Northern Europeans are the most tolerant

At least, that is the claim of a study an article about which was just published in the prestigious journal ‘Science’.

It really is a most fascinating study which tracks the spread of the genes responsible for lactose tolerance throughout the human population.

Did you know that there were actually three separate gene mutations that enable humans to digest milk into adulthood, each one in a different geographic area?  One is from Western Africa, another is from Asia and the third one is believed to have occurred in the plains of Hungary and made its carriers capable of producing so many more fertile offspring that they outperformed the initial inhabitants.

This third one is now most concentrated from central to northern Europe.

There is a nifty map in the article showing lactose tolerance within the human population:

MAP SOURCE: REF. 2

Most people who retain the ability to digest milk can trace their ancestry to Europe, where the trait seems to be linked to a single nucleotide in which the DNA base cytosine changed to thymine in a genomic region not far from the lactase gene. There are other pockets of lactase persistence in West Africa (see Nature 444, 994–996; 2006), the Middle East and south Asia that seem to be linked to separate mutations3 (see ‘Lactase hotspots‘).

The single-nucleotide switch in Europe happened relatively recently. Thomas and his colleagues estimated the timing by looking at genetic variations in modern populations and running computer simulations of how the related genetic mutation might have spread through ancient populations4. They proposed that the trait of lactase persistence, dubbed the LP allele, emerged about 7,500 years ago in the broad, fertile plains of Hungary.’

Very fascinating and the article, with maps and fascinating factoids, like that most of the European cattle are genetically closer related to Middle Eastern cattle than to the aurochs that were native to Europe.

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