Along the River of Eves
Tracking my maternal lineage over the past several million years
I’ve been interested in seeing where I fit into the scheme of human history. And by history, I mean the last 5–7 million years since the hominids diverged from Gorillas, Bonobos and, finally, Chimpanzees. There is nothing special about that starting point. It is not even a defined point; more of a very slow separation from the chimpanzee lineage.
In this long view of history, I am African. I may see myself as an American of European descent, but that part of my history has lasted at most 15,000 years, a length of time dwarfed by the tens of thousands of years the family spent in western Asia, and the millions of years in Africa.
Mitochondrial DNA, which is inherited from one’s mother, can be used to track one’s maternal line through both time and geographical location. Over time, mutations in mitochondrial DNA accumulate. Specific sets of mutations define what is known as a haplogroup, and we can roughly estimate the time at which the haplogroup arose and the location where it originated. Based on my mitochondrial DNA, the unbroken line of mothers that gave rise to me left Africa about 60,000 years ago and spent tens of thousands of years in southwest Asia. It is not clear when they arrived in Europe, but 10,000 to 12,000 years ago they had made it to the northern part of the Iberian Peninsula in Western Europe. This timeline roughly corresponds to the warming of Europe after the last glacial period. From Spain, my family followed the warming weather north. Based on genetic and genealogy studies, for the last several hundred years my maternal ancestors have lived in Scotland, Ireland, France and Germany.
My Y chromosome paints a similar but less precise story. The best I can say is that the continuous line of fathers from which I am descended left Africa about 75,000 years ago, spent around 70,000 years somewhere in Asia, and migrated to Europe about 5,000 years ago.
Examining the last few hundred years is interesting from the perspective of understanding the recent flow of people around the world. It is also more tangible. I can go to specific places in the world knowing that my ancestors must have stood in the near vicinity of where I stand. I can also identify specific relatives or, at the very least, regions with high concentrations of extended family members. My father’s family is from Asturias and Galicia in northern Spain. In spite of the facts that my family lived in those regions only two to four generations ago, and that I lived in Spain for a large portion of my life, I know of no specific relative that remains in either of those regions. I do know that, genetically, I am closer to a sample of residents from those two regions than I am to residents of any other area of the world, with the exception of two regions of Germany, from which my mother’s ancestors immigrated to the U.S. in the early to mid 1800s. My mother’s people live in Baden-Württemberg, in what is now southern Germany near the French and Swiss borders, and in northern Germany near Denmark.
I would like to travel back along the route taken by at least one line of ancestors, probably my maternal line. I would go from San Francisco to Cincinnati and then to South Germany. At that point the path becomes nebulous. I would have to make my way to southern Europe, presumably by going through France and crossing the Pyrenees into Spain. I would then slowly move east along the Mediterranean coast until I reached Turkey, cross the Bosporus at Istanbul and continue along the length of Turkey until I could turn south again, through Syria and Jordan. It is not clear where my ancestral maternal haplogroup made the crossing from Africa to Asia, but there are two reasonable choices: the crossing between Africa and the Sinai Peninsula directly north of the Gulf of Suez, or the crossing between the Horn of Africa and the Arabian Peninsula. I would probably choose the second of these and follow the Red Sea through Saudi Arabia and into Yemen where I would cross the Bab al-Mandab straight to Djibouti. From there it makes sense to head west to the Omo Kibish sites, near the Omo river in southern Ethiopia, where some of the oldest anatomically modern human bones have been found, and then follow the Great Rift Valley down the eastern half of Africa towards South Africa.
Human evolution isn’t consistent with the biblical idea of a unique Eve. Each haplogroup is founded by another in a sequence of Eves. They form a stream that spills out of Africa, breaking into smaller and smaller branches as they fill the world. My branch of this river has passed through America, Europe, Asia and Africa. If I followed the stream backward towards its source, it would start off as a solitary journey. As a man, my path is completely different from that of my wife and children, whose journey would start in Kerala, in the southern part of the Indian subcontinent. Somewhere in the Middle East our paths would converge, as would the paths of almost every human not living in Africa.
There is no obvious stopping point. Humans quickly extended to many parts of Africa, and we will probably never be able to specify a geographic origin. Nor is there anything special about Homo sapiens or the genus Homo. The river of Eves doesn’t start with humans but continues millions of years backwards in time. Eventually, following the path of human evolution stops making sense and somewhere in Southern Africa I’ll get tired and fly home.