Modern Mind

that interested Wilson and Cann was that it is inherited only through the mother – it therefore does not change as nuclear DNA changes, through mating. Mitochondrial DNA can therefore only change, much more slowly, through mutation. Wilson and Cann had the clever idea of comparing the mitochondrial DNA among people from different populations, on the reasoning that the more different they were, the longer ago they must have diverged from whatever common ancestor we all share. Mutations are known to occur at a fairly constant pace, so this change should also give an idea of how long ago various groups of people diverged. 32
    To begin with, Wilson and Cann found that the world is broken down intotwo major groups – Africans on the one hand, and everyone else on the other. Second, Africans had slightly more mutations than anyone else, confirming the palaeontological results that humanity is older in Africa, very probably began there, and then spread from that continent to populate the rest of the world. Finally, by studying the rate of mutations and working backward, Wilson and Cann were able to show that humanity as we know it is no more than 200,000 years old, again broadly confirming the evidence of the fossils. 33
    One reason that the Wilson and Cann paper attracted the attention it did was because its results agreed well not only with what the palaeontologists were discovering in Africa, but also with recent work in linguistics and archaeology. As long ago as 1786, Sir William Jones, a British judge serving in India at the High Court in Calcutta, discovered that Sanskrit bore an unmistakable resemblance to both Latin and Greek. 34 This observation gave him the idea of the ‘mother tongue,’ the notion that there was once, many years ago, a single language from which all other languages are derived. Joseph Greenberg, beginning in 1956, began to re-examine Sir William Jones’s hypothesis as applied to the Americas. In 1987 he concluded a massive study of native American languages, from southern South America to the Eskimos in the north, published as
Language in the Americas,
which concluded that, at base, the American languages could be divided into three. 35 The first and earliest was ‘Amerind’, which covers South America and the southern states of the US, and shows much more variation than the other, northern languages, suggesting that it is much older. The second group was Na-dene, and the third Aleut-Eskimo, covering Canada and Alaska. Na-dene is more varied than Aleut-Eskimo, all of which, says Greenberg, points to three migrations into America, by groups speaking three different languages. He believes, on the basis of ‘mutations’ in words, that Amerind speakers arrived on the continent before 11,000 years ago, Na-denes around 9,000 years ago, and that the Aleuts and Eskimos diverged about 4,000 years ago. 36
    Greenberg’s conclusions are highly controversial but agree quite well with evidence from dental studies and surveys of genetic variation, in particular the highly original work of Professor Luca Cavalli-Sforza of Stanford University. In a series of books –
Cultural Transmission and Evolution
(1981),
African Pygmies
(1986),
The Great Human Diasporas
(1993), and
History and Geography of Human Genes
(1994) – Cavalli-Sforza and his colleagues have examined the variability of both blood, especially the rhesus factor, and genes around the world. This has led to fairly good agreement on the dates when early humans spread out across the globe. It has also led to a number of extraordinary possibilities in our
longue durée
history. For example, it seems that the Na-dene, Sino-Tibetan, Caucasian and Basque languages may be related in a very primitive way, and once belonged to a superfamily that was broken up by other peoples, shunting this superfamily into backwaters, and expelling Na-dene speakers into the Americas. The evidence also shows great antiquity for Basque speakers, whose language and blood is quite different from those around them. Cavalli-Sforza notes the contiguity between the Basque nation and the early sites of cave art in Europe, and wonders whether this is evidence for an ancient people whorecorded their hunter-gatherer techniques on cave walls and resisted the spread of farming peoples from the Middle East. 37
    Finally, Cavalli-Sforza attempted to answer two of the most fascinating questions of all – when did language first appear, and was there ever a single ancestral