New scientific research using advanced analysis of DNA from all over the world has found that the most recent common ancestor on our father's side — known as Y-chromosomal Adam — lived about the same time as the most recent common ancestor on our mother's side — so-called Mitochondrial Eve. That period of Adam's lifetime, scientists discovered, was between 120,000 and 156,000 years ago. This is the very first time scientists have sequenced the entire Y chromosome in the cells of many men to determine our ancestry (and Adam's life), though for some time now scientists have known that Eve probably lived somewhere between 99,000 to 148,000 years ago. Until now, scientists had not known whether Adam and Eve had lived during the same period.

But why would anyone doubt that Adam and Eve lived at the same time?

The Garden

Despite the biblical nicknames given by scientists, so-called Y-chromosomal Adam is simply the man who gave rise to the Y-chromosome genes of all contemporary men while so-called Mitochrondrial Eve is the woman responsible for passing down mitochondrial DNA, which is inherited from the mother. (Biologically men have both an X and Y chromosomes, while women have two X chromosomes.) Mitochondrial DNA was the first significant part of the human genome sequenced by scientists.

"The Y chromosome and the mitochondrial genome have been used to estimate when the common patrilineal and matrilineal ancestors of humans lived," write the authors in their paper published in Science.

Although other people lived during the same period as Adam and Eve, these two were the most successful at producing surviving offspring. Adam's male progeny bred and their Y genes survived while his contemporaries either failed to have male progeny or those they had didn't survive or didn't also produce male progeny. In other words, Adam's contemporaries might also have descendants alive and well today, but their offspring did not descend through patrilineal lines — along the line of fathers.

"Those contemporaries could have passed on many other genes to present-day peoples," Chris Stringer, director of the Human Origins Program at the Natural History Museum in London, told National Geographic.

"The real significance of the date of our common Y-chromosome ancestor, is that it effectively gives us an upper limit on when our species began to leave Africa," author and geneticist Spencer Wells told National Geographic.


"Previous estimates for Adam were based on a smaller amount of data and less-diverse population," Carlos Bustamante, a genetics professor at Stanford University and study author, told Bloomberg.

To identify the most recent common ancestor (MRCA), scientists used Y chromosomes obtained through the Human Genome Diversity Project, an international resource composed of cell lines contributed by laboratories around the world and maintained at the Centre Etude Polymorphism Humain in Paris. In their research, the geneticists studied and traced chromosomes from 69 men in several populations in sub-Saharan Africa, Siberia, Cambodia, Pakistan, Algeria, and Mexico.

From all the evidence gathered until now, scientists have constructed two theories of ancestry. The "Out of Africa" model suggests that our ancestors swept out of Africa in the past 200,000 years and essentially replaced all the indigenous people they encountered. Geneticists theorize that this view of history does not mean that possibly some of our nuclear DNA derives from humans who were not part of the migration out of Africa. And so a competing theory exists: "Multiregionalism" asserts that humans are descended from several archaic Old World populations.

No matter which model holds true or whether they both do (in some way scientist have not yet understood), genetic studies help anthropologists understand patters of migrations as well as their timing, all of which contributes to the wider scientific view of both genetic diversity and the evolutionary process that led to modern humans.

Source: Poznik GD, Henn BM, Yee M-C, Sliwerska E, Euskirchen GM, Lin AA, et al. Sequencing Y Chromosomes Resolves Discrepancy in Time to Common Ancestor of Males Versus Females. Science. 2013.