Mongolia is another Asian area that may have a high prelavence of lactose tolerance, as their diet is based mostly on the milk and meat of goats. This makes perfect sense given the Gobi desert's colder temperatures which would preserve dairy products longer.

I suppose some of the higher altitude regions of northern India have cold enough temps to keep milk longer, and have a correspondingly higher lactose tolernce index, but the lower lying areas may have less tolerance due to higher temps.

Some actual data on the thermoclines of N. India, especially a map like the one for HIV resistance, matched over a map of the local's lactose tolerance, would be work well here.

Mongolia is another Asian area that may have a high prelavence of lactose tolerance, as their diet is based mostly on the milk and meat of goats.


Prevalence of primary adult lactose malabsorption in three populations of northern China:
Lactose malabsorption was most frequent in a subgroup of Han (Chinese) from northeastern China (229 of 248 subjects, 92.3%). Among 198 Mongols from Inner Mongolia, there were 174 lactose malabsorbers (87.9%). The frequency of lactose malabsorption was lowest in a group of Kazakhs, traditional herders from the northwestern region of Xinjiang (149 of 195 subjects, 76.4%).

mongols might have ways to prepare milk products which obviate the need for lactose tolerance (fermentation?). more on lactose malabsorption.

also, I suppose some of the higher altitude regions of northern India have cold enough temps to keep milk longer, and have a correspondingly higher lactose tolernce index, but the lower lying areas may have less tolerance due to higher temps.

the highest max temps can be found in the plains of north-central india, where milk (butter) usage is also maximal. there are probably historical and climatic factors, but altitude-temperature is too simplistic.

Dairy is used as milk (unspoiled) and in curdled forms such as yoghurt, cheese and buttermilk. "Spoilage" of milk does not preclude its use. South Indians are large users of yoghurt and diluted buttermilk. A South Indian meal typically ends with a course of buttermilk/yoghurt with rice and spicy pickles.

"Dairy is used as milk (unspoiled) and in curdled forms such as yoghurt, cheese and buttermilk. "Spoilage" of milk does not preclude its use."

Very true. think of Fulanis in west Africa

In things like yoghurt, most of the lactose would have been already been digested by bacteria.

*yogurt

Ashkenazi Jews carry the highest concentration of the Delta 32 mutation, and probably the first families settled Poland (which included Lituania) some 700 - 800 years ago, exactly when D 32 started propagating, why they call this a Viking Mutation and not an Ashkenazi Jewish mutation?

Jaimito,

You make a good point, if the Delta32 mutation originally spread due to its ability to ward off typhoid fever, and only later was it found to ward off HIV, then the Ashkenazi Jews would seem like the most likely original population - by virtue of the fact that they were largely absent from country areas and concentrated in the urban centers of the day, which were lacking in sanitation and harbored all kinds of urban diseases like typhoid fever.

Jaimito, do you have a data source for your claim? As I notice that the article says about Delta32:

we estimate the origin to be outside of northern Europe and selection intensities to be strongest in the northwest.

The NorthWest of Europe is Britain and Ireland, and an alternative explanation why selection would seem so high here - which I have alluded to previously - is that during the great famine in Ireland, a huge percentage of the population were consigned to "Poor Houses", where they lived in concentrated sqalor, and mostly died from typhoid and TB, rather than starvation. This would skew the remnant population to have higher Delta32, assuming that the allele was already in the local population at a lower frequency - maybe having been introduced by Sephardic Jews brought by the Normans.

Actually I found the data table - Delta 32 allele frequencies - for this article, and it doesn't include any data for Ireland and Britain - as far as I can tell - just Iceland, which is strange??

that was me...

pconroy,

* the Normans brought French Ashkenazi Jews to Britain, not Sepharadi ones.

* Irish famine ocurred in the 19th century

* I claim nothing at all. But as you say, resistence to epidemics would tend to develope in unsanitary urban environments, to where Middle Age Jews were forced. The Roman Trastevere is a permanently flooded hellhole, the Venetian ghetto is a contaminated industrial wasteland, Speyer, Franfurt, Prague, Vienna's ghettos were overpopulated jailhouses. It makes little sense that healthy-living body-developer Viking warriors would host an endemic focus of epidemic diseases like TB and smallpox. Medieval ghettos are more probable.

Jaimito,

As regards which Jewish group the Normans brought with them as retainers, this article on Jewish Immigration to England, implies that they were Sephardic:
Until very recently, Jews represented the only substantial non-Christian presence in Britain. The first definite settlement occurred shortly after 1066
and later...
The return of the Sephardi Jews (expelled in 1290)

As regards when the Great Irish famine occurred, I'm aware that it occurred recently, but its dual effect of starvation and then ensuing disease - due to the practics of confining the poor in crowded, unsanitary living quarters - devasted up to 25% of the population, so it would be enough to alter the genetic landscape of the Irish in a decade or so, something that medieval ghettos did to the Jews over centuries.