Mark Stoneking, a molecular anthropologist in Germany, was researching different human populations, back in 2007, to find out if he could piece together a history of their origins and migration patterns across the planet. He did this by analyzing genetic variations in DNA that he'd taken from cheek swabs. Around this time, he heard claims that there is more DNA in saliva than in blood. Skeptical, he and his research team ran a test. They found that there is, in fact, more DNA in saliva than in blood; but this is because much of the genetic material comes from microbes.