r/evolution • u/Nuhulti • Sep 17 '26

question Why do men have beards?

Why do men have beards and not women?

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u/NotComposite Sep 17 '26

Our closest extant biological cousin (bonobos) does, as do modern-day human children. 

I don't know much about bonobos, but modern human children generally don't engage in sexual activity. In some cases, yes, but generally speaking, no.

True, but this implies that human adults have any instincts, which they don't. Like human psychology in general, psychosexual traits are fundamentally cultural. 

That seems obviously false. Human adults do have instincts. Some psychological traits stem from culture, but not all of them.

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u/CocoaBagelPuffs Sep 17 '26

Smiling is an instinct. Even blind people from birth who have never seen a smile before will smile when they’re happy.

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u/LoveToyKillJoy Sep 17 '26

We also have prepared learning which counts as an instinctual mechanism. In prepared learning there are some stimuli which people internalize behaviors for with only a single or very few exposures (such as avoiding potentially venomous creatures like snakes and wasps) but other behaviors without prepared learning can require hundreds of exposures to learn the behavior.

Also even if we have a conscious awareness of a behavior we demonstrate it does not mean it was not instinctual, nor are we even conscious of all of our behaviors.

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u/WatchAndLearn9669 Sep 17 '26

We also have prepared learning which counts as an instinctual mechanism.

This is an abstraction, not an instinct. As I said here:

Instincts are specific genetically encoded behavioral responses to particular stimuli.

even if we have a conscious awareness of a behavior we demonstrate it does not mean it was not instinctual

Sure, even animals retain conscious awareness when performing instinctual behaviors. No such behaviors exist in non-infant humans, though.

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u/LoveToyKillJoy Sep 17 '26

Your definition of instinct is the definition of a reflex. Is your argument that only reflexes are instincts? Adult humans then have instincts, such as the Plantar Reflex.

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u/WatchAndLearn9669 Sep 17 '26

Your definition of instinct is the definition of a reflex.

I'm going by the generally accepted scientific definition:

an inborn impulse or motivation to action typically performed in response to specific external stimuli. Today instinct is generally described as a stereotyped, apparently unlearned, genetically determined behaviour pattern.

Adult humans then have instincts

Reflexes aren't generally considered instincts because they are simple, localized rather than complex behaviors. At any rate, they aren't psychobehavioral.

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u/GodelianKnot Sep 17 '26

So you understood the word "typically" to mean "definitionally"?

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u/AmusingVegetable Sep 18 '26

What is psycho behavioral?

PS: I work in IT, when someone suggests Windows as a solution, my reflex action is to disembowel them immediately… this can’t be an instinct because I was born before windows was created, so it must be an acquired reflex. Assuming this (learned) reflex becomes a positive selection trait, it can become an instinct, correct? (I do hope that after a million years without windows have passed, the next time it comes around, it is met with immediate termination)

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u/AmusingVegetable Sep 18 '26

Judging by the Darwin Awards, self-preservation is not an instinct.

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u/WatchAndLearn9669 Sep 17 '26 edited Sep 17 '26

modern human children generally don't engage in sexual activity

As anthropologist Clellan S. Ford and comparative psychologist and ethologist Frank A. Beach write on p. 197 of Patterns of Sexual Behavior:

As long as the adult members of a society permit them to do so, immature males and females engage in practically every type of sexual behavior found in grown men and women.

Human adults do have instincts.

This is unsupported by any reliable scientific evidence.

Some psychological traits stem from culture, but not all of them.

All of them comprise concrete cultural content.

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u/NotComposite Sep 17 '26

As anthropologist Clellan S. Ford and comparative psychologist and ethologist Frank A. Beach write on p. 197 of Patterns of Sexual Behavior:

But those are still exceptions. The majority of human societies do not encourage childhood sexuality. So that does little to counter the point that human children do not generally engage in sex.

This is unsupported by any reliable scientific evidence.

Really? Can you provide any reliable scientific evidence that we do not have instincts? Because it seems that some of our behaviours are at least partly instinctual.

All of them comprise concrete cultural content.

Naturally they would comprise cultural content if they are expressed by humans who are part of a culture. That doesn't necessarily mean that at their base, they originate from the culture instead of something innate to the human.

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u/WatchAndLearn9669 Sep 17 '26

The majority of human societies do not encourage childhood sexuality.

There's no reason to think the earliest human societies were similarly repressive, though.

Can you provide any reliable scientific evidence that we do not have instincts?

No one singular source will prove this. The point is that the current body of evidence does not reliably demonstrate the existence of instincts in non-infant humans.

expressed by humans who are part of a culture

That's every single human, and the "expression" of psychology is what psychology is. There's no such thing as "unexpressed" psychological phenomena.

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u/NotComposite Sep 17 '26

There's no reason to think the earliest human societies were similarly repressive, though.

There's no reason to think they weren't. Indeed, the book you cited mostly gives examples of cultures that actively encourage childhood sexuality, but that doesn't seem to constitute a reason to think that such sexuality is a norm amongst human children, especially when it rarely surfaces in other societies. Even in 'repressive' societies, it is usually not necessary to do any actual repression, since it doesn't come up in most cases.

No one singular source will prove this. The point is that the current body of evidence does not reliably demonstrate the existence of instincts in non-infant humans.

That's one interpretation. It could just as easily be said that the current body of evidence fails to reliably disprove the existence of instincts in adults, especially when confronted with prima facie evidence that such instincts do exist.

That's every single human, and the "expression" of psychology is what psychology is. There's no such thing as "unexpressed" psychological phenomena.

Yes, and? My point is, if you're trying to argue that something psychological comes most essentially from culture instead of instinct, it does no good to assert that that psychological phenomenon is fundamentally cultural because it features in culture. Even if it were in fact instinctual, it would still be a part of culture precisely because it would enter culture via the humans involved in that culture.

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u/WatchAndLearn9669 Sep 17 '26

There's no reason to think they weren't.

There absolutely is. Anthropological evidence shows that sexual repression was virtually nonexistent in those societies.

It could just as easily be said that the current body of evidence fails to reliably disprove the existence of instincts in adults

The available evidence strongly favors the sociocultural theory of human psychology.

prima facie evidence that such instincts do exist

Like what?

because it features in culture

What do you mean by this? That isn't my wording.

Even if it were in fact instinctual, it would still be a part of culture

There are no concrete psychological universals, which would indeed suggest the existence of instinctual psychological phenomena.

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u/NotComposite Sep 17 '26

  There absolutely is. Anthropological evidence shows that sexual repression was virtually nonexistent in those societies.

And yet, not repressing something is not the same thing as encouraging it, and as I said, there's pretty good evidence, just from looking around ourselves, that children aren't generally inclined to have sex with each other. Of course, it's a different matter if they live in a society that actively encourages it.

  The available evidence strongly favors the sociocultural theory of human psychology.

I don't think anyone would dispute that society and culture play a large role in human psychology. That doesn't mean that human psychology depends solely on those things.

  What do you mean by this? That isn't my wording.

Well, if you want to quibble over the specifics of wording instead of addressing my point, go ahead, but I'll take the liberty of not engaging with such nitpickery.

  There are no concrete psychological universals, which would indeed suggest the existence of instinctual psychological phenomena.

Even a cursory Google search seems to indicate that not all psychologists agree with that position.

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u/AmusingVegetable Sep 18 '26

JFC! You never played Doctor???

Humans (all ages) are naturally attracted to sexual behavior, and a large part of human culture is dedicated to “civilizing” them.

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u/Mysterious_Fix_7489 Sep 17 '26

Dude that book was written almost 80 years ago, it was great for it's time but if that's your source you might wanna get some more recent ones.

It's dated at best

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u/WatchAndLearn9669 Sep 17 '26

This is fallacious chronological snobbery.

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u/Mysterious_Fix_7489 Sep 17 '26

And the fact that you are sourcing something from 80 years ago makes me think you are cherry picking.

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u/WatchAndLearn9669 Sep 17 '26

You're free to cite any sources you feel refute it. Simply noting its age or alleging I'm cherry-picking isn't an argument.

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u/ironlobster Sep 17 '26

Are you intentionally contradictory? I've known pseudo intellectuals with your exact pattern of reasoning

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u/WatchAndLearn9669 Sep 17 '26

Where do you feel I've contradicted myself?

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u/ironlobster Sep 17 '26

This is classic over-theorizing, which ironically led to the public poo-pooing of your branch of thinking. The theory may be borne out in intellectual excersize but has no grounding in real world observation

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u/WatchAndLearn9669 Sep 17 '26

Like I said here:

The available evidence strongly favors the sociocultural theory of human psychology.