both of the two tracks which lead back to her from the present day. If she lived further back still, there might be two or more mutations. By counting the differences between the two sequences, we can estimate the length of the matrilineal connection between any two people in the world. To put dates on to this we need to know the mutation rate for mitochondrial DNA. We will look in greater depth at how the rate is estimated in a later chapter (see Chapter 11). The best estimates are that, on average, if two people had a common ancestor ten thousand years ago then there would be one difference in their control region sequences. If the common maternal ancestor of two people lived twenty thousand years ago, then we would expect to see two mutational differences in their mitochondrial DNA.
Of course, there is not the faintest chance of knowing from any written source whether any two people were related through their maternal lines twenty thousand years ago, so we work it the other way around. If two people have exactly the same control region sequence, their common ancestor will have lived, on average, some time in the last ten thousand years. The Tsar and I do have the same control region sequence. So our maternal ancestry, working back through, on my side, my mother Irene Clifford and her mother Elizabeth Smith and on the Tsarâs, through his mother, the Dowager Empress Marie Fedorovna and her mother Louise of Hesse-Cassel, Queen of Denmark, most likely converges on a common ancestor who lived within the last ten thousand years. Not close enough for me to make a realistic claim to the Romanov fortunes, I think.
Measuring ancestral connections in tens of thousands of years may seem too crude to be interesting. However, although the mitochondrial mutation rate seems incredibly slow, it is fortunately just about right for studying human evolution over the last hundred thousand years â which is when most of the action happened. If the mutation rate had been much faster than it is, relationships would be harder to follow. If it were much slower, there would be too few differences between people to see any patterns at all. Taking the next logical step, if any two people can trace a common maternal ancestor, it follows that any group of people can do the same. I slowly realized that we held in our hands the power to reconstruct the maternal genealogy of the whole world. Not exactly world domination; but Iâm sure my distant cousin, Nikolai Aleksandrovich, Imperial Tsar of all the Russias, would have approved. The question was: where should we begin?
6
THE PUZZLE OF THE PACIFIC
At nine-fifteen every evening Air New Zealand flight NZI takes off from Los Angeles International Airport. Within thirty seconds it has crossed the short stretch of dry land between the end of the runway and the ocean. There is no throttling back of the engines to cut down on the noise levels. There is no need. Flight NZI is now over the Pacific, and will not see land again until it crosses the Coromandel peninsula on the North Island of New Zealand as it makes its approach to Auckland. But that is still seven thousand miles and fourteen hours ahead. Between then and now there is only the open ocean beneath us â the apparently endless reach of the Pacific Ocean. Sprinkled across this vastness are thousands of islands, but so dwarfed are they by the sea that you are very unlikely to catch even a glimpse of any of them from the plane. And yet, by the time the first European ships began to explore the Pacific, every one of these islands had been found and settled by the people I have come to regard as the greatest maritime explorers the world has ever seen â the Polynesians.
I would like to be able to say that my decision to work in Polynesia was the result of careful planning, of balancing the scientific advantages of studying island populations with the difficulty and expense of working on the other side of the world. I would like to be
Of course, there is not the faintest chance of knowing from any written source whether any two people were related through their maternal lines twenty thousand years ago, so we work it the other way around. If two people have exactly the same control region sequence, their common ancestor will have lived, on average, some time in the last ten thousand years. The Tsar and I do have the same control region sequence. So our maternal ancestry, working back through, on my side, my mother Irene Clifford and her mother Elizabeth Smith and on the Tsarâs, through his mother, the Dowager Empress Marie Fedorovna and her mother Louise of Hesse-Cassel, Queen of Denmark, most likely converges on a common ancestor who lived within the last ten thousand years. Not close enough for me to make a realistic claim to the Romanov fortunes, I think.
Measuring ancestral connections in tens of thousands of years may seem too crude to be interesting. However, although the mitochondrial mutation rate seems incredibly slow, it is fortunately just about right for studying human evolution over the last hundred thousand years â which is when most of the action happened. If the mutation rate had been much faster than it is, relationships would be harder to follow. If it were much slower, there would be too few differences between people to see any patterns at all. Taking the next logical step, if any two people can trace a common maternal ancestor, it follows that any group of people can do the same. I slowly realized that we held in our hands the power to reconstruct the maternal genealogy of the whole world. Not exactly world domination; but Iâm sure my distant cousin, Nikolai Aleksandrovich, Imperial Tsar of all the Russias, would have approved. The question was: where should we begin?
6
THE PUZZLE OF THE PACIFIC
At nine-fifteen every evening Air New Zealand flight NZI takes off from Los Angeles International Airport. Within thirty seconds it has crossed the short stretch of dry land between the end of the runway and the ocean. There is no throttling back of the engines to cut down on the noise levels. There is no need. Flight NZI is now over the Pacific, and will not see land again until it crosses the Coromandel peninsula on the North Island of New Zealand as it makes its approach to Auckland. But that is still seven thousand miles and fourteen hours ahead. Between then and now there is only the open ocean beneath us â the apparently endless reach of the Pacific Ocean. Sprinkled across this vastness are thousands of islands, but so dwarfed are they by the sea that you are very unlikely to catch even a glimpse of any of them from the plane. And yet, by the time the first European ships began to explore the Pacific, every one of these islands had been found and settled by the people I have come to regard as the greatest maritime explorers the world has ever seen â the Polynesians.
I would like to be able to say that my decision to work in Polynesia was the result of careful planning, of balancing the scientific advantages of studying island populations with the difficulty and expense of working on the other side of the world. I would like to be
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