Mitochondrial Eve

[Hierophant]

Does anyone here have a good understanding of Mitochondrial Eve? I understand the concept, but the mechanics of how one human became the Über matriarch is beyond me. How does all other human lines die out and only one female is able to maintain the human line? Was this really early stage of humanity on the scene, therefore we had a limited amount of humans to deal with. I am struggling to grasp the reality of this concept.

[TheRedneckProfessor]

So, to begin with, let's understand mitochondria.  Mitochondria are the "power houses" of the cell.  They are membrane bound organelles which are responsible for generating the energy which the cell uses for cellular activities.  The energy, in the form of adenosine triphosphate, or ATP, is derived from the sugars and carbohydrates in our diet, which the mitochondria are able to convert into ATP.   

 

Because of the important role they play in cellular function, mitochondria contain their own, separate chromosomes.  The DNA that makes up these chromosomes is generally inherited from the mother.  As a result, your genetic makeup is roughly 51% your mother's DNA, and 49% from dear old dad.

 

https://www.genome.gov/genetics-glossary/Mitochondria

[TheRedneckProfessor]

One prominent hypothesis, based primarily on similarities in mitochondrial DNA worldwide, is that, at some point early in the evolution of modern humans (usually placed at ~200,000 years ago), an event took place in which a single female had multiple daughters, while either the rest of the females had mostly sons or were childless.  Because this single female had a plethora of daughters, her mitochondrial DNA was passed to each of them; and because each daughter was capable herself of producing her own progeny, this same mitochondrial DNA was then passed down to the successive generations, with granddaughters and great-granddaughters also passing it on to their respective offspring. 

 

Thus, it is thought (but not definitively concluded) that the bulk of mitochondrial DNA can be traced back to a single female, known as Mitochondrial Eve.

[TheRedneckProfessor]

https://florida.pbslearningmedia.org/resource/585719bf-a860-4f09-9888-3a68879df132/mitochondrial-eve-and-homo-sapiens-in-africas-great-rift-valley/

[Hierophant]

33 minutes ago, TheRedneckProfessor said:

One prominent hypothesis, based primarily on similarities in mitochondrial DNA worldwide, is that, at some point early in the evolution of modern humans (usually placed at ~200,000 years ago), an event took place in which a single female had multiple daughters, while either the rest of the females had mostly sons or were childless.  Because this single female had a plethora of daughters, her mitochondrial DNA was passed to each of them; and because each daughter was capable herself of producing her own progeny, this same mitochondrial DNA was then passed down to the successive generations, with granddaughters and great-granddaughters also passing it on to their respective offspring. 

 

Thus, it is thought (but not definitively concluded) that the bulk of mitochondrial DNA can be traced back to a single female, known as Mitochondrial Eve.

 

It's this part right here. In what situation does only one female have a bunch of daughters, while everyone else has sons or is childless. What is there 20 people on the planet?

[TheRedneckProfessor]

15 minutes ago, Hierophant said:

 

It's this part right here. In what situation does only one female have a bunch of daughters, while everyone else has sons or is childless. What is there 20 people on the planet?

There would be several possibilities.  It could be that several females all had daughters but for whatever reason only one set survived.  This could have been the result of a plague, some kind of natural disaster, or any number of coincidental circumstances. 

 

Females quite often died during childbirth; and infant mortality would have been quite high.  It should also be noted that modern humans acquired the bulk of our immune system genetics through interbreeding with Neanderthals; so disease among the early modern human species would also have been rife, and with a high mortality rate.

 

Most scientists do seem to posit that, at the time, the modern human species was still quite new and the population was rather small.  As a result, it could have been quite possible that one matriarchal lineage contained enough surviving progeny to affect a large swath of the extant population.  Not too dissimilar from the idea that Ghengis Khan successfully bred with so many women that a large percentage of people today have a bit of his DNA within their genetic makeup. 

[Hierophant]

That does make sense. Thank you for your input.

[pantheory]

2 hours ago, Hierophant said:

That does make sense. Thank you for your input.

 

Yes, I found it an interesting story also based upon my research. The location of her life (Eve) and progeny seems to be from west Africa about 200,000 thousand years ago. This seems to be around the country of Nigeria today. Because of the long history of the genus homo going back maybe 2 million years, there were probably other Mitochondrial Eves before her but maybe none of our species Sapiens. The peoples there must have been warlike to enable their survival and the spread of their genetics. There must have been even a greater number of tribal wars, cannibalism, and rape in those times so for Eve to have had many children, my guess is that she was relatively good looking, strong, and had more than one male partner, either voluntarily or otherwise. From there her genetics seem to have spread east and then north to become a part of the last major migrations out of Africa.    

 

Women who have many children also can retain the ability to continue to have children to a later age. Today that extends naturally up to about age 50, She had to have had many female children. It seems that times then were harsh outside of Africa, the middle of the last ice age 200,000 years ago, whereby those of the genus homo did not fair so well outside of Africa greatly reducing their numbers.  This enabled her genes to spread and have a greater impact when modern humans came back to Europe and Asia about 60,000 years ago. My guess is that her genetics were also very good, meaning she and her female children were probably very strong, healthy, fertile and prolific. When spreading out of Africa her genetics eventually mixed with the Homo-Heidelbergensis ancestors, Neanderthal, and Denisovans that lived outside  of Africa, that all probably descended from the first human migrations out of Africa about 2 million years ago, the Homoerectus,  likely being the first prolific humans of the genus homo in and outside of Africa.

 

https://en.wikipedia.org/wiki/Recent_African_origin_of_modern_humans

 

https://en.wikipedia.org/wiki/Early_human_migrations