The Neanderthal—with his Mousterian culture—seems to have invaded Europe from Asia toward the end of the third and last interglacial, anywhere from 80,000 to 125,000 years ago, and to have left from 15,000 to 100,000 years ago, depending on what authority you choose, and how that authority dates the last interglacial. Unlike his predecessors, the Neanderthal lived in caves; but that was probably because he was the first man in Europe to survive a glacial winter—tens of thousands of them. The Neanderthal seems to have disappeared quite suddenly from Europe, taking his Australoid features with him. There are traces of him in Africa, and also in Palestine where he is thought to have produced a hybrid among the Mount Carmel people. Sir Arthur Keith said, in 1915, that the Neanderthal never left Europe, but was merely absorbed into the next peoples. We can see the Neanderthal profile on an occasional passer-by. Most anthropologists are rather cool to the Neanderthal. They cast him quite outside the sacred ranks of our ancestors. They say he was not _Homo sapiens_—merely _Homo neanderthalensis_. This means that he was a sort of dead end, a blind alley, up which one sort of ape-man ran, while another was taking a turn that ended in his being master of the atom but not of the atomic bomb. Other anthropologists do not agree. Like Keith, they take the Neanderthal into the sacred circle—at least at stud. Radiocarbon Dates for the Mousterian However early the Mousterian culture may have begun, the later stages fall within the range of one of the archaeologist’s most interesting and precise techniques for dating. This is the radiocarbon, or Carbon 14, method.[19] Much simplified, it depends upon the following phenomena: Most plants are radioactive, and so are all animals that depend directly or indirectly upon these plants for food. This radioactivity is found in a rare form of carbon called radiocarbon, or Carbon 14. While a plant or an animal is alive, it contains a constant proportion of this radioactive material. Radiocarbon is always breaking down and disappearing, but while a tree or a bird or another animal lives, this material is being renewed. When this same tree or animal dies, it stops acquiring new radiocarbon, and therefore its radioactivity decreases. Heartwood from a 4,000-year-old sequoia tree is appreciably less radioactive than the living outer layer. Antlers shed by a buck in the last spring are more radioactive than any reindeer antlers left in a cave in France by Old Stone Age hunters 17,000 years ago.