I'll start with my question: Do you agree with Melissa McEwen's critique of Jack Kruse's (mis)use of evolutionary biology?
I should note that I am a fan of both McEwen and Kruse.
McEwen's blog post is here:
McEwen accuses Kruse of equivocating between two views of evolution - one static, the other malleable. She writes, "Therein lies an essential paradox - on one hand our genes are “paleolithic,” but on the other they are malleable simply by thinking differently."
Here are some initial thoughts toward answering my question.
I'm pretty sure that everybody who studies and thinks about genetics these days distinguishes between (i) the underlying DNA sequence - which often underlies 'static' views of genetics - and (ii) changes in gene expression that can be inherited by the previous 1-3 generations - this is the realm of epigenetics, which often underlies the 'malleable' view of genetics. Yet both the genome and the epigenome have static and malleable features that are relevant to us as seekers of health.
Over time both genes and epigenetics evolve - the DNA sequence evolves, but the nature or pattern of shorter term changes in gene expression also evolves.
My understanding is that Kruse believes that cold adaptation opens up an evolutionarily-old metabolic pathway that lies dormant in - and is thus available to - all of us. He made similar 'old pathway' speculations when he talked about rewiring the hypothalamus in the leptin reset series.
So epigenetic changes are short-term and thus not stable over 30+ generations. Yes, however, changes to the nature of how epigenetics works can and, in fact, must reflect the long-term evolution of our epigenome. There is a difference between (i) the evolution of the epigenome which delimits the scope of possible epigentic effects, and (ii) those epigenetic effects. The former evolves over the long term, the latter changes over a small number of generations.
My understanding is that epigenetic changes begin with changes in gene expression that occur in response to environmental inputs of one generation, and that these changes can transfer to the next 1-3 generations in the form of altered probabilities in gene expression. The thought that 'might just change your DNA' is the first generation of change in epigenetic gene expression.
I am clearly not an expert in genetics or epigenetics (nor do I think that McEwen or Kruse are). However, I see a pretty intuitive - though perhaps charitable - interpretation of Kruse that saves him from the charge of equivocation. Perhaps he is not 'having it both ways' - rather, he is just talking about the genome and epigenome as most do: Both 'systems' evolve, both effect probabilities of gene expression, and both thus have static and malleable features that are worth speculating about because they might be relevant to achieving health.
What do you think? Do you agree with Melissa McEwen's critique of Jack Kruse's (mis)use of evolutionary biology?