On Fri, Aug 9, 2013 at 9:43 PM, Chris de Morsella <[email protected]>wrote:
> some feel Epigenetics should only refer to the actual molecular > mechanisms (such as DNA methylation and histone modification) that alter > the underlying gene expression; I find this restrictive and use epigenetics > to also describe inheritance of changes in the expression of genes. There > appears to be increasing evidence that points to epigenetic inheritance > Yes, but that also means that epigenetic inheritance is fundamentally less important than the traditional sort. If you don't have the gene then you just don't have it and that's all there is to it, but if you have the gene but it's not expressed because of one simple methyl group then one of your sperm could lack those 4 atoms (CH3) and your offspring, or his offspring, could inherit the fully functional complex gene even if there was no sign of its expression in you. > maternal nicotine exposure during pregnancy is linked to asthma in the third generation in disease models. [...] Isn’t this essentially describing a Lamarckian process? I don't dispute the existence of epigenetic changes even if it's far less important than Mendelian inheritance, but where is the acquired characteristic? If exposure to nicotine led to nicotine tolerance in the parent and the offspring then it would give some support to the inheritance of acquired characteristics, but instead you've just got asthma. It's not news that some chemicals increase the rate of mutation. And besides, you need a lot more than the inheritance of acquired characteristics for Lamarckian evolution to work, you need a way to separate the good acquired characteristics from the bad (asthma is bad), and only Darwinian natural selection can do that. John K Clark -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
