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Comment by dschiptsov | Hacker News Reader

There. Is. No. Data. Flow. From. Phenotype. Back. To. Genotype.

It just does not work that way. Mutations could be favorable and unfavorable, but there is no mechanism that "adaptations" are encoded back into genome.

Some random mutation which persisted in one population and wiped out in another has been selected due to environmental factors, such as climate and availability of food sources, does not imply that it is necessarily better or advantageous for a different environment.

And, of course, a diet could not cause genetic changes. Mutations could be selected in a population within some particular environment or wiped out in another.

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That claim is turning out to have exceptions: http://learn.genetics.utah.edu/content/epigenetics/inheritan... In some circumstances, epigenetic markers are retained and passed to the next generation.

That isn't the claim they are making, because that would be a huge claim. I think the author knows that the occurrence of mutations aren't present because they are eating veggies. Instead, they mean they are being selected because they are eating veggies.

Correlation is not causation.

Phenotype changes can affect the rate of mutations and lead to faster evolution allowing to discover in time a trait essential for survival under new conditions. Although indirect, this is still a data flow. Without a particular phenotype the population would simply not able to discover in time the necessary mutation and survive.

Nope. Mutations in a single organism are almost irrelevant. They must propagate via offsprings (be selected in meiosis) and eventually spread throughout population, otherwise they will be lost. This is a protective mechanism without which there will be no stable traits and no complex organic life at all.

I fail to see how this disproves that phenotype can alter genotype through the speed of mutations. The point is that after environmental change there is a limited timeframe when a population can develop a trait essential for survival in the new situation. If the rate of mutations is low, the whole population will simply die.

However, if by phenotype changes the mutation rate can be increased, then the population can adopt. In that case the new genotype trait essential for survival will be available only in offspring coming from phenotype that allowed faster rate of mutations. This is a data flow from phenotype to DNA.

Mutations are random. Increasing mutation rates for such a complex organisms as humans is the same as increasing the probably of cancers and negative mutations. Only bacteria could afford this.

Species whose mutation rate fluctuates according to its diet wouldn't last too long.

Oversimplified models doesn't represent mostly-stohastic reality, especially in genetics.

And, still, the one way flow of information is the fundamental principle which makes complex organs such as heart, brain or liver possible.

Everything which contradicts a fundamental principle is merely a mental abstraction. Or a story.

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