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Half-Male, Half-Female Fowl Explain Birds' Sex Determination 117

Posted by timothy
from the fish-nor-fowl-except-fowl dept.
Kanan excerpts from a BBC report out of Scotland: "A study of sexually scrambled chickens suggests that sex in birds is determined in a radically different way from that in mammals. Researchers studied three chickens that appeared to be literally half-male and half-female, and found that nearly every cell in their bodies — from wattle to toe — has an inherent sex identity. This cell-by-cell sex orientation contrasts sharply with the situation in mammals, in which organism-wide sex identity is established through hormones." Kanan also supplies this link to some pictures of the mixed-cell birds.
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Half-Male, Half-Female Fowl Explain Birds' Sex Determination

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  • Interesting (Score:4, Funny)

    by interkin3tic (1469267) on Thursday March 11, 2010 @03:53PM (#31444010)

    So would one of these hermaphrodite chickens be called a half-cock?

    I agree with the section "Clucking confusing."

    • by RCGodward (1235102) on Thursday March 11, 2010 @03:56PM (#31444056)
      I think this story is for the birds... I'm sorry...
      • Re: (Score:1, Troll)

        by dov_0 (1438253)
        I agree. What a ridiculous premise regarding sexual identity. So an XX or XY chromosome pairing in every cell of a mammal is nothing to do with gender? WTF? Since when is a study of 3 individuals considered decent research anyway? Also, when a flock of chickens suddenly loses it's rooster, the dominant female will sometimes act as a rooster. That isn't hormonal? It's crazy what people try and pass off as science these days...
        • Re: (Score:3, Interesting)

          by icebike (68054)

          Also, when a flock of chickens suddenly loses it's rooster, the dominant female will sometimes act as a rooster. That isn't hormonal?

          This does happen.

          Apparently this is not all that common, that is, not every hen can become a henry, and perhaps TFA suggests the means by which this does happen when it does.

          Apparently One in 10,000 hens can change sex [answers.com], usually in response to a gonad ceasing to function. One professor explained it this way: [angelfire.com]

          "Yes a type of sex reversal does occur in poultry. Both a right and left ovary start to develop in the embryo but between day 7 and 9 of incubation the right gonad ceases to continue development.

          • Re: (Score:3, Informative)

            by Darinbob (1142669)
            What's new is that the DNA of the chicken is different on the left and right sides. It's not just developing new sexual characteristics due to hormones. If you take one of these hens that later became a rooster and checked the DNA, it would show up as female on both sides.
        • by zero_out (1705074)

          So an XX or XY chromosome pairing in every cell of a mammal is nothing to do with gender?

          Sex (noun) and gender are two distinct things. Sex is genetic, while gender is hormonal. Transgenered people are of one particular sex, and a different gender. Some animals can change, hormonally, based on non-genetic factors. They change their gender based on the presence or absence of certain members of a gender of their species being present in their population. Take out the males, and females become males. It's similar to the way that women living in the same home will eventually be on the same me

          • Re: (Score:2, Insightful)

            by dov_0 (1438253)

            Sex (noun) and gender are two distinct things.

            Well, no. Sex and gender identification are two different things.

            Have you ever noticed that in same-sex pairings, it is common for one member to act very masculine, and the other act very feminine, regardless of what the pair's actual sex is?

            Sometimes, yes, sometimes no. What you are speaking about is quite irrelevant to the discussion and has less to do with gender identification than emotional roles in relationships, which is an entirely different thing.

      • Re: (Score:3, Funny)

        by c++0xFF (1758032)

        If two sexually scrambled chickens get together, will one lay scrambled eggs?

      • by ArcherB (796902) on Thursday March 11, 2010 @04:30PM (#31444690) Journal

        Since this seems to be the "joke" thread, allow me to put in my $0.02

        I was on a farm doing research on genetic engineering and kept seeing something zip around at amazing speeds. I asked the farmer what it was and he told me it was chickens.

        "See," he said, "the drumstick is everyone's favorite part of the chicken. So we engineered chickens with three legs. For every two chickens we sell, it's like we are selling three, leg-wise. It actually reduces waste since the factories don't find themselves with extra breasts and other crappy parts that they have to throw away or turn into chicken nuggets."

        I said, "WOW!!!! That's amazing. How do they taste?"

        He replied, "Hell if I know. We haven't been able to catch one yet!"

        ________________________________________________________

        Please, tip your waitress.

    • by pwnies (1034518) *
      That's actually what the story's headline was. I'll still give you credit for wit though seeing as no one on /. rtfa.
    • by BraksDad (963908)
      And flees (do birds have flees or some equivalent?) jumping off would be going off half-cock.
  • by kimvette (919543) on Thursday March 11, 2010 @03:54PM (#31444028) Homepage Journal

    About one in every 10,000 chickens is gynandromorphous, to use the technical term.

    That's somewhat close to the rate of intersex conditions in mammals, including humans.

    • by dimeglio (456244)

      I wonder if this is true for dinosaurs as well and if certain events affecting reproduction contributed to their extinction.

    • by TheLink (130905)

      > That's somewhat close to the rate of intersex conditions in mammals, including humans.

      Yeah, there are chimeras:

      http://en.wikipedia.org/wiki/Chimera_(genetics) [wikipedia.org]

      • by Ma8thew (861741)
        That's different. Chimeras are the result of the cells of two individuals combining into one organism. Chimeras are unlikely to be intersex as one cell line will form the sexual organs. Intersex refers to individuals with ambiguous sexual characteristics, and can be caused by several factors. Neither of these can result in gyandromorphism in humans.
  • gynandromorphs? (Score:2, Redundant)

    by Sponge Bath (413667)
    Shouldn't that be hermaphorochicken?
  • by InsertWittyNameHere (1438813) on Thursday March 11, 2010 @04:04PM (#31444234)
    So each cell has it's own this.getSexualOrientation() function.

    Whereas mammals have a global static variable where SEXUAL_ORIENTATION = MALE or FEMALE.

    This is interesting because I thought we all inherited from a common ancestor. Was sexual orientation not defined in the root class?
    • All definitions in the root class can be overloaded, I guess.
    • Ohhhhhhhh, ok. Now I get it. Geez when I RTFA it was like reading a whole new language.
    • Re: (Score:3, Insightful)

      by danlip (737336)

      No, the common ancestor of all animals almost certainly reproduced asexually (as do many primitive animals today), so it would not be defined by the root class. There are of course more recent common ancestors between birds and mammals, but XY seems unique to mammals.
      See ZW sex-determination system [wikipedia.org] and X0 sex-determination system [slashdot.org].

      • by dwye (1127395)

        First, your link to the explanation of the X0 system is broken.

        Second, I don't know for certain, but I think that the sex determination function is handled like Common Lisp inheritance (inherited from an instance, not an abstraction like a class definition, especially of a root class) rather than C++, Java, C#, etc. Evidently, said function was replaced in the mammalian line, just as color vision was (birds and reptiles have four primary colors, most mammals have only two, and pro-simians and primates have

        • Re: (Score:3, Interesting)

          by danlip (737336)

          that was meant to be a wikipedia link, something weird happened when I did a preview, edited again, and submitted (I had missed a closing quote before the first preview, but I think that caused slashdot to munge the URL, but I was going quickly). In any case you can search on that in wikipedia.

          My point is there are lots of ways to do sex determination. Echidnas and Platypuses are particular weird in this way (and in every other way), even though they are mammal they don't use XY.

          And of course, in the most

    • by FlyingBishop (1293238) on Thursday March 11, 2010 @04:33PM (#31444740)

      In both cases, each cell has its own this.getGender() function.

      In both cases, I would imagine the code looks something like this:


      class cell {
            int gender; // should really be a bool, need to fix that at some point.
            proteinFactoryBuilder asdf; // find a better naming scheme ... ...

            getGender() { /* I don't really have time to go back and fix this right now, but if I'd known I'd be making multicellular organisms with this shit I wouldn't have put this at the cellular level. Anyway, we're stuck with it, so for now I'm just returning the gender variable and I'll leave it to callers to figure out wtf to do with unexpected output. */
                return gender;
            }
      }

      Small wonder it's a little more confusing for birds.

      • by Jurily (900488)

        I'd imagine there is no written code involved in today's organisms. However, the very first cell had this:

                int survival_chance_of_mutation = rand(); // who cares, it'll crash anyway

      • Re: (Score:3, Informative)

        by dwye (1127395)
        Your example code is cute, except that the inheritance system is more like Common LISP (inheritance from an instance) rather than C++ (inheritance from a Platonic Ideal of the class). Please rewrite appropriately.
        • by mcgrew (92797) *

          I would think it was more like machine code than even assembler, let alone LISP or C, unless you think God has a compiler. It is certainly a RISC computer, since there seem to be only four instructions that are paired to produce other instructions.

      • by chooks (71012)

        int gender; // should really be a bool, need to fix that at some point.

        That's not a bug -- it's a feature. Some life forms (e.g. slime molds) have more than two [si.edu] "genders".

    • by reverseengineer (580922) on Thursday March 11, 2010 @04:35PM (#31444766)
      Mammals actually handle sex inheritance in an inverted arrangement from birds. Whereas mammals use the X/Y system, where males are the heterogametic type (XY) and females are the homogametic type (XX), birds (and some other animals) use a "ZW system" where males are ZZ and females are ZW. A notable feature of ZW determination is that the Z chromosome is more like a full-fledged chromosome with many genes, unlike the mammalian Y chromosome which has been paring down its genes so that it contains the sex-determining gene SRY, some genes necessary for sperm production, and little else.

      This might go a long way towards explaining gynandromorphism in birds. In mammals, maleness is handled in a top-down fashion- the Y chromosome does not explicitly specify most aspects of the male phenotype, instead simply encouraging the cells that go on to make androgens, which then go on to produce a cascade of developmental effects throughout the body. In birds, the Z and W chromosomes both may have enough genes that sex determination can be handled from the bottom up, locally in each cell.
      • Re: (Score:3, Insightful)

        by MikeV (7307)

        ...unlike the mammalian Y chromosome which has been paring down its genes so that it contains the sex-determining gene SRY, some genes necessary for sperm production, and little else. ...This might go a long way towards explaining gynandromorphism in birds. In mammals, maleness is handled in a top-down fashion- the Y chromosome does not explicitly specify most aspects of the male phenotype, instead simply encouraging the cells that go on to make androgens, which then go on to produce a cascade of developmental effects throughout the body.

        Even so, with the XY chromosome - cutting off body parts and taking hormones does not make a man a "woman" any more than flapping one's arms makes one a bird. Mammals sex inheritance isn't as neutered as the interpretation of the article suggests - only that fowls goes a bit deeper into it than mammals.

    • by GodfatherofSoul (174979) on Thursday March 11, 2010 @04:35PM (#31444778)
      First-year computer science students rejoice! God doesn't know how to do OOD either!
    • by fusiongyro (55524)

      From what I gathered, in mammals it's more like all the cells are Observers and what they're observing are hormonal signals that indicate sex.

      And as someone else observed, this is about sex, not gender identity or sexual orientation. This will get messy in a hurry.

    • ...Nevermind. We're on Slashdot after all... *sight*
    • by dimeglio (456244)

      Apparently. Sex has to be specified in each single object through a getter/setter method.

      But the root class has only one private method. All we know is if we inherit the class we're alive.

    • Re: (Score:3, Funny)

      by Hurricane78 (562437)

      So each cell has it's own this.getSexualOrientation() function.

      That’s Java right? Then, wouldn’t that be this.getFactoryFactory().getOrientationDeterminationFactory(this.getFactoryFactory().OrientationDeterminator.SEXUAL).getSexualOrientationDeterminator().execute()?

    • Whereas mammals have a global static variable where SEXUAL_ORIENTATION = MALE or FEMALE.

      I'm sure you are aware that humans are mammals and humans do not come in 2 genders. There is such a thing called intersexed which is considered a 3rd gender. Maybe people should stop being ignorant and look it up sometime. (Referring to yours and another child post off yours.) http://en.wikipedia.org/wiki/Intersex [wikipedia.org] It is more common than you think.

    • by mcgrew (92797) *

      So each cell has it's own this.getSexualOrientation() function.
      Whereas mammals have a global static variable where SEXUAL_ORIENTATION = MALE or FEMALE

      Actually, no. Mammals, even humans, can have XXY and XYY genes. There are mammals, even humans, born with both penuses and vaginas, and others with both testes and ovaries.

    • Its only in recent days these are all made public. In the root class such stuff were defined private.
    • "Whereas mammals have a global static variable where SEXUAL_ORIENTATION = MALE or FEMALE."

      Or both or neither or something else entirely :P

      (I'm presuming by 'sexual orientation' you mean either sexual or gender identity, as opposed to who they are attracted to)

  • n00bs (Score:5, Funny)

    by DriedClexler (814907) on Thursday March 11, 2010 @04:10PM (#31444326)

    They're not the first ones to be checking out a nice-lookin' bird and then see from another angle that "she" is really a man.

    • I have a feeling there is a really embarrassing story to go with the above statement.
    • But don’t you know about the bird?
      Because everybody knows about the bird.
      Ba-ba-ba baa-baa-ba baba-baba ba, baba-baba-ba baba-baba-ba,
      ba-ba-ba baa-baa-ba baba-baba ba, baba-baba-ba baba-baba-ba,
      don’t. you. know. about. the. biiird?
      Everybody knows about the biird...
      Ba-ba-ba baa-baa-ba baba-baba ba, baba-baba-ba baba-baba-ba,
      ba-ba-ba baa-baa-ba baba-baba ba, baba-baba-ba baba-baba-ba,
      Ba-ba-ba baa-baa-ba baba-baba ba, baba-baba-ba baba-baba-ba,
      ba-ba-ba baa-baa-ba baba-baba ba, baba-baba-ba baba-baba

  • Now you'll have a fresh material to argue which came first...

  • When I was about five years old, I happened to find my grandfather's copy of How to Sex Chicks. I didn't know much about the reproductive act, but I knew that there was something provocative about the phrase "sex chicks", although the book itself, on close examination, seemed innocent enough (how to tell if a baby chicken is a boy chicken or a girl chicken).
    • by Jesus_666 (702802)
      I wonder how many people who work at a farm talked about sexing chicks at length in public (like in a bar) just to creep out the people around them?

      "Man, yesterday I spent all day sexing chicks. After ten hours of sexing I was pretty beat."
      "Yeah, I know. And sometimes you stuff 'em into the box and some manage to get out and you have to go after them..."
      "Worst thing is, it turned out half of them were male. What do we do with three hundred male chicks?"
      "Well, you could sell them to that cat food factor
  • Seriously. What I'm inferring from the article is that you can see the difference in the cells, e.g. male vs. female....

    So how the hell have they never noticed that female and male birds have these slightly different cells before, and reached the non-hormone driven conclusion before this?

    • So how the hell have they never noticed that female and male birds have these slightly different cells before, and reached the non-hormone driven conclusion before this?

      The main problem is that when they got a sample of these chickens, they always arrived just before lunch, so they had a barbeque instead of inspecting them. With the recent budget cuts at the Post Office, the deliverys now arrive after lunch.

    • by Muros (1167213)

      Seriously. What I'm inferring from the article is that you can see the difference in the cells, e.g. male vs. female....

      So how the hell have they never noticed that female and male birds have these slightly different cells before, and reached the non-hormone driven conclusion before this?

      What they're saying is that the development of cells seems to be independent of the hormones that are present in the bloodstream. In mammals of mixed sex, the development of the entire body depends on the mix of hormones, you do not see distinct male and female parts of the body, even if the cells in those body parts are predominantly genetically of one sex. With these chickens the opposite is the case, and you could not infer that from studying a normal single sex bird.

    • Re: (Score:3, Informative)

      by Chris Burke (6130)

      Seriously. What I'm inferring from the article is that you can see the difference in the cells, e.g. male vs. female....

      Yeah you can see that their sex chromosomes are different.

      So how the hell have they never noticed that female and male birds have these slightly different cells before, and reached the non-hormone driven conclusion before this?

      Because to notice this you have to specifically study the birds who have cells that are mixed between male and female, and then notice that the sexual characteristic

  • silly (Score:3, Informative)

    by ascari (1400977) on Thursday March 11, 2010 @04:20PM (#31444534)
    It's well known that birds have a completely different sex determination mechanism than mammals. For example, mammals (other than the platypus) use X/Y or X/0 chromosomes to determine sex. Birds on the other hand use Z/W chromosomes for sex determination, as do most fish, some insects and some reptiles. So the big eyed "Ooooh, who would've thunk that birds aren't handling it the way we mammals do?" attitude of the article seems kind of silly considering we've known about this striking difference for a long time. Imagine that it actually mattered... Suspect they just wanted a reason to publish those cool pictures.
    • Re: (Score:3, Interesting)

      by Chris Burke (6130)

      Birds on the other hand use Z/W chromosomes for sex determination, as do most fish, some insects and some reptiles. So the big eyed "Ooooh, who would've thunk that birds aren't handling it the way we mammals do?" attitude of the article seems kind of silly considering we've known about this striking difference for a long time.

      Okay, but knowing that the nature of the sex chromosomes is different isn't the same as knowing that the overall mechanism by which the sex of the organisms is determined is different.

      • by ascari (1400977)

        I see your point, but we've always known that there are many different mechanisms in play on the chemical level (like pH in some fishes), the genetic/chromosomal level, the cellular level and the organism level even within classes. Consider single cell organisms with "genders": at the most primitive level hormones have no role, whereas genetics does. Is it reasonable to assume that this could have carried over to some higher organisms?

        I thought TFA even concedes that this very mechanism has been observed

        • Re: (Score:3, Insightful)

          by Chris Burke (6130)

          why should we assume that the implementation on the organism level would be identical? Isn't it more intuitive that there would be differences? But finding the "unexpected" makes for a better article than finding the expected...

          Nobody ever thought they'd be identical, and of course there will be differences. That's not the same as expecting it to be completely opposite.

          Expecting some kind of difference is not the same as expecting this difference. This difference was unexpected.

          You can't say that because

        • by khallow (566160)

          In other words, given that we know that sexual differentiation is a phenomenon that has evolved at multiple times via multiple genetic mechanisms in multiple phyla, classes and orders why should we assume that the implementation on the organism level would be identical?

          Do we know that it has occurred more than once (with the evolution of eukaryotes [wikipedia.org])? My impression was, despite the process of sexual differentiation being remarkably variable in its manifestation, there's no indication that it came about more than once.

    • by LurkerXXX (667952)

      It's probably also worth mentioning sex determination in reptiles, which is sometimes determined by the temperature the eggs were incubated at, rather than simply by what chromosomes were transferred. Biology can be a wild thing.

      http://www.scientificamerican.com/article.cfm?id=experts-temperature-sex-determination-reptiles [scientificamerican.com]

  • So I wonder if the applies to spices that can change sex at "will". I seem to recall that there are some fish, frogs and lizards that can do this.

    • Re: (Score:3, Informative)

      by clone53421 (1310749)

      No... I’m thinking those species would have sexes which were entirely hormone-driven.

      That’s basically the exact opposite of the chickens, in which sexes apparently have very little to do with hormones, and are entirely based on the genetics of the cells.

      Humans would be somewhere in between. A man will grow breasts if you give him enough hormones, but you’ll have to do something surgically to change the penis...

      • by Chris Burke (6130)

        Humans would be somewhere in between. A man will grow breasts if you give him enough hormones, but you'll have to do something surgically to change the penis...

        My gf showed me pictures in her biology text of what were genetically men who appeared externally to be completely female, including with vaginas. Internally they lacked a uterus.

      • Re: (Score:1, Informative)

        by Anonymous Coward

        > A man will grow breasts if you give him enough hormones, but you’ll have to do something surgically to change the penis...

        The female is the base body type for humans. Everyone starts with a "female" body, but men produce chemicals called androgens that turn them into men. With things like AIS, people who are genetically male can end up with what appear to be female bodies.

        So, basically, you have it backwards. The androgens make female-looking bodies into males. There's no reverse of that (e.g

        • by Anonymous Coward

          Back in my Bible School I distinctly remember in the Book of Job around Chapter 27 that "His breasts are moistened with milk" to be a distinguished cause of how men are expected to raise female children from their breasts and the wives are to raise the male children from their breasts akin to correct the societal acceptance of gender. It is obvious that subconscious reasoning is established early in the attractions of developing minds to what they perceive as their drive.

          On a related note, I am a hermaphro

          • Back in my Bible School I distinctly remember in the Book of Job around Chapter 27 that "His breasts are moistened with milk" to be a distinguished cause of how men are expected to raise female children from their breasts and the wives are to raise the male children from their breasts akin to correct the societal acceptance of gender. It is obvious that subconscious reasoning is established early in the attractions of developing minds to what they perceive as their drive.

            If you’re not trolling, you’re wrong. There are 42 instances of the word “milk” in the Old Testament. Only one of those is in the book of Job (10:10) and it is metaphoric: “Did you not pour me out like milk and curdle me like cheese”. The passage you referred to does not exist, not in the book of Job or anywhere else in the Bible.

        • The androgens make female-looking bodies into males. There's no reverse of that (e.g. you can't ungrow a penis).

          A woman cannot undergo hormone treatment to grow a penis either. So either the physical development is regulated at least partly by genetics, or hormones trigger development but genetics lock out certain development paths after the baby is fully developed.

          So on the one end of the spectrum you’ve got certain lizards, which can produce hormones to change themselves into the opposite sex; you’ve got humans, who cannot, but who exhibit certain features of the opposite sex if they have hormones intro

    • You forgot dinosaurs.
    • by Narcocide (102829)

      Which spice section are you shopping in?!

  • Hurray! (Score:3, Funny)

    by clone53421 (1310749) on Thursday March 11, 2010 @04:25PM (#31444600) Journal

    Now we can produce twice as many chicken breasts.

    I suppose we’d better not be going off half-cocked, though. More grant money!

  • that as we all know is 100% male oriented.
  • Did anyone else wonder how " Half-Male, Half-Female Fowl" can explain anything to anyone, seeing as they are...fowl?
  • Another story about Al Gore.

  • Any bird can teach you something about the birds and the bees, assuming of course, that you're not a bee.

  • the fact that it can talk, and apparently give a scientific lecture, would have been seen as much more newsworthy.
  • Wow. How often will you ever read that outside of a police report about a domestic dispute?
  • .. wasn't that interesting. The only reason to click on this story is to read some /.ers comments.
  • They call it Chimerism. Sorry to cook your goose... video part 1 [youtube.com] video part 2 [youtube.com] Link 1 [wikipedia.org] Link 2 [wordpress.com]

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