Over the past few years, gaining an insight into your genetic heritage has become easily accessible through home-testing kits from companies like AncestryDNAⓇ, My Heritage and 23andMe. While these DNA tests have given millions insight into where their DNA comes from, not many people know much about DNA heritage. Here we’ll talk about the oldest known common genetic ancestor: mitochondrial Eve (mtEve).
DNA (deoxyribonucleic acid) is the key constituent of chromosomes present in the nucleus of most cells. DNA in the mitochondria (commonly coined the powerhouse of the cell due to its involvement in cellular respiration) codes for 37 genes.
Every cell in your body has the same DNA, however, different cells express specific proteins due to differential gene expression. The endosymbiotic theory proposes that mitochondria, as we know it today, developed from the symbiotic relationship with a bacteria consumed by ancient humans that has been retained throughout evolution. Hence, mitochondria's independent genome.
Mitochondrial DNA (mtDNA) is of interest in heritage studies as it is matrilineal (inherited only from the mother) and is believed to be of a different origin from nuclear DNA. MtDNA has been traced back as far as to find the oldest mother in the lineage of modern humans, mtEve.
In anthropogeny, there are multiple theories of human evolution, two of the main theories being the multiregional hypothesis and the “Out of Africa” hypothesis. Both of these theories agree that early life originated from Africa millions of years ago but differ in their explanation of the origin of modern humans.
The multiregional hypothesis proposes that earlier on in evolution, humans moved away from Africa and multiple regions have evolved into modern humans independently - with some interaction with other regions over time. Some scientists defend the multiregional hypothesis with ‘regional variation’ (racial differences) that are present today - suggesting that regional variation came to be due to natural selection within distinct regions.
Although both hypothesis have received academic backing, some would argue that genetic evidence favours the “Out of Africa” hypothesis which suggests that modern humans all originated from mtEve who lived in East Africa. Modern populations all over the world are descendants of mtEve who migrated to various global regions a relatively 'recent' time. Multiple publications have come to the similar conclusion that current human mtDNA originated from a single population in Africa (pictured), dating back to at least 200,000 years ago.
To clarify, mtEve was not the only woman of her time, and she is definitely not the first woman on earth (evidence has been found of human life dating back over 4 billion years ago). This being said, there many questions for historians and scientists alike. For instance, why is it this woman (mtEve) that is mother of modern humans? What genetic traits meant that her offspring is the only existing population left on earth today? Is there a reason that she was living in Eastern Africa? The room for future exploration is vast.
It is mind-blowing to think that it may have been the case that if every person reading this blog post, traced back their family tree for thousands of generations, they'd end up in the same place; mtEve. The study of anthropology continues to unravel the complex tale of human history and shows the power of cross-talk between genetics and history in developing a clearer picture of human evolution.
Below is more information on mtEve:
The Unmasking of Mitochondrial Eve (article) by R Lewin, 1987
The mitochondrial genome: structure, transcription, translation and replication (article) by J-W Taanman, 1999
Mitochondrial DNA and human evolution (article) by B Pakendorf and M Stoneking, 2005
We Travel To Kenya To Learn About The First Woman In History (video) by Ladylike
By Tomi Akingbade, Founder