DNA change due to agriculture

[Bastian]

Hello.

This may be interesting to republish (and comment) on SOTT :
_http://www.nytimes.com/2015/11/24/science/agriculture-linked-to-dna-changes-in-ancient-europe.html

 

[Eboard10]

Hello.

This may be interesting to republish (and comment) on SOTT :
_http://www.nytimes.com/2015/11/24/science/agriculture-linked-to-dna-changes-in-ancient-europe.html

Thanks for sharing the article Bastian. The author of the study makes some interesting remarks, including the rise of many diseases with the advent of agriculture but he seems to miss the link between changes in certain features in Europeans and adoption of carbs following the introduction of farming. On the issue of dairy, the study shows that the SLC22A4 gene helping in the digestion of milk came about only after the introduction of farming. The gene codes for a protein that helps cells absorb the amino acid ergothioneine which is needed by the body but is found at low levels in wheat and other crops.

The study then tries to link changes in skin colour of Europeans to reduced levels of Vitamin D intake. The early hunter-gatherers in Europe were darker skinned before lighter skinned Anatolian farmers populated the area. A new genetic variant later emerged making people even lighter skinned. The team attributes this to lower levels of Vitamin D intake due to a reduced intake of meat, but it's also likely that the change took place with the influx of light skinned nomads known as the Yamnaya, some 5,000 years ago, coming from the Russian Steppes and mixing with the already present population in Western Europe.

The last point that is brought up concerns differences in height between European populations:

The new collection of ancient DNA also allowed Dr. Reich and his colleagues to track the puzzling evolution of height in Europe. After sorting through 169 height-related genes, they found that Anatolian farmers were relatively tall, and the Yamnaya even taller.

Northern Europeans inherited a larger amount of Yamnaya DNA, making them taller, too. But in southern Europe, people grew shorter after the advent of farming.

Dr. Reich said it wasn’t clear why natural selection favored short stature in the south and not in the north. Whatever the reason, this evolutionary history still shapes differences in height across the continent today.

I am quite surprised how Dr. Reich is unable to link the short height of Mediterranean people to adoption of a carb based diet when in the previous sentence it's written that people grew shorter after the advent of farming. There have been several studies showing how the advent of agriculture and the change in diet to one based of starchy foods led to a number of diseases, dental cavities and short height.

The Worst Mistake in the History of the Human Race

Usually the only human remains available for study are skeletons, but they permit a surprising number of deductions. To begin with, a skeleton reveals its owner's sex, weight, and approximate age. In the few cases where there are many skeletons, one can construct mortality tables like the ones life insurance companies use to calculate expected life span and risk of death at any given age. Paleopathologists can also calculate growth rates by measuring bones of people of different ages, examine teeth for enamel defects (signs of childhood malnutrition), and recognize scars left on bones by anemia, tuberculosis, leprosy, and other diseases.

One straight forward example of what paleopathologists have learned from skeletons concerns historical changes in height. Skeletons from Greece and Turkey show that the average height of hunger-gatherers toward the end of the ice ages was a generous 5' 9'' for men, 5' 5'' for women. With the adoption of agriculture, height crashed, and by 3000 B. C. had reached a low of only 5' 3'' for men, 5' for women. By classical times heights were very slowly on the rise again, but modern Greeks and Turks have still not regained the average height of their distant ancestors.

Agriculture Expanded as Farmers Pressed North, Not Because Hunter-gatherers Adopted the Practice

After the ancient genomes were assembled, they compared the sequences with those in public databases that document genetic variants in modern populations. What they found was "a clear signal" that the hunter-gatherers shared more DNA variants with people alive today in Finland than the farmers did, and that the farmer shared more with modern inhabitants of Italy, Greece and other Mediterranean countries than did the hunter-gatherers.

Thought I'd share my thoughts on this, FWIW.