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za419 t1_iv2pszj wrote

Reply to comment by ab2377 in Why don't we have Neandertal mitochondrial DNA? by nodeciapalabras

She's called Mitochondrial Eve. Her male counterpart is Y-chromosome Adam.

The correct way to read this is, all living women have an unbroken daughter-to-mother line with Mitochondrial Eve, and all living men have an unbroken son-to-father line with Y-chromosome Adam.

That doesn't mean there were no other women or men in their time, nor that none of the others reproduced, nor that none of the other's bloodlines survived - just that all of Mitochondrial Eve's female contemporaries' bloodlines either died out or was solely carried by sons at some point, and a similar deal for Y-chromosome Adam.

They also never met. Actually, if I remember correctly, they lived several hundreds of thousands of years apart.

We also don't know anything about the individuals, and there's nothing special about them - if you went back to the time of Mitochondrial Eve (assuming you could nail it down to a specific generation, which I don't think we have with absolute certainty), and found her tribe somehow, you wouldn't be able to tell her apart from the other women. Actually, who she is changes all the time - If a woman who's carrying the last copy of a mitochondrial branch (imagine Eve has two daughters, and one of their female lines has only one surviving woman) dies daughterless (either doesn't have surviving children or only has sons), then the title of Mitochondrial Eve might move down a generation (if Eve had two daughters and one line dies out, then the daughter who's female lines survive is the new Mitochondrial Eve).

It's more of a statistics thing than anything - it's just if you trace back all the women you must eventually find a common mother. That's Mitochondrial Eve.

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Chemiczny_Bogdan t1_iv31t2s wrote

> all living women have an unbroken daughter-to-mother line with Mitochondrial Eve

Since all humans regardless of sex have mitochondrial DNA (unlike a Y chromosome), all living men also descend from the Mitochondrial Eve.

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Lambsio t1_iv3kkmg wrote

What about mitochondrial Eve's mother?

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za419 t1_iv3qa0v wrote

There's no word for her.

But Mitochondrial Eve is the most recent such woman - If her mom had multiple daughters it's entirely possible she used to be Mitochondrial Eve, but no longer is because one of her daughter's female lines was broken.

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ab2377 t1_iv4djzk wrote

quoting @za419: Actually, who she is changes all the time - If a woman who's carrying the last copy of a mitochondrial branch (imagine Eve has two daughters, and one of their female lines has only one surviving woman) dies daughterless (either doesn't have surviving children or only has sons), then the title of Mitochondrial Eve might move down a generation (if Eve had two daughters and one line dies out, then the daughter who's female lines survive is the new Mitochondrial Eve).

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MaineSnowangel t1_iv3uisg wrote

I believe mitochondrial Eve’s mother would be a singular mitochondria outside of a human cell.

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byllz t1_iv3tw9u wrote

Mitochondrial Eve likely hasn't changed in quite a while. With rapid population increases since agriculture became a thing, lines are much less likely to die off.

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za419 t1_iv3yty3 wrote

Ehhhh... Maybe.

Fertility rates among some demographics is dropping pretty quickly, which could easily end a line.

And lines end by chance too - even with an increasing population, an endangered line just needs a few accidents, or a few lesbians, or a few child free daughters, or even just a random generation of sons to come to an end.

Now, most lines that end won't be ancient enough to move mitochondrial eve - since it can only move down if exactly one of her daughters has a surviving female line.

But, the point is that "Mitochondrial Eve" isn't a permanent title, or one specific super important person - it's flexible. Who she is changes with time.

A lot of people overstate the importance of Mitochondrial Eve - not that she isn't important to our development, obviously everyone on earth literally has a part of her in us - but she isn't unique. If you went back in time and shot her, another woman would take her place, and you'd come back to an earth that's probably very different, but probably also is still populated by many humans - And there are probably plenty of humans back then you could have shot and changed history even more.

Indeed, any given woman alive today who has/will have multiple daughters could become mitochondrial eve at some point in the very distant future - It's not impossible, though it's kind of unlikely at this point.

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byllz t1_iv4038c wrote

It isn't just the growth, it is the sheer population. Suppose you had an ancient generation that was down to 2 women with matrilinear descendants. One line accounts for 99.9999% of the current population, and the other the rest. If your world population is 1,000,000, then the likelihood you will have a new Eve pretty soon is high, as there is currently only 1 woman left of the minority line, and the chance of any given woman not having daughters, or her daughters not having daughters is pretty high. But if the world population is 8,000,000,000 then the chance of a new Eve is low any time soon as you would need 8000 such occurrences.

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Ok-disaster2022 t1_iv31q3s wrote

If were going to extend biblical metaphor, it's better to also use the names of Noah and Namaah.

A y chromosomal male is better identified as Noah, whereas a mitochondrial Eve is Eve. After all Noah's sons brought their wives in the genetic bottleneck.

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za419 t1_iv38tsb wrote

Eh, probably.

I think the Bible metaphor sucks because it gives the impression that no one else was around or passed on their genes, and that's very not true. It works on the surface level (in a "everyone's ancestors" sense), but it lends itself to being misunderstood and requiring a huge comment to clarify what it means.

I believe the original name was "lucky mother", which... Lost out for obvious reasons.

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