Monday, October 05, 2015

Why do men have nipples?


i) Darwinians sometimes taunt creationists with the question: Why do men have nipples? They seem to think that's inconsistent with creationism. Perhaps they think Christians are embarrassed by discussing nipples. 

ii) To begin with, it's not as if there's a good evolutionary explanation. Male nipples have no survival value.

And it makes no sense to say male nipples are vestigial organs. Even on evolutionary grounds, it's not as though men evolved from mammals that were exclusively female. Even from an evolutionary standpoint, mammals were always sexually differentiated. For that matter, so are reptiles, from which mammals allegedly evolved. 

iii) To my knowledge, the reason men have nipples is because men and women share the same basic underlying design. Our bodies have most things in common. Engineering is conservative. 

Sexual differentiation is due to sex chromosomes and male or female hormones. But that leaves many underlying structures intact. 

Even in sexually mature adults, if you administer male sex hormones to women or female sex hormones to men, they develop some characteristics of the opposite sex. 

iv) Sexual arousal is based, in part, on touch. Because male nipples have nerves, that's an "erogenous zone." So it's not useless. 

v) It's sometimes said that all humans begin as female in the womb, but that's simplistic. The male or female DNA is present from the get-go. 

vi) Finally, lactation is a remarkable process. We think of animals as food. And trees produce food. But for animals to produce food is rather remarkable, if you think about it. Women have a whole little factory for producing a vital food stuff. 

6 comments:

  1. Steve made several good points.

    A few further thoughts:

    1. Why stop at asking why men have nipples? Why not go further? Why not ask, for example, why women have two nipples when one may do just as well?

    After all, suckling on one breast can cause milk flow not only in that breast but also in the other breast, whereas having a single nipple or breast could presumably prevent this secondary milk flow, make the whole nursing process more efficient, make the mother less uncomfortable with potentially leaky breasts, etc.

    2. Also, maybe men having nipples isn't really the main issue. Presumably the main issue is why men have nipples if they don't lactate.

    a. If so, this assumes lactation is the only function of the nipple. But there are other functions like Steve pointed out (e.g. sexual arousal).

    b. In addition, the areola around the nipples have sweat glands.

    c. The nipples of both men and women are highly vascular. There are a lot of blood vessels (e.g. arteries, veins) in and around the male and female nipples.

    Maybe an evolutionist could argue if men didn't have nipples then there wouldn't need to be blood vessels in the nipple area.

    However, we could argue, if these blood vessels didn't exist (or were re-routed), then would their non-existence effect other aspects of the body?

    d. Not to mention there are lymphatic vessels in and around the nipple.

    e. I suppose the main point of all this is we shouldn't consider the nipple in isolation, but as part of a bigger picture (e.g. the nipple is part of what's known as the nipple-areola complex).

    3. I completely agree with Steve's fifth point:

    "v) It's sometimes said that all humans begin as female in the womb, but that's simplistic. The male or female DNA is present from the get-go."

    Just to briefly elaborate:

    Genetic sex is normally determined at conception i.e. XX (female) or XY (male). There's a gene on the Y chromosome called the SRY gene which induces a male phenotype. Without the SRY gene, a female phenotype develops. So, the female phenotype (not genotype) is the default, but the male phenotype (not genotype) requires the SRY gene.

    In short, genotypes are normally fixed at conception, whereas phenotypes differ depending on the presence or absence of the SRY gene (among other things; I'm simplifying here).

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  2. After reading the title of the blogpost I decided to think of reasons on my own to compare with what Steve and others would write. The following are some reasons I came to in the order I though of them. One of them turned out to be an answer Steve gave.

    1. In God's eyes male nipples might be more aesthetically pleasing that no nipples. I'm sure some humans agree. God doesn't just design for survival purposes. God is an artist and isn't limited to "functionality" in that sense.

    2. Nipples are "erogenous zones: as Steve also pointed out.

    3. Nipples can ensure a sense of commonality between the sexes. I'm reminded of the Star Trek TOS episode where there was racism and discrimination within a species because some had white and black faces on opposite sides. Similarly, if men didn't have nipples that might have caused discrimination for or against males or females. "You HAVE nipples, hah hah!" Or, "You DON'T have nipples, hah hah!"

    4. There's (more than?) anecdotal evidence that human males can breastfeed. If true, then the whole atheistic objection falls to the ground.

    http://www.scientificamerican.com/article/strange-but-true-males-can-lactate/

    Here's a YouTube video: https://youtu.be/DiXp_See_Bs

    rockingwithhawking wrote: d. Not to mention there are lymphatic vessels in and around the nipple.

    If that's true, then male nipples may preserve a function of the immune system that fights off infection.

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    1. Annoyed: If that's true, then male nipples may preserve a function of the immune system that fights off infection.

      I don't know. I caught a bad cold this past weekend, and my nipples seemed to be just as useless as always.

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    3. Their immunological usefulness may be in conjunction with other bodily organs & functions, thus making it difficult to single out their unique contribution. So, without further investigation, one can't definitively say they're udderly useless.

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  3. I always thought it had to do with symmetry. Nature has tons of symmetries. We divide live into bilaterian and non-bilaterian life. Why wouldn't a designer who like symmetries not do it with in the sexes? Women have nipples, men have nipples. I always though this question was kind of dumb.

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