From Joanna Masel at Big Questions Online:
With the error rate in this example, that could be enough for natural selection to take notice. To see how, imagine you have a permanent, germline mutation that doesn’t affect how well your protein works in normal cases, when it’s transcribed and translated correctly. But the mutation does change the fraction of error-containing variants that work properly, say from 40 percent to 42 percent. That means slightly less work for your cells’ garbage-disposal system and more fitness for you — making you healthier and more likely to survive and reproduce. In other words, this mutation benefits you, evolutionarily speaking. Natural selection doesn’t just judge how well a gene works when its proteins are produced correctly, but also how well all the error-containing versions of the gene’s proteins work.
Because the same protein variants can be produced either by mutation or by gene expression error, evolution under constant pressure from developmental errors leads to improvements not only in developmental robustness, but also in what biologists call “evolvability” — the capacity to produce genetic variants that help adaptation. For evolution by natural selection to work, a reasonable fraction of genetic mutations has to be not just harmless but also helpful. This seems like a tall order. Aren’t random changes to any highly complex thing likely to break it, rather than improve it? Yes, but they are much less likely to break it, and hence more likely to improve it, if those mutations have already been prescreened.
One of the “incorrect” protein variants your body produces in error today could be the new “normal” tomorrow, if the right permanent germline mutation comes along.
Without errors, in other words, evolution’s creativity would be stifled. If we were already perfect biological organisms, evolution would have nowhere to go — no diversity to explore, no fountain of creativity. The takeaway? Embrace the waste, the mess, and the errors — embrace the imperfection. Without it, the diverse wonders of the natural world could not have come to be. More.
Note: “Natural selection doesn’t just judge how well a gene works when its proteins are produced correctly, but also how well all the error-containing versions of the gene’s proteins work. ”
Sure. It’s amazing what Darwin’s followers are willing to believe about how randomness can produce complex, highly specified information.
See also: Darwin will save us from Boltzmann brains
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