About 30,000 years ago Neanderthal man disappeared, displaced by Homo sapiens, a taller, slimmer, altogether agile and more handsome—at least to our eyes—race of people who arose in Africa 10,000 years ago, spread to the Near East, and then were drawn to Europe by the retreating ice sheets of the last great ice age. These were the Cro-Magnon people, who were responsible for the famous cave paintings at Lascaux in France and Altamira in Spain—the earliest sign of civilization in Europe, the work of the world's first artist. Although this was an immensely long time ago—some 20,000 years before the domestication of animals and the rise of farming—these Cro-Magnon people were identical to us: they had the same physique, the same brain, the same looks. And, unlike all previous homonids that roamed the earth, they could choke on food. That may seem a trifling point, but the slight evolutionary change that pushed man's larynx deeper into his throat, and thus made choking a possibility, also brought with it the possibility of sophisticated, well-articulated speech. Other mammals have no contact between their airways and their esophagi. They can breathe and swallow at the same time, and there is no possibility of food going down the wrong way. But with Homo sapiens food and drink must pass over the larynx on the way to the gullet, and thus there is a constant risk that some will be inadvertently inhaled. In modern humans, the lowered larynx isn't in position from birth. It descends sometime between the ages of three and five months—curiously, the precise period when babies are likely to suffer from Sudden Infant Death Syndrome. At all events, the descended larynx explains why you can speak and your dog cannot.