Publisher: W. W. Norton & Company
Cover: Debra Morton Hoyt
reviewed by: Lynard Barnes 10/4/2005
Summary: Excellent explanation of DNA.
Few sojourns are as enlightening about human nature as a walk through the world of research science. In Bryan Sykes’ THE SEVEN DAUGHTERS OF EVE, we get to take such a sojourn, brief though it is. A vignette embedded in an otherwise informative and entertaining book.
Of the early challenges to the validity of mitochondrial DNA as a “the prime molecular interpreter of the human past”, Sykes discusses the March 1999 article by Maynard Smith in which the argument is made that the number of mutations in mitochondrial DNA were too many to have arisen by mutation alone. In the same issue of “Proceedings of the Royal Society” magazine, research was presented by six authors, including Erika Hagelberg, a former associate of Sykes’, suggesting that mitochondrial DNA, rather than passing directly from mother to offspring, underwent recombination (splitting and rejoining with a different mitochondrial DNA molecule). Both the theory and the research results, if valid, would mean that mitochondrial DNA could not be used to trace DNA sequences back in time. The benefit of having this roadblock suddenly placed in the path of mitochondrial DNA application was that it forced additional research. The consequences however were that the contrary theory and research, especially the recombination theory, added ice-chunks to the dark clouds already hanging over mitochondrial DNA. As Sykes points out early in his book, when U.S. evolutionary biochemist Allan Wilson and his two students, Rebecca Cann and Mark Stoneking, published their 1987 research paper, “Mitochondrial DNA and human evolution” in Nature magazine, they presented a revolutionary concept. Science does not abide revolutions quietly.
Nearly eighteen months after the Erika Hagelberg mitochondrial DNA recombination research paper, a “correction” was published. Sykes writes, “Getting to the truth had been an exhausting, unpleasant and distressing experience.” Robert Graysmith reports in his book, AMERITHRAX (to be reviewed here in October 2005) that “the first American crime to attract national attention was committed by a scientist.” The scientist was Dr. John White Webster. He murdered Dr. George Parkman in 1849. The motive for the murder was apparently jealousy. Sykes’ annoyance at the behavior of his former colleague is minor in comparison to murder, but the science community seems to harbor as many predatory egos as it does innovative brains. End of vignette.
What Bryan Sykes’ THE SEVEN DAUGHTERS OF EVE is really about is the path DNA research took to arrive at a point where mitochondrial DNA became acceptable evidence of modern Man’s advance through nearly two-hundred thousand years of time. The concept that all people are related is difficult to grasp, even though it makes sense logically. Sykes reinforces the logic with a clear, concise exposition of the science. In the process, he effectively tackles the last vestige of the theory supporting a regional development of modern Man. Though there is no DNA available from Neanderthals (Homo neanderthalensis), the absence of any exotic DNA material in European populations is a strong argument that there was no transfer of genetic material between these earliest of human-like populations (Neanderthals) and the third wave of humanoids migrating out of Africa some two hundred thousand years ago. He offers two possible explanations as to why such genetic transfers did not occur. Both are enlightening and fascinating.
Beyond the science, though using mitochondrial DNA haplogroups as his foundation, Sykes launches into a make-believe history of seven women who lived seventeen to forty-five thousand years ago and were the ancestors of most Europeans alive today. It is a historical-reconstruction based on the cultural perspective e of a twenty-first century scientist. Are there problems with this? You bet. While Sykes avoids the obvious pitfalls, the impression is given that Helena, Katrine, Xenia and the rest are matrons of a culture. The impression is unavoidable because he ties them to geographical regions. Well, mitochondrial DNA groups do seem to have a geographic base. But the research is not about geography, it is about people and the one salient fact coming through the research is that people own the globe, the globe, or some small portion thereof, does not own the people.
At this stage of mitochondrial DNA research, stereotyping of groups sharing the same mitochondrial markers provides no useful purpose. Sykes diligently attempts to avoid this even while telling us about Helena and her ingenious menfolk kin, or Jasmine and her inept-hunter husband.
In the final chapters of THE SEVEN DAUGHTERS OF EVE, Sykes returns to the pure science. He states that there are thirty-three maternal clans recognized world wide. Thirteen of them are in Africa. There are two surprises in all this. First, “. . . Africa has only 13 percent of the world’s population, it lays claim to 40 percent of the maternal clans.” The second surprise, based on the mitochondrial DNA evidence, is that only one of the thirteen African clans are responsible for populating the rest of the world. He calls this mitochondrial Eve, Lara. He touches upon the other clans briefly-the four clans found among native Americans with accumulated mutations placing their arrival in the New World within the last thirteen thousand years. Korea and Japan were also populated about the same time, though he says much more has to be done on documenting the migration of peoples into Japan.
Aside from the really good discussion of mitochondrial DNA in this book, there are little side-bars interwoven into the text which makes them non-side-bars. One such concerns Sykes and his team’s procurement of “the golden hamster”. Sykes remembered reading as a child that all the caged golden hamsters in the world were the descendants of just one female. Eventually, the secretary of the Syrian Hamster Club of Great Britain, Roy Robinson, was contacted and he confirmed that there was a “Mother of All Hamsters”-or more germane, a mitochondrial Eve Hamster. The first golden hamsters reached the United States in 1938. In 1947 “a piebald hamster appeared in one breeding colony-the first of many coat colour varieties, caused by spontaneous mutations in the coat colour genes, it showed itself because of the inbreeding within the colony.” Through selective breeding, the golden hamster now comes in a variety of colors. But Sykes’ recounting of this story raises more questions than he answers. In something as simple as the color of a hamster’s coat, is there a limit to the effects of mutation resulting from inbreeding? The common sense answer would seem to be yes, but common sense is not necessarily science. Does this concept of mutation and inbreeding apply to an explanation of the thirty-five distinct (someone counted) shades of human skin coloring?
THE SEVEN DAUGHTERS OF EVE is definitely worth reading. You can flip past the history reconstruction of the seven daughters however and not miss anything of importance.