Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

Lamarckism, as it is understood toady, but not as it was understood by Lamarck himself (see XXVIII.2), is based on the concept that the modifications of bodily structures and functions that occur during the lifetime of an organism through the effect of external factors are both an adaptive reaction to these factors and are also hereditary, i.e. transferred to progeny.If a person often walks around barefoot, an orthodox Lamarckist would assume that very thick skin would be formed on the soles of his feet to protect them against injury and that this would appear in his progeny in the next generation.The first assumption, if it  were to hold in general, is questionable.If we ignore the specific case of strengthening of muscles as a consequence of training, we find that the reactions of an organism to extreme stress are mostly not very adaptive.If we frequently encounter an area with foreign chemicals, we will most probably become allergic to them, if we remain in noisy places, our ears don’t become more resistant to the negative effect of noise, but we rather tend to become deaf, excessive fat in the diet tends to destroy the gall bladder rather than training it to be more efficient.

The second assumption, that the change could be hereditary, is completely improbable.For example, we do not know of any mechanism through which genetic information could be transferred from the phenotype to the genome, from a protein to the DNA.Reverse transcriptase, which is sometimes considered in this context, can only provide for transcription of RNA to DNA, i.e. the incomparably simpler step of the two-step transfer of information from proteins through RNA to DNA.  Examples that were mentioned in Section III.12, similar to other, frequently only theoretical cases, based on the possibility of inter-generation transfer of epigenetic information affecting the expression of the individual genes (see II.8.2), only simulate the properties of Lamarckian evolution.However, in actual fact, they only provide further evidence that Darwin’s model of evolution is, in principle, correct.This always involves a specific and frequently very complicated molecular mechanism that, to a certain degree, enables avoidance of the nonexistence of reverse flow of genetic information from proteins to DNA.In all cases, this mechanism is of great importance for the survival of the individual or the population and thus we can readily imagine how it occurred through random mutations and how it was fixed by natural selection.If the organism were capable of reacting to external effects through the formation of an adequate and hereditary modification in its bodily structure, the complicated and frequently awkward mechanisms of generation of adaptive mutations such as are encountered, e.g., in bacteria and protozoa, would not have had to be formed.