Inherited memory, kind of:
Darwin, I am told, once speculated that the strong muscles of a blacksmith were to a degree inherited by his sons.  This required a mechanism.  He envisioned something called “pangenes” distributed throughout the body.  The intensity of orgasm might be due to the sensation of these pangenes rushing to the gonads bringing accounts of the state of the tissues so the information could be passed along.

In recent years this notion, and it was only a passing one, has not won Darwin many friends.  The “New Synthesis,” now about a hundred years new, proclaimed that evolution consisted of natural selection working on genes transmitted according to the rediscovered Laws of Mendel.  That was an improvement over the time when the geneticists taught that the evolutionists were stupid or insane or both and the evolutionists taught that the geneticists were sons of Satan, if I follow the concepts. 

Things are now less clear.  (Virginia Hughes The Sins of the Father NATURE vol. 507 no. 7490 March 6, 2014 page 221)  What seems to be the case is that you can take a male mouse, expose it to some smell and shock it with electricity to a degree that is not agreeable to the mouse.  Do this repeatedly.  Let the mouse mate with a female which has never been exposed to the smell or a shock.  The offspring have a heightened sensitivity to the smell; it makes them edgy, and they learn more rapidly than did their sires to fear the shock.

This is inheritance of acquired characteristics, something that was roundly scorned until recently.  Surely this is mediated by some epigenetic mechanism.  Somehow it is carried in the sperm, and it cannot be a matter of DNA change. 

So on the light side old Darwin’s pangenes are having, if not the last laugh, at least occasion for a wry smile.  Nobody has yet brought up the intensity or orgasm bit yet, and I surly shall not. 

But when I look at the possible mechanism for the fertility depression entailed by insufficient consanguinity I find I am a bit more old fashioned.  The changes in methylation pattern I envision are inherited blindly without regard to any environmental factor. 

But it does make you wonder.  Do you suppose that simple cultural exposure to different people could reduce fertility in humans?  They say (and this we were taught at Harvard Medical School decades ago) a pregnant female mouse exposed to the smell of a strange male will abort.  I can’t say nay because I have no relevant numbers, but it certainly is not the way I am thinking.

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