Most recent common ancestor and Mitochondrial Eve

[nobahar]

Hello!

I am trying to piece together an understanding of the two concepts, the most recent common ancestor and Mitochondrial Eve.
I would like to know if there is a distinction between sexes, because it seems as though the most recent common ancestor could be a male, a female, or both (a 'mate for life' pair). This is because a male could have mated with numerous females. If he is the only male to have descendants alive today, then he will be the most recent common MALE ancestor to everyone alive today. But having mated with a number of females, this means that there is no one female of that time same period who is a most recent common FEMALE ancestor. For our Greatⁿ grandfather's Birthday, we will all meet for a big party at the same house, for our Greatⁿ Grandmother's Birthday, we'll be at different places perhaps on different days. Moving backwards to find the common ancestor of those females with whom the male mated, would identify the most recent common FEMALE ancestor of all those alive today. It could of course be the other way round, with one female mating with several males. In this case, the most recent common FEMALE ancestor to everyone alive today would be this female, but the males with whom she mated would not be the most recent common MALE ancestor. We'll all meet for our Great^m Grandmother's birthday, but not all of us will meet for Great^m Grandfather's Birthday. Again, going back to find the common ancestor of the males would identify the most recent common MALE ancestor. Finally, the most recent common ancestors of all of us may have be a conjugally faithful pair, whom we all can call our Great^p grandparents.
Another issue I have is with Mitochondrial Eve. Surely, Mitochondrial Eve is the most recent FEMALE common ancestor? If she wasn’t, then other females would have descendants alive today. Yet Wiki (although I may have misunderstood) seems to suggest that they are not the same thing.

I fear I am completely misguided in my reasoning. I’ll hopefully pop back once I’ve had more time to think about it, but any input would be helpful.
Any help would be much appreciated.
Many thanks.

 

[madcat8000]

Well its important to remember that these are concepts and not absolute truths that can be proven. We can say pretty well that modern humans appeared at a certain range of time and in a certain area. It probably wasnt started by an individual but by a group, as small as a family or as large as a former species with a large range. For whatever reason this group faced pressures that favored members with language abilities, full walking erectness, and a few other things that we consider vital to being "modern humans". Saying it was a singular common ancestor makes it easier for people to understand. In reality, as a group more and more "modern genes" were passed around and "primitive genes" were lost as their owners had fewer friends, mates, and obtained less food. One day in our history a modern human was born but honestly it was a community effort. And he might not have sired all modern humans as the others were mostly modern and so other fully modern humans just emerged spontaneousy. Because of recombination of genes between males and females during reproduction 2 99% modern humans can produce a 100% fully modern human.

Mitochondrial Eve is simular, but again is more a description of time. All the mitochondria in our cells came from this one source. She did exist but all we can say is that all the other early human mitochondrial sources were culled. What it means is that it would take said amount of time for all the variations in mitochondrial genes between humans to have happened.

Also remember that useing DNA to date things requires a number of assumptions and if those assumptions are challenged the numbers might have to be recalculated.

 

[nobahar]

Many thanks for the response madcat8000. I will try to come up with a more thought-out response once I've had time to consider what you have written. I just wanted to remark that I believe that, by the definition (whether, as you say, it is necessarily true for a single individual), Mitochondiral Eve is not the same as the most recent female common ancestor, because Mitochondrial eve is only the female who has an uninterrupted series of female descendants, uniterrputed by males. This does not exclude other females of the same time as Mitochondrial Eve from having 'present day' descendants. Therefore, Mitochondrial Eve is not the most recent female common ancestor.

 

[TechnoPagan]

. . . Mitochondiral Eve is not the same as the most recent female common ancestor, because Mitochondrial eve is only the female who has an uninterrupted series of female descendants, uninterrupted by males. This does not exclude other females of the same time as Mitochondrial Eve from having 'present day' descendants. Therefore, Mitochondrial Eve is not the most recent female common ancestor.

Mitochondria is not passed through males, only females. Sperm contributes no mitochondria, only eggs do. Every person on Earth can be traced directly to Mitochondrial Eve. There are no other surviving mitochondrial lines. She is the most recent female common ancestor.

 

[TechnoPagan]

There was also a Y-chromosomal Adam, who lived about 50,000 to 80,000 years later than Mitochondrial Eve. All male humans inherited the "Y" chromosome from him.

 

[madcat8000]

Well technichly it can be passed from male to child in humans but at least 99.9% of the time its female to child. Personaly I think the issues with the more common mitochondrial recombination makes it a useless point at best. But that's a personal belief.

 

[nobahar]

Mitochondria is not passed through males, only females. Sperm contributes no mitochondria, only eggs do. Every person on Earth can be traced directly to Mitochondrial Eve. There are no other surviving mitochondrial lines. She is the most recent female common ancestor.

Thanks TechnoPagan. Your post implicitly implies that there is a distinction that can be drawn between sexes in terms of most recent common ancestor.
The concept of the most recent common ancestor is confusing - or at least for me it is. It seems that it only has relevance when referring to specific lines. For example, as you corrected my error, Mitochondrial Eve is the most recent female common ancestor (we all call her Greatⁿ Grandmother): she is the female from whom we are all descended but only through a single line (an all female line). Other females will have contributed descendants that are alive today; is it possible for one of them to claim to be related to everyone alive today? Even if it is not through a female, they may still bear some relationship to everyone? In which case, she is also all of our Greatⁿ Grandmother, just through a different line, one that may involve Grandmothers and Grandfathers of various powers of Great. A similar story can be put forward for an all male line, I assume this is Y-Chromosome Adam. I was thinking of the female who can claim to be the ONLY female to have descendants alive today. If the concept of Mitochondrial Eve is true, providing you go back far enough, I do not see why the concept of the 'Mother of Modern Humans' can't also be true. Even if it means going back before anatomicaly modern Humans if necessary. Although I suppose that's kind of a trivial point.
Any further help appreciated. Feel free to correct me!
Many thanks.

 

[nobahar]

Personaly I think the issues with the more common mitochondrial recombination makes it a useless point at best. But that's a personal belief.

Can you elaborate for me?
Thanks in advance.

 

[TechnoPagan]

Well technichly it can be passed from male to child in humans but at least 99.9% of the time its female to child. Personaly I think the issues with the more common mitochondrial recombination makes it a useless point at best. But that's a personal belief.

I'm not sure I'm understanding your post. With mitochondrial DNA (mtDNA) there is no recombination. The mother passes mtDNA to her children intact (excluding mutations). Fathers don't pass on mtDNA at all.

 

[TechnoPagan]

Other females will have contributed descendants that are alive today; is it possible for one of them to claim to be related to everyone alive today?

There are no other, known mitochondrial lines in homo sapiens despite extensive, world-wide testing. It may be that there is some very isolated group in Africa who belong to a different mitochondrial line, but the odds are pretty slim.

 

[nobahar]

There are no other, known mitochondrial lines in homo sapiens despite extensive, world-wide testing. It may be that there is some very isolated group in Africa who belong to a different mitochondrial line, but the odds are pretty slim.

Thats interesting, and certainly adds clarity. If we do not consider the Mitochondrial relationship, I thought that perhaps it is possible for another female to make a claim as being related to everyone alive today. Perhaps Adam's mother would qualify? By virtue of being his mother, she can draw a connection to everyon alive today, not merely a subset.

 

[madcat8000]

Recombination:

http://www.genetics.org/cgi/content/full/159/2/749

http://genomebiology.com/2000/1/1/reports/014

http://hmg.oxfordjournals.org/content/13/24/3171

EVERYWHERE you look mitochondria seem to get to break the rules. This is because they are sooooooooooooo important.

 

[madcat8000]

Paternal inheritnece

http://biology.ucsd.edu/classes/old.web.classes/bimm100.FA04/lecture/Paternal_mtDNA.pdf

Example of a male who inherited 90% of his fathers faulty MTDna, at least in his muscles.

http://en.academic.ru/dic.nsf/enwiki/3086503

Again its extensively rare, but so are people and monies devoted to studying mitochondria so we may be missing alot.

 

[madcat8000]

Another post about this subject

https://www.physicsforums.com/showthread.php?t=25701

It must be remembered that no matter how confined by us they are, mitochondria still have some of their bacterial tricks and have a modicurm of independence because they have their own genes. This is the last place to make assumptions.

 

[TechnoPagan]

Paternal inheritnece

http://biology.ucsd.edu/classes/old.web.classes/bimm100.FA04/lecture/Paternal_mtDNA.pdf

Example of a male who inherited 90% of his fathers faulty MTDna, at least in his muscles.

http://en.academic.ru/dic.nsf/enwiki/3086503

Again its extensively rare, but so are people and monies devoted to studying mitochondria so we may be missing alot.

That's a new one on me.

 

[nobahar]

Thanks for all the information madcat8000. If I get 20 mintues free I'll have a better look!
I assume that the general implication is that the fidelity of mitochondrial transfer is not absolute. This may through a spanner in the works for Mitochondrial Eve, but I was more interested in the details of the concept - how it works, it's theoretical consequences, and any similar concepts that may exist. I suppose using mitochondria to trace the most recent female common ancestor is just a technique, I don't know if this necessarily negates the existence of a most recent female common ancestor.