My understanding of the requirment for externalization of the testes is that it is nessecary for healthy sperm manufacture to keep the temperature slightly lower that that of the body
There really isn’t any room for the penis in the abdomen. Where would it go? Unless penises were tiny (and therfore on average worse at impregnating females), they would take up vital space in the abdomen used for storing other organs. This might also make men less efficient runners and hunters.
On a side note, I think I heard on a nature show that gorillas have tiny penises, but compensate for this by having tons of semen that shoots out fast. Maybe its safer to have a smaller penis – less change of getting it snagged on a bush.
I suppose there are an infinite possibilities for sexual equipment positioning and type, like it does not necessarily have to be between the hind legs like it is in all species, but it is.
Since all species, including humans, fight with their front end, the reproductive equipment is away from the action and protected. It is also in a good position for couples mating to keep their defensive ‘ends’ away from the action and on the lookout for any approaching danger. I mean, some animals blow their wad in like 30 seconds. Chances are humans used to be similar in speed because of a dangerous environment – at least until the pleasure part of it kicked in for all year long.
As a little point here, the female reproductive organs are very well protected, essentially self cleaning and very durable. The male equipment is actually as tough as the female’s – for the penis can take quite a bit of abuse. However, the testes are the weak point. (As all of us men know all to darn well.) Perhaps that is why there are two testicles. A man can loose one and still breed, get the hormones he need to be aggressive and to function normally.
A side point here: It takes more radiation to sterilize a man’s sperm than it does to kill him. By the time any radiation knocks the boys off, the owner is finished and won’t care anymore.
As others have noted, there really is no problem with it being too exposed. It’s a false assumption that the penis is in a vulnerable position.
I mean, here are 6 billion of us running around. I’d say it’s protected well enough that it hasn’t made any evolutionary difference.
Just to ket you know you’re not alone, Mr Lunasea has a “Turtle.” I was so surprised the first time I saw him flaccid I said “Damn, man where did it all go?”
Back to the OP: I would guess that Homo Sapiens evolved to have a more prominent penis for the same reason that women have evovled to have prominent breasts. Bigger penis=more fertile, bigger breasts=more fertile (as in already breastfeeding a child.)
PLease not that this is a WAG.
::Flogging myself for typos::
Since no one else has, I would like to say that Keeve’s post near the beginning is a very interesting idea. Though I don’t think that the (flaccid) penis is vulnerable enough to sustain serious damage in everyday early man life, I think his point might be an explanation for the exposed testes. (Other than the heat regulation thing)
Once again, I’d like to thank all the posters. I’m starting to get a coherent picture of the penis in my head. [insert joke here]. However, I’d like to keep this thread going for two reasons.
First, one thing that has come up here is that the true need for male external genitalia is the testes, which need to be external so that the sperm don’t roast. Well, which moron in the R&D department of Evolution, Inc. decided to design sperm that aren’t heat resistant? Fartrekker argues that human sperm is more susceptible to heat b/c they are more complex than animal sperm. Which all due respect, Trekker (and I liked the rest of your posts), I ain’t buying this one. Humanity is too closely related to other animals (e.g. sharing 98% of our DNA with chimps) for me to accept that our sperm is somehow special and more complex.
The obvious answer for sperm needing lower temperatures is that sperm, unlike most of the rest of human cells, is motile, and their flagellum mechanisms are delicate. But, aren’t there various and sundry motile unicellular organisms who **can[/] survive internal human body temperatures? My first thought is that there are parasites in our bodies right now who are motile.
So, any thoughts on this?
Sua
P.S. The second reason for keeping the thread going is so it can reach 1000 views, all because I used the word “penis” in the subject line. heh heh, heh heh.
[QUOTE]
*Originally posted by Dr. Lao *
**
Uh, John Wayne Bobbit? I know it was re-attached, and “performed” (in those porn films I heard he was in) but was he fertile? (Here’s hoping NOT! Darwin & all.)
Or how about that guy in the news a while back who cut off his own? (I’d search for a cite, but I don’t think the company network would appreciate me searching for “cut-off penis”.) My guess is he’s infertile from trauma to his penis.
P.S. to Dr. Lao-
I appreciate your point.
Just visualize my previous post
with a winky smilie at the end.
Human sperm is not “more complex” – the temperature issue is just that and shared with other warmblooded mammels. Our equipement is a rather exageratted form looking quite like other primates including our close, close relatives, the chimp.
Wait. Birds are warmblooded. In fact, their body temperature is higher than ours. Yet, their testis are internal. Areodynamically, it makes sense. Also, what is this about human sperm being “more complex”? That is news to me.
I don’t think that there is any evolutionary reason why mammals’sperm needed lower than body temperatures to survive; but once it evolved that way, it cannot be changed. But why DID testicles evolve outside the body, then?
“From whence” is redundant.
Continue all penis discussion now, please.
I have to giggle at the notion that females would be attracted to a guy walking around with an erection. Penises, for all their versatility, aren’t the most attractive appendages around.
Trust me, there’s nothing more sexy than a guy with a smooth, defined body…and a pair of boxer shorts!
Penises are just fine where they are & how they are, it’s the stupid hips that came in undersized yousee, unable to protect it.
Trust me, there’s nothing more sexy than a guy with a smooth, defined body…and a pair of boxer shorts!
**
[/QUOTE]
Damn straight, PunditLisa! 
I love guys to death, but thank God the penis is aaall the way down there! I always thought of it as a way to get off, not something to look at…
I can think of fewer things more true than Dr. Lao’s statement, “There are huge advantages to having a penis.”