Analyzing DNA from the cheek cells of a group of Mongolians enabled geneticist Spencer Wells, an Explorer-In-Residence at the National Geographic Society, to figure out whether they were indeed descendants of the notorious warrior who lived 800 years ago and thousands of miles away. Such exotic historical enigmas are daily fodder for Wells who is in the midst of the Genographic Project (GP)—a massive undertaking to sample human DNA from around the world to illuminate human genetic and migratory history.
“There is a history book in your DNA [that reveals] how people are related to each other all over the planet and how we have moved around,” says Wells.
The last 10,000 years are of particular interest to Wells who, since childhood, wanted to be an historian. “I was fascinated by Egypt and Greece and Rome and all of these great empires and I’m very interested in the impact of these empires on the patterns of genetic variation—for example, can we see traces of the Phoenicians in North Africa?” says Wells.
His latest adventures have led him to discover that Thomas Jefferson’s ethnic background is not quite as one would expect. He has hunted down possible descendents of Solomon, the third king of Israel. And, he has entered a world where science and religion converge—the search for what he calls the “scientific Adam,” the man who gave rise to all men today and the “trunk” of the human family tree. Wells has used DNA to trace this common ancestor back to Africa and perhaps to the very plains where he may have hunted. He has even identified a living tribe with an ancient lineage that offers a window into the life of “scientific Adam”—and, the face of one of the tribe members served as a model to determine what he may have looked like.
Unlike medical geneticists who study genetic changes that cause morphological differences or diseases, population geneticists like Wells study genetic changes that don’t have any effect at all. These changes, called genetic markers, are created by random mutations in the DNA and are passed down through the generations. Each population accumulates its own distinctive set of markers.
As these mutations are pretty rare, if two people share one of these markers that suggests they share an ancestor. By comparing DNA samples from many different populations, Wells hopes to reveal the shape of the human family tree, from twigs to trunk.
Wells has traveled the world studying genetic patterns for about the past 15 years. He’s completed fieldwork in central Asia, India, and the Middle East collecting samples from about 10,000 people. Analysis of these samples revealed a broad-brush view of how man originated in Africa and moved around planet to Australia and Central Asia.
“But,” says Wells, “10,000 samples isn’t enough to reveal details about how we are all related and moved around.” To figure out the details he proposed a project that required 100,000 samples—the Genographic Project.
As part of the GP, 10 centers scattered around the globe will each take blood samples from 100-200 indigenous populations (50 to 100 individuals per population) over the next five years. Together the project should yield data on at least 100,000 individuals.
Everyone knows a little about their parents, grandparents, and maybe even their great grandparents—but beyond that is a historical realm. “People always ask ‘it must be really tough to get samples from tribes in remote regions’ but that’s not true. When you explain to people that they are carrying this history book in there genome, in their blood, and that you can help them read it they are fascinated—most people want to participate.”
“I’ve sampled in Lebanon and Christians and Muslims alike want to know if they are related to the Phoenicians—they are intrigued by the chance they could be a descendent of this great imperial power,” says Wells.
Similarly on the island of Pate, off the coast of Kenya near the Somalia border, the people have an oral tradition that they are related to Chinese sailors who washed ashore on 400-foot ships and married local women. Wells discovered that the residents of Pate don’t have any Chinese Y chromosomes but they have Y-chromosomes from everywhere else—India, Pakistan, the Middle East, and Europe. However, the presence of 15th century Chinese pottery on the island suggests that there may be truth to the tales and more genetic sampling is needed.
“Genographic is not really a genetics project. It is using genetics as a tool to study history and anthropology. I’m interested in the impact of the Inca empire on the genetic patterns in upper Amazonia, in Central Asia I want to look at the impact of Alexander the Great,” says Wells as he rattles of a hit list of historical mysteries that he hopes to solve.
The GP has taken on a particular urgency because of massive migrations currently in progress. People are leaving their ancient homelands, moving to the cities, and becoming part of the melting pot. As people marry individuals from other cultures genetic patterns are quickly scrambled. If Wells can’t identify the location where a particular genetic pattern arose, it becomes tricky to identify how different ethnic groups are related to one another.
“This makes the job of a population geneticist very difficult because though you carry your genes with you, you lose the context in which that genetic variation arose,” says Wells.
A symptom of this mixing is the rapid decline in the number of spoken languages in the world. In the year 1500, linguists estimate 15,000 languages were spoken; today there are 6,000. By the end of the century about half to 90% of those are going to be extinct, says Wells. “We are going through a period of cultural mass extinction. We have a narrowing window of opportunity to collect genetic samples from indigenous populations where people have stayed put for a very long period of time.”
Wells hopes that by studying the DNA from these groups he can locate where particular genetic changes occurred and when, which will reveal how our ancestors migrated around the planet.
To date, Wells has visited about 50 countries to sample different genetic lineages. Of all the indigenous tribes he has met, the Hazabe of Tanzania have had the greatest impact on Wells.
“I have hung out with other Bushmen and they are fascinating. But most of them don’t actually live the hunter-gatherer lifestyle. They can still mock it up for a film crew but none of them actually live in villages. The Hazabe live as hunter-gatherers. They are actually pulling up trees and carving bows and arrows and they make fire by rubbing sticks together, it is amazing and it really does give you an insight into the way people probably lived 50 or 60 thousand years ago.”
You don’t need to be a member of an indigenous tribe to participate in the Genographic Project. Log onto https://www.nationalgeographic.com/genographic/participate.html to find out how you can contribute to the scientific endeavor of deciphering the human family tree and, learn about your ancestors.
University of Minnesota Campuses