Angela
Elite member
- Messages
- 21,823
- Reaction score
- 12,329
- Points
- 113
- Ethnic group
- Italian
See the original paper:
https://www.cell.com/ajhg/fulltext/S0002-9297(21)00051-3
"Tuberculosis (TB), usually caused by Mycobacterium tuberculosis bacteria, is the first cause of death from an infectious disease at the worldwide scale, yet the mode and tempo of TB pressure on humans remain unknown. The recent discovery that homozygotes for the P1104A polymorphism of TYK2 are at higher risk to develop clinical forms of TB provided the first evidence of a common, monogenic predisposition to TB, offering a unique opportunity to inform on human co-evolution with a deadly pathogen. Here, we investigate the history of human exposure to TB by determining the evolutionary trajectory of the TYK2 P1104A variant in Europe, where TB is considered to be the deadliest documented infectious disease. Leveraging a large dataset of 1,013 ancient human genomes and using an approximate Bayesian computation approach, we find that the P1104A variant originated in the common ancestors of West Eurasians ∼30,000 years ago. Furthermore, we show that, following large-scale population movements of Anatolian Neolithic farmers and Eurasian steppe herders into Europe, P1104A has markedly fluctuated in frequency over the last 10,000 years of European history, with a dramatic decrease in frequency after the Bronze Age. Our analyses indicate that such a frequency drop is attributable to strong negative selection starting ∼2,000 years ago, with a relative fitness reduction on homozygotes of 20%, among the highest in the human genome. Together, our results provide genetic evidence that TB has imposed a heavy burden on European health over the last two millennia."
The negative selection selection seems that you die too early to procreate. So why did the negative selection only take hold 2000 years ago?
It's a very confusingly written abstract and paper. The abstract says the negative selection started 2,000 years ago (and in the paper it's tied to the Iron Age and dense populations living in close proximity to animals), but the paper has different dates, i.e. 5,000 years ago for Europe, for example, which would be around the time of the arrival of the Indo-Europeans. Perhaps it was because of more reliance on domesticated animals?
See article in Science Magazine:
https://www.sciencemag.org/news/2021/03/how-tuberculosis-reshaped-our-immune-systems
"Think of humanity’s worst plagues, and the Black Death, the Spanish flu, and COVID-19 all come to mind. Millions have died in those deadly pandemics, but their toll pales in comparison with that of tuberculosis (TB), which has killed more than 1 billion people over the past 2000 years—and still kills 1.5 million people worldwide every year. But how and when TB got to be so deadly has long been a mystery."
"The researchers found that the P1104A mutation was ancient—they spotted it in DNA from a farmer who lived 8500 years ago in Anatolia (what is now Turkey) and calculated that the mutation arose at least 30,000 years ago. Anatolian farmers and Yamnaya herders spread this gene variant as they moved into Central Europe. By studying changes in the frequency of the variant over time, the researchers estimated that about 3% of the population carried the gene until about 5000 years ago. By the middle of the Bronze Age, about 3000 years ago, 10% of Europeans had the trait. But since then, its frequency plummeted to 2.9%—the same rate as among today’s Europeans."
"The steep plunge coincides with when TB’s modern variant emerged, according to ancient DNA studies. Quintana-Murci and his team ran computer simulations on how population size and migration influenced the gene’s frequency. They propose that TB killed or seriously sickened one-fifth of those with two copies of the variant, few of whom had offspring who survived after the end of the Bronze Age, 2000 years ago. As a result, natural selection acted strongly and quickly to weed out the deadly gene variant to low levels, the researchers report today in The American Journal of Human Genetics."
"The earliest evidence of TB comes from skeletons buried in the Middle East 9000 years ago, soon after the invention of agriculture. But the variant that kills humans today—Mycobacterium tuberculosis—emerged 2000 years ago, when people lived in denser settlements alongside domesticated animals, often reservoirs for TB."
If you are on @23andMe
you want to browse for Rs34536443 and see if you are G (good) or C (not good)
I'm heterozygous. I knew I would be; actually surprised I'm not CC. My mother's family was riddled with it in the 19th and first half of the 20th century.
This is part of what infuriates me about illegal immigration; these people are not tested and are responsible for the resurgence in the U.S. The strains are also more resistant to anti-biotics. When we came to this country, the first thing you had to submit as part of your documentation was that you were free of TB.
Not to mention, of course, that they're testing positive for Covid now that the flood gates are open.
if you are on @23andMe
you want to browse for Rs34536443 and see if you are G (good) or C (not good)