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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...
      • by dov_0 (1438253) on Thursday March 11, 2010 @04:18PM (#31444480)
        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:Interesting (Score:3, Interesting)

          by icebike (68054) on Thursday March 11, 2010 @05:10PM (#31445276)

          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. If in the adult, the left ovary is removed or fails to function the right gonad hypertrophies to become a testis-organ and thus "a male' instead of what was a hen."

          The implication of this is with regard to TFA is that failure of one gonad cease development leads to the double expression of traits documented in the story.

          So there is nothing new here that hasn't been known for some time with regard to chicken sex other than that the normal failure to enter stasis can lead to odd birds.

          • Re:Interesting (Score:3, Informative)

            by Darinbob (1142669) on Thursday March 11, 2010 @06:37PM (#31446522)
            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) on Thursday March 11, 2010 @05:19PM (#31445430)

          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 menstrual cycle. Non-genetic factors influence hormones, and gender is hormonal.

          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? It's my understanding that there is no hormonal difference, but one just adopts the behaviors of the other gender. This seems consistent with the idea of a chicken flock losing its rooster and a female acting as one without any hormonal changes. Now this is purely anecdotal, but I believe it to be accurate.

          • Re:Interesting (Score:2, Insightful)

            by dov_0 (1438253) on Thursday March 11, 2010 @05:39PM (#31445712)

            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.

      • by Anonymous Coward on Thursday March 11, 2010 @04:19PM (#31444508)

        To get to the other gestalt.

      • by c++0xFF (1758032) on Thursday March 11, 2010 @04:23PM (#31444564)

        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) * <j@jjcm.org> on Thursday March 11, 2010 @03:59PM (#31444128) Homepage Journal
      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) on Thursday March 11, 2010 @10:29PM (#31448344)
      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.

  • gynandromorphs? (Score:2, Redundant)

    by Sponge Bath (413667) on Thursday March 11, 2010 @03:56PM (#31444054)
    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?
  • 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.

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

  • by handy_vandal (606174) on Thursday March 11, 2010 @04:19PM (#31444496) Homepage Journal
    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 Gertlex (722812) on Thursday March 11, 2010 @04:20PM (#31444532)

    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?

    • by SnarfQuest (469614) on Thursday March 11, 2010 @04:40PM (#31444872)

      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) on Thursday March 11, 2010 @04:46PM (#31444960)

      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.

    • by Chris Burke (6130) on Thursday March 11, 2010 @04:56PM (#31445102) Homepage

      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 characteristics vary over the same organism in accordance with which cells are male and which female.

      Otherwise, you're just observing that a chicken is genetically male or female, and has male or female traits. That doesn't distinguish between a per-cell sexual determination, and mammals' overall hormone-based one.

  • 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:silly (Score:3, Interesting)

      by Chris Burke (6130) on Thursday March 11, 2010 @04:49PM (#31445012) Homepage

      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. The assumption was that it was still essentially the same -- sex chromosome in the egg cell ends up controlling the formation of male or female gonads, which then release male or female hormones, which then control the sexual characteristics of the organism as a whole. And this is pretty reasonable on its face, since chickens do develop male/female gonads which do release sex hormones. It's largely the same, right up to the point where those hormones are what determine sex for every cell or not.

      In mammals that's the case. Every cell in your body could be carrying X/Y chromosomes, but if due to some disorder you aren't producing male hormones but instead female ones, you will acquire female secondary sexual characteristics.

      Now we know this isn't the case for birds, that every cell has its own sexual identity independent of hormones, and no we have not known about this striking difference until now.

      • by ascari (1400977) on Thursday March 11, 2010 @05:28PM (#31445576)

        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 before in insects and some mammals. When Clinton says "We assumed that sex determination in birds would follow the mammal pattern" it makes me wonder why he made that assumption, or if it was just a convenient null hypothesis. Or if it just a buildup to how truly "amazing" the discovery is. Given the differences in chromosomal origin of sex between different animal groups wouldn't it have been equally reasonable to assume that the developmental patterns would diverge? 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? Isn't it more intuitive that there would be differences? But finding the "unexpected" makes for a better article than finding the expected...

        • Re:silly (Score:3, Insightful)

          by Chris Burke (6130) on Thursday March 11, 2010 @05:37PM (#31445676) Homepage

          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 a difference of some kind is to be expected, that therefore whatever difference actually shows up was also expected. That's what strikes me as silly.

        • by khallow (566160) on Thursday March 11, 2010 @06:25PM (#31446364)

          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 Anonymous Coward on Thursday March 11, 2010 @05:12PM (#31445314)
      Platypus? Who'd be weird enough to mention a platypus on slashdot?
      Waitaminute... Hans [google.com], is that you?
    • by LurkerXXX (667952) on Thursday March 11, 2010 @08:01PM (#31447388)

      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]

  • by spribyl (175893) on Thursday March 11, 2010 @04:25PM (#31444596)

    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:Changing Sex (Score:3, Informative)

      by clone53421 (1310749) on Thursday March 11, 2010 @04:30PM (#31444682) Journal

      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) on Thursday March 11, 2010 @05:10PM (#31445282) Homepage

        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:Changing Sex (Score:1, Informative)

        by Anonymous Coward on Thursday March 11, 2010 @06:27PM (#31446388)

        > 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. you can't ungrow a penis).

        • by Anonymous Coward on Friday March 12, 2010 @02:52AM (#31449280)

          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 hermaphrodite; I have both fully functioning male and female organs; My clitoris is at the tip of a shaft that many call a penis, but it's just something many people would imply usage to such fluid exchange. Even my girlfriends say that there is an ongoing study about how during certain conditions of diet and environmental factors their all-female body can produce viable fluids that would cause female ovaries to be fertilized when presented from one woman to another. There are even studies showing that the fertilization factors of fluid of men or women interacting with one-another is much to consider as more stimulation for non-receptive egg to begin dividing and incubating what was already inherent as to it's anchor upon the womb wall. This competes against male seminal fluids in the manner that what is thought to be non-competitive biological functions of the same species is actually an environmental trait not of this world that was introduced some time ago into all species to make their lives more redundant in retaining genetic health in any given species.

          Evidence of it happening recently is in reduced populations of only reptilian organisms. Outside of reptilians, the obvious commemoration of fish behaviour is overrated. In reptilians, it is more a 3rd gender. What is seen in mammals today could be attributed to enumeration more-so as a complete 5th gender respective of Royal family lineage dating back to Germany and even some factors of Scotland. Consider how the base brainstem of man-kind, otherwise known as the Archon center, is identical to a primitive reptile; this follows the course of Bible Studies that suggest many of the de jure men documented in the Holy Bible would be sired in means of not self-preservation but interaction with a more functional gender not on this planet. This dates back to areas of Scotland and proto-Ireland concerning druidism and competition to the serpent race that makes various appearances in the Holy Bible. Islam if for the most part very silent on the subject in these anatomical forms, but considers surgical correction to be the common route, as opposed to Budhism that would rather accept this as evidence rather than anomaly and the gifted creature to appraise and harness oneself in look for another receptive creature like itself. Budhism follows into the Specie(al) isolation as a Garden of Eden approach for likeness of the matter to reveal a cause to rise from dormacy.

          So the interchange of organs go, just as you would say; ovipositors only a dominant trait among non-mammalians and non-reptiles, whereas unusual lifeforms as reptilian or insectoid it's all kissing lips for fluid exchanges or beverage mixing just as what's happening between spontaneous perpetuation between tribal lesbians.

          • by clone53421 (1310749) on Friday March 12, 2010 @09:23AM (#31451240) Journal

            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.

        • by clone53421 (1310749) on Friday March 12, 2010 @08:43AM (#31450860) Journal

          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 introduced into them; and on the opposite end of the spectrum you have fowl, in which hormones appear to have no effect on which sex is developed, that being determined by DNA alone.

    • by northernfrights (1653323) on Thursday March 11, 2010 @04:33PM (#31444728)
      You forgot dinosaurs.
    • by Narcocide (102829) on Thursday March 11, 2010 @04:39PM (#31444856) Homepage

      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!

  • by Anonymous Coward on Thursday March 11, 2010 @04:33PM (#31444730)

    What does this mean for "the birds and the bees" now?

  • by Anonymous Coward on Thursday March 11, 2010 @04:36PM (#31444800)

    really puts me in a fowl mood...

  • by Anonymous Coward on Thursday March 11, 2010 @04:37PM (#31444804)

    Is Sam a straight cock with a confusing lesbian side?

  • by Nomaxxx (1136289) on Thursday March 11, 2010 @04:40PM (#31444876) Homepage
    that as we all know is 100% male oriented.
  • by 101010_or_0x2A (1001372) on Thursday March 11, 2010 @04:51PM (#31445038)
    Did anyone else wonder how " Half-Male, Half-Female Fowl" can explain anything to anyone, seeing as they are...fowl?
  • by Vinegar Joe (998110) on Thursday March 11, 2010 @07:14PM (#31446932)

    Another story about Al Gore.

  • by Chemisor (97276) on Thursday March 11, 2010 @07:28PM (#31447076)

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

  • by ezzthetic (976321) on Thursday March 11, 2010 @09:43PM (#31448110)
    the fact that it can talk, and apparently give a scientific lecture, would have been seen as much more newsworthy.
  • by SlappyBastard (961143) on Thursday March 11, 2010 @09:49PM (#31448150) Homepage
    Wow. How often will you ever read that outside of a police report about a domestic dispute?
  • by formfeed (703859) on Thursday March 11, 2010 @10:21PM (#31448302)
    .. wasn't that interesting. The only reason to click on this story is to read some /.ers comments.
  • by msu320 (1084789) on Friday March 12, 2010 @01:15AM (#31448970)
    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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