AFRICANGLOBE – A few months ago, when I energetically swabbed the inside of my cheek for National Geographic’s Genographic Project, I had no idea that my DNA contained genes from two extinct hominids.
A budding citizen scientist, I donated my DNA to the greater cause, intent on contributing to the body of knowledge about my ancient human ancestors.
At the outset, I knew more than most people did about their family lineages. My father’s English Protestant roots extended back 15 generations, to 1670 in London and Massachusetts. And my mother’s roots, the Irish Roman Catholic side of the family, had been traced to 1780, the year her relatives arrived in Prince Edward Island.
My Anglo-Irish lineage had seemed unassailable—or that’s what I believed—before I received the genographic roadmap of my DNA.
Like many of my fellow citizen scientists—more than 618,000 people from more than 140 countries donated their DNA—the results of National Geographic’s Genographic Project left me speechless.
I was humbled to discover that my mitochondrial DNA contained markers—unique sets of genetic mutations passed down, from mother to child, and used to identify and track discrete populations—indicating that my out-of-Africa DNA profile was comprised of 44 percent Northern European, 36 percent Mediterranean and 18 percent Southwest Asian.
I was also surprised to learn that my ancestors had left Africa, some 60,000 years ago, travelling through Israel, Saudi Arabia, India, Turkmenistan, Russia, the Caucasus Mountains, Italy and Spain. Even more astonishing was the discovery that my DNA double helix contained a 5.5-percent contribution from two extinct hominids.
Simply put, my DNA is made up of 2.8 percent Neanderthal, an extinct hominid cousin who disappeared from Europe and the Middle East about 30,000 years ago, or maybe earlier. My DNA also contains 2.7 percent Denisovan, a recently-discovered hominid cousin that once roamed Asia. In 2008, during a cave excavation in Siberia, paleoanthropologists discovered the well-preserved remains of a Denisovan adult and a young girl who had lived 40,000 years ago.
Launched in 2005, the Genographic Project has exceeded National Geographic’s expectations, shedding light on our deep collective past.
“The greatest history book ever written is the one hidden in our DNA,” said Dr. Spencer Wells, renowned population geneticist and team lead of National Geographic’s Genographic Project on the project’s website. Using state-of-the-art genetic science, investigators employ a collection of 150,000 DNA markers (or identifiers) to analyze DNA from around the world.
According to National Geographic, “Mitochondrial Eve” is the common direct maternal ancestor of the X chromosome found in all women. She was born in East Africa some 180,000 years ago.
Determining the other half (the paternal side) of my DNA history is more problematic. As a female, I lack the Y chromosome. Therefore, in order to map my paternal lineage, I need a DNA contribution from a close male relative, like my father or brother. Since my father is deceased, and I don’t have a male sibling, I’m content to focus on the X chromosome-side of my ancestral history.
My direct maternal lineage flows from Mitochondrial Eve, and has been traced to 67,000 years ago, to a group of people in East Africa dubbed the “L3″ family branch.
Many of the L3 family branch fanned out across the African continent. And, in more recent history, L3 descendants were transported from Africa to the New World, during the African slave trade.
My wandering L3 ancestors, likely on the move in search of food and water, migrated from Africa to the eastern Mediterranean region and West Asia where they encountered Neanderthals.
According to National Geographic, humans “made love and not war,” with their closely-related hominid cousins, eventually overwhelming the smaller populations of Neanderthals and Denisovans. In contrast, because the indigenous peoples of Africa didn’t migrate from Africa to Eurasia, they don’t have any Neanderthal DNA.
By 55,000 years ago, the “R” family branch of my out-of-Africa relatives was established in West Asia. This branch of the family tree also included well-travelled explorers who left Turkey and moved north, across the Caucasus Mountains of Georgia and southern Russia.
Some 30,000 years ago my ancestors in the “HV” family branch, which included Cro-Magnon man, the first early modern humans, moved north, across the Caucasus Mountains and into eastern Europe. Subsequent mitochondrial genetic mutations in my DNA, which occurred during the past 30,000 years, point to the development of four distinctly new family branches.
Prior to the onset of the Neolithic and Bronze ages (8,000 to 800 BC), my hunting-and-gathering relatives migrated from Eastern Europe to the warmer climes of the Mediterranean, keeping ahead of the advancing ice sheets. The end of the ice age, marked by retreating glaciers and a warming climate, precipitated waves of human migration northwards to Western Europe.
Participation in National Geographic’s Genographic Project has taken me on an incredible personal journey.
Despite the fact that I’m a scientist, albeit a geoscientist, I remain mystified that the deep story of my human lineage can be reconstructed from a smidgeon of my DNA that fits on the head of a Q-Tip. This type of personalized, hands-on scientific discovery is an amazing vehicle to educate the general public on the relevance of science and society. And, this type of magical discovery can captivate the imaginations of children, our scientists of the future…
View this personalized infographic showing my ancient ancestry from National Geographic’s Genographic Project:
By: Susan Eaton