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LucidElement

Mysterious Extinction

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Mr Walker
15 hours ago, Ozymandias said:

Oh, for God's sake! It is not biologically possible for one pair of adult humans to give rise to the entire human race, never mind the morality of incest.

Fox News? Get a life!!??

That is not necessarily true, although it was not the biblical Adam and Eve involved.

 Mayr’s argument about extreme loss of diversity lost much of its force when population geneticists (M. Nei, T. Maruyama and R. Chakraborty 1975 Evolution, 29(1):1-10) showed that even a bottleneck of a single pair would not lead to massive decreases in genetic diversity, if followed by rapid population growth. When two individuals are taken at random from an existing large population, they will on average carry 75% of its heterozygosity (M. Slatkin and L. Excoffier 2012 Genetics 191:171–181). From a bottleneck of a single fertilised female, if population size doubles every generation, after many generations the population will have over half of the heterozygosity of the population before the bottleneck (Barton and Charlesworth 1984, Ann. Rev. Ecol. Syst. 15:133-64). If population growth is faster than this, the proportion of heterozygosity maintained will be higher. 

https://natureecoevocommunity.nature.com/users/24561-richard-buggs/posts/22075-adam-and-eve-a-tested-hypothesis

 

It is almost scientifically certain that all humans on earth today have one female ancestor in common 

Some scientist with a mischievous sense of humour called her Eve.

https://science.howstuffworks.com/life/evolution/female-ancestor.htm

 

Follow these lineages back far enough and you get to what scientists call the Adam and Eve of genetics. "These are individuals who really lived in the past. There was really some woman at some point in the past who was the common ancestor of all modern mitochondrial DNA and there really was one man who was the common ancestor of all Y-chromosomes," says Jobling. "They didn't necessarily live at the some time - the evidence suggests they didn't - but they were both probably within Africa."

Y-chromosomal Adam probably lived 65,000 years ago, and mitochondrial Eve was around some 150,000 years ago. The people living around the same time as these two individuals would have passed their genes on like Adam and Eve but their Y-chromosome and mitochondrial DNA lines would have eventually died out. "You only need a man who doesn't have any sons or a woman who doesn't have any daughters for one of those lines to die," says Jobling. I have no sisters, so I am the end of the line for my mother's mitochondrial DNA.

https://www.theguardian.com/science/2005/apr/28/evolution.genetics

 

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Doug1029
On 11/27/2018 at 4:15 AM, Ozymandias said:

Oh, for God's sake! It is not biologically possible for one pair of adult humans to give rise to the entire human race, never mind the morality of incest.

Fox News? Get a life!!??

The Pharaohs married their sisters and other close relatives, as did many wealthy men in ancient times and even in China into the 20th century.  This was a practical solution to the problem of support for a woman who had no husband, for whatever reason.  It was a common practice and, apparently, a humane one.  In ancient Jewish society, a woman whose husband died was expected to marry and have children with his brother.  This was to keep the family line going.

Genetic studies have shown that the optimum degree of relatedness for production of healthy children is second cousin - having one great-grandparent in common.  That gives the best compromise against inbreeding, yet still obtaining the benefits of similar genes that lead to genetic compatibility.

A couple I knew in college met and started dating.  They flipped out over each other and were planning to get married when the boy's father and girl's mother took them aside and pointed out that they were half-brother-and-sister.  The marriage was called off.  That's how the affair finally got exposed.  How's that for having "the sins of the father" visited on his progeny?

Whether incest is moral or not depends entirely upon the society you live in and what alternatives that society offers.

Doug

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psyche101
7 hours ago, Doug1o29 said:

The Pharaohs married their sisters and other close relatives, as did many wealthy men in ancient times and even in China into the 20th century.  This was a practical solution to the problem of support for a woman who had no husband, for whatever reason.  It was a common practice and, apparently, a humane one.  In ancient Jewish society, a woman whose husband died was expected to marry and have children with his brother.  This was to keep the family line going.

Genetic studies have shown that the optimum degree of relatedness for production of healthy children is second cousin - having one great-grandparent in common.  That gives the best compromise against inbreeding, yet still obtaining the benefits of similar genes that lead to genetic compatibility.

A couple I knew in college met and started dating.  They flipped out over each other and were planning to get married when the boy's father and girl's mother took them aside and pointed out that they were half-brother-and-sister.  The marriage was called off.  That's how the affair finally got exposed.  How's that for having "the sins of the father" visited on his progeny?

Whether incest is moral or not depends entirely upon the society you live in and what alternatives that society offers.

Doug

The cheetah population sufferers many genetic disabilities due to inbreeding after a population bottleneck. 

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