From the paper:

Lactase persistence is inherited as a dominant mendelian trait in Europeans1, 2, 4. Adult expression of the gene encoding LPH (LCT), located on 2q21, is thought to be regulated by cis-acting elements5 (Fig. 1). A linkage disequilibrium (LD) and haplotype analysis of Finnish pedigrees identified two single SNPs associated with the lactase persistence trait: C/T-13910 and G/A-22018, located approx14 kb and approx22 kb upstream of LCT, respectively, within introns 9 and 13 of the adjacent minichromosome maintenance 6 (MCM6) gene4 (Fig. 1). The T-13910 and A-22018 alleles were 100% and 97% associated with lactase persistence, respectively, in the Finnish study4, and the T-13910 allele is approx86%–98% associated with lactase persistence in other European populations6, 7, 8.

It is interesting that Finns have such a high level of lactose tolerance and such problems with alcohol.

The fact that all these cattle-herding cultures had a (different) mutant gene to 'work with' so to speak makes you appreciate the depth of human genetic variation. Wonder how many other lactose-tolerance variants are out there, unselected for and undetected...

Sloppy thing from the article: Genetic evidence shows that the mutations conferred an enormous selective advantage on their owners, enabling them to leave almost 10 times as many descendants as people without them.

Over what time frame? Not a single generation, obviously, but surely the advantage would be more than 10x counted from then until the present day?

its funny how we find this covergent evolution in light skin (between Europeans and Asians) in lactose tolerance (in East Africans and Europes) but we never assume there are any convergent genes related to brain size and intelligence.

If we find one gene in Europeans but do not find it in Africa we assume it to be the "missing link" to prove African intellectual inferiority and stop assuming there might be convergent evolution. Hmmm... Refering back to the two genes that supposedly influence brain structure/size. It was also funny one of them is hardly found in Japanese, who we know are highly intelligent and the other is found to be the most prevalent in groups, such as people in Papua which hardly score well on IQ tests.

Has anyone ever defined what the selective advantage of this mutation is? Is it based on getting more energy from milk, or from not suffering lactose intolerence?

Non digested lactose should be digested by the microbiota in the gut, leading to the production of short chain fatty acids. The fatty acids are absorbed and represent about 66% of the ingested energy, which makes me question it is a function of energy gain.

I suppose non digesters may get diarrhea from lots of lactose, which would cause negative selection. Yet, supposedly one of the ways to improve lactose intolerence is to drink more milk, the theory being that this selects for beneficial lactose digesters in the gut such as the bifidobacterium and lactobacilli.

I suppose chronic diarrhea would make one less successful with the ladies, and make it harder to pass on the message.

Qrious: “its funny how we find this covergent evolution in light skin (between Europeans and Asians) in lactose tolerance (in East Africans and Europes) but we never assume there are any convergent genes related to brain size and intelligence.”

There have been many posts and comments on GNXP concerning IQ and racial hybrids. In particular the possibility of getting the best alleles from different racial groups has been discussed. (E.g., IQ studies of Japanese-European children in Hawaii.)

There has also been discussion that different racial groups and different genders have evolved different brain architecture and function that result in differing mental strengths and weaknesses. (fMRI studies that show men and women use different brain regions to solve the same problem.)

It is interesting that Finns have such a high level of lactose tolerance and such problems with alcohol

This may be due to milk and dairy products being vulnerable to bacterial contamination while alcohol has anti-bacterial properties. The alcohol may help to kill off some of the bacteria in their diet.

If we find one gene in Europeans but do not find it in Africa we assume it to be the "missing link" to prove African intellectual inferiority and stop assuming there might be convergent evolution

The reason why people assume that Africans are intellectually inferior is because of their performance on IQ tests as the link below shows:

IQ And Global Inequality: “The Most Important Contribution To Economic Understanding Since Adam Smith.”

It is interesting that Finns have such a high level of lactose tolerance and such problems with alcohol


This may be due to milk and dairy products being vulnerable to bacterial contamination while alcohol has anti-bacterial properties. The alcohol may help to kill off some of the bacteria in their diet.

I think that retaining the ability to produce lactase beyond about age 5 is of much more importance to children than it is adults. It means that many more children, IMO, will survive to maturity and go on to improve their parent's reproductive success. More than that, it probably lead to those offspring being better able to compete with other individuals as well.

Alcohol tolerance, on the other hand, was probably only needed in adulthood as most societies prevent children from drinking alcohol (mothers do) and primitive societies could not really produce much of it.

I remember reading recently that the reason we eat grains and milk might be because they are (slightly) addictive. I'll try and find the link

Ah, here we go:
http://membres.lycos.fr/xbeluga/ ...griculture.html

I know there was another related site that led me to it, but I can't remember what it was. For all I know it might have been gnxp.

I think that the competitive advantage of adult lactose tolerance is not only (and possibly not mainly) in better nutrition, but in parallel changes in fighting ability. Pastoral life requires different abilities from sedentary agricultural economy, and nomadic pastoralists have developed all over the world better mobility, better ability to fight as group (possibly against wild animals), and more aggressivity. The Fulani pastoralists (100% Africans) have invaded and the Sahel and founded many kingdoms, exploiting local agriculturalist populations. Mongol pastoralists also took over irrigated agricultural cultures in the Mesopotamian valleys and in the Central Asian oasis like Samarkand and Buchara (destroying them). The Nordic pastoral peoples have also conquered their part of the world, such as the Normans taking over Britain, and the last century's colonial movement.

Large groups of lactose intolerant peoples survive in China, Southern Africa, pockets of Amerindians.

Pity we have to die before we can watch the coming episodes of this fascinating evolution thing.

jaim, less lactose tolerance east asian nomands have been whooping more lactose tolerance west asian nomands and sedenartists for nearly 2,000 years now since the huns. this suggests that the optimum for the jaim klein theory of fighting lactose digesters implies that one can overshoot. on, and the little historical details (yes, i know, not a general concern of yours) like the conquest of northern europe by the romans and subsequent rule for 500 years, etc. etc.

TommyBoy:

Bias analyst of data by paleoconservative facists does not impress me.

It should be noted that the Chinese feed their kids rice gruel (variously called Conjee or porrige etc).

I seem to recall selection for processing the carbs etc in rice.

I seem to recall selection for processing the carbs etc in rice.

yes.

Qrious, if we put aside the issue of evolution and genes for a moment and just focus on IQ, even James Flynn would say the average is significantly lower in Africa than Europe. Flynn is not a fascist, paleoconservative, libertarian or even a liberal but a self-described socialist.