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Science

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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  • 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.

  • 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.

  • 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.

  • by danlip (737336) on Thursday March 11, 2010 @08:01PM (#31447386)

    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 literal real world sense, it is all inherited from instances.

  • 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.

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