Hey dudes, my (XX) female coworker said, "The (Xy) Male is the Weaker Sex?????"

  • twonutbuster

    Posts: 96

    Dec 14, 2008 1:15 PM GMT
    She said in a recent study, the tiny Y chromosome, is dying in a guys nutz, and XX chromosome will soon take over the world.... WTF!!!!

    Please tell me this isn't true???????

    twonutbuster
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    Dec 14, 2008 1:27 PM GMT
    the male population is dying out... the male population is shrinking.

    its believed that environmental issues are causing the male species is slowly disappearing.

    but women wont take over the world.. they forget that they need men as much as men need women.
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    Dec 14, 2008 1:34 PM GMT
    Studies have demonstrated that its the opposite, every year there are more born boys than girls.... and not because I say so, here is my source:

    http://www.scienceblog.com/cms/boy-or-girl-it%E2%80%99s-fathers-genes-17986.html
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    Dec 14, 2008 2:16 PM GMT
    just tell her that's because women are genetically evil and always will be...and go about your day.


    LOL
  • coolarmydude

    Posts: 9190

    Dec 14, 2008 5:08 PM GMT
    Give her a pearl necklace! That will shut her up.
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    Dec 14, 2008 5:13 PM GMT
    Actually I heard that as well... somethign that has to do with genetics and evolution. Too lazy right now to research it since i'm in a blogging fight with local fundamentalists on my newspaper's website. Sorry
  • coolarmydude

    Posts: 9190

    Dec 14, 2008 5:15 PM GMT
    Be careful. It's Sunday....their strongest day of the week.
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    Dec 14, 2008 5:34 PM GMT
    coolarmydude saidBe careful. It's Sunday....their strongest day of the week.


    I'm doing well:

    http://morningsentinel.mainetoday.com/commentsCMN.html?id=5710002&sec=news/local&com_sent=1

    Anyways... back to female dominace!

    Creatures of the phyla Rotifera & Arthropoda can reproduce via Parthenogensis: Unfertilized eggs becoming new individuals
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    Dec 14, 2008 8:46 PM GMT
    At least we don't get periods.... ; ) Still plenty of us to look at!
  • joeindallas

    Posts: 484

    Dec 14, 2008 8:58 PM GMT
    She may be right. Genetically males are victims to many illnesses that women are not. Hemophilia and color blindness are the most common. I have been told 80% of carrier based illlesses are targeted men not women.Since WW2 we have been used tons ofd pestisides that are estogren based this has been getting into the food supply and reeking havoc with the traditional ratrio of Males to Females which had been 104 mlaes at birth to every 100 females,
  • MSUBioNerd

    Posts: 1813

    Dec 14, 2008 9:24 PM GMT
    I'd need a reference to whatever study she claims to be talking about, but I'm betting there was a good deal of misreporting and misunderstanding going on here.

    This needs a bit of terminology, so bear with me. A gene is generally just a genetic location. An allele is a specific copy of a gene. In the ABO blood group, for instance, there's one gene with three alleles: A, B, and O, and it's the combination of which 2 of these alleles you have that eventually determine if your blood type is A, B, O, or AB. Alleles are arranged into chromosomes, which are just large bodies of genetic material. The vast majority of human body cells have 46 chromosomes, which are arranged in pairs. 22 of these pairs are no different between the sexes; the final pair consists of either two X chromosomes if female, or an X and a Y if male.

    In normal chromosome pairs, while you get one from your father and one from your mother, the alleles you have on the chromosome 3 you got from your father, for instance, probably do not exactly match either one of his two copies of chromosome 3. He might have had one chromosome have alleles A-B-C-D-E while the other had a-b-c-d-e, and the chromosome you got from him was A-B-c-d-e. This is because in producing sperm or egg cells, a process called recombination occurs. Essentially, recombination makes a new chromosome by tracing along one copy of an existing one for a while, then switching over to the corresponding part of the other copy. More than one recombination can happen per chromosome. As a result of recombination, genes that are far apart from each other on a chromosome don't tend to have specific alleles staying together, while genes that are very close to each other tend to be inherited as a set.

    Evolutionarily, the X and Y chromosomes used to be just another pair of chromosomes. In so happened that a gene which turns the genetic switch in sex determination landed on the chromosome that was to become the Y--the sry region on the Y chromosome is what causes you to be male, and if it were inactivated early in your development you would be female, as mammals default to female. From that point onward, there was an evolutionary pressure to put other genes that would only be expressed in males near the sry region on the developing Y chromosome, so they wouldn't be lost in recombination. On the other hand, anything needed by both men and women would tend to move off of the Y chromosome and either onto a normal pair, or onto the X chromosome, as both men and women have at least one X and all of the normal pairs. As this happened, recombination between the X and the Y was suppressed, as the two chromosomes stopped recognizing each other as being just a different version of each other. As a consequence, the Y chromosome is now much, much smaller than the X chromosome, and there are very few genes on it, almost all of which have specifically to do with being male. Similar patterns have been observed in other organisms which have different sex chromosomes than mammals--birds have the ZW pair, in which males are ZZ and females are ZW, and the W chromosome is smaller and has fewer genes than the Z chromosome.

    That being said, once the Y chromosome's genes all have to do with being male, and are useful in males, there is no further evolutionary pressure for the chromosome to shrink further, and certainly no pressure for it to disappear entirely. Without massive changes, a mammal that lost all of the Y chromosomes in its population would also lose all of its males and go extinct because no new offspring would be born.
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    Dec 14, 2008 9:43 PM GMT
    twonutbuster saidShe said in a recent study, the tiny Y chromosome, is dying in a guys nutz, and XX chromosome will soon take over the world.... WTF!!!!

    Please tell me this isn't true???????

    twonutbuster


    Tell her that this may be true, but because she is a female she can't post in RJ.
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    Dec 14, 2008 9:46 PM GMT
    Thanks MSUBioNerd for outlining the presence of genes and chromosomes and setting up the terminology. Do you know of any cases of species going extinct from losing all of a specific chromosome or gene? Just curious.
  • OptimusMatt

    Posts: 1124

    Dec 14, 2008 9:59 PM GMT
    joeindallas saidShe may be right. Genetically males are victims to many illnesses that women are not. Hemophilia and color blindness are the most common. I have been told 80% of carrier based illlesses are targeted men not women.Since WW2 we have been used tons ofd pestisides that are estogren based this has been getting into the food supply and reeking havoc with the traditional ratrio of Males to Females which had been 104 mlaes at birth to every 100 females,


    Actually, the male Y chromosome doesn't code for a whole lot - its REALLY small. A good chunk of problems actually arise in the faulty X chromosome which has no 'real' homologous counterpart and therefore has its 'faulty' genes expressed. So really - its a female problem. Again.

    Christ, first original sin, now this...
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    Dec 14, 2008 10:47 PM GMT
    That's OK. I'm still glad I'm a guy.

    (Also remind your friend of her remark the next time she needs something moved LOL)
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    Dec 14, 2008 11:31 PM GMT
    MSUBioNerd saidAs a consequence, the Y chromosome is now much, much smaller than the X chromosome, and there are very few genes on it, almost all of which have specifically to do with being male. Similar patterns have been observed in other organisms which have different sex chromosomes than mammals--birds have the ZW pair, in which males are ZZ and females are ZW, and the W chromosome is smaller and has fewer genes than the Z chromosome.


    Very interesting. icon_biggrin.gif *laps it up*

    Okay some questions, if I may. When did sexual dimorphism start to happen anyway and why?

    Also why do birds and reptiles have ZZ as males and ZW as females, which asides from letting them be theoretically capable of parthenogenesis, also would seem to imply that for them males are the default gender. I always thought females were the default gender of everything since only they have the capability of reproduction. :/
  • OptimusMatt

    Posts: 1124

    Dec 14, 2008 11:44 PM GMT
    Sedative said
    MSUBioNerd saidAs a consequence, the Y chromosome is now much, much smaller than the X chromosome, and there are very few genes on it, almost all of which have specifically to do with being male. Similar patterns have been observed in other organisms which have different sex chromosomes than mammals--birds have the ZW pair, in which males are ZZ and females are ZW, and the W chromosome is smaller and has fewer genes than the Z chromosome.


    Very interesting. icon_biggrin.gif *laps it up*

    Okay some questions, if I may. When did sexual dimorphism start to happen anyway and why?

    Also why do birds and reptiles have ZZ as males and ZW as females, which asides from letting them be theoretically capable of parthenogenesis, also would seem to imply that for them males are the default gender. I always thought females were the default gender of everything since only they have the capability of reproduction. :/


    That's a WHOLE lot of evolutionary biology you're asking for icon_razz.gif

    Quickly MSU, dissertate that shit.
    hehe

    Actually, its quite interesting how certain species have developed methods of producing various 'types' of individuals based on X and Y content. Bees, for example. I don't have my genetics textbook here with me but the method in which drones/males/queens are created is actually pretty neat.
    Then again, so are chimeras. And turner females. Lol - they have webbed digits, among other things.

    Genetics is so much fun. icon_biggrin.gif
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    Dec 15, 2008 12:05 AM GMT
    BioMatty said

    That's a WHOLE lot of evolutionary biology you're asking for icon_razz.gif

    Quickly MSU, dissertate that shit.
    hehe

    Actually, its quite interesting how certain species have developed methods of producing various 'types' of individuals based on X and Y content. Bees, for example. I don't have my genetics textbook here with me but the method in which drones/males/queens are created is actually pretty neat.
    Then again, so are chimeras. And turner females. Lol - they have webbed digits, among other things.

    Genetics is so much fun. icon_biggrin.gif


    LOL. Well, I always wanted to know why dimorphism is needed anyway. Seems just like inviting problems to me. Unless it's actually a form devolution in a way. Just tell me quick, which came first... the egg, the rooster... or the hen? icon_lol.gif

    On bees: I thought that it simply had to do with the cells they were incubated in and the food the workers fed them? Aren't queens developed in a special queen chamber? I don't remember. But unless the queen knows what 'caste' the egg will develop into when she lays her eggs I wouldn't think genetics has much to do with it, more like environmental conditions and food...

    ...wait. She does, doesn't she? icon_confused.gif

    I do agree though. Genetics is fascinating. It is, after all, the primary reason to the development of life itself. I'll be darned if I have to wade through a genetics textbook to find out about that though. LOL My interest in biology is more on the 'field' variety than the 'lab' one. icon_wink.gif

    EDIT: Though sexual polymorphism DOES make sense in social insects. icon_razz.gif
  • OptimusMatt

    Posts: 1124

    Dec 15, 2008 12:17 AM GMT
    well genetically bees are set up in such a fashion that unfertilized eggs (I think, anyways) result in drones. I'm not sure how other colony insects do it but I suspect a similar method. These drones are unable to reproduce because they don't have the required amount of chromosomes to create viable offspring and probably don't develop the biological machinery required to do it anyways.

    Off the top of my head, sexual dimorphism probably evolved as an answer to a need for increased genetic viability - MSU described meiosis (the creation of sex cells i.e. sperms/eggs) and how your body 'shuffles' the genes around to create a similar but distinctly different set of chromosomes for your potential offspring. Sexual dimorphism increases the variety of genes found within the offspring due to the chromosome sets coming from 2 different sources and therefore increases the likelyhood of mutation. As mutations are often deleterious, but very much required for a species' viability, this is a very effective way to ensure that mutation can/does occur at a very high rate.

    Just rambling, but I suspect its a valid. icon_biggrin.gif
  • kew1

    Posts: 1595

    Dec 15, 2008 12:25 AM GMT
    Also look up gender determination in reptiles - determined by incubation temperature.
  • MSUBioNerd

    Posts: 1813

    Dec 15, 2008 12:36 AM GMT
    It's ZW because the ancestral chromosomes are different from the ancestral XY chromosomes.

    Alright, haplodiploidy (the bee/ant/wasp method of sex determination) off the top of my head: The queen essentially exists for reproduction. After her mating flight, she stores sperm for the rest of her life. Virtually all of the bees you encounter are sterile females, and are diploid, meaning that they have two copies of each chromosome. Males are haploid, meaning they only have one copy of each chromosome. They also exist pretty much solely for sex, and are often actually killed by it. The incubation cells for males and future queens are indeed larger than for workers, as both are bigger than worker bees. However, the specific incubation environment requirement you're thinking of is something called royal jelly, which is fed to future queens and differentiates them from workers.

    And these are only three of the sex determination systems. Some reptiles have sex determined by the temperature at which the eggs incubate, and it's not even always consistent between species whether high temperature leads to male or female. In some fish, sex is determined by relative age or size in the social group, but again, in some species older and/or larger leads to females, in others it leads to males.

    Sexual dimorphism has pretty much been around since there were two sexes. It merely means some sort of physical difference between the sexes. Humans are a moderately sexual dimorphic species, with women being about 85% the size of men. Some apes are significantly more dimorphic, like the orangutan. Others are substantially less so, like a number of gibbon species. Sexual dimorphism in body size is a pretty good marker for the long-term mating strategies of a species--the more parental care a male provides to the offspring, the smaller the expected size difference between males and females. Where males fight each other for dominance of a group of females, females will tend to be a size determined by the ecology of their obtaining food and avoiding predation, while males will (generally) be larger because being bigger makes them better fighters. Because mammals, in general, have very low degrees of paternal care, and because this low level of paternal care is very widespread over the phylogenetic tree, it's reasonable to expect that low levels of paternal are the ancestral condition in mammals, and that sexual dimorphism is therefore ancient.

    As for whether birds default to males or females, we don't really know. A large part of why we can figure this out in humans is from unusual cases like Turner's syndrome (45 chromosomes: the normal 44 autosomes plus an X) where the patient is female, and Kleinfelter's syndrome (47 chromosomes: the normal 44 autosomes, two X chromosomes, and one Y), where the patient is male. Birds with extra or missing Z or W chromosomes dies from it. Some insects share the ZW system, and in some of them Z0 females exist, and in others ZZW females exist, so it looks like in some cases the W causes the individual to be female and in others it's that two copies of the Z cause the individual to be male.
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    Dec 15, 2008 12:46 AM GMT
    Fascinating.
  • MSUBioNerd

    Posts: 1813

    Dec 15, 2008 12:52 AM GMT
    In case it hasn't been made clear yet, I'm teaching several courses on evolution in the coming semester... ;)
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    Dec 15, 2008 1:09 AM GMT
    I should really be sleeping. LOL. But really very interesting MSU, thanks. icon_smile.gif Better than a National Geographic article LOL

    On social insects, I was an ant fanatic once. I built several antfarms and read all I can about them. This brought back a LOT of memories. hehe. Just something to add I guess. In primitive ants, females are less differentiated from each other. The ponerines I think, and bulldog ants. In which, every female is fertile, and there is no queen-worker differentiation in the females. I'm not sure about wasps and bees, but I think the solitary ones also have males which do not die immediately after mating (the males in more advanced social insects often die after the 'nuptial flight' because of devolution of their feeding capability anyway - they can't eat by themselves).

    Also that of limpets and groupers which change their sexes as they age. In these instances, sex is determined by environmental factors rather than heredity, do all of them have more or less the same types of chromosomes in each individual? i.e. no male-determining/female-determining chromosome, and the sex determination is based on switching certain genes off and on either by will or by environmental factors.

    Thus differing from sexually dimorphic species which have gender specific chromosomes are doing this by the fact that the gender determining chromosome is somehow 'dominant' over the other. Like Y in humans since Kleinfelter's are always male and Turner's female. Though again, as you said, birds and reptiles do seem to be based on the presence of 2 Z's. Bleh too complicated. Don't answer that, they're more like rhetorical questions LOL

    And yeah I do see the role of sexual dimorphism in evolution. Secondary sexual characteristics for example. How they develop would be pretty interesting to study, especially in species in which males and females vary greatly in their form. (Birds of Paradise, Peafowl, Anglerfish, Siamese Fighting Fish, Swordtails, etc.)

    Hm... even plants are sexually dimorphic at times, but in a different way than animals, so not probably something inherited from the same primeval ancestor with dimorphism, different evolutionary paths I guess. So younger than protozoans, fungi, and molds. icon_razz.gif I googled a bit. And it seems rotifers show sexual dimorphism already. So pretty ancient indeed.

    Anyway, have to sleep. Thanks for the interesting posts! ^_^

  • Dec 15, 2008 1:25 AM GMT
    Everytime a cell divides (mitosis) when the chromosomes pull apart, a very very very small piece at the end of the chromosomes breaks off. This in the short term doesn't affect anything, BUT over 50 years from birth this adds up and when the chomosome is too short, there are a loss of vital genes and the cell will go into apoptosis and die. This is where females have the advantage. They have 2 X chromosomes while we have 1 X and 1 Y. Female cells can lose 1/4 of one of the Xs and still remain healthy because the other X chromosome will take over function of the other. If men lose 1/4 of our Y, that is incompatable with life and the cell will die. No cell can live with one X or just one Y so when we lose function of the Y, our cells die and our body will eventually die. That is why (one main reason) women live longer then men.

    There is an enzyme (forgot the name tolemerase?) that adds nucleic acids to the ends of the chormosome leading to increased cell function and life.