https://en.wikipedia.org/wiki/Genetic_recombination https://en.wikipedia.org/wiki/Mitochondrial_Eve
See also
Mt-Eve, Y-Adam
URL https://barryhisblog.blogspot.com/p/mt-eve-y-adam.html
Oh dear. We still have creationists who think that the concepts of "mitochondrial Eve" and "Y-chromosome Adam" confirm the Biblical myth of Adam and Eve.
In sexual reproduction, genes "crossover". This means that half of the DNA from each parent goes into the offspring. Think of it as combining two packs of playing cards, taking one of each particular value and suit from one or the other pack, in turn. Repeat this process over multiple generations, with other packs. What are the chances of, say, the queen of hearts and the jack of diamonds being accompanied by other cards from the original packs after, say, 1,000 generations? (I can do the math, but trust me, they are very, very slim.) Most likely, Mt-Eve contributed only her mitochondrial DNA to the current human population, just as Y-Adam likely only contributed his Y-chromosome to all modern males. Of course, their contributions have changed and diverged over the generations, due to mutation, but they are still recognizable as having come from the same original genetic elements. It is overwhelmingly likely that the rest of our DNA came from other individuals' DNA (card packs in my analogy). There is no connection between the genetic Adam and Eve (who likely never met - never even lived in the same place at the same time) and the Biblical ones, other than the words used to denote them.
BTW, the mitochondrial "MRCA" means the Most Recent Common Ancestor (that gave us our mitochondrial DNA), and not any mythical, original woman that we all inherited all our DNA from. She had ancestors too. ;)
Mt-Eve and Y-Adam are connected with the mythical first man and first woman of Hebrew scripture in name only. Mt-Eve is the LAST woman to bequeath her mitochondria to us all, and Y-Adam was the LAST man to bequeath his Y-chromosome to us all. It is very doubtful that they contributed anything else to our genomes, and it is highly doubtful that they ever met, or even lived at the same epoch. All the rest of our DNA comes from other individuals, and there were many of them, no doubt, who pre-dated these two individuals. If they had called them LUMtD (last universal mitochondrial donor) and LUYCD (last universal Y-chromosome donor), it wouldn't have wasted so much time, energy and futile electrons on creationist discussion boards.
https://en.wikipedia.org/wiki/Genetic_recombination https://en.wikipedia.org/wiki/Mitochondrial_Eve
https://www.forbes.com/sites/michaelmarshalleurope/2018/11/26/no-humans-are-probably-not-all-descended-from-a-single-couple-who-lived-200000-years-ago/
https://en.wikipedia.org/wiki/Genetic_recombination https://en.wikipedia.org/wiki/Mitochondrial_Eve
https://www.forbes.com/sites/michaelmarshalleurope/2018/11/26/no-humans-are-probably-not-all-descended-from-a-single-couple-who-lived-200000-years-ago/
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Why do you spend so much time fighting something you don't believe in? If our origins are simply by chance then all of this is meaningless and you're wasting valuable time trying to educate people on something that has no practical application in life. The time they waste teaching evolution in schools should be spent on something valuable like financial literacy.
ReplyDeleteBarry's answer shows a place it can be quite useful. It's also useful in the fields of biology, including medicine.
DeleteFinancial literacy would no doubt be a good thing to know coming out of school. We teach evolution to get scientific literacy.
Origins of genetic diversity which includes humans isn't meaningless to humans. It's also no more "simply by chance" than losing money on slot machines at the casino.
Someone said, "Show me where the evidence suggests all these other people, in the beginning."
ReplyDeleteIt is simple logic. Try to follow. A woman has a baby girl. Her mitochondrial DNA is inherited by the baby. Roughly half of her nuclear DNA is also from her. The other half is from the father. The baby girl grows up and has a baby girl of her own. The new baby inherits the maternal mitochondrial DNA, and a half of her mother's nuclear DNA. (A quarter of her grandmother's nuclear DNA.) Repeat this process for just a few generations, and the maternal-line nuclear DNA becomes negligible, or is lost altogether. But the mitochondrial DNA is still the same. A similar thing happens with the paternal DNA. It's only the Y-chromosome that gets passed down in an undiluted patrilineal succession. The rest of the nuclear DNA gets diluted in the same way as with the matrilineal succession. To claim that there were no other individuals involved is just that - an unsubstantiated claim.