Natural selection in humans

Researchers at deCODE Genetics in Reykjavik, Iceland, have discovered a large chromosomal rearrangement in the human genome that appears to have been selected for in some European populations.1The rearrangement, a 900-kilobase inversion polymorphism at chromosome 17q21.31, appears in two lineages, H1 and H2, that have diverged for as many as 3 million years with no evidence of having recombined. The H2 lineage – rare in Africans, almost nonexistent in East Asians, but found in 20% of Europ

Charles Choi
Feb 13, 2005

Researchers at deCODE Genetics in Reykjavik, Iceland, have discovered a large chromosomal rearrangement in the human genome that appears to have been selected for in some European populations.1

The rearrangement, a 900-kilobase inversion polymorphism at chromosome 17q21.31, appears in two lineages, H1 and H2, that have diverged for as many as 3 million years with no evidence of having recombined. The H2 lineage – rare in Africans, almost nonexistent in East Asians, but found in 20% of Europeans – appears to undergo positive selection in Iceland, with carrier females having 3.2% more children per generation and higher recombination rates.

"The data are very, very strong," says David Reich of Harvard Medical School. "It's difficult to imagine this can be an artifact."

The way these lineages dramatically diverged tipped off the deCODE team to the presence of an inversion, since inversions are known to suppress exchange of variants by recombination...