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March 06, 2003

Jews just got lucky?

Nick Wade indicates that genetic drift, not selective pressures might have resulted in the high rates of lysosomal diseases among Ashkenazi Jews. Lots of thoughts can come out of this, but I'll let readers weigh in.... (thanks to Steve Sailer for the link, you might want to read Greg Cochran's essay on overclocking too).

Update: From the message board (and this does tend to make sense to me-Wade's article was a little garbled it seems)-


Risch doesn't make a lot of sense. One of the key arguments is that high frequencies of _multiple_ mutations of the same gene or worse yet multiple mutations in each of a number of metabolically related genes, is incredibly unlikely. But that has happened: there are three overly common Tay-Sachs mutations among the Ashkenazi, two overly commom Gaucher mutations, three Niemann-Pick mutations of roughly equal frequency, two elevated mucolipidosis type IV mutations. Tay-Sachs, Gaucher, and Niemann-Pick all invovle sphingolipd degradation, and the sphingolipids that pile up in mutant homozygotes (and are presumably mildly elevated in heterozygotes) are nerve growth factors.

Boas calculated that the probability of the Gaucher mutation distribution alone is less than 1 in 500: Risch doesn't address this at all.

I have no idea what his point is in comparing geographic distributions of lysosomal- and non-lysosomal mutations, considering that many or most of the non-lysosomal mutations have _also_ been made common by selection. CF has, almost certainly. There's evidence that strong selection is occuring at the BRCA1 locus (again two mutations). Slatkin has said that there must have been selection elevating the factor XI clotting disorder mutations ( again two different mutations). The connextin-26 deafness mutation has clearly been favored by natural selction in many populations, probably as a disease defense.

Posted by razib at 05:44 PM




"The oldest mutation, one that causes a blood-clotting disorder known as Factor XI deficiency, occurred 120 generations ago, or 2,200 years ago, when the Jews first became a distinct people in the Mideast."

I thought Jews first became a distinct people around 1600 BC or 1700 BC (Moses later leading them out of Egypt around 1100 BC). Figuring around 30 years to the generation, "120 generations ago" makes around 3,600 years ago, which takes us back to around 1600 BC. So, "2,200 years ago," or 200 BC, must be a typo.

Posted by: Unadorned at March 6, 2003 08:19 PM


some groups-like the tribe of Dan-were almost certainly late additions to the Jewish people....

Posted by: razib at March 6, 2003 08:25 PM


Just off-track here but whatever, I thought it was funny reading some article by a guy who said the tribe of Dan ended up in Ireland as was in fact none other than the pre-gaelic Tuatha De Danann people, before they were largely destroyed by mass immigration of course :).

Posted by: ShakeyKane at March 6, 2003 08:58 PM


since the danaans were made into godlings and gods (lugh of the long hand) that seem at least partly indo-european (the aforementioned lugh-the sun god and father of cu cuhlain), they were probably at least celtic. perhaps they were brythonic-and later overwhelmed by the goidelic milesians (gaels) that arrived circa 500 according to the irish mythos.

also-diane e. of letter from gotham indicated that the tribe of dan might be the danans mentioned by homer-one of the sea peoples, and possibly greek.

Posted by: razib at March 6, 2003 09:14 PM


Jim Fitzpatrick's knowledge of the Tuatha de them is based mostly on what was written by the early christians on the pre-literary oral folklore on these people. It mentions indeed that they may have been in greece or from it(Thebes).

http://www.jimfitzpatrick.ie/mythology/tuatha.html

It seems these texts are hugely praising of the form of the Dan:

"They are described in Cath Maige Tuired as "the most handsome and delightful company, the fairest of form, the most distinguished in weaponry and apparel, skilled in music and sports, the most gifted in intellect and temperament that ever came to Ireland".

"That tribe was bravest of all and inspired fear and dread in their enemies for the Tuatha Dé excelled all the races of the world in their proficiency in every art."

In the Book of the Dun Cow it is said that the learned did not know where the Tuatha Dé were from but it seems likely they came from the heavens on account of their intelligence and the excellence of their knowledge of the otherworld."

Its seems to be anyway that with structures such as the 5000 year old building at newgrange with its built in clock, on the strength of my own half-assed conjecture, there almost certainly were quite a few very advanced tribes knocking about in celtic europe. Pity none of them got thier act together and kept a proper writing system going such that if a tribe as the Dan was rambling around the continent some more evidence would be available.

Posted by: at March 7, 2003 12:02 AM


Risch doesn't make a lot of sense. One of the key arguments is that high frequencies of _multiple_ mutations of the same gene or worse yet multiple mutations in each of a number of metabolically related genes, is incredibly unlikely. But that has happened: there are three overly common Tay-Sachs mutations among the Ashkenazi, two overly commom Gaucher mutations, three Niemann-Pick mutations of roughly equal frequency, two elevated mucolipidosis type IV mutations. Tay-Sachs, Gaucher, and Niemann-Pick all invovle sphingolipd degradation, and the sphingolipids that pile up in mutant homozygotes (and are presumably mildly elevated in heterozygotes) are nerve growth factors.

Boas calculated that the probability of the Gaucher mutation distribution alone is less than 1 in 500: Risch doesn't address this at all.

I have no idea what his point is in comparing geographic distributions of lysosomal- and non-lysosomal mutations, considering that many or most of the non-lysosomal mutations have _also_ been made common by selection. CF has, almost certainly. There's evidence that strong selection is occuring at the BRCA1 locus (again two mutations). Slatkin has said that there must have been selection elevating the factor XI clotting disorder mutations ( again two different mutations). The connextin-26 deafness mutation has clearly been favored by natural selction in many populations, probably as a disease defense.

Posted by: gcochran at March 7, 2003 11:31 AM


Analyzing the probability for multiple mutations of the same gene is difficult. The problem is that some intron mutations may themselves increase the probability of other errors, so that there could be an underlying 'increased mutability' mutation that make multiple mutations in the same area more likely than they might otherwise be. Overall I agree with Cochran's argument, though.

Posted by: bbartlog at March 7, 2003 11:57 AM


Like many people born in Russia, I can recognized a Jew on a street from 20
paces, sometimes from behind, by racial and ethnic features. Racial features
are pretty common for many Mediterranean people. To my surprise, I found the
same racial and ethnic Jewish features in Irish and people from the United
Kingdom. Many of them look like Jes from Eastern Europe

Posted by: naphtali at May 5, 2003 07:12 PM