is quite flexible as it suits the needs of its practitioners.

Not true. Even your dear Bible holds some of the science of the time. Their observations led them to believe that everything was created by a human like organism that was oniscient and omnipotent. Since then we've refined our measuring tools and refined our observations and discovered that isn't the case. You're reading a 2000 year old book and assuming that it's current events. If you want to deny the advances of science, feel free to enjoy polio, the death of 50% of your children, that is if you aren't sterilized by cholera or rampant parasitic infections.
not rated yet Feb 28, 2010
Planck said it: "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it. "
My science was developed in the last 20 years, your "science" was developed 2000 years ago. Seeing as you still cling to yours it appears Planck was wrong.
I am disappointed with the ego and arrogance of many in science.

Which is more arrogant:

Finding out a deeper truth and evidencing it to the masses with calculated observation


Telling everyone God did it and saying that's the end of the story?
not rated yet Mar 06, 2010
I always grin with the irony of a self aware human evolved from matter saying that its not possible for matter to become self aware.

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