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Biologists Debunk the "Rotting Y Chromosome" Theory
An anonymous reader writes "Biologists have previously predicted that that the male sex-determining Y chromosome, which once carried around 800 genes, like the X, has lost hundreds of them over the past 300 million years, will mutate itself out of existence, leading to the eventual extinction of men. However, researchers of a study published in the latest issue of Nature found evidence to suggest that the Y chromosome will not shed any more of the 19 ancestral genes that it is left with."
It really seems like a non-issue regardless of whether or not the Y chromosome is "rotting." Evolution moves slowly enough that by the time it would become an issue, humans will probably have learned enough about genetics to prevent it from happening if necessary. The other alternative is that we decide it's a good idea and speed the process up by a lot.
But the Y chromosome evolved because sexual reproduction has advantages over asexual reproduction. Until that is nolonger true I can't imagine Y going anywhere.
Suppose that someone inherited from his father an Y-Chromosome without the "Manliness Gene". Then he would not have a functioning reproductive system and leave no offspring. The "Manliness Gene" can be lost by a random mutation, but the mutation will never be carried on to the following generation, unless a new sex-determining mechanism already exists.
In soviet russia the government regulates the companies.
The comments made me think of this: http://www.psy.fsu.edu/~baumeistertice/goodaboutmen.htm . The changing roles of the sexes and modern technology are causing people to honestly ask the question, what are men FOR? As I look back on 50 years of life and 35 years of dating/interacting with females, I wonder too.
If "the right combination" is intelligence + virtually no trace of autism symptoms, then why not just take the intelligence part and leave off the crippling disability? Autism is not a prerequisite to high intelligence. There are plenty of truly brilliant people out there who aren't autistic at all.
I used to work in a school for autistic children. I was just the IT guy, but I was in the classroom at times and saw how hard the kids had to work to grasp things that most toddlers can do intuitively. I think it's unfortunate that when kids like that overcome their illness and do great things, people think "Wow, he sure benefited from those genes" instead of "Wow, that guy must have worked really hard to become so brilliant despite his disability."
Bingo!
Humans would have to evolve a new mechanism of determining sex before the Y chromosome could lose its function.
It's always been obvious that the disappearing Y was bullshit. What we have is a selection pressure that shrinks the Y down to its essential core, which apparently is not much less than the 19 genes and other noncodong DNA it carries in humans.
What is so worrying about a chromosome becoming smaller over millions of years? If any of the genes that were on it were vital to humans, we wouldn't be here (or rather, they wouldn't have disappeared, since their absence would have been selected against). And what's with the extrapolation - can you really take a past evolutionary trend and use it to project future changes?
If that worries you, how about this: Within a much smaller time frame, our fur has disappeared, our bones and skin have become thinner and our brains have grown. If that trend continues, then eventually we'll have no bones or skin, and our brains will be too big for our bodies to carry.
Lack of recombination is generally a Bad Thing, hence no other asymmetric pairs. So the questions are why does the X-Y system lead to asymmetry, and why do we have X-Y rather than a system which allows full symmetry (e.g. temperature dependent sex determination, as in many reptiles)?
While I'm sure it has been thought about, I don't know the answer to the first question. It seems quite viable to have a single sex determining gene (SRY in nearly all mammals) but still have full symmetry and recombination everywhere except in the middle of that particular gene. One possibility is that faulty male-specific genes (other than SRY) would not be selected against so strongly, as half the time they are in a female where the fault has no effect. With asymmetry this is not the case, so long as the gene has migrated to the Y chromosome.
The answer to the second question might simply be contingency of history: if we evolved from temperature-dependent sex determination, but became live-young-bearing-with-regulated-temperature, clearly a new sex determination method is needed, and maybe X-Y (or W-Z) was easier to evolve to than some other environmental selection method. It isn't hard to see how a gene affecting the threshold temperature in a temperature-dependent system could mutate into an XY or WZ system.
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So you're a creationist and someone who doesn't understand what evolution and natural selection are. Natural Selection is one mechanism of evolution, there are others. Evolution is not survival of the fittest as you incorrectly believe. Evolutions is "...any change across successive generations in the heritable characteristics of biological populations." Thus color blindness is inheritable characteristic.
You might want to do some research before posting about things you don't understand.
The problem is you are leaving a critical step out of your analogy. All you're simulating is one generation of random mutation on one single "organism". You're leaving out several crucial steps. Try the same thing with hundreds of the same component. After your "mutation", try "killing off" all the bad designs that come about through outcomes 1 and 2, then creating copies of the ones that survive through 3 and 4, then repeating the process over and over again. If you did, you would find that the overall process will tend towards #4 of improved function, because those are going to be the ones that survive to be copied. If you were a computer programmer, you would call this a "genetic algorithm". Many interesting, functional designs have come about this very trial and error process that you think is impossible.
Your problem is that all you see is random mutation, but conveniently leave out the natural selection half.
Happily, wikipedia provides a great list of GA applications, and one of them looks like it does exactly what you say is impossible.
kurzweil_freak
5th Kyu Genbukan Ninpo/KJJR student
Be the darkness that allows the light to shine.