Posted on 01/16/2005 7:32:58 PM PST by PatrickHenry
Researchers in Iceland have discovered a region in the human genome that, among Europeans, appears to promote fertility, and maybe longevity as well.
Though the region, a stretch of DNA on the 17th chromosome, occurs in people of all countries, it is much more common in Europeans, as if its effect is set off by something in the European environment. A further unusual property is that the genetic region has a much more ancient lineage than most human genes, and the researchers suggest, as one possible explanation, that it could have entered the human genome through interbreeding with one of the archaic human lineages that developed in parallel with that of modern humans.
The genetic region was discovered by scientists at DeCode Genetics, a biotechnology company in Reykjavik, Iceland, which has made the Icelandic population, with its comprehensive genealogy and medical records, a prime hunting ground for the genetic roots of common diseases. Their finding is published in today's issue of Nature Genetics in a report by Dr. Kari Stefansson, Dr. Augustine Kong, Dr. Hreinn Stefansson and other DeCode scientists.
The report seems likely to receive considerable attention, even though it raises as many questions as it answers. "I thought it was one of the most interesting papers in population genetics I have ever read," said Dr. Nick Patterson, a mathematician at the Broad Institute in Cambridge, Mass., who advised DeCode on the article but has no other connection with the company.
The region came to light during the search for a schizophrenia-causing gene, which turned out not to be there. But the DeCode researchers noticed that the DNA sequences they had examined did not seem to agree with those in the standard human genome sequence, said Dr. Kari Stefansson, DeCode's chief executive.
The lack of agreement turned out to be caused by the fact that the region exists in two forms in the Icelandic population. The region is not a single gene but a vast section of DNA, some 900,000 units in length, situated in the 17th of the 23 pairs of human chromosomes. In some Icelanders, the DeCode team found, the section runs in the standard direction but in others it is flipped. Looking for any physical consequence, the DeCode researchers found that women carrying the flipped, or inverted, section tended to have slightly more children.
The section carries several known genes, not one of which has any obvious connection with fertility. It is not clear why inverting the section should have any effect on the number of children, Dr. Stefansson said. But the inversion does increase the rate of recombination, the shuffling of genes between generations that is a major source of genetic novelty. That could account for some of the increase in fertility.
The DeCode scientists found that the chromosome 17 inversion is rare in Africans, almost absent in Asians, but present in 20 percent of Europeans, the same frequency as in Iceland. The inversion seems to have been favored by natural selection among Europeans in fairly recent times, perhaps the last 10,000 years. "Maybe something switched it on in the European environment, such as an interaction with diet," said Dr. David Reich, a population geneticist at the Broad Institute.
Fertility is doubtless affected by different genes in different populations, and DeCode found a genetic element special to Europeans because that is where it was looking. The increased frequency of the inversion in Europeans is one of a growing number of examples of recent human evolution.
The inversion itself, however, is surprisingly ancient. Its age is revealed by its counterpart, the standard or noninverted section of chromosome 17. The standard and inverted regions cannot exchange genetic elements during recombination because their DNA sequences do not match. Hence, unlike most of the rest of the genome, which gets shuffled in each generation, the two forms have existed separately since their creation. This event presumably happened when the region came adrift from its parent chromosome and got knitted back in the wrong way round.
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So . . . is this another "Boys from Brazil" thing ?
I'll buy the DNA difference, but the effects seem to be completely opposite of what is stated.
The Europeans also have a socialism gene.
I cant help but wonder if that ancient parallel humanoid was Neanderthal.....
Europe's current negative fertility rate at present is due to standard-of-living issues, not genetics
It's really more about industrialization
Actually, that version was more intriguing, with rape and subhuman interbreeding.
Decode's alternative proposal is that the flipped version was carried for many years in a different human lineage, one of the archaic populations that preceded the emergence of anatomically modern humans in Africa 150,000 years ago. Then, in some episode of rape or interbreeding, a single copy of the flipped version entered the modern human lineage some time before humans left Africa 60,000 years ago.
Is there any historical evidence to back up these assertions?
A poor man's riches are his children. This goes for white people as well.
LOL. They sure don't make white guys like they used too.
Take away my riches, then. He's costing me about 20 grand a year at college.
LOL!!!!
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