But this isn't what happened. The scientists were not considering the emergent effects from whether different traits might be linked. When they selected the best egg-layers in generation 1, they were inadvertently also selecting for aggression. The dominant hens had naturally produced more eggs than the subordinate hens that they bullied and pecked. The real-life effect of the experiment was that egg production per hen did increase, but egg production per cage plummeted. As illustrated in the right side of the image above, few of the hens in the subsequent generation lived — the rest had been pecked to death by the chickens with dominance genes. In contrast, a parallel experiment selecting not the best egg-laying individual per cage, but the best overall egg-laying cage , and letting all hens in that cage reproduce, resulted in an impressive 160% increase in eggs-per-cage in just a few generations. The point of this example is that genes that promote individual success can result in unexpected (often counterproductive) results when interacting with other individuals -as a whole. Selection occurs at multiple levels and scales, not only at the level of the gene, or the individual. TaaL: Seems like kind of an ornery thing to do to chickens, but I guess you ’ re going to feed your current billions somehow, and I suppose the more eggs each chicken lays, fewer chickens have to live in those horrid little boxes. And 70 billion chickens a year is a lot of little boxes. Of course, one might approach that same issue by limiting the number of fertilized human eggs and giving the chickens a break or even having humans simply eat their factory-fixed nitrogen and protein in vegetable form, but something tells me I ’ m courting an aggressive pecking response by even suggesting it. Having spoken up on behalf of non-human life – which I will often do here as the sole nonhuman participant - I ’ ll note that the complexity of “ multilevel selection ” means that despite the hardwired advantages of the human gene agenda, MLS gives rise to many implications and possibilities. You are not doomed to dance like a puppet at the behest of your genes, though you do inherit that tendency. Will future generations of your kind resemble the chickens in the left or right pictured cage above? Or perhaps be outside the “ gene agenda ” cage entirely...?
The Bottom Line: Selection happens at multiple levels of an evolving system simultaneously, with emergent results that cannot be
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