The human diaspora from Africa that populated the world has been the subject of several recent studies. At first, these books were bulwarks against the tide of "Multi-regionalism" - the idea that an early version of our ancestral species evolved into Homo sapiens at different times and places. Genetic research, including that of the author, has shown that we're all descended from a small African population. Placing our origins on one continent simplifies the task of analysis of tracking our movements. In this book, Wells explains how the examination works and what it reveals of our ancestry.
The tool is "markers" on the genome. For females it was the DNA in mitochondria, the cell's "powerhouse". For males, it is changes on the Y chromosome, that molecular structure triggering a shift from the default embryo condition. The author demonstrates how these indicators are detected and how they allow us to track our ancestry back in time. The markers designate genetic "borders" between groups of people who share a common ancestor in the deep past. The groups are called "haplotypes" - for which Wells, at least in the case of Europe, uses the term "clan". There are seven of these clans - designated by letter labels such as "R", "J" or "N" - descended from male originators. The approach is reminiscent of Bryan Sykes "Seven Daughters of Eve" , except Wells follows the male lineage where Sykes used mitochondrial DNA to source female origins. Both authors focus on the European records as being more complete and readily available. Wells also finds but five female lines as opposed to Sykes' seven.
Wells discusses how genetic "clocks" can postulate a rate of mutation over a long span of time to roughly determine the age of the haplogroup. Much of this assessment is sustained by archaeological record. The procedures pinpoint his own grandmother's ancestry, which is ostensibly Danish, to origins in the Middle East, some ten thousand years ago at the beginning of the adoption of agriculture. The shift to the Middle East leads Wells to examine people living today with roots in far corners of the world. One notable example is "Phil", whose Native American background becomes the start of a study of Siberian people. There have been many disputes about the origins of the Western Hemisphere's human settlers. Wells travelled to the Asian North to recover genetic data. The information clearly defines the link between Indian populations here and their ancestry in Eastern Asia.
Wells puts some effort into explaining how DNA works, what counts as a "mutation" and how these changes can be tracked down the generations. With enough samples from living populations in historically stable circumstances, he can provide maps of the distribution of the haplogroups and frequency of the haplotype in a given area. Ireland, for example, is populated almost exclusively by a single haplotype. He explains that The Genographic Project he heads is keen to collect more data, both to refine the European and Native American data, but to enlarge the information from other parts of the world. Clearly, this is a book "in progress", but stands firmly as a good basis for understanding the foundations of such research and its enlargement of knowledge of humanity. Although he states this book is "less technical" than his "The Journey of Man", there is sufficient information on how the data collection and analysis is undertaken to make the book readable and interesting to everybody. [stephen a. haines - Ottawa, Canada]