It's really great. Read more: Sex, genes, the Y chromosome and the future of men. Of course, it wasn't on the Y chromosome.
Read more: Born this way? So, for instance, in crocodiles, if the eggs are incubated where it's hot, they'll all be male. There's a lot of variation that happens because making sperm, you have to go through many, many, many cell divisions.
Graves said it was also clear that mate choice hetero or homosexuality was highly genetic, and independent of sex determination. By expert name By keyword. Birds that are half-male, half-female Very occasionally a bird is found with one side male, the other female. But isn't that terrific?
Surprisingly, this mechanism is more common in vertebrates than the familiar mammalian system in which the presence or absence of a Y chromosome bearing the SRY gene determines sex. It makes sense for females in poor condition to hatch more female chicks, because weak male chicks are unlikely to surmount the rigours of courtship and reproduction.
The discovery of the human male-determining gene, SRY, how it works, how it evolved and defined our sex chromosomes, well illustrates the value of comparing distantly related animals and the folly of relying on humans and mice for an understanding of the most fundamental aspects of mammalian biology.
Publication types Comparative Study Review. In a ZW female embryo, the single copy of DMRT1 permits the gonad to develop into an ovary, which makes estrogen and other related hormones; a female bird results. So I really had nothing to do with sex at all until one day, when the gene from the sex determination gene on the Y chromosome had been - you know, lots of people are looking for it, not including us, and I saw a wonderful paper coming out from America claiming that they had found this gene.
We have a lovely grant called "Sex in Dragons".