Old Wives' Tales
Have you ever heard that you'll catch a cold if you go out in winter with wet hair? Or...
In 2006 a team of genetic researchers discovered evidence of recent human evolution. The discovery relates to the ability of humans to digest lactose, the main sugar found in milk. Lactose is broken down in the body by an enzyme called lactase. Throughout most of human history, the genes that control lactase production were switched off when a child was weaned because lactase was no longer needed. When cattle were first domesticated about 9,000 years ago, humans continued to consume milk into adulthood, however. As a consequence, natural selection favored genetic mutations that kept lactase production switched on in adults. Such mutations are known to have occurred among people in Europe who raised cattle. Now researchers have identified similar mutations among people in East Africa. These mutations are believed to have taken place as recently as 3,000 years ago. This date corresponds with the evidence that suggests cattle-raising tribes arrived in parts of East Africa about 4,500 years ago.
Have you ever heard that you'll catch a cold if you go out in winter with wet hair? Or...
Today, high heels are worn mostly by women. But this has not always been true. In past yea...
One of the most pressing health problems in the United States today is obesity. As of 2005...