But information of this kind cannot be passed on genetically, and there is indeed no known mechanism by which it could be. It is only in exosomatic heredity that this kind of transfer can come about. We can learn to make and wear shoes and pass on this knowledge ready-made to the next generation as readily as we can pass on the shoes themselves. By no manner of means can the blacksmith transmit is brawny arms to his children, but there is nothing to stop his teaching his children his trade so that they grow up to be as strong and skillful as himself. I mean a state of affairs in which the generation of diversity is itself genetically provided for.
Mendelian heredity provides for the preservation of genetic diversity for an unlimited period.
The reversibility of exogenetic evolution Another important difference is this. Genetic evolution is conceivably reversible, just as it is thermodynamically conceivable that a kettle put on a lump of ice will boil. It's very unlikely, that's all. This is what specially frightens us when we contemplate the consequences of some particularly infamous tyranny that threatens to interrupt the cultural generation between one generation and the next. This reversion to a cultural Stone Age is what each political party warns us will be the inevitable consequence of voting for the other.