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The Evils of Inbreeding: A Workaround
05-10-2017, 12:47 PM
Post: #1
The Evils of Inbreeding: A Workaround
There are well known problems with the concept of the entire human race being descended from a single pair of parents. Such intensive inbreeding would lead to serious genetic problems and extinction in short order.

Catholicism allows interpretation of much of the Garden of Eden story as metaphorical and also allows for the physical form of humans being the result of evolution. However, universal descent from Adam cannot be denied because all humans (except two) are born with original sin passed on by the act of procreation. This is spelled out in the Humani Generis encyclical of Pope Pius XII. See especially articles 36-38.

Here is the most pertinent part.

Quote:37. When, however, there is question of another conjectural opinion, namely polygenism, the children of the Church by no means enjoy such liberty. For the faithful cannot embrace that opinion which maintains that either after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all, or that Adam represents a certain number of first parents. Now it is in no way apparent how such an opinion can be reconciled with that which the sources of revealed truth and the documents of the Teaching Authority of the Church propose with regard to original sin, which proceeds from a sin actually committed by an individual Adam and which, through generation, is passed on to all and is in everyone as his own.

An individual Adam is mentioned, but an individual Eve is not. Paul also dwells on the “Sin of Adam” as the source of universal sinfulness. For the original sin concept to work, there must have been one Adam. But how many Eves might there have been? Could there have been a larger pool of DNA available? Maybe much larger? All females endowed with a human soul by an act of special creation of course. All descendants would inherit the ‘Sin of Adam’ and so pass on original sin

Polygamy is all over the Old Testament. Solomon even had 300 wives and 700 concubines. (Although one wonders why he would want a thousand mothers-in-law.) Many ‘Eves’ would fit right in with OT male chauvinism.

Any expert scientists around (nationality unspecified) who could comment on the continuing genetic viability of one male, many females as the origin of a large population?

Wink

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05-10-2017, 01:26 PM (This post was last modified: 05-10-2017 02:00 PM by clarence clutterbuck.)
Post: #2
RE: The Evils of Inbreeding: A Workaround
If more than one mixed gender pair are needed to ensure the continuation of a species, does this mean that several pairs of iguanas must have stowed away on rafts from the South American mainland to found the three species of Galapagos iguanas, and what about Madagascar's Lemurs, which are also thought to have colonized the island by travelling from Africa on rafts after Madagascar had separated from the African mainland? Madagascar's first Lemurs not only prospered but fuelled an adaptive radiation of over 100 related species. What exactly is the number of mixed gender pairs necessary to ensure a species' long-term survival?

More on topic. If God had created further females for Adam to reproduce with, wouldn't he soon have run out of Adam ribs?
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05-10-2017, 01:57 PM
Post: #3
RE: The Evils of Inbreeding: A Workaround
Many Eves does not solve the problem of inbreeding when a few generations later God said "Let's drown 99% of the population" and left us with Noah and his three sons and their wives.

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05-10-2017, 02:06 PM (This post was last modified: 05-10-2017 02:19 PM by Imprecise Interrupt.)
Post: #4
RE: The Evils of Inbreeding: A Workaround
(05-10-2017 01:26 PM)clarence clutterbuck Wrote:  If more than one mixed gender pair are needed to ensure the continuation of a species, does this mean that several pairs of iguanas must have stowed away on rafts from the South American mainland to found the three species of Galapagos iguanas, and what about Madagascar's Lemurs, which are also thought to have colonized the island by travelling from Africa on rafts after Madagascar had separated the African mainland? Lemurs not only prospered but fuelled an adaptive radiation into over 100 related species. What exactly is the number of mixed gender pairs necessary to ensure a species' long-term survival?

More on topic. If God had created further females for Adam to reproduce with, wouldn't he soon have run out of Adam ribs?

I was not defending the 'single pair equals extinction' viewpoint, just importing it from other threads. There is such a thing as inbreeding depression. But whether extinction is inevitable would seem to assume that being homozygous for a recessive trait is necessarily bad. It might be beneficial if it happens to be a good fit when a small population is forced into a new environment, such as being expelled from Eden or sent into the Land of Nod.

Concerning ribs, perhaps some forerunner of this was in operation.

[Image: adams-rib-smoke-house.jpg]
(05-10-2017 01:57 PM)Alexa Wrote:  Many Eves does not solve the problem of inbreeding when a few generations later God said "Let's drown 99% of the population" and left us with Noah and his three sons and their wives.

Of the 8 people on the Ark, 4 (the wives) could have come from very diverse genetic populations. The other 4 (Noah and the sons) would have similar but not identical DNA. Not as much of a problem as a single male, if that is a problem when multiple females are present.

And here I sit so patiently waiting to find out what price
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05-10-2017, 02:57 PM
Post: #5
RE: The Evils of Inbreeding: A Workaround
(05-10-2017 12:47 PM)Imprecise Interrupt Wrote:  There are well known problems with the concept of the entire human race being descended from a single pair of parents. Such intensive inbreeding would lead to serious genetic problems and extinction in short order.

Catholicism allows interpretation of much of the Garden of Eden story as metaphorical and also allows for the physical form of humans being the result of evolution. However, universal descent from Adam cannot be denied because all humans (except two) are born with original sin passed on by the act of procreation. This is spelled out in the Humani Generis encyclical of Pope Pius XII. See especially articles 36-38.

Here is the most pertinent part.

Quote:37. When, however, there is question of another conjectural opinion, namely polygenism, the children of the Church by no means enjoy such liberty. For the faithful cannot embrace that opinion which maintains that either after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all, or that Adam represents a certain number of first parents. Now it is in no way apparent how such an opinion can be reconciled with that which the sources of revealed truth and the documents of the Teaching Authority of the Church propose with regard to original sin, which proceeds from a sin actually committed by an individual Adam and which, through generation, is passed on to all and is in everyone as his own.

An individual Adam is mentioned, but an individual Eve is not. Paul also dwells on the “Sin of Adam” as the source of universal sinfulness. For the original sin concept to work, there must have been one Adam. But how many Eves might there have been? Could there have been a larger pool of DNA available? Maybe much larger? All females endowed with a human soul by an act of special creation of course. All descendants would inherit the ‘Sin of Adam’ and so pass on original sin

Polygamy is all over the Old Testament. Solomon even had 300 wives and 700 concubines. (Although one wonders why he would want a thousand mothers-in-law.) Many ‘Eves’ would fit right in with OT male chauvinism.

Any expert scientists around (nationality unspecified) who could comment on the continuing genetic viability of one male, many females as the origin of a large population?

Wink

Interesting question - could the human race be saved if Adam procreated with x women instead of one? Smile

I think you'll be aware that this is all about (complicated) statistics

Relevant numbers: the number of recessive harmful genes that are passed on,
the number and gender of offspring of A&E or A&xE (xE being the number of "many females") have, to name the two most important.

I think looking at the difference between the two cases works best: in case of A&E all offspring have the same genes, so them procreating with each other, or with A or E creates the worst case inbreeding scenario - many recessive genes being expressed, leading to serious problems: basic genetics calculates 42% of nonviable offspring in the first generation, and quick extinction within a few more.

(interlude: these numbers demonstrate how ridiculous it is to say, as some people have, that "inbreeding is not that bad"). They are correct - it is in fact totally disastrous!

In the second case we have inbreeding between half-brothers/half-sisters (not counting the ones that have a go with Adam!), which dilutes the number of recessive harmful genes to 50%. The harmful genes furthermore need to be paternally sex-linked to have full effect. I think the math at this point is already pretty complicated, so I wouldn't dare venture what the exact "flipping point" could be for x.

My feeling would be that for 2-10 women, extinction is still inevitable, but for higher numbers, statistics, and a lot of offspring, might save the population. Those numbers are partially based on known facts about small inbred populations, with e.g. 20 men and 20 women (that are all partially related), that in the end still all die.


It's btw funny how Christians hammer away about "family values", while inbreeding apparently was part of God's plan from the word go - but he himself nevertheless then continues to condem it in various places in the Bible Big Grin

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05-10-2017, 03:29 PM
Post: #6
RE: The Evils of Inbreeding: A Workaround
(05-10-2017 02:57 PM)Herminator Wrote:  
(05-10-2017 12:47 PM)Imprecise Interrupt Wrote:  There are well known problems with the concept of the entire human race being descended from a single pair of parents. Such intensive inbreeding would lead to serious genetic problems and extinction in short order.

Catholicism allows interpretation of much of the Garden of Eden story as metaphorical and also allows for the physical form of humans being the result of evolution. However, universal descent from Adam cannot be denied because all humans (except two) are born with original sin passed on by the act of procreation. This is spelled out in the Humani Generis encyclical of Pope Pius XII. See especially articles 36-38.

Here is the most pertinent part.

Quote:37. When, however, there is question of another conjectural opinion, namely polygenism, the children of the Church by no means enjoy such liberty. For the faithful cannot embrace that opinion which maintains that either after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all, or that Adam represents a certain number of first parents. Now it is in no way apparent how such an opinion can be reconciled with that which the sources of revealed truth and the documents of the Teaching Authority of the Church propose with regard to original sin, which proceeds from a sin actually committed by an individual Adam and which, through generation, is passed on to all and is in everyone as his own.

An individual Adam is mentioned, but an individual Eve is not. Paul also dwells on the “Sin of Adam” as the source of universal sinfulness. For the original sin concept to work, there must have been one Adam. But how many Eves might there have been? Could there have been a larger pool of DNA available? Maybe much larger? All females endowed with a human soul by an act of special creation of course. All descendants would inherit the ‘Sin of Adam’ and so pass on original sin

Polygamy is all over the Old Testament. Solomon even had 300 wives and 700 concubines. (Although one wonders why he would want a thousand mothers-in-law.) Many ‘Eves’ would fit right in with OT male chauvinism.

Any expert scientists around (nationality unspecified) who could comment on the continuing genetic viability of one male, many females as the origin of a large population?

Wink

Interesting question - could the human race be saved if Adam procreated with x women instead of one? Smile

I think you'll be aware that this is all about (complicated) statistics

Relevant numbers: the number of recessive harmful genes that are passed on,
the number and gender of offspring of A&E or A&xE (xE being the number of "many females") have, to name the two most important.

I think looking at the difference between the two cases works best: in case of A&E all offspring have the same genes, so them procreating with each other, or with A or E creates the worst case inbreeding scenario - many recessive genes being expressed, leading to serious problems: basic genetics calculates 42% of nonviable offspring in the first generation, and quick extinction within a few more.

(interlude: these numbers demonstrate how ridiculous it is to say, as some people have, that "inbreeding is not that bad"). They are correct - it is in fact totally disastrous!

In the second case we have inbreeding between half-brothers/half-sisters (not counting the ones that have a go with Adam!), which dilutes the number of recessive harmful genes to 50%. The harmful genes furthermore need to be paternally sex-linked to have full effect. I think the math at this point is already pretty complicated, so I wouldn't dare venture what the exact "flipping point" could be for x.

My feeling would be that for 2-10 women, extinction is still inevitable, but for higher numbers, statistics, and a lot of offspring, might save the population. Those numbers are partially based on known facts about small inbred populations, with e.g. 20 men and 20 women (that are all partially related), that in the end still all die.


It's btw funny how Christians hammer away about "family values", while inbreeding apparently was part of God's plan from the word go - but he himself nevertheless then continues to condem it in various places in the Bible Big Grin


Homozygous recessive alleles are not necessarily fatal. European royalty is still around. Big Grin Inbreeding is one possible source of speciation. Ref But on the whole inbreeding in a very small population is going to be really problematic. But then maybe Adam had a harem like Solomon. After all it was supposed to be paradise. Tongue

And here I sit so patiently waiting to find out what price
You have to pay to get out of going through all these things twice
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05-10-2017, 04:10 PM (This post was last modified: 05-10-2017 04:12 PM by Herminator.)
Post: #7
RE: The Evils of Inbreeding: A Workaround
(05-10-2017 03:29 PM)Imprecise Interrupt Wrote:  Homozygous recessive alleles are not necessarily fatal.

True, and this why I mentioned the recessive harmful ones. Bunches of them will yield phenotypes that are not harmful at all (e.g. eye color). Still, there's plenty known that are harmful, ranging from leading to debilitating diseases, to lethal stuff.

(05-10-2017 03:29 PM)Imprecise Interrupt Wrote:  Inbreeding is one possible source of speciation. Ref But on the whole inbreeding in a very small population is going to be really problematic.

Very.

I know of these numbers of ca. 40 people for small populations, but I'm sure there must be more more examples and numbers out there. The inbreeding laws are there for a reason!

(05-10-2017 03:29 PM)Imprecise Interrupt Wrote:  But then maybe Adam had a harem like Solomon. After all it was supposed to be paradise. Tongue

Big Grin

I'd like to see some actual calculations (for the number of different women for Adam), but this would be an extremely difficult excercise, simply because of the number of genes to start with...

Intriguing stuff!

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05-10-2017, 05:03 PM (This post was last modified: 05-10-2017 05:06 PM by Alexa.)
Post: #8
RE: The Evils of Inbreeding: A Workaround
(05-10-2017 02:06 PM)Imprecise Interrupt Wrote:  Of the 8 people on the Ark, 4 (the wives) could have come from very diverse genetic populations. The other 4 (Noah and the sons) would have similar but not identical DNA. Not as much of a problem as a single male, if that is a problem when multiple females are present.

Nope. They've calculated the number of people necessary to populate a space colony. I believe the lowest number proposed was 80. And even that is only to sustain the population for about 200 years.

Not to mention that Noah only took two of each animal on the ark, which isn't anywhere near close to enough genetic diversity in animals. And that really depends on what they mean by 'kind'.

I think the required number for humans is either 1000 or 10,000. Else humans would go extinct.

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05-10-2017, 05:39 PM (This post was last modified: 05-10-2017 05:41 PM by Imprecise Interrupt.)
Post: #9
RE: The Evils of Inbreeding: A Workaround
(05-10-2017 05:03 PM)Alexa Wrote:  
(05-10-2017 02:06 PM)Imprecise Interrupt Wrote:  Of the 8 people on the Ark, 4 (the wives) could have come from very diverse genetic populations. The other 4 (Noah and the sons) would have similar but not identical DNA. Not as much of a problem as a single male, if that is a problem when multiple females are present.

Nope. They've calculated the number of people necessary to populate a space colony. I believe the lowest number proposed was 80. And even that is only to sustain the population for about 200 years.

Not to mention that Noah only took two of each animal on the ark, which isn't anywhere near close to enough genetic diversity in animals. And that really depends on what they mean by 'kind'.

I think the required number for humans is either 1000 or 10,000. Else humans would go extinct.

Apparently 27 is a sufficient starting number.

Quote:In 1790 nine of the mutineers from the Bounty, along with the native Tahitian men and women who were with them (six men, eleven women and a baby girl), settled on Pitcairn Island
[…]
By the mid-1850s, the Pitcairn community was outgrowing the island. Its leaders appealed to the British government for assistance, and were offered Norfolk Island. On 3 May 1856, the entire population of 193 people set sail for Norfolk … However, after 18 months on Norfolk, 17 of the Pitcairners decided to return to their home island; five years later another 27 followed.
[…]
The population peaked at 233 in 1937 and has since fallen owing to emigration, primarily to New Zealand.

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

And here I sit so patiently waiting to find out what price
You have to pay to get out of going through all these things twice
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05-11-2017, 12:15 AM
Post: #10
RE: The Evils of Inbreeding: A Workaround
(05-10-2017 05:39 PM)Imprecise Interrupt Wrote:  
(05-10-2017 05:03 PM)Alexa Wrote:  
(05-10-2017 02:06 PM)Imprecise Interrupt Wrote:  Of the 8 people on the Ark, 4 (the wives) could have come from very diverse genetic populations. The other 4 (Noah and the sons) would have similar but not identical DNA. Not as much of a problem as a single male, if that is a problem when multiple females are present.

Nope. They've calculated the number of people necessary to populate a space colony. I believe the lowest number proposed was 80. And even that is only to sustain the population for about 200 years.

Not to mention that Noah only took two of each animal on the ark, which isn't anywhere near close to enough genetic diversity in animals. And that really depends on what they mean by 'kind'.

I think the required number for humans is either 1000 or 10,000. Else humans would go extinct.

Apparently 27 is a sufficient starting number.

Quote:In 1790 nine of the mutineers from the Bounty, along with the native Tahitian men and women who were with them (six men, eleven women and a baby girl), settled on Pitcairn Island
[…]
By the mid-1850s, the Pitcairn community was outgrowing the island. Its leaders appealed to the British government for assistance, and were offered Norfolk Island. On 3 May 1856, the entire population of 193 people set sail for Norfolk … However, after 18 months on Norfolk, 17 of the Pitcairners decided to return to their home island; five years later another 27 followed.
[…]
The population peaked at 233 in 1937 and has since fallen owing to emigration, primarily to New Zealand.

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

There's a difference between a starting number and a total number - the latter is described by the "Population bottleneck" (see Wiki). For the latter 10,000 is the indeed the usual number given.

Apparently Pitcairn was a very "safe" island (no natural disasters, no diseases etc).

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