Genetic ‘Adam and Eve’: All Humans are Descendants of One Man and Woman Who Lived Over 100,000 Years Ago
According to the creation myth of the Abrahamic religions, Adam and Eve were the first man and woman and the ancestors of all humans. While non-believers refute the idea of a God that created human beings in the Garden of Eden, scientific research has revealed that all humans alive today are descendants of one man and one woman who may have lived at the same time over 100,000 years ago.
In 1987, studies of mitochondrial DNA (which tracks maternal ancestry), suggested that all human beings were descendants of one woman who may have lived in Africa about 200,000 years ago. Similar research has been carried out on the Y chromosome of men (which tracks paternal ancestry), from various places, but here the estimates of research vary quite widely—from 60,000 years to 580,000 years ago. However, in 2013, a study published in the journal Science showed that almost every man alive today can trace his origins to one man who lived approximately 135,000 years ago, and that this ancient man was alive at the same time as the woman who his known as the ‘mother of all women’, providing evidence for an ancient ‘Adam and Eve’, popularly known as Y-chromosomal Adam and mitochondrial Eve.
Adam and Eve by Peter Paul Rubens, 1628 (public domain)
Most Comprehensive Study on Male Sex Chromosome
The research team reached their conclusions by carrying out the most complete study to date on the male sex chromosome. The study involved sequencing the entire genome of the Y chromosome for 69 men from seven global populations. By assuming a mutation rate linked to archaeological events (such as the migration of people), the team concluded that all males in their global sample shared a single male ancestor in Africa roughly 125,000 to 156,000 years ago.
A similar analysis has also been conducted to trace back a common ancestor of all women, known as ‘mitochondrial Eve’. The DNA from mitochondria, the energy centre of a cell, is carried inside a female’s egg, so only women pass it on to their children. The DNA held inside mitochondria can therefore reveal the maternal lineage to ancient ‘Eve’, who is believed to have lived in Africa between 99,000 and 148,000 years ago – almost the same time period during which the Y chromosome ‘Adam’ lived.
Adam and Eve Did Not Reproduce
Before getting too excited, the research team were eager to emphasize the fact that the genetic ‘Adam and Eve’ are not the same as the biblical Adam and Eve. “They weren't the first modern humans on the planet,” reports LiveScience “but instead just the two out of thousands of people alive at the time with unbroken male or female lineages that continue on today”.
Y-chromosomal Adam and mitochondrial Eve were just the two out of thousands of people alive at the time with unbroken male or female lineages that continue on today. Example chart showing the evolution of mitochondrial DNA (CC by SA 3.0)
Scientists point out that this ancient ‘Adam’ and ‘Eve’ probably didn’t live near each other, let alone reproduce. The dates provided on both the male and female side are only an estimation. Different DNA samples lead to different estimates of how old our common ancestors really are and only further analyses will help to pinpoint a more precise date range. Variations in results are due to the fact that gene studies always rely on a sample of DNA, which can never provide a complete picture of human history.
Researchers are now working on studies that incorporate more diverse populations and are aiming to narrow the time window to a more precise range.
Top image: Adam and Eve by Jacob Jordaens, 1640s (public domain)