The Seven Daughters of Eve

Thought I would step into the world of genetics, or more precisely, the world of mitochondrial genetics. I spent several enjoyable evenings reading Bryan Sykes account of his research into the DNA carried by these intracellular hitchhikers, and what it indicates about our ancestry.

Quickly, mitochondria are the little entities that exist within each cell and give the cell the ability to use oxygen to produce energy. They are passed only from mother to children, no mitochondria take a ride on the male sperm. Also, mitochondria do not undergo any kind of DNA recombination; Their strands are passed identically down to children (except for the occasional mutation.) Therefore, mitochonrial DNA represent an unbroken maternal line leading back. The rate of mutations gives us a distance, in time, when two lines separated.

One of the things that was bothering me as I read the book was his focus on the genetics of Europe and Europeans. The Seven Daughters are the Seven women, at various times in the past (from 45,000 to less than 15,000 years ago), whose strains of mitochondria are still present in Europeans today. Certainly those aren't the only strains worldwide, I kept thinking. And towards the end, Dr Sykes reveals that so far 33 strains, or clans as he dubs them, have been identified world-wide.

Through the markers in our mitochondria human migrations can be plotted, and some surprising placements come to light. That Neanderthals and early humans did not mix can be ascertained, also that the Polynesians spread from West to East (Thor Heyerdahl notwithstanding). But, even more, the full mixing of peoples throughout history; that there was not just one, but perhaps two waves of people who moved into the Americans from the Bering Straight. And, where we often define 'race' as a distinct group, the research indicates that there are substantial portions of each population that have mitochondria bearing markers more common to other populations. We are all related back to these 33 women, and our relatives have widely dispersed throughout the globe.

Professor Sykes gets high marks for making science come alive in this engaging book. I really enjoyed both his descriptions of the work to get DNA out of old bones, and his accounts of having to defend his team's initial conclusions. He takes the challenges seriously, and provides convincing research to defend his claims, which have now been widely accepted. That he turned some previously held ideas on their head and increased our understanding of the human tale makes for some pretty exciting reading.