Wednesday, March 18, 2020

Some Thoughts on Sex and Human Evolution

My father taught human evolution and cultural and physical anthropology, and he shared his passions with his kids, which influenced my own academic interest in neuroscience. Between his influence and my own training I have a decent understanding of how the human brain and body work and how radically our mating patterns and reproductive systems differ from even our closer relatives. And I do occasionally indulge in speculations about "evolutionary psychology" in order to help people understand how human sexuality got so messed up. However, I always acknowledge the uncertainties and the speculative quality of any such discussion of the peculiar origins of human sexuality.

I find the subject irresistible because human sexuality is weird. VERY weird! Most mammals have relatively consistent mating systems. They may have bizarre customs, but all members of a single species do pretty much the same things in roughly the same ways. But human mating systems are mixed up, messed up, and incredibly diverse.

To start with, we have by far the worst reproductive systems of all the mammals:

Maternal death rates: Without modern medicine we have the highest death rates in childbirth of any mammal, rivaled only by the hyena, and far higher than any other.

Menstruation: Other mammals can reabsorb a defective embryo with no fuss, but humans have a chorionic placenta that requires a complex menstrual cycle in order to flush out defective embryos. There is nothing nice and cuddly and natural about this. It is a uniquely debilitating and wasteful system. No other female mammals suffer from anything like it.

Extremely low conception rate: Most mammals have a conception rate of 90-99% per ovulation. Because of our bizarre menstrual cycle, we have a much lower conception rate than other mammals, around 15-20% per ovulation for fertile couples having regular sex, and less than 1% for a random act of intercourse. Women who are trying to conceive may require more than a dozen ovulations and hundreds of copulations to get pregnant, even if both partners are fertile and healthy.

In addition, our bodies seem designed to be confusing:

Cryptic ovulation: To complicate the conception problem, our ancestors evolved what is called "cryptic ovulation." Unlike any of our close primate relatives, there was no way people in prescientific societies could tell when a woman was fertile, so trying to conceive required frequent copulation throughout the cycle.

Full breasts on fertile and infertile females: Unlike any other female mammal, adult women have breasts that remain enlarged and prominent even when they are not pregnant or nursing. This hides yet another possible clue that a female is not fertile.

We also have a combination of rare mating patterns that together make us unique:

Nonreproductive sex: Humans, dolphins, and pigs seek out recreational sex. Bonobos use brief genital rubbing as a way to establish social ties and resolve tension. But most other mammals have zero interest in intercourse without the specific cue of a female who is ovulating and in heat.

Sexual frequency: One consequence of these evolutionary adaptations is that humans are incredibly oversexed by mammalian standards. Even in a monogamous marriage, a woman can easily have sex 10,000 times or more if both partners remain in good health, far more sex over a lifetime than other female mammals experience.

Social monogamy: Most mammals, including our closest cousins, are polygamous and opportunistic about sex; humans are in the small fraction, about 15%, of mammals that practice some kind of pair bonding and coparenting. Even in officially polygamous human societies, the vast majority of marriages involve only two people.

(Note: This is not to say that humans don't cheat on their spouses. As in other pair-bonding species, many individuals do stray if given the chance. Also, like many
monogamous species, humans often practice serial monogamy, changing partners after a period of exclusivity together.)

Extreme variation: Humans have THE most varied, conflicted, and confusing courtship rituals and mating systems in the animal kingdom. We may marvel at the peculiar things some non-human species do, but there is a great deal of consistency within each species. Among humans, different cultures set different rules for nearly every aspect of mate selection. Just the idea of a courtship process that sometimes takes minutes and sometimes takes months or years, would be inconceivable for other mammals.


Speculating about how we got so messed up is fun and can be illuminating, and I sometimes find it irresistible. So I'm no one to throw stones at someone else just because they do some "evo-devo" theorizing or make pop science points based on somewhat speculative neuroscience.

On the other hand, I'm in a good position to judge when people are stretching the research way too far and presenting wild claims and mere guesses as if they were facts. For a really good example of the difference between junk science and the responsible use of the existing research, see Sex at Dawn and Sex at Dusk. (Spoiler: Dawn is dishonest garbage; Dusk is a great read, meticulously honest, informative, and fun.)


Anyway, I hope this digression has piqued your curiosity about evolution and the weirdness of human sexuality. What strange, mixed-up creatures we are!

14 comments:

  1. I am so happy you wrote again your wisdom, after so long :D Thank you and welcome back!!

    ReplyDelete
  2. Hi, I love the site but I have notice while navigating many hyperlinks and navigation links are broken due to the sensitive content warning becoming an infinite loop.

    See yourself the different between the two links:
    http://moderntantra.blogspot.com/
    https://moderntantra.blogspot.com/

    Please enable HTTPS Redirect on your blog to fix this issue! You can try following this guide if you are unaware of how to do this:

    https://geekyplug.com/enable-https-on-blogspot-blog/

    Thanks a lot for everything and hopefully this can be fixed so the blog can be more easily navigated!

    AS

    ReplyDelete
    Replies
    1. Thanks for the tip! I think I fixed it. Let me know if it's still not working for you.

      SA

      Delete
  3. Hello! I stumbled upon your blog earlier today and I look forward to diving into your posts.

    I would like to know if you can recommend resources or a regimen to help improve penis firmness. I recently discussed this with a past partner, and the two of us are wondering if there is a "tried and true" way to ensure more reliable intercourse (something other than a pill like Cialis or Viagra).

    During our discussion, we both conceded that poor penis firmness has lead to penetration complications outside of our own intimate relationship. In my case, I believe that anxiety might play a role. Is this a common problem and is there a way to overcome this?

    Thank you,

    MM

    ReplyDelete
    Replies
    1. If Cialis and Viagra don't work for you, or you can't take them for other reasons, your best alternative is an injectable called Trimix. You need a prescription, and getting started takes some instruction, so it's a good idea to see a good urologist who is familiar with it, but it is definitely worth the extra effort. It is very effective and consistently produces higher quality erections than the usual ED pills, without the common side effects.

      Other than that, I would recommend meditation in general and mindfulness-based cognitive therapy (MBCT) in particular for anxiety. As you read the blog, you'll see that meditation is an important part of tantric sex, so doing MBCT is a natural fit.

      I hope this helps!

      Delete
    2. Thanks for getting back to me! Cialis works great, but it's an expensive solution. My hope is to remove the need for a medication, if possible.

      I have already started my journey in meditation and am glad to see that it is a core component of tantric sex (one of the things that draws me to it, actually). MBCT is something that I hope to become well-versed in.

      One more question: kegels keep coming up in my research. Do you personally believe that regular kegel exercises can lead to improvements in penis firmness?

      Delete
    3. FWIW, Cialis is now available as a generic, so it should be much less expensive.

      On kegels, if a person (man or woman) has weak PC muscles, doing kegels can create a big improvement in fitness. For other people, however, it's a small gain at best, and the main reason for doing kegels is to maintain pelvic fitness as you grow older.

      If you can hold a hard kegel clench for 30 seconds and do 100 hard, fast kegel "pops" in a minute, you should be fine. If not, do your kegels ~3x/day until you can, and then do a light set every day or every other day so you don't backslide.

      Delete
    4. Thanks for getting back to me. This is a great starting point and I appreciate the advice!

      Delete
  4. I am so glad to see a post from you again. Do you give online courses? Is there any way of following your work regularly.

    ReplyDelete
    Replies
    1. No courses, but I moderate the r/tantricsex and r/sexover30 forums on Reddit, so you can catch me there! :)

      Delete
  5. A fascinating blog, Shakti! Thank you so much for taking the time to put it all together. I'm just beginning to become interested in Tantra and I really appreciate your clear, well-written text, which draws on your scientific background.
    I do find the new age style, energy-based descriptions of tantra to be difficult to assimilate. I probably need to try to be more accepting of it, since it is not easy to describe the effects in the mind, so using metaphors no doubt helps.
    In any case I do see the effects it has in people, and the benefits on paper are certainly convincing.
    So my journey is starting now and I will be using your early posts as you suggest - let's see how I get on...

    Thanks once again!

    ReplyDelete
  6. Hey Shakti, great stuff.
    I've thought for a long time about how our biology isn't designed for modern life, even though we've tried to design modern life for our biology, and the best way to bridge that gap. And

    (2) That our biology, diet, sex, aggression, etc. are designed to be highly variable, making bridging the gap even more complicated.

    I haven't read your whole blog but I am dying for people to discuss these topics with. I am a male, 25. Reading your blog has legitimized tantra for me as well. Do you have any recommendations for connecting with others who want to tackle and apply these same ideas?

    ReplyDelete
    Replies
    1. I hang out mostly on Reddit these day. I moderate r/tantricsex, but there are other subreddits dealing with human evolution, evo psych, etc., that discuss these and other related ideas.

      Delete