Wherefor Insulin

[colubridae]

This is as near as I understand it
(SD = Segregation Distorter)

Segregation distorters (one of a group of genes the prophet Richard calls outlaw genes) distort the otherwise pristine parity of meiosis.

eg
When a male generates sperm (apoptosis and other cellular death excluded) 50% will be X sperm and 50% will be Y sperm.

Segregation distorters are active genes that ‘distort’ the perfect balance of meiosis.

Sex linked Segregation distorters theoretically have the ability to leave offspring of only one sex.

AFAIK some simulations on sex-linked SDs have shown that extinction occurs in 15 or so generations. An evolutionary eye-blink.

AFAIK no sex-linked SDs have been found.

Prof D claims that sperm SDs would have trouble acting because spermatozoa contain no EPR or golgi to enable the genes to act.
Though in my book if the genes act in the early stages of meiosis all the machinery is still available.

He did claim the egg SDs would have the machinery available within the gamete. Though I couldn’t fathom the action that would clip the x1-x2-distortion.


Somatic (non-sex) SDs have been found.

If sex-linked SDs did cause extinction (not just for neands.) the fossil signal would show a preponderance of one sex.
My bet is any disparity large enough to show up in the fossil record would only occur in the last stages of extinction. I think it is a logarithmic process. This may mean that fossil signal rarely exists.

There are many unexplained extinctions.


When we covered meiotic drive on my course it was not a major part, like most students if it wasn’t a major part I practically ignored it. It’s only caught my attention lately.

Unfortunately I can’t remember the god-botherer site which blathered about it either – the link is somewhere in RDF

See if you can come up with the moral problem that I proposed on RDF when this all occurred to me.
The scenarios are similar to the white plague and Children of Men
Might be worth discussing?


If that sounds like gibberish say and I will try to clarify. Though it’s possible it is gibberish.

[colubridae]

This is as near as I understand it
(SD = Segregation Distorter)

Segregation distorters (one of a group of genes the prophet Richard calls outlaw genes) distort the otherwise pristine parity of meiosis.

eg
When a male generates sperm (apoptosis and other cellular death excluded) 50% will be X sperm and 50% will be Y sperm.

Segregation distorters are active genes that ‘distort’ the perfect balance of meiosis.

Sex linked Segregation distorters theoretically have the ability to leave offspring of only one sex.

AFAIK some simulations on sex-linked SDs have shown that extinction occurs in 15 or so generations. An evolutionary eye-blink.

AFAIK no sex-linked SDs have been found.

Prof D claims that sperm SDs would have trouble acting because spermatozoa contain no EPR or golgi to enable the genes to act.
Though in my book if the genes act in the early stages of meiosis all the machinery is still available.

He did claim the egg SDs would have the machinery available within the gamete. Though I couldn’t fathom the action that would clip the x1-x2-distortion.


Somatic (non-sex) SDs have been found.

If sex-linked SDs did cause extinction (not just for neands.) the fossil signal would show a preponderance of one sex.
My bet is any disparity large enough to show up in the fossil record would only occur in the last stages of extinction. I think it is a logarithmic exponential process. This may mean that fossil signal rarely exists.

There are many unexplained extinctions.


When we covered meiotic drive on my course it was not a major part, like most students if it wasn’t a major part I practically ignored it. It’s only caught my attention lately.

Unfortunately I can’t remember the god-botherer site which blathered about it either – the link is somewhere in RDF

See if you can come up with the moral problem that I proposed on RDF when this all occurred to me.
The scenarios are similar to the white plague and Children of Men
Might be worth discussing?


If that sounds like gibberish say and I will try to clarify. Though it’s possible it is gibberish.

Dear parent Colubridae needs to take more care with 'is writting

[mistermack]

While meiotic drive is clearly possible and does happen, you haven't said why you suspect that it happened in the case of the Neanderthals.
From what I've picked up, it seems to be highly unlikely and rare.
Reason 1) I've not come across one mammal species that is confidently claimed to have become extinct through meiotic drive. There are no higher animals on earth at the moment that are in the throes of a meiotic drive extinction event. ( That I know of ). That alone makes it a rare event.

Reason 2) The ancestors of the Neanderthals had survived four billion years of evolution withour a single meiotic drive extinction event affecting them. Otherwise there would have been no Neanderthals.

So the odds I would say are very heavily in favour of something else, and the spread of modern europeans has to be favourite.

I'm not the man for moral debates, I'm afraid. I have the basic instinct to 'do as I would be done by', and that's as far as I go. To me, there is no right and wrong, apart from what we've inherited as social animals, and had handed down by various developments of society.
.

[colubridae]

While meiotic drive is clearly possible and does happen, you haven't said why you suspect that it happened in the case of the Neanderthals.

Absolutely no evidence whatsoever. Pure spitballing as I said. Like farsight’s ‘postulate’ it simply fits some of the observable facts.

Reason 1) I've not come across one mammal species that is confidently claimed to have become extinct through meiotic drive. There are no higher animals on earth at the moment that are in the throes of a meiotic drive extinction event. ( That I know of ). That alone makes it a rare event.

Actually not relevant. Segregation disorders don’t necessarily involve extinction events. There have been bylliuns of extinction events, many of them inexplicable. I have a vague suspicion that they may be difficult to spot.

Reason 2) The ancestors of the Neanderthals had survived four billion years of evolution withour a single meiotic drive extinction event affecting them. Otherwise there would have been no Neanderthals.

Also not relevant. Should an SD extinction event occur, the ancestors would have survived for billions of years. In fact any extinction event (occurring now) would perforce have been preceded by bylliuns and bylliuns of years of survival.

So the odds I would say are very heavily in favour of something else, and the spread of modern europeans has to be favourite.

Quite so. It was SD or not. The trick is to find the evidence.

I'm not the man for moral debates, I'm afraid. I have the basic instinct to 'do as I would be done by', and that's as far as I go. To me, there is no right and wrong, apart from what we've inherited as social animals, and had handed down by various developments of society.
.

Disappointed.


The aspect that struck me was:-

Should such an SD extinction develop, then humans carrying the SD gene ought to be prevented from producing offspring. Yet those carrying the gene would be perfectly healthy and so would their offspring, and their offspring would be fertile.

[mistermack]

It's funny that study has just come out indicating that modern humans carry Neanderthal genes. I always thought it was strange that there was no interbreeding, I thought that if that was truly the case, there would have to have been a striking visual difference between Neanderthals and Humans, as we usually select our mates by sight.
( A beautiful woman could smell like a horse and grunt like a pig, most men would not be deterrred. (enough) ).
If Neanderthal genes are still all around, then they are not really extinct. Or you would have to say that modern humans are also extinct, except maybe in Africa, and we are all hybrids.
But what it would really show, if this study is confirmed, is that Neanderthals never were a distinct species, nor was modern man.

As far as the moral dilemma goes about the SD extinction problem, I really would be the wrong man to answer it.
People are great, children are fantastic, but to me there are just far too many.
So anything that whittled down the size of the human population wouldn't worry me one bit. As long as it was painless and didn't go all the way to total extinction.
We could always keep a reservoir of sperm and eggs that didn't carry the SD gene.
Perhaps they could invent some super-realistic tamagotchi robot that would satisfy the urge to bring up children.

[colubridae]

It's funny that study has just come out indicating that modern humans carry Neanderthal genes. I always thought it was strange that there was no interbreeding, I thought that if that was truly the case, there would have to have been a striking visual difference between Neanderthals and Humans, as we usually select our mates by sight.
( A beautiful woman could smell like a horse and grunt like a pig, most men would not be deterrred. (enough) ).

The theory of interbreeding has been tossed around for years. This is the first hard evidence that I know of.

If Neanderthal genes are still all around, then they are not really extinct. Or you would have to say that modern humans are also extinct, except maybe in Africa, and we are all hybrids.
But what it would really show, if this study is confirmed, is that Neanderthals never were a distinct species, nor was modern man.

Using the concept of species has been a major bugbear in evolution for a long time. There is no valid definition that doesn’t fall down on some score or another. I would avoid using it in all but the loosest possible terms. What you said above is way to firm to allow the use of the term species.

As far as the moral dilemma goes about the SD extinction problem, I really would be the wrong man to answer it.
People are great, children are fantastic, but to me there are just far too many.
So anything that whittled down the size of the human population wouldn't worry me one bit. As long as it was painless and didn't go all the way to total extinction.
We could always keep a reservoir of sperm and eggs that didn't carry the SD gene.
Perhaps they could invent some super-realistic tamagotchi robot that would satisfy the urge to bring up children.

Don’t understand your quote on the tamagotchi?

Forced birth control for individuals producing healthy fertile offspring for the good of the species is the only way to stop sex-linked SD genes.

Forced birth control for individuals producing healthy fertile offspring for the good of the species is the very definition of eugenics.

This is why I think it’s interesting… If anyone else is, be my guest.

[mistermack]

The theory of interbreeding has been tossed around for years. This is the first hard evidence that I know of.

Yes of course it has. The fossils prove they were in the same part of the world simultaneously. They either interbred, or they didn't.
The earlier genetic studies indicated no significant interbreeding. I don't know the details of this study, but I'm assuming it's in greater depth that the previous efforts, I don't hear of anybody rubbishing their conclusions. I took the conclusions of the earlier studies at face value, I don't remember any 'margin of error' being stressed.
As I said, it's hard to imagine what could prevent interbreeding. The only thing that I could imagine was that perhaps the Neanderthals never lost their body hair like modern man did, and the visual difference was enough to deter both parties.
There did not seem to be enough time of seperation for the offspring not to be fertile.

Using the concept of species has been a major bugbear in evolution for a long time. There is no valid definition that doesn’t fall down on some score or another. I would avoid using it in all but the loosest possible terms. What you said above is way to firm to allow the use of the term species.

Maybe, but I'm in good company:

Professor Chris Stringer, of London's Natural History Museum, said the conclusions had come as a surprise to many experts - including him.

"As one of the architects of 'Out of Africa', I have regarded the Neanderthals as representing a separate lineage, and most likely a separate species from Homo sapiens," he explained.

My position too, based on the earlier studies that didn't indicate any significant interbreeding.

Don’t understand your quote on the tamagotchi?

Just my whimsical solution to the emotional problem of the lack of children.

Forced birth control for individuals producing healthy fertile offspring for the good of the species is the very definition of eugenics.

From a practical point of view, I think people would demand a genetic test when getting married, in the same way that HIV tests are becoming the norm in some parts. I think people would find their own solution to this without 'eugenic' legislation. Many couples would prefer sperm or egg donation, rather than have their children grow up with a genetic 'problem'.
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