I don't know about God, but orgasm does seem to work in mysterious ways. Many men may find women puzzling but what has puzzled everyone, including scientists, psychologists, politicians, religions, and even feminists over centuries, is the phenomenon of the female orgasm.

Female orgasm, what purpose does it serve?
Image | by efes | CC0

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Do vaginal orgasms exist? What the hell is G-spot - an erogenous zone or a fairy tale? A lot of debates revolve around this phenomenon. But the most interesting of all is - why does female orgasm even exist? What function does it serve? Is the female orgasm a by-product of the male orgasm, a remnant of evolution from ancestors, or we are just plain wrong about the assumption - that it not has no adaptive value, whatsoever?

If you were to ask the same question about male orgasm, the answer is pretty clear. It exists as a reward for intercourse. It motivates men to pass on their genes. While the same answer might make sense for women, many men were dazzled by the 10% to 20% of women who just can't orgasm, no matter how hard these men tried (yeah, we believe you) ₁.

Anyway, moving on. Even among those who do experience orgasm, not every woman is able to have an orgasm by penetrative sex and often require external clitoral stimulation. However, like males, does this ability or inability to achieve an orgasm, have an effect on reproductive success of these women? If not, then what is the purpose of female orgasm? If it even has one. Let's analyse all the possibilities one by one, and let's see if we can make sense of orgasms, any better than people have until now.

Does orgasm increase chances of conception?

A question that many biologists have raised is whether female orgasms have a direct biological function. For instance, the male orgasm facilitates ejaculation, so what does a female orgasm do? A few studies did claim that the uterine contractions created by oxytocin surge during the orgasm, have an adaptive role. According to them it creates an in-suck force which causes faster transport of sperm. The faster transport will then increase the probability of conception.

However, Levin in 2011₂, critically analysed this hypothesis and concluded against it. At least until 2011, there seemed to be no strong evidence of faster transport of sperms being facilitated by orgasms. Neither could I find anything conclusive today in 2018. Also, it would rather be counterproductive to accelerate sperm transport. Not only will it reduce sperm competition, but the increased chance of polyspermy would actually be maladaptive.

However, Levin might have missed the point by focusing only on one pathway by which female orgasm could facilitate conception. So Zietsch and Santtila, in 2013₃, rather looked at a different readout for this. They correlated the number of offspring a woman had, with her orgasmic life. Turns out there was a weak but significant correlation between these variables. However, they failed to find this correlation at genetic level. Implying that environment might have had a role to play in this correlation. But before we head in this direction, and conclude from this, I want to consider the following question - is ability to orgasm itself genetic?

The genetics of orgasms and of failure to have them.

Anyway, before using an evolutionary lens on a trait, we first need to determine if that trait has any genetic basis at all. While the ultimate way of knowing that is pinpointing the genes that are involved, it becomes hard to do in the case of multigenic traits. The old school method of twin studies, comes handy in here. So you take women's ability to orgasm and compare them between identical or monozygotic twins and dizygotic twins. Since monozygotic twins share 100% DNA while dizygotic share only 50%, the genetic contribution of a trait should be visible in this comparison. Dunn et al., in 2005 ₄, conducted this study which demonstrated that variation in ability to orgasm has genetic basis. Also we must consider the fact that female sexual expression have increased in the last century, but this did not increase the ease of orgasm for women₁₆. Hence, socio-cultural inhibitions alone do not explain why so many women have never experienced an orgasm. So there is indeed something going on at a biological level, as well. And, I am curious to know what it could be.

Nonetheless, in recent years, after we have sequenced the genomes of so many people, it has become relatively easier to explore the multigenic traits. These studies called Genome Wide Association Studies, or GWAS have also explored the genes involved in orgasms. Burri et al., in 2012₅, studied this database and implicated serotonin and GABA neurotransmitter pathways in female sexual dysfunction. We will come to GABA later, but the serotonin link is rather interesting.

You see, serotonin is famous for its role as an inhibitor of sexual desire and even orgasm₂₂. Take example of selective serotonin reuptake inhibitors(SSRIs), such as prozac, a common antidepressant. The lack of serotonin signalling between some neurons is associated with depressive disorder. This may happen if either the ammount of serotonin secreted by the neuron in the synapse(the point where two neurons interact) is too low, or it's cleared of faster than required by being retaken into the neuron that secreted it, or because the receiving neuron is desensitised to it. So if a drug blocks the reuptake of serotonin back into secreting neurons, this will increase its concentration in synapse and increased concentration is able to counter all three issues mentioned. However, it so happens, that if serotonin is not cleared from the synapse reaching climax becomes really hard. Like you will be there but it just wont transition. Hence it is not really surprising that SSRIs, also hinder ability to experience orgasm in some people₆. Now, imagine having a hypersensitive receptor allele in some women, that would possibly explain why some of them have a hard time climaxing.

So we saw that genetics plays a role in orgasms. We also saw an example of how serotonin pathway and variation of genes in this pathway may explain variation in ability to orgasm. But hold yourself right there, we haven't reached climax yet. Well because it seems that males may need similar pathways to orgasm as well. Which makes us question if male and female orgasms are even all that different, anyway?

Is female orgasm a by-product of male orgasm?

Well according to Llyod₇ and many other researchers, male and female orgasms are quite likely the same. The fMRI and PET scan voyeurism, looking at brains of people having orgasm, revealed that orgasm isn't sexist at all. The brain scans of people having orgasms in those machines reveal that your entire brain goes nuts during the orgasm. More importantly, it is hard to tear apart male brain and female brain on orgasm, they looks the same₈.

However, yet again all this seems to go in favour of Lloyd, who claimed that female orgasms are a by-product of male orgasms. According to her, males are rendered sexually dysfunctional if they don't orgasm. And since evolution has no reason to actively select against female orgasm it just hangs in there, without any selection pressure. Which may explain the variation in ability of women to achieve orgasm. There is no positive selection pressure since it confers no advantage to females, but there is no negative pressure as well. I mean, why would it be negatively selected for, if anything, it feels good.

Female orgasm as an evolutionary leftover.

From the perspective of embryonic development, male penis and female clitoris arise from the same tissue. So one more point in support of Lloyd. Except that clitoral stimulation seemed to have a function of its own in evolution. In many mammals such as rabbits the clitoral stimulation is important for inducing ovulation. And it appears that induced ovulation precedes the automated cycle of ovulation in other mammals and menstruation cycle in humans. Based on this Pavlicev and Wagner in 2016₉, proposed that female orgasms are rather a leftover in evolution, than merely being a by-product. They suggest that as clitoral stimulation became less important in evolution, the clitoris moved away from vaginal opening. Now this may explain why many women need extra stimulation other than penetrative sex to reach the climax. Or why masturbation works better than intercourse for many others. Nevertheless, this still isn't the complete story.

The catch here is that not all orgasms arise from clitoris. On one hand, where the brain scan of orgasms look so similar, on the other it seems that stimulation of different areas - clitoris, vagina, cervix and nipples stimulates different parts of the female brain_{10, 11}. In fact women with spinal cord injury whose brains are disconnected to clitoris can still have vaginal orgasms, via Vagus Nerve Bypass Pathway₁₂. Oh, and then there are those who can think themselves to orgasms₁₃, seriously what's up with them? So that kind of bursts the bubble of clitoris-only orgasms. And if there is no purpose of having orgasms in women why are there so many paths leading to it?

Of labor pain killers and orgasms.

You know, what else lights up in the brain scans of people having orgasms in those fMRI or PET scan machines? The pain centres₈ . But not to induce pain. Remember that GABA neurotransmitter I told you about above. It is an inhibitory neurotransmitter. And it appears that activity in these regions of brain involved in pain, is coming from inhibitory GABAergic neurons. It looks like orgasm is shutting off the pain pathway. Also, in agreement with brain scan is surge of endorphins during the orgasm. Endorphins are endogenous opioids of the body. Let's just say that it is the poppy milk or morphine that your own cells make, to soothe your pain. The pain reducing hypothesis of orgasm is also supported by researchers trying to poke and hurt people while sexually stimulating them. Looks like the pain threshold is pretty high in people having an orgasm and especially if they are having a vaginal orgasm. But what pleasurable orgasms have to do with pain?

Think for a moment what is important for those selfish genes in your cells? A newborn offspring, or worries of worldly problems and even physical pain? They don't care about your survival but they care about your baby, and they also make sure you care for the baby too. So orgasm might be an ultimate state where no pain and no worries exist. Comes handy during conception, but might be even more handy if you can reduce pain during child birth. So, orgasm might be an extrapolation of pain and worry free brain in ecstasy. Stimulation of cervix, vagina and even the pressure on internal legs of clitoris from head of the baby may work together in easing the delivery. ₂₁. Take this to the context of intercourse; Simultaneous stimulation of these parts during the mating seem to induce much more intense orgasms than stimulation of any one of them alone. Maybe, orgasms are just exaggeration of pain reducing function and muscle spasms required for giving birth. Maybe, the pleasure part is just a spandrel (a kind of side benefit, that by itself has no evolutionary purpose).

From the eyes of Evolutionary Psychology

But hang in there for a second. Pleasure is a result of a reward pathway being activated. In fact, the decoupling of clitoris with ovulation may have freed the associated pleasure to find a new job. If you slow down for a moment and recollect what we learnt until now, we saw -

• The ability to orgasm has genetic basis.
• There is no evidence for a direct biological function of orgasm.
• At least clitoral stimulation seem to be an evolutionary leftover.
• Oxytocin and prolactin surge during orgasm.
• Orgasm tend to increase pain tolerance.
• The pleasure associated with orgasm is a reward.
• Even though there was no genetic correlation between number of offsprings, there still exists a significant correlation between having orgasms and number of offspring (probably environmental).
• Some women can orgasm by just thinking about it.

Orgasm - a reinforcer that makes relationships happy

**Orgasm as a social bond catalyst for relationships? **
Image by mores345 | CC0

The last point might be indicating a psychological adaptation of orgasm. In fact, there seemed to be no difference in brain scans of women physically stimulating their body parts vs women who just thought about stimulating them₁₄. This may also explain why a trait with genetic basis, did not correlate with number of offspring parameter at genetic level. So what if female orgasms rather act on female psychology and their relationships than acting directly on reproductive system?

Orgasm as a signal of better mate and better bonds?

Well to understand how much do women value their orgasms, I went ahead and asked my female friends. Apart from them answering that it is a reinforcer to have more sex with their partner, they also said something really interesting. They said that, it made them feel more bonded with their partners.

Their answers were in line with many other surveys conducted in literature. In most of these surveys you will find that while orgasm might not be "the thing" for most women valuing their relationship; however women who had orgasms reported higher satisfaction and happiness₁₅.

In fact another view about female orgasm is that it acts as a mate choice mechanism₁₇. Many women report a higher tendency to achieve orgasm if they feel strongly for the guy. Or maybe they feel strongly for a guy they have orgasms with. Either way, it appears like a positive reinforcement loop₁₆. And then it is common sense, that a stronger bond between parents is definitely healthy for child rearing. Also, in support of this, we saw that oxytocin and prolactin, the hormones famous for bonding and love, surge during orgasm. I think we totally need to explore this possibility as one of the adaptive functions of pleasure associated with sex. After all, we are not the only animals who might be using sex for improving social bonding. Bonobos, our close cousins literally have sex with everyone in their group to build a nice friendly environment. Be it homosexual or heterosexual act. Bonobos do it and it keeps everyone happy and bonded₁₈.

But hey what's up with human penis size being largest among all mammals? My friend thinks that females sexually selected large penis sizes because large penises are more efficient in giving orgasms. Well, she might not be wrong₂₃. Women could definitely find vaginal orgasms sexy and pick mates that are more efficient at providing them.

Sexy sons will pass on my genes.

In this regard, another angle to mate selection is given by sexy son hypothesis. It states that women choose men who have traits of proven reproductive success. Hence, sexy. So if they conceive babies of sexy men, they will have sexy sons who would pass on her genes more efficiently. For instance, older men have proven that they will live longer and hence they are sexy. Because if sons live longer as well, they will have much more chances at passing on her genes. Maybe it is something similar with women liking men capable of giving them orgasms. Because if their son can give orgasms to other females, he will not only be favored more, but will also have a more loving relationship, with healthy kids, who will grow up in loving environment. Or maybe women just have higher tendency to have orgasm with "sexy fathers", that will be males who are also adored by other females₁₉

In the game of mate selection woman may have more strategic cards in their hands.

However, my friend Arathi doesn't agree with the fact that women are even least concerned about passing on the genes. She says that what women look for in a man is a secure and stable relationship. Like women know reproduction is always an option for them, there is more supply of sex on the table than demand. But then is reproducing with this guy worth it. Will he be there to take care of her and provide for her offspring. Why should I waste time on this particular guy? So according to her taking care of her needs in bed is a signal that a woman can use to pick this fellow. But then again why this fellow? Probably because a more nurturing partner improves the well being of offspring. Which again boils down to passing on genes.

I think, what we are seeing here is not one but multiple strategies for mate selection. For instance, Arathi's ideas are in line with fact that a good part of women who don't get orgasm with their partners still report feeling satisfied with relationship. A study₂₄ in 2014, reported that post sex affection such as cuddling can have a positive effect on relationships, as well. So in my opinion, the variability you see across studies about female orgasm is not because, it is a byproduct or a mere leftover from ancestors. This variability probably exists because there are redundant, multiple strategies for mate selection in females. And these strategies don't appear to be mutually exclusive. But then there remains one doubt in my head. Why do some women have to fake orgasms?

Things I do for love - like faking orgasms.

Yet another point in favor of female orgasm as behavioural adaptation for mating, comes from men feeling proud to be capable of giving orgasm to women. Even my friends I discussed the topic with told me that they have faked orgaam at one or more points. Their intention purely being to give ego massage to the guy they were with. Fake orgasms don't only make a huge market commercially, but it appears that many women fake orgasms in relationships. Many say they do that to keep the relationship live and kicking. More like a partner retention behaviour₂₀. So pleasure of orgasms in humans seem to be a positive reinforcement, not only for a person having an orgasm, but also for the partner of this person.

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I know it is really hard to understand and fully solve the mystery of the human orgasm, especially the female one. And it will be yet harder to test if it is adaptive at behavioural level. But it is totally worth the shot (oh come on, there was no pun intended here, seriously!).

Steembasicincome giveaway

Anyway, do you have an alternative explanation for the role, existence and evolution of female orgasm? Do share in comments. I will give 1 SBI share to at least 4 unique and interesting ideas. Just think in terms of evolution.

Science, society and scientific temper initiative - Promoting steemit, steemstem, and scientific-temper.

This post is a result of social media discussion I initiated on a Facebook group - The Progressive Indians (TPI). This is my first experimental attempt at promoting scientific temper in society. The idea is to reward the significant contributors to the discussion for bringing logic to the table, with their ideas. I did intentionally choose female orgasm as topic for first attempt, because what else would make everyone eager to participate? And then isn't everyone an expert on this topic (wink). So I will distribute the reward generated in steem and sbd (but not SP), between all contributors in fiat currency. If this experiments works out I will be doing more such topics.

Apart from promoting scientific temper, this is also my attempt to promote steemit and have more of my friends join it (I hope they do enjoy and join it). And of course since a lot of my friends are researchers in different fields it also gives me a window to expose them to yet another steemstem post. And why not? steemstem is going mainstream and these guys could really contribute if they choose to.

List of contributors who gave valuable insights during discussion on social media.

1. Arathi Cherian (Artist and designer)
2. Sussane Ling (A master student in physics)
3. Rudra P Singh (An undergrad science student)
4. Ayush(Artist and designer)
5. Debjyoti Bardhan (Physicist)
6. This one wants to remain anonymous.

References

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2. Levin RJ. Can the controversy about the putative role of the human female orgasm in sperm transport be settled with our current physiological knowledge of
   coitus? J Sex Med. 2011 Jun;8(6):1566-78. doi: 10.1111/j.1743-6109.2010.02162.x. Epub 2011 Jan 6. Review. PubMed PMID: 21210957.

3. Brendan P. Zietsch, Pekka Santtila, 2013 No direct relationship between human female orgasm rate and number of offspring, Animal Behaviour, Volume 86, Issue 2, Pages 253-255

4. Dunn KM, Cherkas LF, Spector TD. Genetic influences on variation in female orgasmic function: a twin study. Biology Letters. 2005;1(3):260-263. doi:10.1098/rsbl.2005.0308.

5. Burri A, Hysi P, Clop A, Rahman Q, Spector TD. A Genome-Wide Association Study of Female Sexual Dysfunction. Huang Q, ed. PLoS ONE. 2012;7(4):e35041. doi:10.1371/journal.pone.0035041.

6. Higgins A, Nash M, Lynch AM. Antidepressant-associated sexual dysfunction: impact, effects, and treatment. Drug, healthcare and patient safety. 2010;2:141-150. doi:10.2147/DHPS.S7634.

7. This is what your brain looks like during an orgasm
   By Joseph Stromberg on April 1, 2015.

8. The Case of the Female Orgasm Bias in the Science of Evolution by Elisabeth A. Lloyd

9. Pavličev M, Wagner G. The Evolutionary Origin of Female Orgasm. J Exp Zool B Mol Dev Evol. 2016 Sep;326(6):326-337. doi: 10.1002/jez.b.22690. Epub 2016 Jul 31. PubMed PMID: 27478160.

10. Komisaruk BR, Wise N, Frangos E, Liu W-C, Allen K, Brody S. Women’s clitoris, vagina and cervix mapped on the sensory cortex: fMRI evidence. The journal of sexual medicine. 2011;8(10):2822-2830

11. Pfaus JG, Quintana GR, Mac Cionnaith C, Parada M. The whole versus the sum of some of the parts: toward resolving the apparent controversy of clitoral versus vaginal orgasms. Socioaffective Neuroscience & Psychology. 2016;6:10.3402/snp.v6.32578. doi:10.3402/snp.v6.32578

12. Komisaruk BR, Whipple B, Crawford A, Liu WC, Kalnin A, Mosier K. Brain activation during vaginocervical self-stimulation and orgasm in women with complete spinal cord injury: fMRI evidence of mediation by the vagus nerves. Brain Res. 2004 Oct 22;1024(1-2):77-88. PubMed PMID: 15451368..

13. Thinking Yourself To Orgasm Could Boost Feelings Of Well-Being by Helen Thomson.

14. Wise NJ, Frangos E, Komisaruk BR. Activation of sensory cortex by imagined genital stimulation: an fMRI analysis. Socioaffective Neuroscience & Psychology. 2016;6:10.3402/snp.v6.31481. doi:10.3402/snp.v6.31481

15. Nathan D. Leonhardt, Brian J. Willoughby, Dean M. Busby, Jeremy B. Yorgason, Erin K. Holmes,
    The Significance of the Female Orgasm: A Nationally Representative, Dyadic Study of Newlyweds' Orgasm Experience, The Journal of Sexual Medicine, Volume 15, Issue 8, 2018

16. Kontula O, Miettinen A. Determinants of female sexual orgasms. Socioaffect Neurosci Psychol. 2016 Oct 25;6:31624. doi: 10.3402/snp.v6.31624. eCollection 2016. PubMed PMID: 27799078; PubMed Central PMCID: PMC5087699.

17. Wheatley and Puts, 2015 Evolutionary Science of Female Orgasm from book The Evolution of Sexuality (pp.123-148)

18. 7 Things Bonobos Can Teach Us About Love and Sex, by Christopher Ryan Ph.D.

19. The 'Sexy Sons' Theory of What Women are Attracted to in Men, by Raj Persaud, M.D. and Peter Bruggen, M.D.

20. Kaighobadi F, Shackelford TK, Weekes-Shackelford VA. Do Women Pretend Orgasm to Retain a Mate? Archives of sexual behavior. 2012;41(5):1121-1125. doi:10.1007/s10508-011-9874-6.

21. Women don’t need to ‘switch off’ to climax, orgasm study shows

22. Harry A. Croft, Understanding the Role of Serotonin in Female Hypoactive Sexual Desire Disorder and Treatment Options, The Journal of Sexual Medicine, Volume 14, Issue 12, 2017, Pages 1575-1584, ISSN 1743-609

23. Penis Size Matters in Bed, Study Finds, By Stephanie Pappas

24. Muise A, Giang E, Impett EA. Post sex affectionate exchanges promote sexual and relationship satisfaction. Arch Sex Behav. 2014 Oct;43(7):1391-402. doi: 10.1007/s10508-014-0305-3. Epub 2014 Apr 29. PubMed PMID: 24777441.

Yes!! Yes!! Don't stop!! Right there!!
Climax of the article

Signing off
@scienceblocks