S6.02: Would you Adam and Eve it? In search of our earliest genetic ancestors
Hello, and welcome to Genetics Unzipped - the Genetics Society podcast, with me, Dr Kat Arney. In this episode we’re going back to the very genesis of our species - pun intended - in search of the genetic Adam and Eve. Who were they? When and where did they live? Were there really just two of them? And how should we really be referring to these ancient ancestors anyway?
Then the Lord God formed a man from the dust of the ground and breathed into his nostrils the breath of life, and the man became a living being.
The Lord God said, “It is not good for the man to be alone. I will make a helper suitable for him.”
But for Adam no suitable helper was found. So the Lord God caused the man to fall into a deep sleep; and while he was sleeping, he took one of the man’s ribs and then closed up the place with flesh. Then the Lord God made a woman from the rib he had taken out of the man, and he brought her to the man.
This description of the creation of the first humans - Adam and Eve - from the biblical book of Genesis is a cool story. But in my opinion, the scientific truth about the origins of humans is way cooler - and an awful lot messier.
Humans belong to the primate family, which first split off from other mammals around 85 million years ago. A quick 75 or so million years later, and these proto-primates had diversified into a range of apes, including what we now refer to as hominids, or great apes. This included the ancestors of species like gorillas, chimpanzees, bonobos and orangutans who lived in trees and walked on four legs, and another group who were a bit different. These curious creatures became terrestrial, living on land, not in trees, and were bipedal, meaning they walk on two legs. Their brains also became much larger.
This bunch, collectively known as Homo, is the group that modern humans evolved from. The journey from proto-monkeys to humans was nothing like that image you sometimes see, showing the steps from monkey to caveman to modern human - something we’ve covered in detail back in season 3 when we took a closer look at some icons of evolution. Instead, it was a much more complex, twisted family tree, with plenty of crossing branches and dead ends along the way. There are all kinds of strange ancestors lurking in our human family tree, including Ardipithecus and Australopithecus, along with many that we may never know.
The earliest known ‘proper’ human species, known as Homo habilis, was discovered in 1964, and lived around 2.8 million years ago in what’s now known as Tanzania in Africa. Over the next few million years there’s a bunch of species like Homo erectus, Homo Heidelbergensis and, of course, our most famous cousins the Neanderthals, who managed to get out of Africa and spread through Europe and Asia.
We can date the appearance of the earliest fossils of Homo sapiens - that’s you, that is - to just over 300,000 years ago - a relatively small group of individuals that originated in Africa and stayed there until relatively recently, before venturing out and conquering the world. Woo, go us.
Given the difference between this evolutionary origin story and the biblical one, you might think that the terms ‘Adam and Eve’ have no place in modern science. But you’d be wrong.
The idea that there is some kind of ancient founding father and mother of our species is remarkably sticky. And it’s one that is - kind of - backed up by modern population genetics. By analysing descendants' DNA, specifically Mitochondrial DNA (mtDNA) which is passed down from mothers and Y-chromosome DNA passed down from fathers, geneticists have been able to trace back our ancestry hundreds of thousands of years to the most recent female and male common ancestors from whom they believe all humans alive today are descended from. These individuals have been nick-named Y-chromosomal Adam and Mitochondrial Eve.
According to this theory, all men possess Y chromosomes inherited from Y-chromosomal Adam and all women contain mitochondrial DNA inherited from Mitochondrial Eve. So, does this mean these two people were the first of our species? Well, it’s complicated.
All about (genetic) Eve: the quest to find the female founder of our human species
We find out how researchers are using mitochondrial DNA to find the ‘mother of all mothers’
Origin of man: In search of the original Y chromosomal Adam
Y chromosomes and surnames pass from father to son, shedding light on origins, inheritance and migration.
Upcoming deadlines at the Genetics Society
Before we go, here are some important upcoming dates for your diary.
1st March is the deadline for the Society’s next round of public engagement grants, with small grants up to £1000 and larger grants up to £5000 available to support online or in-person public engagement activities relevant to genetics. It’s a great opportunity to spread the word to the wider world.
The 3rd of March is the deadline for abstract submission for The Genetics Society’s 2023 Spring conference on gene regulatory networks, to be held at St Catherine’s College Oxford on 12th-14th April. Early-bird cheap registration also closes on 6th March, so get your skates on.
And finally, tickets are still available for the upcoming For Your Inspiration event at the Royal Institution in London from 6 to 9pm on 17th March, in partnership with The Genetics Society. Aimed at young people aged 13 and upwards, as well as adults, there will be a stimulating talk as well as hands-on activities with researchers from around the country, showing how they are using cutting edge genetics research to learn more about the amazing diversity of life on our planet. Standard tickets are £16 or £10, £7 for RI members and patrons, and free for RI young members.
That’s all for now. We’ll be back next time taking a look at the latest research investigating public attitudes to genetics.
For more information about this podcast including show notes, transcripts, links, references and everything else head over to geneticsunzipped.com You can find us on Twitter @geneticsunzip and please do take a moment to leave us a rating in the Spotify app or review us on Apple podcasts - it really makes a difference and helps more people discover the show.
This episode of Genetics Unzipped was written and presented by me, Kat Arney, with additional research and scripting by Holly McHugh and Eleanor Bird. It’s a First Create the Media production for The Genetics Society - one of the oldest learned societies dedicated to promoting research, training, teaching and public engagement in all areas of genetics. You can find out more and apply to join at genetics.org.uk. Our theme music was composed by Dan Pollard, and the logo was designed by James Mayall, audio production is by Emma Werner and our producer is Sally Le Page. Thanks for listening, and until next time, goodbye.
Image credits:
Mitochondria with crystalline inclusions, Image courtesy of Mike Kayser (Wellcome Collection)
Normal human male metaphase, Y banding, Image courtesy of the Wessex Reg. Genetics Centre (Wellcome Collection)
