Years later, a ruler declares one of those copies the definitive manuscript, and a rush is on to make many copies of that version — so whatever changes from the original are in this presumed important copy become widely disseminated.
Scientists attempt to date genetic changes by tracing back to such spread, using a statistical model that assumes genes have a certain mutation rate over time.
"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.
Lahn and colleagues examined two genes, named microcephalin and ASPM, that are connected to brain size.When Hodaya becomes non-observant—has sex, stops keeping kosher, stops observing the Sabbath—she never quite feels a part of the secular world: She may have split with God, but her friends still understand things about her the non-religious can’t.She’s still welcome at Shabbat dinner—even if no one will drink the wine she brings, because she brought it over in a Shabbat-breaking taxicab.For the microcephalin gene, the variation arose about 37,000 years ago, about the time period when art, music and tool-making were emerging, Lahn said.For ASPM, the variation arose about 5,800 years ago, roughly correlating with the development of written language, spread of agriculture and development of cities, he said."We, including scientists, have considered ourselves as sort of the pinnacle of evolution," noted lead researcher Bruce Lahn, a University of Chicago geneticist whose studies appear in Friday's edition of the journal Science."There's a sense we as humans have kind of peaked," agreed Greg Wray, director of Duke University's Center for Evolutionary Genomics.If those genes don't work, babies are born with severely small brains, called microcephaly.Using DNA samples from ethnically diverse populations, they identified a collection of variations in each gene that occurred with unusually high frequency.But in the world of , dating is the dramatic equivalent of other show’s car chases and gunfights: the heart-stopping part.The group dates with both excessive matter-of-factness and hidden vulnerability. ) Yifat rebounds from Nati’s rebuff not by wallowing, but by making another, much more sensible romantic choice for herself.