Why Isn't 'Mitochondrial Eve' 'Y-Chromosomal Adam's' Mom?

[JazzFusion]

Why Isn't 'Mitochondrial Eve' 'Y-Chromosomal Adam's' Mom??

I hope the title explains my question.

I understand that Y-Chromosomal Adam is the most-recent y-chromosomal common ancestor of every living human. I *think* I understand that there may be other recent common male ancestors, but they wouldn't have passed on their Y-chromosomes to every living human without an unbroken patrilineal chain (as required to pass a common y-chromosome?). I get that it has been shown that every human alive today has inherited mitochondrial DNA from Mitochondrial Eve. And I *sorta* get that means that Mitochondrial Eve must be the most-recent female common ancestor for the human population.

So, how come we don't all have common mitochondrial DNA from Y-Chromosomal Adam's mother?

 

[mgb_phys]

Men potentially have more offspring than women.
Women rarely have more than a few surviving children, men can have pretty much unlimited.
Imagine an inhabited desert island where Brad Pitt (or whoever is hunk of today) washes ashore, he could conceivably (sorry) be the father of all the next generations of kids, but they would all have different mothers.
For a particular women to be the mother of everyone would require that all the other womens children die.

 

[D H]

So, how come we don't all have common mitochondrial DNA from Y-Chromosomal Adam's mother?

Why should we? For example, suppose Y-Chromosomal Adam's mother only had sons.

 

[JazzFusion]

...Brad Pitt ...could conceivably (sorry) be the father of all the next generations of kids, but they would all have different mothers.

BUT, they would all have the same grandmother. Therefore, they would all inherit the same mitochondrial DNA from Brad's mom (...or am I missing something?)

Why should we? For example, suppose Y-Chromosomal Adam's mother only had sons.

Maybe this is the part I'm missing. Doesn't mitochondrial DNA pass to all offspring, male or female?

 

[mgb_phys]

Maybe this is the part I'm missing. Doesn't mitochondrial DNA pass to all offspring, male or female?

No, only eggs have mitochondria - so they are passed on (edit "inherited") only through the female line.
That's the whole point of the mitochondrial eve stuff.

(actualy sperm do have a few but they are only little and aren't passed on)

 

[kldickson]

mgb_phys, mitochondrial DNA is passed from mothers to their offspring regardless of the offspring's sex. We all come from eggs and sperm .

 

[kldickson]

Men don't pass mitochondrial DNA.

 

[mgb_phys]

mgb_phys, mitochondrial DNA is passed from mothers to their offspring regardless of the offspring's sex.

But they are only further passed on through daughters - that is the important point the OP was missing.
You get all you mDNA from your mother, your maternal grandmother and so on ...

 

[JazzFusion]

But they are only further passed on through daughters - that is the important point the OP was missing.
You get all you mDNA from your mother, your maternal grandmother and so on ...

This was exactly the part I was missing :shy: Thanks.

Went back to Wikipedia: Mitochondrial DNA comes from the egg portion of the zygote, so all mammals receive mDNA from the female line only. (Technically, would that be all sexually-reproducing species receive mDNA from the female line only?)

OK, if I now understand this, I *think* this means that 'Mitochondrial Eve' is NOT the most-recent female common ancestor (because that could be Y-Chromosomal Adam's mom, or someone even more recent), but she is the most-recent matrilineal common ancestor. Is this correct?

 

[BoomBoom]

So, how come we don't all have common mitochondrial DNA from Y-Chromosomal Adam's mother?

This would only be possible if Eve was Adam's sister.

 

[mgb_phys]

This would only be possible if Eve was Adam's sister.

Or his clone!
Are rib-based stem cells allowed in the bible belt?

 

[mgb_phys]

(Technically, would that be all sexually-reproducing species receive mDNA from the female line only?)

Yes, it's not impossible that there is some species (probably not a mamal) where the sperm has some mDNA that makes it into the egg but I don't know of any.

Adam's mom, or someone even more recent), but she is the most-recent matrilineal common ancestor. Is this correct?

Correct, ancestor is used slightly differently in genetics than in family trees.

Also mitochondrial eve is much older than y-chromosone Adam because of the number of offspring. It takes many generations for chance early deaths and son-only families to end up with a single female ancestor, but it only takes a good looking or powerful chieftain with a roving eye to be Y-chromosone Adam.

 

[JazzFusion]

I just clicked on one of the 'related links' from the bottom of the page:

"Mitochondrial DNA Recombines": https://www.physicsforums.com/showthread.php?t=25701

It appears that enough paternal leakage of mDNA may occur to off-set the previous mDNA clock calculations by some TBD amount. It will be interesting to follow this as it develops!

 

[jamesv87]

Yes, it's not impossible that there is some species (probably not a mamal) where the sperm has some mDNA that makes it into the egg but I don't know of any.

Indeed. There are some species of mussel where mtDNA can be transmitted through the paternal line. There is also a type of algae (genus Chlamydomonas) with two genders, + and -, where both gametes contribute chloroplasts (and chloroplast DNA) to the zygote, which is usually only inherited maternally. The chloroplasts then proceed to attack each other until the ones from the + gender inevitably win. The last special case that I know of is a slime mold with 13 genders arranged in a sort of hierarchy, where mtDNA is always inherited from the "higher" parent.

 

[Danger]

a slime mold with 13 genders

Lucky buggers! I can't even talk W into a 3-way...