Death of the Y gene and humanity

F

fedr808

1100101
Valued Senior Member
I'm just bringing this up because i thought maybe you guys would find it interesting.

There is some speculation by geneticists that the human race will die off not because of lack of food or war but because of the death of the Y chromosome. You see, when the paternal and maternal genes come together, they basically trade off data, but only one kind of gene can trade with another of the same kind. If you guys have seen those lists that number our genes and picture them. Those are the genes that will switch off together. A number 5 gene cannot trade with a number 10 gene it will not work.

The problem is that trading genes is essential, if a gene does not trade for long enough genetic defects occur, and these aren't the ones that cause retardation, these are the kind that will kill the embryo before it even forms.

Basically the gene goes rotten and it dies. Now of course all of the genes except for the Y are able to trade off every time so this really never happens.

What would happen is that it is almost like being told a phone number one day and remembering it 5 hours later. Now, trading genes is sort of like you repeating the numbers in your head. But imagine if you never think about the number again which is hard to do. 5 hours later maybe you remember the several digit number, but the problem is that often you will get a number or two switched or replaced with something else. This would be a total disaster to the genes.

Also this deteriotion of lack of trading will only cause problems after what is theoretically several million years.

Now here is the big problem

With two X's that make a female they are able to trade off and switch. The problem with the Y is since it is an XY the Y cannot trade with the X. So what happens is that the Y mutates an incredibly minute amount every several generations.

The fear with geneticists is that if it mutates too much than the chromosome will not be recognized as even a piece of DNA and will be rejected and the embryo will inevitably be female because if there is only one X it will still be a girl.

So the problem is that eventually the Y chromosome will mutate so much it will be rejected by the embryo, and this is a problem.
 
So guys are semi-retarded mutants? Geez that explains everything! What information has been lost through this minute mutation in every generation?
 
nothing. The Y chromosome only carries the thing that makes a male baby. Everything else is on the other 47 chromosomes.
 
Here is some stuff that may interest you:

There has been no significant loss in the Y chromosome in 6 million years

In 2003, Page reported that the modern-day Y has an unusual mechanism to fix about half of its genes and protect them from disappearing. But he said some scientists disagreed with his conclusion. The new paper focuses on a region of the Y chromosome where genes can't be fixed that way.

Researchers compared the human and chimpanzee versions of this region. Humans and chimps have been evolving separately for about 6 million years, so scientists reasoned that the comparisons would reveal genes that have become disabled in one species or the other during that time.

They found five such genes on the chimp chromosome but none on the human chromosome, an imbalance Page called surprising.

"It looks like there has been little if any gene loss in our own species lineage in the last 6 million years," Page said.

That contradicts the idea that the human Y chromosome has continued to lose genes so fast it'll disappear in 10 million years, he said.

"I think we can with confidence dismiss .... the 'imminent demise' theory," Page said.
http://www.livescience.com/health/050901_ap_y_chromosome.html
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The Y chromosome has figured out how to save itself: self love

The report said biologists in the US had made a remarkable discovery: "Denied the benefits of recombining with the X, the Y recombines with itself."

The ultimate guys' night out. Simply put, the Y chromosome figured out a Herculean way to save itself from extinction by making an incredibly difficult hairpin turn and swapping molecular material with itself

http://www.theage.com.au/articles/2003/07/09/1057430271984.html
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There is always a way out:

Plenty of species a lot older than our own are still going, so how is it that they are not vulnerable to extinction by the same process of Y-chromosome decay? They will all eventually face the same challenge and I suspect that many species have already gone under for this very reason. Some, however, have found a way round their death sentence.

One strategy is to recruit genes on other chromosomes to take over the job of male development. It is a race against time. Can a species get all the genes it needs off the Y-chromosome, or recreate them elsewhere, before the chromosome finally vanishes? Always the last gene to go will be SRY, the male master switch itself. We know it is capable of smuggling itself onto another chromosome - the evidence lies in the rare cases of males who have no Y-chromosome.

Lots of species may have tried variations on this theme to avoid extinction, but it seemed that none succeeded until, in 1995, researchers found a mammal that had managed to escape this fate. When they looked at the chromosomes of a small burrowing rodent called the mole vole, Ellobius lutescens, which lives in the foothills of the Caucasus mountains, they discovered that the male voles didn't have a Y-chromosome. Neither, it transpired, did they have a master SRY gene either. This inconspicuous little rodent has managed to activate a gene relay one or two stages down the line from SRY. And only just in time. The mole vole Y-chromosome has now completely disappeared. The vole is now safe from Y-chromosome-driven extinction, the only mammal species known to have succeeded in getting itself out of danger.

http://www.guardian.co.uk/science/2003/aug/28/genetics.genderissues
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So never fear, men will be sticking around for some time yet. :D


PS also, this is a Biology thread. Human Science generally deals with psychology, sociology and anthropology.
 
Umm okay i find that questionable. You cannot recombine one gene without another of the same kind. What you mean is that it can recombine itself. Compare it to buying on ebay, if you buying something from someone is recombining, what you mean is putting up a thing to sell, and then buying it from yourself. It will not do anything at the end of the day.

Simply put, you need two y chromosomes to recombine.
 
The Y chromosome has been around far longer than the 6 million year divergence of apes/humans - all modern placentals have Y chromosomes. It has improved with age.

If a deleterious mutation occurs on a Y chromosome, there is no complimentary chromosome to mask/cover-up for the mistake, and thus the outward expression would be a deleterious male of the species. Deleterious males [ones with obvious defects] do not survive long.

Thus, the Y chromosome will only reproduce/spread with positive mutations, not deleterious ones. Positive mutations also immediately confer added benefit to the male, and that male will thus tend to have more offspring than the other males of the species, thus spreading the positive mutation until it becomes fixed [every male has it] in the species.
 
fedr808 said:
Umm okay i find that questionable. You cannot recombine one gene without another of the same kind. What you mean is that it can recombine itself. Compare it to buying on ebay, if you buying something from someone is recombining, what you mean is putting up a thing to sell, and then buying it from yourself. It will not do anything at the end of the day.

Simply put, you need two y chromosomes to recombine.
Click to expand...

Quite the little skeptic aren't you?

A man always receives an X chromosome from his mother and a Y chromosome from his father. Only the tips of the X and Y chromosomes match to allow them to segregate properly. The middle of the Y chromosome is like no other chromosome. It contains 78 genes, most dedicated to sperm production, but a few for housekeeping functions.

Its unique makeup leaves the Y with no partner to lend good genes. The old theory about the Y chromosome held that this solo performance was sure to be a swan song.

But the complete sequence of the chromosome shows that the Y is in little danger of dying out. Instead, it is its own best match.

"It's so repetitive, it's basically like a hall of mirrors," said Richard Wilson, director of the Washington University Genome Sequencing Center.

The tiny chromosome is full of chemicals arranged like palindromes — words or phrases that read the same way forward or backward. One of the most famous palindromes, "Madam, I'm Adam," pales in comparison to those on the Y chromosome. The largest of the repeated sequences on the Y is 3 million bases long — 1.5 million bases in each direction, differing by only one base, or letter, in 10,000, Wilson said.

Such sequences pair up, creating a hairpin curve in the chromosome. A gene on one side of the palindrome can repair damage to its twin on the other half of the hairpin. The self-repair mechanism keeps the Y from degrading into the genetic junk pile that many scientists thought it was.
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http://community.seattletimes.nwsource.com/archive/?date=20030619&slug=chromo190


The flip side:

But the Y chromosome's reflective nature also could be a downfall, the researchers admit.

"The hall of mirrors is also fragile, and the Y is easily broken," Page said.

Repair machinery within the cell may snip off the hairpin structures in an effort to get rid of extra DNA, or the good copy of a gene may convert to the mutant form, inactivating the gene. Deletions on the Y chromosome are the most common cause of male infertility, Page said.
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The only worry is that eventually, fewer and fewer Y chromosomes will work. They all become defective at some time, some before others. Yes we do have this problem but the arguement is that it is replaced. Imagine if there are 100,000 Y chromosomes out there, now by now maybe 1,000 have died because of this. Yes they will be replaced by more humans. The problem is that now we only have 99,000. The worry is that after a while every one will eventually die off.

Also Y chromosomes cannot recombine with themselves it is impossible. You need two chromosomes of the same kind to recombine together. If there is an XY than where is the second y?

Also, yes all animals have the Y chromosomes. But each time a new species forms the Y chromosome is essentially reset and is 100% healthy again. for humans this is when we became a distinct species from chimps.

Here's an analogy. Imagine if you wrote a binary code with a certain pattern every 7 numbers. lets say, 1000001, this is a bit of the gene, and you repeated it over and over on a sheet of papaer and printed it. What should happen when it recombines, one rectangle of that 7 digit code should get cut off of sheet a, and then should be traded with a different 7-digit code on sheet b, lets say 1000011. That way they have recombined and each sheet is different from before. What you are suggesting is taking sheet a cutting out TWO rectangles and swapping them. Absolutely nothing happens, you have the same code as before. You need two genes/ sheets of paper to recombine.
 
I think we have another ten million years before we have to worry about this. If we don't destroy ourselves before then.
 
Deletions on the Y chromosome are the most common cause of male infertility, Page said.
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At least such harmful deletions won't be able to propagate further, which I now notice is similar to what Walter has said.
 
What i meant is that it is not like retardation where if the person never reproduces the gene never gets passed on and theoretically the retardation would die out. The genetic problem is in every single male in the world and is just a ticking time bomb. It doesnt matter if the bomb goes off in a male and he becomes infertile, because every other Y chromosome will do it eventually.
 
I'm sure that's incorrect. What mechanism would cause the cell to not recognize DNA as DNA, as stated in your first post? And I was responding to a very specific line from one of SAM's links; the one I quoted, in fact. I was not responding to your opening comments.
 
It recognizes it as DNA it does not know what to do with it. Like if you put a pig dna chromosome with a human DNA chromosome in a human egg. They would not recombine and join because they would not recognize each other. Each species has certain genetic key that when put together the genes recognize each other and recombine, sort of like a fail safe.

The worry is that the slow mutation of the Y chromosome will mutate this key and the other chromosome will not recognize and reject it.
 
>.> basically a human chromosome can only trade with a human chromosome. There is a code in our genes like a password that tells a chromosome that it can bond with the other chromosome. The fear is that this code may get screwed up in the Y chromosome and it will no longer be recognized and it will not join with the X
 
Still does not make sense. I would recommend some reading up on "recombination" for starters. Also DNA is DNA. There is chemically no difference between bacterial, human or pig DNA.
 
>.>

Duh.

But there is a difference between the DNA in humans and chimps. If you impregnated a human egg with chimp sperm. You wouldn't have a half and half. The egg would reject the DNA.

That's what i mean by rejected.

Human DNA will only bond to Human DNA, END OF STORY.
 
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