Each of our cells contains many clocks. Unlike your typical clock that can be easily read on its own, our clocks are best read in a shop full of others. They are comparative clocks that tell the story we are most interested in, our story. Where did we come from and where might we be headed?
Consciously or not, we are quick to assign people to various groups based on what they look like or what words come out of their mouths. But skin color, facial features, height, and other external features are very plastic evolutionary speaking and not particularly indicative of the time that has elapsed since splits have occurred genetically. Genetic markers like DNA, mtDNA, blood types, and even languages are better time keepers. They show us that it hasn't been long (tens of thousands of years for some) since the various "races" shared a common ancestor. Not only that, but many of those races have mixed since then and hence aren't as "pure" as we think, and for the prejudice aren't as "pure" as they would like.
By measuring the differences in DNA strands using a large sample of diverse populations, Cavalli-Sforza has been a pioneer in re-constructing the history and movements of modern humans. Principal components and multidimensional scaling (two methods of performing these reconstructions) substantially agree. The evolution of human languages, too, helps to confirm this history of ours. Neither is entirely straightforward however. Genes get mixed when foreigners mate (which occurred through a variety of ways in ancient times including concurring nations and international trading) and languages can be replaced through similar means. But there are methods to unraveling those episodes, both in genetics and in linguistic studies.
Using the method known as principal components to analyze and compare genes among diverse peoples, the author and others created maps of population movements during the past 10,000 years. To their surprise and pleasure, these independent maps correlated almost perfectly with the archeological maps provided by unrelated (but now becoming more intertwined) scientific fields. A synthesis on this topic is in the works uniting genetics, archeology, linguistics, and similar fields which historically haven't been linked this tightly.
As one would think, and as Darwin prophesied, the genetic data lines up pretty much with the theories of linguistic evolution. Both can be organized and displayed as trees which have similarities far beyond the odds of chance alone. Many of the non-similarities can be explained away by known events such as nations being conquered by smaller populations which then force a language change on the captors. The invaders didn't have the time, inter-relations, or the numbers to change the genes of the subjects completely, or even mostly. Cavalli-Sforza sums up the theme of genes and languages proving the same point with the following:
"Genetic research can certainly help the understanding of linguistic evolution, and vice versa." (p. 172)They are complimentary disciplines.
Genes, Peoples, and Languages is filled with illustrations that help to clarify and show graphically our history. In the final chapter, Cavalli-Sforza waxes more philosophical and lets out more of his personal, liberal views. He also discusses social/cultural and linguistic evolution in this last chapter but stops short of using the term meme. Overall, Genes, Peoples, and Languages is a good book that falls short of being a great book by the non-usage of a decent editor. The data is accumulating rapidly now so I imagine a more comprehensive, even more accurate, and better written piece on the same subject will emerge in this decade.
from the publisher:
Luigi Luca Cavalli-Sforza was among the first to ask whether the genes of modern populations contain a historical record of the human species. Cavalli-Sforza and others have answered this question-anticipated by Darwin-with a decisive yes. Genes, Peoples, and Languages comprises five lectures that serve as a summation of the author's work over several decades, the goal of which has been nothing less than tracking the past 100,000 years of human evolution.
Cavalli-Sforza raises questions that have serious political, social, and scientific import: When and where did we evolve? How have human societies spread across the continents? How have cultural innovations affected the growth and spread of populations? What is the connection between genes and languages? Always provocative and often astonishing, Cavalli-Sforza explains why there is no genetic basis for racial classification and proposes that a comparison of blood types is a far better means of determining "genetic distance" and explaining linguistic and cultural differences.
A panoramic tour of the major discoveries in genetic anthropology, Genes, Peoples, and Languages gives us a rare firsthand account of some of the most significant scientific work of recent years.
Luigi Luca Cavalli-Sforza was born in Genoa in 1922 and has taught at the Universities of Cambridge, Parma, and Pavia. He is currently Professor Emeritus of Genetics at Stanford University and is the author of The History and Geography of Human Genes.