In Embryo Development, Non-DNA Information Is at Least as Important as DNA
As Casey Luskin noted earlier, Australian biologist Russel Bonduriansky has just published an interesting article in Trends in Ecology and Evolution titled "Rethinking Heredity, again." The article is a critique of the neo-Darwinian Central Dogma, which has been taken to imply that all significant inheritance is through DNA and that DNA controls embryo development (consistent with the presumed evolutionary role of DNA mutations). But we now know that DNA is only part of the story: The embryo inherits developmental information from its parent that is not contained in DNA sequences, and non-DNA information is at least as important as DNA in directing embryo development.
Evidence shows that non-DNA developmental information can be inherited in several ways. For example, it can be inherited through chromatin modifications, which affect gene expression without altering underlying DNA sequences. Another example is cytoplasmic inheritance, which involves cytoskeletal patterns and localization of intracellular molecules. Still another example is cortical inheritance, which involves membrane patterns.
Curiously, Bonduriansky mentions chromatin modifications and cytoplasmic inheritance only in passing, and he doesn't mention cortical inheritance at all. Instead, he focuses almost entirely on the possible inheritance of acquired characteristics, including behavioral and cultural traits. I can't help wondering if this is because acquired characteristics are easier to incorporate into evolutionary theory, which gets the last word in his article. If so, then this would be an example of how a preoccupation with evolutionary theory can divert attention away from some of the most interesting (and potentially most revolutionary) aspects of heredity and development.