A short history of nearly everything - Bill Bryson [231]
So why then, you may well ask, if the Neandertals were so stout and adaptable and cerebrally well endowed, are they no longer with us? One possible (but much disputed) answer is that perhaps they are. Alan Thorne is one of the leading proponents of an alternative theory, known as the multiregional hypothesis, which holds that human evolution has been continuous—that just as australopithecines evolved into Homo habilis and Homo heidelbergensis became over time Homo neanderthalensis, so modern Homo sapiens simply emerged from more ancient Homo forms. Homo erectus is, on this view, not a separate species but just a transitional phase. Thus modern Chinese are descended from ancient Homo erectus forebears in China, modern Europeans from ancient European Homo erectus, and so on. “Except that for me there are no Homo erectus,” says Thorne. “I think it's a term which has outlived its usefulness. For me, Homo erectus is simply an earlier part of us. I believe only one species of humans has ever left Africa, and that species is Homo sapiens.”
Opponents of the multiregional theory reject it, in the first instance, on the grounds that it requires an improbable amount of parallel evolution by hominids throughout the Old World—in Africa, China, Europe, the most distant islands of Indonesia, wherever they appeared. Some also believe that multiregionalism encourages a racist view that anthropology took a very long time to rid itself of. In the early 1960s, a famous anthropologist named Carleton Coon of the University of Pennsylvania suggested that some modern races have different sources of origin, implying that some of us come from more superior stock than others. This hearkened back uncomfortably to earlier beliefs that some modern races such as the African “Bushmen” (properly the Kalahari San) and Australian Aborigines were more primitive than others.
Whatever Coon may personally have felt, the implication for many people was that some races are inherently more advanced, and that some humans could essentially constitute different species. The view, so instinctively offensive now, was widely popularized in many respectable places until fairly recent times. I have before me a popular book published by Time-Life Publications in 1961 called The Epic of Man based on a series of articles in Life magazine. In it you can find such comments as “Rhodesian man . . . lived as recently as 25,000 years ago and may have been an ancestor of the African Negroes. His brain size was close to that of Homo sapiens.” In other words black Africans were recently descended from creatures that were only “close” to Homo sapiens.
Thorne emphatically (and I believe sincerely) dismisses the idea that his theory is in any measure racist and accounts for the uniformity of human evolution by suggesting that there was a lot of movement back and forth between cultures and regions. “There's no reason to suppose that people only went in one direction,” he says. “People were moving all over the place, and where they met they almost certainly shared genetic material through interbreeding. New arrivals didn't replace the indigenous populations, they joined them. They became them.” He likens the situation to when explorers like Cook or Magellan encountered remote peoples for the first time. “They weren't meetings of different species, but of the same species with some physical differences.”
What you actually see in the fossil record, Thorne insists, is a smooth, continuous transition. “There's a famous skull from Petralona in Greece, dating from about 300,000 years ago, that has been a matter of contention among traditionalists because it seems in some ways Homo erectus but in other ways Homo sapiens. Well, what we say is that this is just what you would expect to find in species that were evolving rather than being displaced.”
One thing that would help to resolve matters