Showing posts with label Kin selection. Show all posts
Showing posts with label Kin selection. Show all posts

Wednesday, June 27, 2012

EO Wilson responds in NYTimes

In an opinion piece published online EO Wilson responds directly to his critics regarding his recent rethink of a long held tenet of evolutionary biology.  Wilson officially abandoned his long-held belief that cooperative and altruistic behavior among some organisms can be simply explained as a veiled selfishness (kin selection) in 2010. This came after a lifetime promoting the opposing view. In a controversial peer-reviewed Nature paper titled "the evolution of eusociality" Wilson explains why he thinks kin selection theory is insufficient to explain altruistic behavior and ought to be replaced with multi-level selection theory. With the publication of this paper Wilson and coauthors ignited a massive debate that has recently unfurled in popular media. Wilson explains.

A strong reaction from supporters of kin selection not surprisingly ensued, and soon afterward more than 130 of them famously signed on to protest our replacement of kin selection by multilevel selection, and most emphatically the key role given to group selection. But at no time have our mathematical and empirical arguments been refuted or even seriously challenged. Since that protest, the number of supporters of the multilevel selection approach has grown, to the extent that a similarly long list of signatories could be obtained. But such exercises are futile: science is not advanced by polling. If it were, we would still be releasing phlogiston to burn logs and navigating the sky with geocentric maps.

Though I may not accept multi-level selection theory currently I do like Wilson's point that "science is not advanced by polling."  As a citizen of a post-enlightenment democracy my hope is that all politics will eventually die at the hand of science. Politics is subject to rhetoric. Science in an idealized sense is immune to rhetoric. Science can be spun in all kinds of directions but at its core really is not subject to opinion. The existence of seasonal Antarctic ice layers measurable for nearly 740,000 years is indisputable. The existence of fossilized trilobites in Cambrian geologic formation is indisputable, the fact that you and I have nearly identical genetic code for hemoglobin molecules is indisputable. And so I am undaunted by this new debate in evolutionary theory. In the new version of the group selection vs. kin selection debate no one person's opinion will affect the validity of one over the other. 

Read EO Wilson's entire opinion piece here. See my previous coverage of this topic here and here. So far IMHO Steven Pinker has given the most complete analysis of the debate particularly the short comings of group selection theory.

Thursday, June 7, 2012

Collaborative Genes

By Kristopher Hite

The trait I admire most in a fellow thinker is the ability to entertain an idea without necessarily swallowing it whole. With that in mind, I eagerly listened to E.O. Wilson's On the Shoulders of Giants address at the World Science Festival in New York City last week.

I recently wrote about Wilson and his controversial rethink of altruism. Long story short, Wilson has created a ruckus by abandoning his long-held belief that cooperative and altruistic behavior among organisms can be simply explained as a veiled selfishness. When an organism appears to behave altruistically by sacrificing themselves or putting themselves in danger it is actually just the individual genes jockeying to survive by keeping identical copies of themselves alive in their relatives. This theory is known as inclusive fitness.

 In place of inclusive fitness E.O. Wilson now seems to embrace the controversial concept of “group selection.” This is the idea that genes for altruism persist by benefiting the entire group. The altruistic trait persists by helping groups themselves multiply; grow into larger and larger networks with more and more biomass. In group selection theory this all happens despite the fact that the altruistic trait is detrimental to the individual. Altruistic genes that band together and cooperate out compete groups of genes that act selfishly.

To me, both models seem like they could apply to different genes.

After the address, I had the rare opportunity to ask Wilson directly about his recent change of heart. I asked,
"If the gene is the basic unit of selection—the physical thing that makes it though the sieve of natural selection—then why do we need a 'group selection' model? And if a gene is not the basic unit of selection, then what is?" 

The question struck a chord. Wilson replied that he had been anticipating it, in fact, and quickly acknowledged that that his recent move away from the theory of inclusive fitness had rankled many people, including the famed evolutionary biologist Richard Dawkins who has popularized the selfish-gene view of evolution and has been a vocal critic of group selection. But Wilson stuck to his guns, saying,

"Yes, the gene is the basic unit of selection, but the phenotype is the target. It is as simple as that." 

Wilson flashed a smile, and for a moment I was starstruck, caught up in the glow of Wilson's legendary charm. The spell broke when I began to really chew on his answer. I was still extremely confused about how the concept of "phenotype as target" was supposed to justify group-selection theory. As I rode the elevator downstairs, I felt a pang of guilt for not pressing harder. I imagined a tiny Richard Dawkins sitting on my shoulder, eyebrows in a scowl, chiding me, "Kristopher, don't you remember how beautifully I explained all this to you in my book, The Selfish Gene?? How could you turn on me? Hamilton had it right, the gene is the one ring to rule them all everything else is myth!"

On the other shoulder (the "giant shoulder," one might say), I pictured a miniature E.O. Wilson, still charming in his diminutive tweed blazer, reassuring me, "Kristopher, everything is going to be alright as long as we work together in this big happy peer-reviewing group of ours."

I was, and still am, torn. As I stepped out of the elevator, I serendipitously met Nobel Laureate Harold Varmus, former head of the NIH, and I took the opportunity to ask him what he thought E.O. Wilson meant when he said "phenotype is the target of selection." Dr. Varmus clarified—somewhat. Phenotype, he explained, is the vehicle genes ride inside the physical manifestation of the genes. Selective environmental pressure, like changing atmospheric oxygen levels, or changing local climates are not capable of acting directly on any single isolated gene.

After I directed Dr. Varmus and his wife to the Christopher Street subway station, I continued to replay his answer in my head. If natural selection happens at the level of the physical manifestation of the genes – the phenotype, and there is no organism in existence with only one gene inside, then all genes must be collaborative in a sense.

And this is where I am in my thought process. If you have any corrections or criticisms I welcome them. They will only add to my understanding.