A stretch of DNA linked to Covid-19 was passed down from Neanderthals 60,000 years ago, according to a new study. Scientists don’t yet know why this particular segment increases the risk of severe illness from the coronavirus. But the new findings, which were posted online on Friday and have not yet been published in a scientific journal, show how some clues to modern health stem from ancient history. “This interbreeding effect that happened 60,000 years ago is still having an impact today,” said Joshua Akey, a geneticist at Princeton University who was not involved in the new study. This piece...