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

"Mudita - The Fine Art of Enjoying Others" Sermon Audio Delivered 10/23/2011

Below is the link to the audio of the sermon that I delivered at the Unitarian Universalist Church of Tallahassee on 10/23/2011.  Transcript here: http://thesymbiont.blogspot.com/2011/10/mudita-and-fine-art-of-enjoying-others.html

https://docs.google.com/leaf?id=0B4a-CcAjSGDSYzA4NGE5MGEtNzA2Zi00YWYxLWE5NmItNjJlZjJkNzliMjg2&hl=en_US

Symbiosis - Sermon by Painting

This painting is a sermon.  It’s the foundation and basis for how I think about morality, how I struggle to live and essentially my worldview.  Captured best by the Bible quote, “It is more blessed to give than to receive,” symbiosis, or the living together of two different organisms, provides tangible evidence of sorts that cooperation works.  In fact, put better, that cooperation out competes competition.  Far from nature being a ruthless typification of, “Red in tooth and claw,”  these six panels highlight the generosity and love woven throughout life. Explanation of the six panels provided below (from left to right starting with the top row):  

1. Gaia (the Greek goddess of the Earth) is the idea of thinking of the Earth as one massive self-regulating, cybernetic organism.  This idea is also combined with a concept that life promotes life.  E.g., a tree existing in a field makes it possible for squirrels to live in its branches, eat its nuts, birds to nest in it, wasps to pollinate its flowers, the shade provides a moist microclimate for fungi and other plants, etc.  Life promotes life.  Because the tree exists a multitude of life is possible.  The other classic example from the book Gaia by James Lovelock is our atmosphere.  Because life has come before us our atmosphere now is composed of 21% oxygen (a by-product of photosynthesis), 78% nitrogen (a bacterial byproduct) and .0039% carbon dioxide (removed from the atmosphere by photosynthesis).  Without life having proceeded us to make a hospitable atmosphere we'd have a very, very similar atmosphere to our nearest neighbor Mars--95% carbon dioxide (runaway greenhouse).  Life has made our life possible--Gaia.

2. The second panel is about endosymbiosis, which is the concept that the mitochondria within our bodies, who essentially power our body by the production of ATP, are former bacteria.  This should truly hit you if it hasn’t before--the best science out there says that you aren’t one organism.   You’re the combination of at least two different critters that have become so mutually dependant for the last 2 billion years or so that we’re inseparable now.  Evidence for this can be seen that mitochondria has its own set of DNA (a plasmid just like bacteria, which is very important for phylogenetics), that they divide just like bacteria (which is why it’s important for genetics; it passes uncombined with another sex cell from the mother’s egg cell.  Meaning you only have your mother’s mitochondria, not your father’s.), they have peptidoglycan cell walls like bacteria and so on and so forth--basically they are *just* like a bacteria.  Billions of years ago an anaerobic bacteria (“us”) combined with a aerobic bacteria (our mitchondria) to create a cell that could survive in either condition.  We teamed our forces and made all complex life, including us, possible.  Go cooperation!

3. The next panel highlights how we’re a host for bacteria.  I’ve seen vastly varying numbers, but one source said that humans are generally composed of somewhere around 10 trillion cells.  Guess how many bacteria cells you have on and in your body?  Around 100 trillion!!  So, not only are you the combination of at least two different bacteria, but by cell count you are 10 times more actual bacteria than human!!!  Why?  Because that bacteria, generally speaking, majorly benefits us by breaking down organic matter that our body isn't good at breaking up--you can thank bacteria for helping digest carbs, proteins and fats as well as producing essential vitamins like vitamin K and many B vitamins.  We depend on trillions of other organisms just to eat.

4. Maybe around a billion years ago life had a great idea.  Let’s not just cooperate in energy production (endosymbiosis) and structure/division of labor (multicellularity) but also genetically--thus sex was born.  By combining genes the best of one organisms genes can be put with the  best of another’s.  Contrast that with bacteria that mostly evolve through random mutation--which is more often than not quite deleterious.  We sexually reproducing organisms survive and evolve by teamwork.  We pool the best of what we have and create something even better--synergy.

5. The 5th panel highlights the interconnection of our foods--the substances that make our survival possible.  Plants cooperate with bugs to transport their DNA to reproduce in exchange for a tasty, nutritious treat of pollen/nectar.  That’s why flowers exist.  Their beauty is a physical display and celebration of cooperation.  The same is true for fruit. Fruit exists to give nutrition in exchange for seed dispersal.  

6. The final panel focuses on the love of a mother and child.  From a biological perspective that mother needs the child to pass on her DNA and the child needs the mother for nutrition and socially relevant information for future reproduction and survival.  From an experiential perspective the two experience a level and power of connection and love unrivaled in the universe.

The Bible speaks truth--it is more blessed to give than to receive.  Why?  Because it works.  The winnowing pragmatism of evolution proves it.  If we try and live our lives in defiance of this truth we only hurt ourselves.  Cooperation out competes competition.  We ought to make this the basis of every relationship, government, family, economic system.  It works.  To paraphrase Ben Franklin, we shall hang together or surely we shall hang apart.

Spider Pictures - A Celebration of 200 Million Years of Engineering

Here are some pictures that I ferreted out to make a power point presentation for a Halloween themed science camp.  Enjoy. :)