Theoretically, any European could have her or his mitochondrial DNA sequencing and analyzed in order to situate their origin in one of the seven clans. Each of the seven circles represents a specific mitochondrial DNA sequence persevered over thousands of years via maternal inheritance, and the size of the circles represent the proportion of Europeans who share each sequence. Each line represents mutations, or differences, between the sequences that they connect, and the distances separating any two circles is proportional to the number of mutations separating each sequence. The dashed line between Ursula and Xenia indicates an “even deeper genealogy through which our species, Homo sapiens, is connected to the other, extinct, humans, the Neanderthals and Homo erectus, and eventually back to the common ancestor of humans and other primates” (275). Pretty AWESOME, in my opinion…
Over several years, Sykes and his team managed to obtain hundreds of DNA samples from Europeans all throughout the continent. By sequencing the mitochondrial DNA of each individual (sequencing refers to the process by which the individual base pairs making up the genetic code are parsed out), Sykes and his team were able to obtain side-by-side comparisons of each individual’s mitochondrial genetic code. Based on these side-by-side comparisons, he was then able to draw ancestral lineages.
But how? It all has to do with mutations, or changes in the individual segments of the DNA that simply appear as variations. Although perhaps obvious, unlike the hamster mitochondrial DNA, the sequences of the human samples varied—in the hundreds of bits and pieces of the mitochondrial control regions from all his European samples, Sykes and his team would find, one, two, or maybe eight, at most, differences (mutations) among all of the samples. It was ultimately based off of these differences that Sykes constructed his family trees. Except, what Sykes found was that these family trees didn’t resemble trees at all. Instead, Sykes found himself drawing groups—clans, as Sykes called them—of different mitochondrial sequences that more closely resembled networks than anything else. Sure enough, seven clans gradually became clearer and clearer. At the center of them? Seven sequences, each representing a different maternal ancestor whose mitochondrial DNA has persisted for tens of thousands of years through hundreds of generations of women (See “Mapping European Ancestry”). Sykes would go on to successfully defend the legitimacy of his claims against all sorts of skeptics, before endeavoring to name and imagine the lives of each of these seven women.
Enter the Seven Daughters of Eve: Ursula, Xenia, Helena, Velda, Tara, Katrine, and Jasmine.
Bryan Sykes’ research into the origins of modern Europeans relies almost entirely on the inheritance patterns of mitochondrial DNA. Going to great lengths in order to be clear and thorough, Sykes spends much of the first half of his book detailing how and why mitochondrial DNA proved to be the saving grace of his research.
In the early years of his research, in “one of those rare moments when an idea suddenly arrives from the recesses of the mind,” Sykes remembered that he had once read that all of the pet golden hamsters in the world were descendents of only one female (57). Sykes also knew that, unlike nuclear DNA, which is inherited from both parents and undergoes all sorts of mixing, mitochondrial DNA is inherited solely from the mother. This would mean, he concluded, that if he were to theoretically test hundreds of pet hamsters, they would, save for perhaps a single mutation here and there, have identical mitochondrial DNA sequences.
Thus, Sykes set out to examine the control regions (relatively stable regions of DNA) of hundreds of different pet hamsters, hoping to see little to no variation among them. Sure enough, the control region of the mitochondrial DNA remained completely stable—”from that very first hamster captured in the Syrian desert to its millions of great-great-great…great-grandchildren from every corner of the world, the control region DNA had been copied absolutely faithfully with not even a single mistake” (61-62).
Considering that Sykes’ ultimate goal was to examine the genetic lineage of over 150,000 years of human evolution, the mitochondrial control region offered the perfect model through which he could do exactly this!
It was using this method that Sykes uncovered the origin of the Polynesian people back to Asia rather than South America and ultimately, the ancestors of modern Europeans.