The Genealogy of Mice

Hello Ghazal, my dear,

I interprete the missing answer to my last e-mail as a sign, that you got cought so much by Lee Silvers book on “Mouse Genetics”. I hope that you find it not just scientifically interesting, but also entertaining.
To be honest, I always have problems seeing a lot of heroic activity in observations on how cells after irradiation battle to repair their DNA or commit suicide for the sake of the entire organism. It is either just a matter of adaptation, or opportunism as we would call in humans, or a battle between two armies fighting with unequal weapons (physical radiation and biological enzymes). Both, opportunism as well as stupid heroism in a war was definitely not what contributed a lot to progress during human evolution.
In case of the mouse genetics and antropology, however, the question which physiological and behavioural properties drive the development is realy fascinating. Did you red about the two dominant mouse sub-species (M.m.domesticus, or the west-european house-mouse and M.m.musculus or the eastern field-mouse). Most of the mice strains we keep in the laboratory world-wide are genetic recombinats between these two.

Now comes the exciting interrelation of the two sub-species: domesticus established its dominant area in south-western europe, from the mediterranean countries up to Germany. M.m.musculus, in contrast populated the old-world from central Germany further east (Poland, Czech, Russia, China to the Pacific ocean). Believe it or not, the boundary between the eastern and the western Mouse Hemisphere went from northern Germany down to the south at the Alp mountains, first along the river Elbe and then along the river Isar. Some even believe, that Neuherberg is located right on this very tiny zone where occasionally the eastern M.m.muscullus and the western M.m.domsticus encounter (B.t.w., if the whole mapping is 100% precise with the Isar-river representing the border-line, we here in Daglfing would belong to the M.m.musculus world, whereas you in Unterschleissheim would already live in M.m.domesticus hemisphere).
The small border stripe where animals of the both sub-species occupy a common area, occasionally see genetic mixing of the two. They can form hybrids, and in the laboratory it was shown that the hybridn offspring between musculus and domesticus are also fertile, i.e. in theory they could give rise to next generations and a whole new sub-specie. In nature, however, the occasional happening of matings between the two give rise to hybrid offspring, that seem to have a selective disadvantage. They are less fit and never increased in population size. So the mixing area remained restricted to this small stripe in central germany (good for science, of course, since therefor we got the relatively homogenous animals for laboratory strains).

What also gave me a shiver when I red this is the funny co-incidence of the above mentioned “demarcation line” between eastern M.m.musculus and western M.m.domesticus with the former iron curtain that devided the eastern, socialist part of Europe from the western, capitalist world. This iron curtain also run north to south along the river Elbe.
Could it be that this artifical devision into an eastern and an western world during the second half of the 20th century was already planned early in evolution. Strange idea, I must admit, but sometime we are much less self-determined as we always like to show, in particular if it is in politics and military activities, in which people sometimes follow instincts like an animal.

The connection between the geographic distribution of M.m.domesticus and M.m.musculus with human history has another, more peaceful aspect. The new world, i.e. North and South America, did not had mouse at all before the european occupation in the 15th century began. Mice were brought over to the new continent on board the ships of the conquerers. Since most of these ships came from western europe (Spain, Portugal, France, England), they importet M.m.domsticus in Amerika, where still today it is the dominant mouse. Only a very tine stripe along the pacific coast (California) was first occupied by settlers from asia (Russia, later Chinese and Japanese), which brought there M.m.musculus. Again, like in Europe, the geographic distribution of the two sub-species remains there very separated.

I hope you are well, and I hope you don”t mind getting e-mails from me.
(sorry, I don”t have a mailing list on which your address is just one among another million, and from which I could easily remove yours. The e-mails are always personally just for you. So if you find them boring or otherways annoying, you have to delete them right away. I will keep them anyhow in my outbox, they are like a diary).

Have a nice and sunny day


PS: You have not suggested a time to visit the castle Oberschleissheim today or tomorrow. In case I don”t hear from you I”ll come tomorrow afternoon.

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