The nose knows: (Look, I never said I had any originality.)
It’s sort of like a knee jerk.  I say to someone, “You know.  You have to marry near kin for you and your children to have normal fertility, something like closer than seventh cousin.” 

I get the response, “Aha, so if you marry someone of a different race, it’s a lot worse.” 

When I say, “Not a bit of it.  The fertility curve has leveled off by the time you get out to eighth cousin the curve is as flat as a flounder.”  Well, almost, but it is certainly leveling off.  At this point either I lose them if we are speaking in person, or if they have misrepresented me in print they feel under no compulsion to set matters straight.

All right.  Let me say it again, hoping not to lose you.  In all the data I have looked at, I see no evidence of any effect of “race” or anything you might call that on fertility.  And that is my only interest.  In case physical and mental health follow the same logic, I don’t see that either. 

Quite the contrary.  In every part of the world I see dynasties and civilizations perishing on exactly the same time scale.  And if you want a specific test, Montezuma was killed by Cortez, and even the Spanish of the time thought that was not right.  So they invited children of Montezuma over to Spain to be members of the noble class.  Their descendants survive to this day.  There was no hybrid breakdown, no infertility I know of except that which would be attendant on a marriage between people of neighboring towns.  Since the ancestors of Montezuma had gone eastward from the place where Cro-Magnon interbred with Neanderthal, while the ancestors of the Spanish had gone westward, those two lines were as separate as you please.  Well Cro-Magnon specifically refers to Europeans.  They were taller or at least as tall as modern humans and had bigger brains.  Maybe Neanderthal genes had something to do with that.  At all events between east and west there is no unbridgeable genetic divide.

Whether that is true among the even older divides in Africa, I have no useful data.  What data I have seen I can no longer find so I do not pursue it.

The problem comes not when you have a vast distance between couples, but when you pile outbreeding generation upon outbreeding generation.  There, depending on the outbreeding strategy, it seems to take either five (no good data, only hints) generations or ten (300 years, and I will go to the wall on that one.) generations for disaster to ensue.

Having taken it for so many years, I had copped the attitude, “Look.  What you call “racial” differences are cosmetic and nothing else.  Maybe the cosmetic differences had some helpful effect in the past.  Otherwise they should not have evolved.  But at this point they mean nothing.”  Of course I made the mental reservation that maybe heavy melanin production was useful in regions where bright sunlight and warm temperatures made sunburn and skin cancer a bigger problem than elsewhere. 

So now I take it on the nose from the other direction.  It appears now (Air Conditioning All in the Nose NATURE vol. 474 no. 7352 June 23, 2011 page 423 reviewing Am.J.Phys.Anthropol, doi:10.1002/ajpa.21523(2011)) according to a team led by Marlijn Noback of Eberhard Karls University, Tubingen, Germany that there is more to it.  Instead of looking at the outsides of noses, which would be a natural for cosmetic effects, they measured nasal cavities using modern medical imaging technique.  People from colder places had higher, narrower spaces. 

It is pointed out that this permits more contact between the nasal mucosa in incoming air, which means colder dryer air can be breathed during exertion while still protecting the deeper airway.  The natural question is whether the added height makes up for the decreased breadth so that there is no penalty in resistance to breathing.  Of course there must be a cost in terms of circulation.  The nose is richly vascular, and any increased blood flow to it adds to the burden of the overall circulation.  But if the air is moist and warm, there would be no call for the extra flow anyway.

One wonders whether the shorter, wider cavity has less resistance and under clement conditions is simply better while the taller, narrower cavity is a specialty item for cold.

Still, I submit that this is not really such an important thing in this day and age when few of us push ourselves to our physical limits often, and then generally only briefly during sports.  You can always open your mouth, you know.

So I take on principle that yes, evolution has made another mark, but unless one is looking to become a professional athlete, it doesn’t make a lot of difference.  And even then, it makes more sense to decide on the basis of what you like to do. 

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