"This paper offers the first proof and clear example of a new kind of human evolution for a specific trait," said Hirschhorn, who is also a senior associate member of the Broad Institute. "We provide a demonstration of how humans have been able to adapt rapidly without needing to wait for new mutations to happen, by drawing instead on the existing genetic diversity within the human population."
Average heights can differ between populations, even populations that are genetically very similar, which suggests that human height might have been evolving differently across these populations. Hirschhorn's team studied variants in the genome that are known to have small but consistent effects on height: people inheriting the "tall" version of these variants are known to be slightly taller on average than people inheriting the "short" versions of the same variants.
The researchers discovered that, in northern Europe, the "tall" versions of these variants are consistently a little more common than they are in southern Europe. The combined effects of the "tall" versions being more common can partly explain why northern Europeans are on average taller than southern Europeans. The researchers then showed that these slight differences have arisen as a result of evolution acting at many variants, and acting differently in northern than in southern Europe.
"This paper explains at least in part why some European populations, such as people from Sweden, are taller on average than others, such as people from Italy," Hirschhorn said.
The researchers were only able to detect this signature of evolution by using the results of recent genome-wide association studies by the GIANT consortium, which identified hundreds of different genetic variants that influence height.
| Contact: David Cameron david_cameron@hms.harvard.edu 617-432-0441 Harvard Medical School Source:Eurekalert |