科學(xué)60秒:古城居民抗病強(qiáng)
City living has obviously influenced human culture—____1____, how you gonna keep ‘em down on the farm after they’ve seen Paree'? But urban life may have also influenced human genes, making the descendants of ancient city ____2____ more resistant to disease. That's according to a study in the journal Evolution.
The researchers started from the ____3____ that densely populated cities would be good places for infectious diseases, which could spread easily from person to person. That situation should have set up selection pressure for the ability to survive such infections.
he scientists sampled the DNA of 17 populations from Africa, Asia and Europe, including longtime urbanites—like Italians, Turks and Iranians—and traditionally rural or nomadic groups, like Malawians or the Saami people of northern Scandinavia.
Then the researchers ____4____ a gene variant that offers protection against diseases like tuberculosis or leprosy. After controlling for any shared ancestry between the groups, they indeed found that the protective gene was significantly more common in cultures with a long history of urban settlement. Which may be some comfort next time someone's ____5____ near you on the subway.