nips

[ydoaPs]

do male nipples serve a function or are they vestigial? if they don't serve a purpose, does that mean females came before males?

[JustStuit]

Doesn't it have something to do with male and female babies being the same in the womb for a few months or something? Then they take on gender attributes but the nipples are already there in both but they only progress in females? Or something. I'm not sure.

[Sisyphus]

Yeah, they develop before any difference between the sexes arises.

 

...now how in the world does it make sense for there to be females before males? They wouldn't be "female," then, they'd be assexual, and our closest assexual ancestors are a great deal older than mammals. Or did you mean something else?

[Glider]

The default embryonic morphology is female, regardless of the genotype of the embryo. It takes testosterone to masculinise the foetus. There are cases of foetal insensitivity to testosterone which result in XY babies being born with female morphology.

 

But essentially, prior to masculinisation, all foetuses are the same. They all have the same basic structures, including nipples. Whether or not these structures develop and how they develop depends upon the presence or absence of testosterone.

[Martin]

do male nipples serve a function or are they vestigial? if they don't serve a purpose, does that mean females came before males?

 

Glider and Sisyphus already answered. I just have a non-expert comment

which is that it takes evolutionary WORK to make some organ or process evolve. and that includes actively erasing it (like the legs of a whale)

 

there has to be some selective pressure---even just to make something go away.

 

so for male mammals to have lost all visible trace of nipples there would have had to be some positive survival or reproductive advantage to having less visible nipples (hard to imagine what!)

 

basically I think Nature just says "Why bother?" If there is no pressure, just turn off the hormones and leave males with undeveloped tits.

 

Same way with PENIS AND CLIT

human females have an undeveloped penis which does not perform the function the penis evolved to perform but there would be no evolutionary advantage to it disappearing

 

I think there is a problem with the word "vestigial". It has the connotation of something that USED TO BE THERE but is gradually getting erased by the passage of time.

 

But it is not like women used to have penises and then gradually lost them. THE SAME CELL TISSUE STRUCTURE can develop into a penis or not.

Same way with nipples. So I would not call the male version "vestigial" if that makes you think of some historical development in the course of time.

 

I would rather say developed and undeveloped. Like developed and undeveloped nipples were THERE FROM THE START, if one is talking about human evolution, or primate evolution.

 

If by "vestigial" you mean the undeveloped form of something that exists in both developed or undeveloped versions ----and may have been there at the species beginning---then it makes sense.

[SkepticLance]

With suitable hormone treatment, male breasts can be made to lactate, delivering milk via nipples. This is not truly vestigial.

[JesuBungle]

So I'm thinkin, as soon as their is a nipple-less male mutation(similar to disney films), females will find them more attractive wiping out males with nipples completely:-)

[ecoli]

The default embryonic morphology is female, regardless of the genotype of the embryo. It takes testosterone to masculinise the foetus. There are cases of foetal insensitivity to testosterone which result in XY babies being born with female morphology.

 

Nope, this is wrong. The SRY gene is the cause of male determination in the embryonic stage. Not testoterone.

 

http://www.google.com/search?q=SRY&start=0&ie=utf-8&oe=utf-8&client=firefox-a&rls=org.mozilla:en-US:official

[CharonY]

Actually it is not wrong. You are only argueing on different levels. The proximate cause of sex determination is indeed testosterone. SRY is a transcriptionfactor that leads to the expression of genes which in turn lead to testis formation (and thus, testosterone production).