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While the mammalian Y chromosome (males only) may be much smaller than the X chromosome that predominates in females (males have one X, females two), this males only chromosome is evolving much faster. As a result male primates were found to be evolving faster than females.  (Source:
The Y chromosome is evolving fast to deal with genetic pressures of varying mating habits, such as chimp group mating

Modern biochemistry and genetics is just beginning to unlock the complex secrets of evolution, the process in which organisms change over long periods of time through random genetic variation and selective pressures.  With a handful of genomes sequenced, scientists can now start mining this data to find interesting trends and evidence of the course evolution is taking, particularly in humans.

A provocative and intriguing new study reveals that past thought on the Y chromosome, the chromosome that instructs mammals to develop into males, may be entirely flawed and that the chromosome, previously thought to evolving at a crawl, may in fact be evolving far faster than other chromosomes.  Human females typically have two X chromosomes, while males have an X and a Y chromosome.

It was previously thought that autosomes (non-sex chromosomes) and the X sex chromosome featured greater diversity (faster evolution) than the Y sex chromosome, a smaller chromosome.  According to the new study, led by Jennifer Hughes, a postdoctoral researcher in Whitehead Institute Director David Page’s lab.  The research indicates that primate males may be evolving significantly faster than females.

To determine how fast the Y chromosome was changing, the scientists needed a point to compare our Y chromosomes against.  The human Y chromosome had been comprehensively sequenced by the Page lab and the Genome Center at Washington University in 2003.  A promising target was DNA from chimpanzees -- a close relative of humans on the evolutionary tree.  However, the 2005 sequencing of the chimpanzee genome excluded the Y chromosome, mostly, due to its hundreds of repeating sequences that threw off sequencing techniques at the time.

Undeterred, researchers at the Page lab and Genome Center at Washington University completed sequencing the chimpanzee Y chromosome, using newer techniques.  What was discovered was amazing.  The Y chromosome, thought to be a musty unchanging stretch of genes had changed significantly between humans and apes in terms of structure and content.  Approximately one third to a half of genes found in the human version of the chromosome were lost in the chimp chromosome, since chimps diverged from humans in the evolutionary tree.

Professor David Page compares these changes to a constantly renovated home, stating, "People are living in the house, but there’s always some room that’s being demolished and reconstructed.  And this is not the norm for the genome as a whole."

Wes Warren, Assistant Director of the Washington University Genome Center, another top genetics expert, agrees that the findings are extraordinary, "This work clearly shows that the Y is pretty ingenious at using different tools than the rest of the genome to maintain diversity of genes.  These findings demonstrate that our knowledge of the Y chromosome is still advancing."

One thing that may be driving faster evolution of the male sex chromosome is differing mating habits between species.  Where as humans typically take a single partner during sexual intercourse, numerous chimpanzees often mate with a single female in a short time period.  Males who produce more sperm, or whose sperm is better at impregnating females will have a better chance at beating the other males' sperm and passing on his genes.

To give an idea of just how profound this effect is, the difference between the rest of the human and chimp chromosomes is only 2 percent.  That means that the male sex chromosome is evolving nearly 15 times faster, or more, on average than the female genome.

The Page lab and the Washington University Genome Center are now looking at the Y chromosomes of several other mammals to further determine if this faster rate of male evolution is a characteristic of primates only, or other mammal lines as well. 

The study on the work was published in the prestigious journal Nature, and can be found here.

The research was funded by National Institutes of Health (NIH) and the Howard Hughes Medical Institute (HHMI).

Where as chimps have evolved to cope with the genetic pressures of group sex, human males and females have evolved on a different course.  Recent research indicated that human females are slowly evolving to be shorter and to carry more weight.

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RE: Study based on unproven assumptions
By AntiV6 on 1/14/2010 1:27:37 PM , Rating: 5
This. ^^^

You shouldn't pin a god as the creator of things that humans cannot currently explain. My bio professor mentioned that when humans do things like this, as time goes on and things are discovered that leaves less and less for the god to do.

Also, if you ever took a genetics class(I'm in one currently), or higher level Biology classes(In these too) you'd know that Humans and Chimps are closely related(think Step bro and sis, sort of). Humans did NOT evolve from chimps, they both evolved from a common ancestor.

There are multiple markers that makes it impossible for Chimps/humans/Orangs/etc. not to be related by some unidentified common ancestor.

It's been about a year since I went over evolutionary biology, but these are the things I can remember:
- Humans and Chimps share a high 90's percent of genetic homology. (98.5% sticks out though, not just from the article)
- Thousands of ancient pseudogenes(fossil genes) that are identical in both chimps and humans, in the same exact location.
- A chimp has two more autosomes than humans do, but, if you merge the 12th and 13th(I believe) autosomes of chimps, you have a nearly identical chromosome to a human's number 2 chromosome.
- Ancient Viral DNA is in the exact same places in both humans and chimpanzees(even with the 12/13 chimp chromosome and #2 human chromosome).
-Transposons/retrotransposons, but I wont go into those. :]

There are many other indicators, I just can't think of them off the top of my head for some reason.

I do believe in a god btw. Jus' Sayin'.

RE: Study based on unproven assumptions
By jahwarrior on 1/14/10, Rating: -1
RE: Study based on unproven assumptions
By MozeeToby on 1/14/2010 2:09:46 PM , Rating: 3
Think of God using DNA/RNA as the programming language like a programmer use’s C++, since a common language is used all species or programs will share DNA and may share more or less depending on biological features.

This doesn't do anything to explain a multitude of things that are present in the genetic record, things that evolution does a good job of explaining.

Why do all marsupials (for example) share variations of genes that are more similar than than same gene in other mammals? More generally, why can a scientist predict with good accuracy which animals will have the most similar coding for a protein? Why is it that if I map species by similarity of a protein, that same map is held to if I do the analysis on a different protein?

Being a programmer, I also like to use tech analogies, and the only analogy that I can think of that fits what we see in genetics is a Genetic algorithm (i.e. one that simulate evolution to solve an engineering problem).

RE: Study based on unproven assumptions
By jahwarrior on 1/14/10, Rating: -1
By MozeeToby on 1/14/2010 4:19:57 PM , Rating: 4
The 'Algorithm' in nature that selects who gets to reproduce is called natural selection. In a genetic algorithm, a fitness algorithm is run to determing which parts of the population 'survive' and get to reproduce and which parts don't. The same way that unfit animals (or plants, or bacteria, or any living thing) never get the chance to reproduce, whereas fit animals do.

Honestly, once you admit A) DNA is the instructions for life and B) DNA copying is imprefect, everything else follows from there. Imperfections in the copy will manifest themselves in the child organism. Most imprefections will cause problems, but some small number of them will improve survival chances. The child organism that recieves mutations that improve survival chances are more likely to reproduce.

That's all that evolution is saying, if you can find a flaw in that argument, have at it. But 150 years of research, catologing, and critical thinking haven't been able to.

By Belard on 1/14/2010 3:00:57 PM , Rating: 1
And your "assumption" that because you don't understand something or it conflicts with your religion than actual research or evidence, then it must be false.

And going by your beliefs, if God created Man... he obviously screwed up when he read the manual. Might have been in Chinese.

By AntiV6 on 1/14/2010 3:41:23 PM , Rating: 2
Haha, no Dailytech article would be complete without a reference to Crysis. :P

Firstly, if there were a few common links like I mentioned in between the organisms then I would agree with you that it could be a coincidence that everything could fall into the same categories. But, seeing as how there are thousands upon thousands of coincidences between the two different organisms, it shows that *beyond a reasonable doubt* shows that the two share a common ancestor [Science doesn't prove, heh, almost made that mistake].

Of course that 1-2% difference is enormous; if it wasn't, chimps would either be much more intelligent than they are(some species of chimps have a very crude language) or humans would be much more stupider. :P haha

You can also add the fact that there are thousands of point mutations in the exact same spot on both chimps/humans genomes [and to a lesser degree other animals].

Interesting argument though, nonetheless. :D

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