I was watching something on the science channel a few weeks ago that enlightened me as to some stuff, one is about why I have nipples. Apparently (and pardon me if you already know this) all human babies default to female. Six weeks(ish) into the preganancy the introduction (or lack) of some gene makes the baby into a male, or leave it alone respectively. Apparently nipples form before 6 weeks, so all humans get nipples. I thought that was interesting and thought I'd share if you didn't already know that. Please, knowledgable people correct me if I got it wrong.
I believe that is correct. All humans are female for the first six weeks of development. When the gene is introduced, the ovaries turn into testes and start the journey to move outside the body.
I wonder why it takes 6 weeks for a gender gene to kick in. Anyone have any insight into this from a biological/evolutionary standpoint?
There was also a guy who said you could tell how much prenatal testosterone you'd been exposed to by looking at the difference (on either hand) between your ring and index finger. I think it was if your ring finger is longer, more testosterone prenatally, and if your index finger was longer, less. He accurately predicted the outcome of a footrace between a bunch of professional runners based on this property.
I guess it probably goes this way. The familiar body functions and the main body parts are developed first before getting into the technicalities of it all. Basically the process is set up in the way that the most important functions and body parts are developed and planned out first. Then after 6 weeks the other important stuff is taken care of. Like two body chasis of cars. First 6 weeks the main stuff is put in...wheels, engine etc etc and then after that the two cars get to have their specific specifications put in. Its a guess.
I'm not certain, but I have heard from someone who would have a reason to find out, that males are capable of lactation.
Yup, they very much are. Men can also get breast cancer. There was case on the news where a man who was suffering from breast cancer was denied coverage by his insurance company due to the fact there were no regulations listed about such a thing in company policy...because it is so rare. He was a heavy man with fairly developed man breasts.
stephen jay gould wrote an essay on it a long time ago. I can't really find it on the internet. The first link has some quotes from this essay. I read it, but it is a long time ago, so my memory is no use. http://www.madsci.org/posts/archives/may97/861311884.Me.r.html http://www.salon.com/health/feature/1999/06/08/nipples/
you cannot call the differentiation (or lack thereof depending on the sex) of cells in a blastula "a man coming from a woman" seriously!!!
Actually I think you can based on the fact that if the gene in question doesn't show up, the baby is a girl. If it doesn't show up, ovaries never turn into testes and well, girl. So yeah, it's a girl until it turns into a boy.
As you all likely know, I'm not a biologist. I'm parroting what I heard on the science channel. I went looking for some link to show the program I saw earlier and couldn't find it. I don't remember the name of the show for sure. It was like "the making of a man" or "how to make a man" or something like that. In it, they presented the "default myth" as if it weren't mythical. The point was that if you didn't introduce the specific gene at the right time, then you get a girl. That's why they promoted it as "default" because something has to happen to change the sex or you get a girl. Given the very little biology I know, seems plausible to me. Obviously though, that doesn't mean much. EDIT: I think that the whole "sex reversal" thing had something to do with all this. They showed a woman was genetically a man. She had xy chromosomes but female sex organs and she never went through puberty. She looked smidge butch too. Please Register or Log in to view the hidden image! I believe the deal was that she lacked the gene thing I was talking about. I don't know though, maybe I got something backwards or wrong.
Thats just gene expression its not a male coming from a female in the strict sense Please Register or Log in to view the hidden image!
It is an embryo stage. In fact the reason why the penis in a man has a slit down the bottom is because that is the same origin of the female vagina, but it stays fused together rather than splitting. Seems men have more origins in female embryology than vise versa.
