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Madame Butterfly

X Chromosone

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This article was in the April 17 issue of the Chicago Tribune in the Perspective section, which they subhead as "a weekly journal of commentary, analysis and opinion".

 

I find the information provided interesting and thought it may provide "sparks" for some interesting comments and provide some food for thought.

 

 

 

Women Just Have Something Extra In Their Makeup

 

What makes them so different, so special, so much smarter?

By Ronald Kotulak

 

Click For Spoiler
After identirying all the genes on the female X chromosome, scientists believe they may be on the verge of understanding the behavioral differences between women and men.

 

It's not "sugar and spice" vs. "snails and puppy dog tails."

 

So far they found that women have 200 to 300 more active genes on their 2 X chromosomes compared to men, who only have one X chromosome.

 

Since the X chromosome has something like 3.4 times more genes involved in brain power than any other chromosome, that extra genetic activity may make females more complex, more variable and possibly more adaptable than males.

 

There is also growing evidence that the X chromosome may be a breeding ground for many of the genes that endowed humans with intelligence, giving rise over evolutionary time, some scientists say, to language and culture.

 

These genes, many researchers agree, could hold the explanation for why humans can write novels, travel to the moon and trace the history of the universe back to the Big Bang.

 

Surprisingly, males may be the first to benefit when a new smart gene comes along. But the downside is that males are also much more prone to crash with the new genes, developing a far greater rate of mental retardation than females when genes links to brain function become mutated and malfunction.

 

The female sex chromosome was originally marked with an X because it had long been a mystery.

 

Scientists got their first chance to begin reading the instructions on the X chromosome when researches reported in the March issue of the journal Nature that they had identified all of it's 1,098 genes.

 

Females were thought to use only one of their 2 X chromosomes, the other being inactivated long before birth. Women inherit one X chromosome from each parent, while men inherit X from their mother and a Y from their father.

 

The theory was that with only one active X chromosome, females would be on a level playing field with the single active X chromosome of males.

 

That seemed resonable, especially since the Y chromosome appeared to be a bit player. Researchers headed by David Page of the Massachesettes Institute of Technology's Whitehead Institute deciphered the Y chromosome two years ago, finding it contained only 78 genes. It's claim to fame is the SRY gene, which confers to maleness.

 

Although there had been earlier evidence that a few genes on the inactivated X of women had broken their silence and become active, scientists were stunned to find that as many as 25 percent of the genes on the inactivated chromosome are working, giving women higher doses of many important gene products.

 

One finding put the X chromosome into a class by itself - of the 25 percent of the active genes on the inactivated chromosome, 15 percent are the same for all women, but 10 percent are randomly active. In other words, behavior, if it is linked to the X chromosome, could have a wide variety of outcomes.

 

"It clearly is a surprising observation and one that has some pretty significant ramifications," said Steve Warren, chairman of human genetics at Emory University School of Medicine. "Now there is clear evidence for genetic influences on all kinds of behaviors, particularly behaviors that a sex gender defined."

 

Having significantly more active genes than men may affect women in many ways, perhaps accounting for such things as their greater longevity, the fact that more female babies survive birth, and the lower heart disease rates among women.

 

"Based on what we have seen, women would be somewhat more adaptive than males on average," said Hungtington Willard of Duke University, who along with Laura Carrel of Penn State discovered that large number of functioning genes on the inactivated X chromosome.

 

"The question then is how much more adaptive, and that's where we have to hedge a little bit because we have to do more research."

 

The greater genetic activity of women could also be the key to understanding behavioral differences between the sexes like women's higher level of verbal and social skills and the increased tendency towards spatial skills and aggression in males.

 

"There is a leve of variability in gene expression in women that does not exiist in men that at least makes it plausibile to suggest that behavior patterns may be more variable among women than among men, " Willard said.

 

That variability has come in handy. Some researchers speculate that women had to be more adaptable because they traditionally had to move to a new location in marriage while the husband stayed put.

 

A Controversial Field.

 

Behavior genetics is a bright new field. But it is also controversial. Harvard President Larry Summers, for example, provoked a storm of dissent when he recently suggested that men might be inherently better at math and science than women.

 

What Summers didn't point out was a 2003 sutdy by the Organization for Economic Co-Operation and Development showing that in 43 industrialized countries, women had greater academic achievements at almost every level.

 

Trying to pinpoint the influences that shape behavior is tricky because the roles of genes and culture are intertwined in a symbiotic relationship.

 

"There is this urge to want all differences between males and females to be understood in simple molecular genetic terms on the X chromosome," Paige said.

"Whether the differences are due to genes that escape inactivation is far from obvious. It's one possible interpretation, but it's very far from being proven."

 

Yet it is commonly agreed that women and men are different both physically and mentally. And it has long been know that the female hormone estrogen and the male hormone testosterone play profound roles in orchestrating the different reproductive attributes as well as the wiring of the brain.

 

More recently, neuroscientists discovered that the environment-things like stimulating experiences or severe stress-affect the performance of genes in ways that can build a super-functioning brain or a stunted one.

 

A way to study the genes themselves and how their activity was parceled out between the two sexes even before hormones or the environment kick in has been missing until now.

 

"If you look at the very early stages of development, there are genes that escape inactivation and are being expressed at a time before the sex hormones even get a chance to start playing and these genes get expressed in the brain differently in boys and girls," said Ian W. Craig, chief of molecular genetics at the Institute of Psychiatry, Kings College London.

 

"For thousands of years, males and femals have been under divergent pressures of selection. Males historically have been hunter-gatherers, competing with other males for food, resources and females, demands that would favor the development of traits for aggression, competitiveness, and spatial awareness," Craig said.

 

Female Coping Skills

 

Females, on the other hand, had to cope with child rearing, surviving and remembering all the things necessary to keep a household together, fostering traits for communicative and social skills.

 

In a backhanded compliment to some of these female traits, the 18th Century philosopher Voltaire quipped: "I hate women because they always know where things are."

 

"It is not surprising," Craig said, "that genes on the sex chromosomes should have evolved along divergent paths, influencing sex-typed behavior.This process likely is going on today as gender roles continue to undergo major cultural changes that have transformed society over the last few generations."

 

To bolster his argument, Craig points to a study with 4,000 pairs of idential twins that he and his colleagues conducted. They found in identical female twin pairs, who have the same genes, that their intelligence, verbalization and social skills varied more widely than in male twin pairs.

 

That suggests, he said, that different genes are working on the inactivated chromosome of each member of a female twin pair, providing each twin with a different set of behaviors.

 

Male identical twin pairs tend to have more similar behavioral patterns because they only have one X chromosome.

 

"There's a growing realization that the differences in behavioral tendencies may in many cases be explained by differences in genes expression. We see this in honeybees and other model animal systems," said Gene E. Robinson, director of neuroscience program at the University of Illinois at Urbana-Champaign.

 

Male honeybees have only one set of chromosomes, and their sole job of life is to mate with virgin queens. There are very few males because there's only one queen bee at a time.

 

Female bees have two sets of chromosomes and they do all the work in a hive. The task a female bee performs,-collecting nectar and pollen, caring for baby bees, building honeycombs, laying eggs-is determind by which genes are turned on in the brain, Robinson and his team found.

 

A danger for males

 

For human males, a solitary X chromosome can be dangerous when genes mutate. Malfunctioning genes on the X, for instance, make males more prone to colorblindness, autism and aggression. Women are more protected from these disorders because they have a second X chromosome with a good gene that compensates for the bad one.

 

One of the genes on the X chromosome associated with aggression and antisocial behavior is called monoamine oxidase A or MAOA. Craig's team found that males with a low-functioning MAOA gene behave normally until they are exposed to stress or a poor childhood. Then they are more likely to resort to violence. The MAOA gene is an example of how a mutation on the X chromosome affects males first. Then the MAOA gene goes wrong, males didn't have the same backup as females do with a second healthy gene.

 

Scientists believe that at one time the X and Y chromosomes were alike but began to go their seperate ways about 300 million years ago, when mammals diverged from reptiles. The Y gradually shrank while the X took on important new survival duties. The X got to be a test bed to determine quickly whether mutations are good or bad. Most mutations are harmful and if they are bad enough, the possessors of the deleterious genes die off and the genes become extinct.

 

But good mutations thrive. Since intelligence is such a successful survival skill, for instance, smart genes swiftly spread through the species, driven by the female preference for intelligent males, maintatins Horst Hameister of the University of Ulm, in Germany.

 

If a smart gene arises on a male X chromosome, females will eventually get it through genetic in heritance from their fathers and eventually they may end up having two, on on each of their X chromosome. But the genes will work somewhat differently in women because of the randomness by which they are turned on or off on their inactivated chromosome.

 

It makes for interesting similarities and differences between the sexes.

 

"Males and females are designed to complement each other rather than to compete for every single thing across the gamut of things people can do", Craig said. "The balance of intellectual skills works out pretty evenly at the end of the day."

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Actually the X chromosome is what men and women have in common, the difference is the male Y chromosome, which has alot less genes than an X, and since women have 2 full X's they have more back up genes for faulty ones, that is why men are more likely to be insane, or a genius.

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Actually the X chromosome is what men and women have in common, the difference is the male Y chromosome, which has alot less genes than an X, and since women have 2 full X's they have more back up genes for faulty ones, that is why men are more likely to be insane, or a genius.

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Well, actually, if you read the article you'd see why the sexes differ.

 

The X chromosome in men is mostly if not entirely inactive.

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Actually the X chromosome is what men and women have in common, the difference is the male Y chromosome, which has alot less genes than an X, and since women have 2 full X's they have more back up genes for faulty ones, that is why men are more likely to be insane, or a genius.

319364[/snapback]

 

 

 

Well, actually, if you read the article you'd see why the sexes differ.

 

The X chromosome in men is mostly if not entirely inactive.

319367[/snapback]

 

Actually, according to the article it's the Y chromosome that is the bit player. So if a female had one active and one inactive X - males and females would be on a basically level playing field. Ah, but that second X isn't inactive.

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I think that's open to interpretation UH, as I don't think many men think their Y chromosome is a "bit player" in any way shape or form, especially since it determines their sex. :wink2: <_<

 

I think that struck me again about research involving the human body, is it seems for years the "male" was the norm for science and there wasn't much research done with women. Is there anyone here who does such research and may give a logical explanation as to why this was?

Edited by Madame Butterfly

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Yes UH, I realize that, I had to type it all out because it wasn't on the CT website today.

 

It was supposed to be a small joke. Apparently it wasn't one at all. <_<

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Yes UH, I realize that, I had to type it all out because it wasn't on the CT website today. 

 

It was supposed to be a small joke.  Apparently it wasn't one at all. <_<

319418[/snapback]

 

Ahhh, yes, I see your point.

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I can see why this isn't in a peer-reviewed journal.

 

When they did their 'research', why didn't they look at contemporary hunter-gatherer societies? If they had, they wouldn't have said that men were the hunter-gathers and women were child-rearers.

 

In hunter-gatherer societies, men tend to hunt while women gather. This means that women provide the bulk of day-to-day nutrition as the men don't always hunt and are not always successful when they do. In modern hunter-gatherer societies, both sexes raise children.

 

They're confusing childhood gender training with genetics. Boys show higher spatial awareness because they get Legos, girls don't because they get dolls. I have good spatial skills for that reason, as I got the building toys as well as dolls.

 

Genetics are not responsible for today's gender roles.

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If you read the top section of the column, this was in the perspective column, not in "science" column".

 

Also, they did point out the nuturing vs. hunter gatherers.

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While there is no question that culture does influence gender roles - there is also some evidence that males and females are different regardless of how their parents socialize them.

 

I had dolls when I was a kid but I still had above average math and spatial skills. (or did when I was in school).

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hey, did you guys know that the only people who can watch the lifetime channel are those with the X chromosome?

 

hehe. sorry if i have offended any of you, i just think that women (including me) are genetically programed to watch that.

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Chifire, did you mean "XX" because men also have an X they are "XY".

 

I do hope your comment about Lifetime was a joke.

 

My tagline for lifetime.

Lifetime - the "Network for women who hate men" :dude:

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If you read the top section of the column, this was in the perspective column, not in "science" column".

 

Also, they did point out the nuturing vs. hunter gatherers.

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I'm not certain what you mean, nurturing is something hunter-gatherers do. Hunting and gathering are not male activities, they are done by the entire family group. To say that one sex does both hunting and gathering is inaccurate. A gatherer does not have the time to hunt, and a hunter does not have the energy to gather.

 

This was not in a scientific journal because it has too many assumptions and inaccuracies to get past even one lenient reviewer.

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This was not in a scientific journal because it has too many assumptions and inaccuracies to get past even one lenient reviewer.

320938[/snapback]

 

Apparently this study was published in the journal Nature (which costs to view) and was reported about in several other science news sites.

 

The gist of the story was - that some genes on both of a female's x chromosomes may be active (rather than one being dormant as previously assumed). Are you saying scientist haven't discovered that some genes on the second chromosome are active?

 

I think everything else was identified as speculation - ie the word may was used in nearly every theory indicating they were not purporting to offer fact but merely possibilities for future research.

 

medicinenet

 

nature

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