From Smithsonian Magazine, By- Margaret Osborne ( Daily Correspondent) Edited by - Amal Udawatta, One small variation in DNA may have helped Homo sapiens out-compete our ancient relatives Skull of a Neanderthal, or Homo neanderthalensis Geography Photos / Universal Images Group via Getty Images When the first Homo sapiens appeared on Earth around 300,000 years ago, they weren’t the only humans roaming the land. Our ancestors were one of about nine early human species alive at the time—and one of at least 21 human species to ever exist, though the exact number is debated. So why, scientists have asked, are Homo sapiens the only ones that are still here? After all, our relatives the Neanderthals had brains of a similar size to ours, yet they went extinct about 40,000 years ago. “[Neanderthals] were in Europe a long time before us and would have been adapted to their environment, including pathogens. The big question is why we would be able to out-compete them,” Laurent N