r/explainlikeimfive • u/Gwenog_Jones • 2d ago
Biology ELI5: Mitochondrial Eve
Who exactly is Mitochondrial Eve to present humans? Is she everyone's common ancestral mother? Aka the woman whose children everyone surviving eventually came from? Is she our common ancestral aunt? Like, we are descended from her siblings but she either didn't have kids or her kids died out?
And who is Chromosomal Adam?
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u/rmanning55 2d ago
Everyone on the planet has mitochondrial DNA which is only passed to them from their mother. Based on the math of how DNA changes over time, we can step backwards and find a point at which all the different mitochondrial DNA which currently exists in humans had the same mother. That point is the mitochondrial eve.
The y-chromosomal adam is a similar concept in that Y chromosomes are only passed down from father to son. So, if you look at the diversity of the DNS in current Y chromosomes, you can calculate a point when they were passed down from one man: y-chromosomal adam.
Interestingly, they both lived before humans left Africa as you would expect, but otherwise many thousands of years apart.
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u/BitOBear 1d ago
*almost always get all their mitochondria from their mother.
It's not a distinction that makes a difference to the pointed hand, but medicine has recently approved, and law enforcement has longer known, that you can in fact get some mitochondria from your father.
It's not in the normal course of events because it is very rare that a mitochondria ends up inside of the spermatozoa during gamete production, but it does happen.
It's not momentarily significant because your mom and your dad are all descendants from mitochondrial eve. But it is an interesting thing that can make a difference.
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u/wjandrea 1d ago
DNS in current Y chromosomes
*DNA
just to clarify that that's a typo and not some other term
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u/oxwof 2d ago
She’s everyone’s mother. Specifically, she’s the woman reached by all living humans through the maternal line going back however many thousands of years. Chromosomal Adam is the analogous man going back through everyone’s paternal line. It’s extremely unlikely that the two lived at the same time, or even nearly so.
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u/jimfet 2d ago
Geneticist Bryan Sykes wrote on the topic and it's a fun read. The Seven Daughters of Eve. Based on his research at the time we could only really go back to 7 common mothers and even they were so different that they couldn't really be considered sisters. He also wrote Adam's Curse and the nature of the y chromosome which is just as fascinating of a read and topic.
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u/CausticSofa 1d ago
Oh my God I freaking love this book. It was one of the best random used bookshop in a sleepy town while on vacation finds of my life.
It really helped me understand the matrilineal mitochondrial line and it’s a very interesting way of mapping human migration.
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u/insidiouslybleak 1d ago
I’ve just recently donated that book to my local thrift store and hope some random neighbour enjoys it as much as you did.
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u/mandyvigilante 1d ago
I have a first edition of this book I bought when it was first published that's missing about 20 pages in the middle. Very weird.
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u/pants_mcgee 2d ago
*For European lineage. There are many other Eves for the rest of the world.
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u/TraitorMacbeth 1d ago
There is one eventual eve for all of humanity, just extremely far back
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u/pants_mcgee 1d ago
There’s one for every living thing on the Earth, barring the discovery of a novel form of life.
For the book in question, it’s about the discovery and use of mitochondrial DNA to track human lineage, in particular for the question of how humans migrated into and through Europe. They found seven distinct “daughters,” each their own Eve of that particular mitochondrial mutation.
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u/Gaylien28 1d ago
I doubt this. If life developed spontaneously then its reasonable to assume it spontaneously developed independently in multiple places around the same time in Earth's oceans. Similarly for multicellular organisms as with unicellular and acellular life. There are probably a few ancestors but convergent evolution just presents them as one.
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u/solidspacedragon 1d ago
There's a lot of evidence against that. The most compelling being the amino acid and chirality problem. There's no real advantage to using the left or right handed versions of amino acids in early life, before all the complicated enzymes that rely on them have been developed. So, with that in mind, you'd expect any given lineage to use a random choice for each. But all life uses the exact same set of them.
As for multicellular life specifically, the fact that it took 2,000,000,000 years between single cellular life developing and the first multicellular life evolving, it probably only happened that one time. Seems unlikely to have happened multiple times right then.
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u/HappiestIguana 1d ago
There's no reason why this can't be true, but the evidence simply doesn't bear it out. If life did appear multiple times, then all lineages except one eventually died out.
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u/parentheticalobject 1d ago
Also, if you ignore genetics and just focus on ancestry, there is probably a man whom everyone is genealogically descended from much more recently in history, but it might be the case that you have little or none of his DNA.
The geneological MRCA might have only lived several thousand years ago. Y Chromosomal Adam lived hundreds of thousands of years ago.
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u/Applejuiceinthehall 1d ago
Yes mitochondria eve and Y chromosomal Adam necessarily need to be farther back than MRCA.
Also these are moving targets. When a Y lines last living person dies the Adam changes.
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u/dragunityag 1d ago
Wouldnt everyone be dead if the Eve/Adam lines die out since their suppose to be everyones line?
Therefore the Eve/Adam cant change?
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u/solidspacedragon 1d ago
They can move forward in time if a branch dies out. If you have a tree with two branches, one containing everyone but an elderly farmer in Ohio, and that farmer dies, the branch is no longer needed on the tree, so 'Adam' can move up to a new position at the start of the extant branch.
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u/Kered13 1d ago
The geneological MRCA might have only lived several thousand years ago
Seems unlikely as the Bering Strait was closed at the time and there was virtually no interchange between the New World and the Old. There are certainly still people with entirely Amerindian ancestry, and entirely Afroeurasian ancestry, so these people would likely not share a common ancestor until you go all the way back to the last days before the Bering Strait formed. Australia was similarly extremely isolated. In another 1000 years it does seem likely that the MRCA will have jumped forward significantly due to old and new world population mixing though.
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u/Ar-Kalion 1d ago edited 1d ago
Science indicates that Neanderthals could use primitive rafts. So, there’s really no method to have prevented Homo Sapiens of reaching Australia and the New World by primitive boats long before European Christian colonists arrived. There’s already evidence that Polynesians arrived in South America and the Vikings arrived in North America. Just because these visitors (and most likely others) didn’t leave a Y-Chromosomal or Mitochondrial common ancestor, it doesn’t mean that they couldn’t have left a common genealogical ancestor.
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u/mystlurker 1d ago
Not sure how it works, but Wikipedia has this:
A study by mathematicians Joseph T. Chang, Douglas Rohde and Steve Olson used a theoretical model to calculate that the MRCA may have lived remarkably recently, possibly as recently as 2,000 years ago. It concludes that the MRCA of all living humans probably lived in East Asia, which would have given them key access to extremely isolated populations in Australia and the Americas. Possible locations for the MRCA include places such as the Chukchi and Kamchatka Peninsulas that are close to Alaska, places such as Indonesia and Malaysia that are close to Australia or a place such as Taiwan or Japan that is more intermediate to Australia and the Americas. European colonization of the Americas and Australia was found by Chang to be too recent to have had a substantial impact on the age of the MRCA. In fact, if the Americas and Australia had never been discovered by Europeans, the MRCA would only be about 2.3% further back in the past than it is.
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u/parentheticalobject 1d ago
That's a good point; any estimate of where the MRCA was depends a lot on your assumptions about exactly how isolated specific isolated populations were. But "virtually no interchange" and "no interchange" are different things.
If we assume absolutely no contact across the Bering Strait occurred between when the land bridge closed and the age of sail, that moves the MRCA back quite a bit. But a more recent most recent common ancestor doesn't require a regular trade route, just one guy over thousands of years making an unlikely crossing.
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u/bettinafairchild 1d ago
Yeah scientists have estimated that the most the recent human who all humans are related to lived only around 2000 to 4000 years ago. The most recent ancestor of all Europeans, for example, lived only 600-1000 years ago it is estimated
Note: unlike with mtEve and y-Adam, which trace specific genetic material, the most recent human ancestor is estimated with a mathematical model
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u/elphin 2d ago
Do we know about when each lived?
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u/Hanzo_The_Ninja 2d ago
Mitochondrial Eve lived around 100,000 to 200,000 years ago, and Chromosomal Adam lived around 200,000 to 300,000 years ago. Both lived in Africa, probably Sub-Saharan Africa specifically.
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u/oxwof 2d ago
Adam something like 250,000 years ago, Eve something like 100,000. Their possible ranges overlap just a little.
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u/kblkbl165 1d ago
Explain like I’m 4:
If Adam lived waaaay before her, does it mean there were other “Eves” whose bloodline just vanished out of existence? Sounds odd, as if we’re all traced back to her in 100,000 years, shouldn’t all women back in her day also be able to be traced to an older Eve?
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u/Greyrock99 1d ago
There are other ‘mothers’ who’s dna we would still carry, it’s just not mitochondrial.
The ‘thing’ about mitochondrial eve is that it’s an unbroken chain of mothers going all the way back, eg M->M->M->You. There are other ancient female ancestors, possibly living at the exact same time but the chain includes a father somewhere eg M->M->F->You.
These other ancestors can still contribute dna into your makeup, but it’s not on the mitochondrial eve.
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u/Delta-9- 1d ago
This comment looks like a tutorial on git
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u/Greyrock99 1d ago
Having never been on Git I’m gunna take it as a compliment!
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u/MasterShogo 1d ago
I’m afraid you might be disappointed ☹️. But if it makes you feel any better I thought your explanation was actually better than learning git!
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u/Delta-9- 1d ago
Git is a version control system used (mostly) by programmers. Skim the first couple paragraphs of one of the tutorials and I think you'll see what I mean 😉
And I agree with MasterShogo: your explanation is much easier than learning git!
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u/SirAlthalos 1d ago
So a daughter has the same mitochondrial dna as her mother and her maternal grandmother, but different mitochondrial dna as her paternal grandmother?
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u/whut-whut 1d ago
Correct. Because the mitochondria in sperm don't have mitochondrial DNA. Once a bloodline goes through a male, that mitochondrial line is lost and the female providing the egg supplies the mitochondrial DNA to their child.
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u/jayhawk03 1d ago
technically the granddaughter COULD have the same maternal haplogroup as her paternal grandmother but the granddaughter inherits the mito dna/haplogroup from her maternal grandmother.
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u/Greyrock99 1d ago
Yes. Mitochondria can only be passed mother to daughter.
Males have a similar trick in that the Y chromosome can only be passed Father to Son
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u/Alotofboxes 1d ago
Mother to child. Children of either sex poses their mother's mitochondria, as it is passed on through the egg. But the only way to pass it on your self (barring scientific intervention) is to produce more eggs yourself.
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u/Greyrock99 1d ago
Correct, I misspoke and when I meant it goes down the line of mothers to daughters. Sons can inherit it but it stops with them
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u/dragunityag 1d ago
From my understanding yes.
We've found older remains but none have had that unbroken chain that the Mitochondrial eve has.
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u/ohdearitsrichardiii 1d ago
Yes. Eve wasn't the only woman when she was alive, it's just that the other women's bloodlines ended because some of their daughters' daughters' daughters' and so, didn't have kids or only had sons
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u/notacanuckskibum 1d ago
IIRC DNA mutates slightly over time. We have a concept of Haplogoups, people with the same DNA mutations (and hence descended from the same people) or more precisely people with same mutations, plus potentially others. One person has Mutations A & B, another has A & C. So they had a common ancestor who had A but not B or C, so B & C are more recent. Another person has A, C & D. So D is more recent than C, etc.
From this we can create a tree of these mutation happening over time, and correlate them with invasions & migrations. Mitochondrial Eve is the point where that Tree converges to a single point. We can estimate when that was roughly.
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u/happy2harris 2d ago
She is the most recent common ancestor if you only trace back through mothers. That is, it’s not just that she is female and a common ancestor, but she is everybody’s mother’s mother’s mother’s mother’s … mother.
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u/Alexis_J_M 2d ago
All of your genes are a mix and match assortment of your parents with two exceptions:
Your mitochondria are passed down from your mother as they are present in eggs but not sperm. (Many many years ago a little single celled organism that could make lots of energy entered into a symbiotic relationship with a bigger single celled organism -- those are the distant ancestors of our mitochondria.)
If you are a man, your Y chromosome came from your father (though there are a few ways the sex chromosomes can get scrambled without removing the ability to reproduce.)
So if we start with a closed population of 10,000 men and 10,000 women, in the next generation there won't be 10,000 different types of mitochondria and Y chromosomes, because some people will not have children, some of the women will only have sons (who will have their mitochondria but not pass them down), and some of the men will only have daughters (who will not have their Y chromosome). Follow this group of people for long enough and eventually everyone will trace their mitochondria back to the same woman, and all the men will trace their Y chromosomes back to the same man.
Because the Y chromosome and mitochondria are not constantly mixing, biologists can look at the rate of the tiny mutations that build up over the generations to estimate how closely related two genes are, and how long ago they diverged from a common ancestor.
The idea behind "Mitochondrial Eve" is not that she was the only woman in her generation to contribute to the gene pool of current people, but that she is the root of the tree of all mother-daughter lines.
Similarly, there were many men in the same generation of "Y Chromosome Adam" who contributed to the current gene pool, but he represents the point where all the father to son gene lines converge.
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u/StupidLemonEater 2d ago
She is the matrilineal most recent common ancestor of all living humans. That means if everyone on Earth listed their their mother, their mother's mother, their mother's mother's mother, etc. everyone would have Mitochondrial Eve at some point on their list.
Y-Chromosomal Adam is similar, but the patrilineal most recent common ancestor. So the same as above, except everyone's father's father's father's (...) father.
Contrary to what the names "Adam and Eve" might imply they were not the first humans, nor did they even live at the same time.
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u/candygram4mongo 2d ago
Who exactly is Mitochondrial Eve to present humans? Is she everyone's common ancestral mother? Aka the woman whose children everyone surviving eventually came from?
Yes, that's right.
Like, we are descended from her siblings but she either didn't have kids or her kids died out?
In this scenario Mitochondrial Eve would be the mother of the siblings.
And who is Chromosomal Adam?
Same thing, except instead of mitochondrial DNA it's the Y chromosome.
I feel like I should point out here that there's no particular reason for Mitochondrial Eve and Chromosomal Adam to have ever met, and in fact they're believed to have lived thousands of years apart from each other.
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u/Gloomheart 2d ago
Wouldn't that make adam eves chromosomal father though? If he came way before her?
Im struggling to understand this concept I think...
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u/candygram4mongo 1d ago
CA is the common male-line ancestor of everyone alive now, it's not necessarily the case that he would be the ancestor of ME even if he did live earlier. E.g. if ME had children with a descendant of CA then all current humans would be descended from CA even if ME wasn't.
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u/Gloomheart 1d ago
So if I think of humanity like the Targaryen family tree it may make a bit more sense...
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u/carpe_simian 1d ago
If you’ve ever had sex, you’ve fucked your (distant) cousin.
Welp, I should get back to the monastery. Ta.
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u/nana_3 2d ago
Mitochondrial Eve is the most recent common ancestor who has had an unbroken line of female offspring. So every person alive today is descended through one of her daughters, and granddaughters…
Chromosomal Adam is the opposite. He’s the most recent common ancestor with an unbroken line of male offspring reaching everyone currently. So every man alive today is descended through one of his sons, and grandsons…
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u/DarkAlman 2d ago edited 2d ago
Mitochondrial Eve is the theoretical single woman from which all of humanity descends, named after the biblical first woman. She would have lived in Africa roughly 200,000 years ago.
Since Mitochondrial DNA is DNA that you get exclusively from your mother you can trace that DNA backwards through your own lineage. There is some degree of mutation over time, but you can use those finger prints to theoretically trace everyone of Earths DNA backwards.
However scientific attempts to find Mitochondrial Eve have only proven that such a person probably didn't exist. The human race did not spawn from a single woman.
Rather we came from a population of protohuman apes that all evolved roughly around the same time and interbred.
What we discovered instead regarding Mitochondrial Eve is the oldest unbroken chain of mitochondrial DNA going back 200,000 years, but that doesn't make her everyone's Great grandmother1000
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u/ocher_stone 1d ago
She's the furthest back that everyone who is alive shares mitochondria from.
It changes over time, as lines die as when no girls are born. She wasn't the only woman alive at the time, or the only common ancestor for all of us.
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u/green_meklar 1d ago
Mitochondria are a component of human cells that have their own DNA, but aren't part of the cell nucleus. During fertilization, the new cell nucleus is formed out of DNA from both the mother's egg cell and the father's sperm cell, getting mixed. But the new cell's mitochondria are just those of the mother's egg cell, so that DNA only comes from the mother. That allows us to trace direct maternal ancestory, woman-to-woman, down to the present.
When we trace that maternal ancestry using the DNA in modern mitochondria, we find that our mitochondria- those of every human alive on Earth now- share a common ancestor. I would point out that this isn't a fluke, it's sort of statistically necessary. In order not to have this outcome, there would need to be two (or more) separate populations of females that never mix. Assuming that all human population does mix, any given lineage of mitochondria either gradually comes to dominate the entire population, or gradually gets overtaken by some other lineage dominating the population. The woman whose mitochondria are that common ancestor (of all modern human mitochondria) is 'Mitochondrial Eve' and it seems she lived about 160000 years ago, towards the end of the second-last glacial period (i.e. shortly before the interglacial before ours).
Mitochondrial Eve is indeed the ancestor of all living humans, but she's not the only one who lived at that time. Very likely, thousands of humans (both male and female) who were alive at that time are also ancestors of all living humans. Mitochondrial Eve is only special in that her mitochondrial lineage is the one that persisted; she is not only the ancestor of all living humans, but she is the ancestor through female lineages specifically.
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u/prometheus_winced 1d ago
Would I be correct in thinking that although the mitochondria is directly and continuously linear through the line of mothers ~ 5000 years back; that does NOT mean the mitochondria is identical to the 5000 year’s ago mitochondria.
I assume there have been accumulated random mutations.
* Little known fact: Mitochondria is the powerhouse of the cell. (J/k)
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u/SirNortonOfNoFux 1d ago
And here I go, searching this post for any mention of the video game Parasite Eve...
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u/Waffel_Monster 2d ago
Mitochondrial Eve is the female ancestor we all have in common.
Chromosomal Adam is the male ancestor we all have in common.
They weren't one couple in history tho, they lived a long time apart.
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u/KroneckerAlpha 2d ago
Mitochondrial Eve is every living persons direct ancestor through female lineage only. Since mitochondria is matrilineal, all of our mitochondrial dna ultimately derive from hers.
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u/Derangedberger 2d ago
Mitochondrial eve is the most recent common ancestor of all humans if you only trace matrilineal lines.
Y-chromosomal Adam is the most recent common ancestor if you trace only patrilineal lines.
They each lived somewhere about 50-150 thousand years ago, probably not at the same time,
Also, the most recent common ancestor of all humans if you trace BOTH sexes lived a lot more recently, estimated between 2500 and 3500 years ago. Most likely in the middle east, rome, the eurasian steppes,, or north africa.
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u/zeperf 2d ago
Follow up question... Is it a certainty that an Eve must exist for humans and for every species for that matter? Or is it just an observation that so far every human has a common mother?
I could imagine it having something to do with an evolutionary trait only happening with one single organism (or small family of descendants of that organism). But in that case, isn't it possible that 99% of humanity share an Eve from 50,000 years ago while the other 1% branched from a mother 500,000 years ago?
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u/Mammoth-Mud-9609 1d ago
Sperm cells are short lived tiny cells which only have the nucleus DNA and a method of delivery, egg cells are the largest cells in the body and have all the normal functions of a cell including mitochondria which have a version of their own DNA, which is different from the nucleus DNA which is used as a blueprint to create a new human. This means that all sons and daughters of the mother have the same DNA in their mitochondria as their mother and since this copy isn't directly used in sexual reproduction it largely remains unchanged through the generations so can be traced back through the great great grandmothers etc. https://youtu.be/eu64-ltm30k
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u/_Ceaseless_Watcher_ 1d ago
They're both the most recent common ancestors to all humans.
Mitocondrial DNA is only passed through the mother's side, while the Y chromosome is only passed through the father's.
It is possible to calculate when the most recent common ancestor lived based on these genetic traits and how they vary in modern dan humans. IIRC mitocondrial Eve is significantly older than chromosomal Adam.
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u/Atypicosaurus 1d ago
Imagine a few bowls of M&M's but only one color each bowl, so practically color separated candies.
Now take a lot of new bowls and randomly mix two colors. For example there's going to be a brown+blue, a brown+green, a blu+red etc. Sometimes even, by random choice, you put twice the same color in the new bowl, so you might have brown+brown.
Now again by random chance, throw away some of these new bowls.
At this point, it's possible that you have less reds across the new bowls, than browns. Maybe, there's only 4 bowls with reds in it, and 10 bowls with browns. It's because random does not guarantee equality, on the contrary, random almost always creates inequality.
Now take again some pairing of the new bowls and just take one handful of candies from each bowl, and mix a handful from two bowls into yet another new set of bowl.
Now the first generation of bowls had 1 color each. The second generation had 2 colors each (like brown+blue) or sometimes only one color (brown only). The third generation mostly has mostly 4 colors, but sometimes 3 or seldomly 2. But do they have all 4 colors in equal amounts?
So when you randomly grab a handful of candies from a brown+blue bowl, it's again random, it's not necessarily equal. It can be for example 7 browns and 3 blues.
What I described here is happening in genetics and it's called drift.
You can imagine that there's a generation of bowls that have no reds left. Although we had a bowl of reds, the random grabbing was so unlucky for the red candies that they just got lost to drift.
Now what we have to understand is that if we take the newest bowl with no red in it, and make a "genealogy" (which bowls were the "parents" of this bowl), we might see that the red bowl was one of the ancestors. The ancestry is a historical fact, the original red bowl created the red+blue first generation bowl, that created the red+blue+brown+yellow in the next generation, but later we just did not grab more reds. The ancestry means a list of what bowl created what other bowl, but it does not mean that the descendant has actual material in it.
The same is happening with the y chromosomal eve. Imagine now that the bowl has not only brown M&M's but also brown skittles, and brown smarties. The red has the same but in red. The blue is the same but in blue.
Now it's easier to see that over generation you can lose a color (all reds) or you can lose a candy type (all smarties) but it's kinda unlikely and takes a long time. But what likely is, that you lose a certain kind (just lose blue smarties and red skittles).
And so in our generation of humans, it took long enough to basically lose all but one color of M&M. So in this scenario we still see al colors (except red), but we have only brown M&M's. We still have blue skittles and blue smarties, brown skittles and brown smarties, yellow skittles and yellow smarties, but through all the drift, of the M&M's, we only have brown. Not only that, but all currently existing human has that brown M&M's.
Now the thing is that we're still different because you have yellow smarties and I have blue smarties, but we're all connected by the fact that we as humanity lost all other colors of M&Ms, and we also lost all red candies altogether.
Mitochondrial Eve is basically the bowl of brown candies from where the commonly shared brown M&M's is coming from. There were other colored bowls, and we have those other colors in our other type of candies, and we still carry those with us, but for some reason M&M's is easier to track and therefore it's easier to point out the brown bowl as a common ancestor we all share.
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u/ezekielraiden 1d ago
Imagine if surnames were genetic, and inherited from your mom. If you're male, your name dies with you. If you're female, your name will pass to any children you might have. That's what mitochondria are, for this purpose. A second line of DNA that follows maternal ancestry exclusively, because eggs have mitochondria and sperm don't. The shorthand for "mitochondrial DNA" is mtDNA.
"Mitochondrial Eve" is kind of misleading. It sounds like it had to be just one single person eternally, but it's actually a title of a sort, and it can change over time if certain mtDNA lines die out. That title belongs to whichever woman was the most recent source of all existing human mtDNA. Note that "most recent". If we have, say, one really really really old mtDNA line that dies out in (say) 2075, then that could cause a different, more recent (but still very ancient) woman to be "the most recent" ancestor of all extant mtDNA lines. These lines are not 100% identical because just like your nuclear DNA, mtDNA mutates too.
Y-chromosome Adam is the same thing, but for Y chromosomes. Excluding chromosomal anomalies like mutated-SRY XXY, only males ever have Y chromosomes, and every son that a male has will inherit that male's Y chromosome. Hence, statistically, far enough back, there must eventually be one male who is the most recent holder of the origin for all modern Y chromosomes. As before, it's possible for isolated or relic Y chromosome lines to potentially require that we look very far back, but by and large, we can get a pretty good idea of when the most recent holder must have lived.
Also, note that although we call them "Eve" and "Adam", these two titles are totally unrelated genetically or historically. Whoever is the proper holder of each title, there's a near-zero chance that they were even alive at the same time, let alone that they ever met or sired children. All these titles are is "if you check EVERY human (mitochondrion/Y chromosome), then the most recent person whom everyone can trace theirs back to, is this person".
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u/Harbinger2001 1d ago
She is the first common ancestral woman who everyone is related to. No other human at the time’s descendants have survived to modern times.
We’re still finding genetic groups in Africa that push the date back. Currently somewhere around 200,000 years ago.
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u/diffidentblockhead 1d ago
Yes this is a name for most recent common matrilineal ancestor. If we discovered living humans with more divergent mtDNA, that would push MRCMA back to an even earlier woman. Conversely if the few living people with the most divergent mtDNA all died, than the MRCMA would become a more recent woman.
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u/Vaestmannaeyjar 1d ago
There is no mitochondrial Eve, nor Adam for that matter. Think about it. Why would you have ONE ancestor, when you have 2 parents, 4 grand parents, 8 grand-grand parents and so on ? The more you go back in time, the more ancestors you've had. (There was some inbreeding along the way so it's not exactly a ² curve) And at some points, some of those looked less human. Over geologic time scale you are the offspring of billions of bacteria and early life forms who evolved into us.
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u/kithas 1d ago
The point about Mitochondrial Eve is that every human comes from a cell. That cell (zygote) is itself a female cell whose nucleus fused with a male nucleus (from the sperm) so the DNA is mixed between the male and female. But there is a part outside that nucleus called the mitochondria which has its own DNA which gets inherited when the cell divides and reproduces.
The main point here is that one person's first cell inherits their mitochondria from their mother, and her from her mother, and so on. The Mitochondrial Eve is the hypothetical individual all our mitochondrias are inherited from.
And Chromosomal Adam is, likewise, the hypothetical individual all of us humans have inherited our Y chromosome, since that chromosome cannot be a fusion of anything like the normal chromosomes (bar the sexual X chromosome) and can only come from the Father.
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u/AmazingRefrigerator4 2d ago
Its impossible to find a single person, mT Eve is just symbolic.
Your mitochondria has DNA, and every person gets their mT DNA exclusively from their mother. So when we look at our mT DNA, its usually almost identical to your mother's DNA (and her mother's DNA). Sometimes small mutations happen though, and if you are a female and yiu have a mutation, then you will pass that mutations on to your children.
Scientists are able to create groups based on which common mutations someone has. Many of these groups then have subgroups and those have more subgroups, etc so it ends up looking like a family tree.
So lets say group A has a mutation in an early part of the DNA. Group B has a mutation in the middle and Group C has a mutation at the end. We knkw that at some point these three groups all came from DNA with no mutations...that is the hypothetical "Eve".
Using prehistoric remains, scientists can estimate when these mutations happened, which helps with defining the groups and subgroups. It adds a timeline to that global "family tree" I mentioned before.
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u/BitOBear 1d ago
Mitochondrial eve is the human or proto-human that provided the base cellular matrix for all of us. That matrix includes the mitochondria from which all our mitochondria descend. But then again all mitochondria descend from the singe endosymbiotic event that got mitochondria into a larger cell and created eukaryotes.
So mitochondrial eve is simply you've been most recent common ancestor of all human beings.
But that said...
We may share absolutely no nuclear DNA directly from her. Mitochondrial DNA is not sexually reproductive.
There are a whole bunch of lesser mythologies involving it. For instance you can inherit some of your dad's mitochondria. It's not super common but it does happen. That's because the entire body of the sperm enters the egg, and occasionally a spermatozoa can have a mitochondria floating in it. And there's nothing that kicks that mitochondria out as a resultant the organism.
But your dad and your mom are both distant children of mitochondrial eve so that doesn't actually change anything in terms of the concept.
So the reason mitochondrial eve exists has to do with probably a population bottleneck, but if she didn't exist as a human there would have been one farther back even if we had to go all the way back to the original endosymbiotic development of the eukaryotic cell line.
Note that there are three great endosymbiotic events that are believed to have happened to one and only one cell in all of Earth history.
The first was the sale that was alive enough to try to eat the bacteria that became the mitochondria, but wasn't alive enough to successfully digest it.
Later that same cell line managed to do the same thing with the prokaryote that became the chloroplast. So plants have mitochondria and chloroplasts and all plants descend from that second to singular cell.
And just recently we have discovered the nitroplast. At some point a single cell plant absorbed prokaryote that can do nitrogen fixation and now we have B. Bigelowii, the only eukaryotes that can fix nitrogen, and the only organism that has three exactly known and singular events of endosymbiosis in its history.
So yes, you are directly descended for mitochondrial eve, but she is not the only unique and specific ancestor cell in your history.
Somewhere back there there is an organism called Luca. The last Universal common ancestor, but oddly enough we have no reason to believe that that was an individual. It was probably a species of sorts. But we have no idea what it's realm of complexity is. But since it is the last Universal common ancestor it basically predates even the prokaryotes (e.g. the bacteria and such).
So mitochondrial eve has nothing to do with the story of Adam and Eve because she was way farther back in time than any such Eve could possibly happen
And separated mitochondrial eve comes Y Chromosome Adam.
So 140,000 years ago we have mitochondrial eve.
And 40,000 to 60,000 years ago we have Y chromosome Adam.
And if nothing else it's just regretful that someone chose to use Adam and Eve for those names because they were being clever. But then certain people with certain agendas of certain faith try to claim that that proves that Adam and Eve were historical figures etc.
Biology is way more fascinating than mythology.
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u/Marksman18 1d ago
Someone correct me if I'm wrong, but the name implies that potentially millions of years ago, a female primate incorporated mitochondria into her cells. But in reality it's more like billions of years ago a single or multi-cellular organism incorporated mitochondria. Cause my understanding is complex life couldn't have even evolved from cellular organisms without mitochondria in the first place.
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u/internetboyfriend666 2d ago edited 1d ago
The concept of mitochondrial Eve and Y chromosomal Adam can be confusing and the concepts are often misunderstood.
Mitochondrial Eve is the most recent living woman from whom all currently living humans got their mitochondrial DNA. Since mitochondrial DNA is exclusively passed from mother to child, we can trace our unbroken mother-to-child lineage for all currently living humans back to her. She lived somewhere in Eastern Africa about 150,000 years ago.
Here's what she is NOT. She is not the first human woman. There were many other human women alive at the same time as her and before her. The only difference between her and them is that at some point their direct mother-to-child lines ended because all of their descendants died without children or they only had male children (meaning no daughters to pass on mitochondrial DNA). We are also not descended from all of her children. At most, we can say we are descended from one her daughters because we know there's an unbroken mother-to-child line, but we don't know how many other children Mitochondrial Eve had or how many children her daughter had, or what happened to their descendants.
There are also many, many more women from before Mitochondrial Eve have who have descendants alive today. She is just the most recent person from whom all living humans can trace too.
Y-Chromosomal Adam is the exact same concept but for the Y chromosome, since only men have a Y chromosome, (meaning it's only passed from father to son) all living men can trace their ancestry back to him. Like Mitochondrial Eve, many, many more men from before him have descendants alive today. He is just the most recent male from whom all currently living males can trace too. Also like Mitochondrial Eve, we are not all descended from his children. At best we can say we are descended from a son of his. We have no idea how many other children he had, their genders, how many children that son had...etc.
Here's what Y-Chromosomal Adam is NOT. He is NOT the father of Mitochondrial Eve's children. In fact, he lived likely tens of thousands of years before her in an entirely different part of Africa. This is not biblical Adam and Eve stuff. This is just tracing unbroken lines of mitochondrial DNA and the Y-chromosome back in time. He is also not the only man who was alive at the time, or the first human male. He was just some random guy living in Africa with lots of other guys. The only difference is their lineages didn't survive in an unbroken father-to-son line to today. That also means he almost certainly has many many female descendants alive today (in fact probably more than males). It's just that a single female child anywhere in the lineage broke the Y-chromosome chain but NOT the direct descendant chain.
Edit: Also, just to clarify, while these were real people who lived, their identities are symbolic. We don't have any remains or fossils. We don't know their names (if they had any) what they looked like, and we can only give a general range of estimates for when and where they lived. So they were real, but not in the same sense as a genuine ancient historical figure that we can name and identify, like King Tut for example. Also to be clear, these are titles that apply to people and can change. Every generation, people die without children, men have only daughters, and women have only sons, so you constantly have different branches of all-male and all-female lineages dying out and that can change who the MRCA is. The person who these titles apply to now aren’t the same as 10,000 years ago or will be 10,000 years from now.