Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!decwrl!fernwood!asylum!ayermish From: ayermish@asylum.SF.CA.US (Aimee Yermish) Newsgroups: sci.bio Subject: Re: The Ubiquity of Tay-Sachs: a shocking but elegant theory Message-ID: <1099@asylum.SF.CA.US> Date: 11 Feb 89 22:01:09 GMT References: <10276@ut-emx.uucp> Reply-To: ayermish@asylum.UUCP (Aimee Yermish) Organization: The Asylum; Belmont, CA Lines: 49 In article eric@snark.uu.net (Eric S. Raymond) writes: >So he went looking for a disease or other environmental factor that was >endemic to south central Russia and the Pripyet Marshes around the time the >ancestors of the Ashkenazim emerged as a distinct population there. Something >sufficiently dangerous that resistance to it was a net win over significantly >higher infant mortality; something for which no less costly adaptation has >been shown in any other human population; and something for which some later >suggestion of significant resistance in the Ashkenazim could be found. > >He found it. A bacterium called `pasteurella pestis' -- the bubonic plague. > >I don't know if he ever tried controlled in vitro test of this hypothesis; in >vivo, of course, would be horribly dangerous. But if true, it would explain >an *awful* lot about the tragic history of the Jews in Europe. Perhaps the >Ashkenazim really *were* (inadvertent) plague-spreaders. Standard theory about >the ghettos escaping the worst effects because of `superior sanitation' always >had sounded kind of thin to me. I wouldn't throw out the idea of superior sanitation so quickly. Yersinia pestis (the name pasteurella is no longer used) is transmitted to humans by flea bites. Bubonic plague manifests, among other things, with serious lymph node swelling especially near the flea bite. In this form, it doesn't transmit between people. In later stages, the lungs can get secondarily infected from the bloodstream, causing "pneumonic plague," which is almost invariably fatal and can in fact spread between people (you cough the bugs into the air and someone else inhales them). I don't recall exact figures, but practically everyone who gets this shows symptoms. If you keep your bodies and homes clean and sanitary, as free as possible of fleas and rats (which is the reservoir of the disease), you don't get bitten by as many fleas and have a lowered probability of getting bitten by one carrying the plague. Also, if you are in a ghetto or other population physically removed from the rest of the population, you minimize your risk of contracting plague via the respiratory route. In any case, the Ashkenazim could not have been spreading the plague a la Typhoid Mary because, as I explained, asymptomatic pneumonic plague is at the very least, extremely rare. Incidentally, the defect in Tay-Sachs is known. (It's an enzyme that produces a certain lipid required in the nervous system) Assuming that rats need the same lipid, with a great deal of effort the in vivo experiment could actually be done. Not an easy one, though. --Aimee -- Aimee Yermish ayermish@asylum.sf.ca.us Program in Cancer Biology ayermish@portia.stanford.edu Stanford University 415-594-9268