In fact, the variations were so common they couldn't be accidental mutations but instead were probably due to natural selection, where genetic changes that are favorable to a species quickly gain a foothold and begin to spread, the researchers report.Lahn offers an analogy: Medieval monks would copy manuscripts and each copy would inevitably contain errors — accidental mutations.During the 2018 election cycle, he could get his wish. Trebek, a native Canadian who became a naturalized U. citizen in 1998, will moderate a 45-minute debate among Pennsylvania’s 2018 gubernatorial candidates as part of the Pennsylvania Chamber of Business and Industry’s annual dinner Oct. Invitations will be extended to all the major candidates, including Democratic incumbent Tom Wolf and the winner of a Republican primary that includes attorney Laura Ellsworth, businessman Paul Mango and state Sen. It’s unclear if Libertarian Party candidate Ken Krawchuk will be invited to participate.“Once the primary campaign is over and there is a Republican nominee, we look forward to sitting down and discussing what debates we will jointly participate in and how those debates are organized,” Jeffrey Sheridan, Wolf’s campaign manager, said in an email.Those criticisms are particularly important, Collins said, because Lahn's testing did find geographic differences in populations harboring the gene variants today.They were less common in sub-Saharan African populations, for example."A different way to look at is it's almost impossible for evolution not to happen." Still, the findings also are controversial, because it's far from clear what effect the genetic changes had or if they arose when Lahn's "molecular clock" suggests — at roughly the same time period as some cultural achievements, including written language and the development of cities.Lahn and colleagues examined two genes, named microcephalin and ASPM, that are connected to brain size.
Or perhaps a prospect who might one day hold such a lofty position."The genetic evolution of humans in the very recent past might in some ways be linked to the cultural evolution," he said.Other scientists urge great caution in interpreting the research.“It is premature at this time, before we even have a Republican opponent, to talk about debates.” Trebek told the Hill in 2013 if he were afforded the opportunity to moderate a political debate, he would take a different approach.“I would not let the politicians get away with standard responses,” Trebek said.
Trebek returned to filming episodes of in mid-January after surgery to treat a subdural hematoma — blood clots on the brain — caused by a fall in October.