Clitoris Evolution

It's hard to write a blog like this without seeming a little prurient.  Forgive me, but this is an important question to 50% of the world's population plus the cerca 98% of males that claim to be heterosexual.

How did the clitoris evolve?  Why does it seem so related but separate from the vagina (and therefore direct reproduction)?  Why isn't it in or a part of the vagina?  Is it just a baby penis?


By-Product: Maybe women  have clitorises for the same reason that males have nipples--we share a common developmental template.  You can't change the female mold because the male mold is so necessary for reproduction.  This template crossover is also the explanation of the G-spot, sometimes known as the female prostate.  One possible argument against this line of thinking is that the clitoris has more nerve endings than the penis, thus showing individuation, distinction and possibly selection for.

Imprinting:  Maybe it's current form wasn't shaped so much by successful copulation as it was maturation masturbation.  I would be interested to see a study of women from Sudan and Somalia that were victims of genital mutilation (the ritual removal of the clitoris and vulva) and see how their brains are possibly wired differently.  Though the study would be rife with confounding variables, it could be enlightening to see if there were differences in what they were attracted to and how much they enjoyed vaginal stimulation (as separate from other forms of stimulation).  Would they be wired the same or does the clitoris play a significant sexualization function in humans?

Secondary Stimulation:  Maybe its shape and function is to cause stimulation by pelvic or scrotal thrusting (depending on position).

Nice Guy Hypothesis:  Since I've read that it takes, on average, five months of intercourse to get pregnant, perhaps the women that are more discriminating about sleeping with men that are more foreplay accommodating end up with men that are better spouses and fathers.  Perhaps a man that pleases his woman as she wants also gives more food to his children and is a longer term mate.

In Other Animals:

• Pigs have the clitoris where it makes sense--in the vagina.
• Spotted Hyenas have clitorises as large as their counterpart's penis.  What's more is that they urinate, mate and give birth through it.  It also comes complete with a pseudo-scrotum and fat lumps shaped like testicles.  There are powerful muscles that cause the clitoris to retract in the females, but the shape and awkwardness of the set up still causes 20% of first time female pregnancies to end in the death of the mother.  Some scientists think that the clitoris size wasn't necessarily selected for, but the high testosterone was selected for among the females (it's higher than in males), which, in turn, causes the growth of the hyperclitoris pseudopenis.  

• Spider Monkeys have the largest clitorises among the primates.  It's as long as the males penis, but has the urethral opening down the length of the clitoris creating a long slit.  Studies have suggested that the size and shape of the clitoris aid in the splash distribution of scent signalling urine while the spider monkey moves through the canopy.  

Further:
http://youtu.be/icx5TucPZpw
http://en.wikipedia.org/wiki/Clitoris
http://discovermagazine.com/1992/jun/evolutionofthebi59
http://www.cirp.org/library/anatomy/cold-mcgrath/
http://blogs.sfweekly.com/exhibitionist/2011/09/the_sweet_spot_could_the_clito.php
http://books.google.com/books?id=r56ov450wbEC&pg=PA265&lpg=PA265&dq=evolution+of+the+clitoris&source=bl&ots=oEKX-SH7Xi&sig=o6Rlk5Zlwzt9_vD17eL6dfzaJ5c&hl=en&ei=IWvaTobxN4TnsQLXp7mTDg&sa=X&oi=book_result&ct=result&resnum=9&ved=0CFIQ6AEwCDgK#v=onepage&q=evolution%20of%20the%20clitoris&f=false
http://en.wikipedia.org/wiki/Pseudo-penis

Human Evolution 'Proofs' in Picture Form

The definition of vestigial: It isn't something that has no purpose, but instead something that's primary function is now lost (secondary functions may remain).

Our ears once were gills:

Human Embryos early on have yolk sacs.  Ya, that's right; like an egg.  Weird vestige.

Prior to  birth the human testicle is inside the body cavity and then descends after birth.  The path the testicle takes isn't very logical, however.  http://phylointelligence.com/vestige.html

Males have nipples.  WTF?  By the way, I had the below after running my last marathon.  I always thought it was a wive's tale that got started somehow.  Believe you me.  No it ain't no lie. Must tape next time.  

Tailbones. 

Some of us can still wiggle our ears:

This pointless organ almost killed me, while in other animals it helps break down cellulose.  The appendix:

Apes of 24 chromosomes.  We have 23.  Here's the evidence that two of theirs got fused into one of ours.  Telomeres (chromosome end marks) in the middle of our second chromosome.  Makes no sense except in the light of evolution.

You know that pink corner to your eye?  Ya, it used to be a nictitating eyelid.

Our inverted retina with a blind spot.  Why don't we have an eye like an octopus on the right (we're on the left below)?  Evolution!

Look familiar?

Why the heck do we have canines?  Well, why not because we once needed them!

Goosebumps.  Pointless now.  Used to fluff us up for warmth or display of size.

Inguinal Hernias - Male testes descend from inside the body after birth.  Why aren't they on outside?  Because males and females are made from the same evolutionary template.  Male testes come down from roughly where the female ovaries are (their equivalent) through the inguinal canal.  This usually works fine, but because evolution isn't perfect it sometimes causes some nasty hernias to come through that same hole.  I'll share the most PG of the pictures I found (freaking thing to Google).

http://en.wikipedia.org/wiki/File:Route_of_vas_deferens_from_testis_to_the_penis.png

How do you like that trip above?  Imperfect design!

Olfaction Pseudogenes

We have the genes to smell a ridiculous amount of different molecules, but they've mutated since we don't have strong selective pressure to keep them.  Meaning if you don't smell all that well you probably won't die.

Our body hair faces in directions that would have aided in dripping water off of our quadruped ancestors.  I.e., they tend to face down when on all fours, belly down.

Lanugo

Around the 6th month of develpment humans become covered in a fine layer of hair called lanugo.   This hair is typically shed about a month  prior to birth.  What's it there for?  To show our ancestry!  

Baby Grasping Reflex

Babies have mega grips.  Can even hold their own weight--by one hand!  Why?  To grip momma's monkey hair!

The Clitoris

Why do women have a clitoris?  Because evolution just uses one template for men and women.  No offense, ladies, but basically it's just an underdeveloped penis.  Something similar can be said of the female orgasm.  Hence why so many women are incapable of achieving one--it's a side effect more than it is an adaptation (arguably).

The same thing's true for the g-spot or Grafenburg spot.  It's alternative name is the female prostate, because that's exactly what it is.  It's male anatomical template leftovers (fortunate leftovers, no doubt).

Retard molars.  Well, they used to be good for something.  Now they just help dentists pay for their children's college.

Vitamin C Synthesis

In humans, vitamin C deficiency causes scurvy, and can eventually cause death. We can’t synthesize vitamin C (ascorbic acid), but our relatives, save for the guinea pig and primates, were able to do so. Therefore, it makes sense that we have a vestigial molecular structure, now defunct, that manufactures the vitamin. The gene required for vitamin C synthesis was found in humans in 1994, but it was a pseudogene, meaning it was present but unable to function. The pseudogene was also found in some primates and guinea pigs, as expected. <http://www.divinecaroline.com/22178/67814-seven-evolutionary-leftovers-human-body/print>

Pharyngeal Nerve - the set up of this nerve is a throw back to our fish past.  In fish this nerve takes a direct route from the brain to the area equivalent to our larynx.  The body plan has changed significantly, but the wiring hasn't.  Since our aquatic days, evolution has pushed our heart down and moved things around so that the nerve that used to be a direct shot now goes right past the larynx (its intended destination), loops around the aorta and back up to where it belongs.  This evolutionary throw back is laughably exaggerated in the giraffe that has a pharyngeal nerve that goes something like 15' out of the way.

Jacobson's Organ

"Jacobson’s organ is a fascinating part of animal anatomy and it tells us a lot about our own sexual history. The organ is in the nose and it is a special “smell” organ which detects pheromones (the chemical that triggers sexual desire, alarm, or information about food trails). It is this organ that allows some animals to track others for sex and to know of potential dangers. Humans are born with the Jacobson’s organ, but in early development its abilities dwindle to a point that it is useless. Once upon a time, humans would have used this organ to locate mates when communication was not possible. Single’s evenings, chat rooms, and bars have now taken its place in the process of human mate-seeking." -- http://listverse.com/2009/01/05/top-10-signs-of-evolution-in-modern-man/

Plantaris Muscle

"The plantaris muscle is used by animals in gripping and manipulating objects with their feet – something you see with apes who seem to be able to use their feet as well as their hands. Humans have this muscle as well, but it is now so underdeveloped that it is often taken out by doctors when they need tissue for reconstruction in other parts of the body. The muscle is so unimportant to the human body that 9% of humans are now born without it." -- http://listverse.com/2009/01/05/top-10-signs-of-evolution-in-modern-man/ 

Darwin's Point -   plica semilunaris 

Darwin’s point is found in the majority of mammals, and humans are no exception. It is most likely used to help focus sounds in animals, but it no longer has a function in humans. Only 10.4% of the human population still has this visible left-over mark of our past, but it is possible that a much larger number of people carry the gene that produces it as it does not always cause the ear tubercle to appear. The point (shown in the picture above) is a small thick nodule at the junction of the upper and middle sections of the ear.  -- http://listverse.com/2009/01/05/top-10-signs-of-evolution-in-modern-man/

Why do we shed our baby teeth?  It's incredibly metabolically wasteful.  The likely answer is that our reptilian ancestors shed their teeth throughout their lifetime to always have a sharp, full set.  We just do it because the genes are leftovers and can't easily be shaken.

Toe nails

You could say they're there to protect the toe from stubbing, but then why aren't they on the ends?

Sweat Glands

The placement of sweat glands on our body suggests that we once quadrupedal.

http://io9.com/5984591/you-probably-dont-know-how-many-holes-are-in-your-body-right-now

Scapula

The shape and placement of our scapulas show that our ancestors were tree climbers.

   

Maxillary Sinuses

The opening to drain is on the top of the sinus, perfect only if you walk on all fours.  Like our ancestors.

http://link.springer.com/chapter/10.1007%2F978-1-4020-9980-9_7?LI=true
http://www.springerimages.com/Images/LifeSciences/1-10.1007_s10764-010-9399-1-5
http://www.sciencedirect.com/science/article/pii/S0047248407001170
http://www.sciencedirect.com/science/article/pii/S0031940605606050
http://www.answersingenesis.org/articles/2012/11/17/news-to-note-11172012
http://www.antiquityofman.com/ape-human.html



LET'S KEEP ADDING TO THE LIST!!!