Half-Male, Half-Female Fowl Explain Birds' Sex Determination 117
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.
Re:Object-sex-oriented? (Score:5, Insightful)
Sex is what you have between your legs.
Gender identity is what you want between you legs.
Sexual orientation is what you want between someone elses legs.
Re:Object-sex-oriented? (Score:3, Insightful)
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].
Re:silly (Score:3, Insightful)
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.
Re:Interesting (Score:2, Insightful)
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:Object-sex-oriented? (Score:3, Insightful)
...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.
Re:Object-sex-oriented? (Score:3, Insightful)
Sexual intercourse is what you have been genetically programmed to do with what you have between your legs.