Comment by digitailor | Hacker News Reader

Comment by digitailor | Hacker News Reader

Well, no one else has said it, so I guess I drew the short straw.

Teenagers are most likely wired for later nights because they have reached initial fertility. They will sneak off in the night to fool around, especially if they haven't had a child yet. At the risk of sounding patronizing, this is how babies are made. Adolescence is the age when women would first become pregnant, and the ancient's concept of marriage was probably not the same as ours. (There is evidence of monogamistic tendencies in humans for a long time but that isn't synonymous with marriage.)

Teenagers are biologically wired to want lots of sex and they tend to do it at night. I would put a lot of money on the fact that that hasn't changed in millennia.

Obviously, this is a critical aspect of the process that allows for the continuation of the human race. Humans didn't have the consistent ability to wait to reproduce until 30 as is common now. And probably not the desire too; I can't see career-building interfering.

The initial party must have ended pretty quickly. Poor ancient teeenagers.

(Edit: considering this speculative is reasonable and factually correct. But speculating there's been behavior change is currently more speculative. What reason do we have to think teens had daytime sex in ancient times and our behavior has changed? What about for mature adults? Never heard of an existing tribal culture that mostly has sex during the day, and that's how we get much of our anthropological evidence.

Humans tend to have sex at night, and the most fertile, desirious and energetic would be wired to spend more time at the time people have sex doing it: that would be selected for because of our primary biological directive. Is there a more logical evolutionary reason?)

Aren't you simply making a baseless guess with nothing to back it up? Why would there be biological pressure to mate at night? I don't understand how you're so self assured (unless you read something on this which I haven't, in which case please share :)) If you don't, then I don't understand the purpose of phrases such as

>The article misses the point almost to the point of absurdity.

>I feel weird having to explain this.

>Academia concerns me sometimes.

I took those out, thanks.

Oh, I don't know about that. In Ekrich's ' At Day's Close: Night in Times Past' [1] seems in pre-industrial age society the norm was 'bi-modal sleep'.

First or "deep" or "dead" sleep, as it was sometimes called, often seems to have taken place shortly after sunset, or at least before 10 in the evening. After two to four hours of the night's deepest rest, people would wake up for an hour or two, then resume sleep for another stretch before rising with the light.

During this waking period, people would relax, ponder their dreams, or have sex.

Many might find the later a good description of teenage behavior. Couple that with the physiological fact that

For men, levels of testosterone are highest during sleep and require at least three hours sleep to reach this peak. [2]

And just maybe teenagers are reverting to form.

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[1] At Day's Close: Night in Times Past - Ekirch (2006)

[2] https://www.sciencealert.com/chemical-messengers-how-hormone...

It'll likely be the nth time Matthew Walker is cited here, but in his interview with Joe Rogan, he mentions this is likely a societal trend rather than a biological need:

https://www.youtube.com/watch?v=pwaWilO_Pig&t=3294

> Joe Rogan: Yeah, I've heard this recently, that people - that you should have two sleeps. The idea of two sleeps.

> Matthew Walker: Yeah, it's actually a little different than the idea of two sleeps. So there was a time in the sort of Dickensian era where people would sleep for the first half of the night, maybe sort of 4 hours or so. Then they would wake up, they would socialize, they would eat, they would make love, then they would go back and have a second sleep. If you look at natural biological rhythms in the brain and the body, that doesn't really seem to be how we were designed. It certainly seems to be something that we did in society, but I think it's more of a societal trend than it was a biological edict. However, we do seem to have two sleep periods. Those tribes will often sleep about 6.5, 7 hours of sleep at night. And then especially in the summer they'll have that siesta like behavior in the afternoon. And all of us have that, sort of this - what's called the post-prandial dip in alertness, just means "after lunch" - and if I measure your brainwave activity with electrodes, I can see a drop in your physiological alertness somewhere between 2 to 4 pm in the afternoon [irrespective of diet].

Note that not everyone is convinced by Ekritch.

http://www.textkit.com/greek-latin-forum/viewtopic.php?f=36&...

Or https://www.ncbi.nlm.nih.gov/pubmed/26480842

I'm not sure this is true. Yes, adolescence is when childbearing ability and the associated hormonal incentives start, but where is this "sex must happen at night" component coming from? If anything, I would guess that's a modern phenomenon being retrofitted onto the past.

I'd say visibility, permission avoidance, the excitement, and I'm sure there's more. Just like now, why would it have changed? For what specific reasons? Obviously spring and summer would be easier. I don't think that's retrofitting; I think we're continuing it still and the lack of recognition of that is confusing me.

I'm positive they figured out how to have sex in the day as well when possible. But nomadic daytime marching would reduce opportunity, and in a hunting culture it would be harder to separate a woman because of daily gender-disparate activities. In a predominantly gatherer culture, perhaps it was easier.

You couldn't do much of anything at night with stone-age lighting technology. Sneaking around at night would be more likely to net you a tryst with a nearby tree branch or ditch than an exciting sexual encounter.

That's why the Moon has been a friend of lovers since dawn of time.

You’re really off about that. Our night vision is actually pretty good, especially if you’ve used it for every night of your life. Fire’s clearly been with us for long enough to be a factor, in addition.

I’m against the hypothesis though, if only for the fact that energy levels peak shortly after waking up - “why we sleep” discusses this a little.

That book also suggests the variety of sleep patterns exists for evolutionary reasons. Ie we are social creatures. Having a multitude of waking/restful cycles in a group kept our ancestors protected with a nearly round the clock group of protectors - who evers sleep cycle woke them up when ever.

>Our night vision is actually pretty good

It isn't good enough to see what's going on when it's actually pitch black, which it is most of the time at night.

> Fire

Lighting a fire at night in the place where you're having sex seems like a pretty good way to get discovered.

> Having a multitude of waking/restful cycles in a group kept our ancestors protected with a nearly round the clock group of protectors - who evers sleep cycle woke them up when ever.

This is a just so story. If we all had the same sleep patterns, you could just as well point out that there would also be advantages to that arrangement.

> It isn't good enough to see what's going on when it's actually pitch black, which it is most of the time at night.

It's pitch-black for city dwellers with eyes unadapted to darkness. Weather allowing, for most of the time you have moonlight providing good enough illumination to (carefully) navigate the outside.

Matthew Walker, PhD in his book "Why We Sleep" discussed sleep cycles and their variances from one person to the next. Specifically, during his discussion of circadian rhythm in chapter 2. From page 22: "As a social species, should we not all be synchronized and therefore awake at the same time to promote maximal human interactions? Perhaps not. As we'll discover later in this book, humans likely evolved to co-sleep as families or even whole tribes, not alone or as couples. Appreciating this evolutionary context, the benefits of such genetically programmed variation in sleep/wake timing preferences can be understood. The night owls in the group would not be going to sleep until one or two a.m., and not waking until nine or ten. [...] Consequently the group as a whole is only collectively vulnerable."

He discussed varying sleep cycles across individuals. Specifically, he suggested society needs to be more inclusive of different sleep patterns and needs. Instead, society rewards people who naturally wake early in the morning at the cost of "night owls". All in the same area of the book.

You're welcome to research and earn your own PhD in neurology and author your own book on sleep patterns, but I'll stick with Dr Walker's work.

I have a PhD, though it isn't in neurology. Speculations don't become any more plausible just because the person making the speculation has a PhD.

> It isn't good enough to see what's going on when it's actually pitch black, which it is most of the time at night.

You mean in a thunderstorm, maybe? Or a fog bank?

On a clear night, even with no moon, humans can see quite well. Since rod vision is used, it is difficult to do fine work (reading, sewing, soldering, ....), but just walking around outside is no problem.

If you want to see the night for yourself, try spending a few nights camping out somewhere away from artificial lighting. Don’t bring along any of those terrible “white” LED flashlights – they completely clobber night vision. It takes about a half hour for eyes to fully adapt to the dark.

>You couldn't do much of anything at night with stone-age lighting technology

I grew up in upstate New York and could actually run 5 miles around the nearby lake in the woods any night, even moonless ones. You can see the silhouette of the trees against the stars and it isn't even really needed once you memorize the trail anyway. And that was just for exercise. I imagine horny teenagers would be even more hard working.

It’s pure conjecture until the commenter posts some sources. Now I feel patronizing pointing it out, but you don’t have to stay up late to have sex. I think this is modern cultural norms being propped with pseudo science.

> but you don’t have to stay up late to have sex.

That doesn't mean that having a 'late night' trait wasn't advantageous to mating. For example, when humans started pair bonding, infidelity may have been more common among those who could sneak out under the cover a darkness while their partner was asleep, spreading that trait further than those who remained monogamous. It is easy to think of many possible reasons why a late night trait could have been advantageous in spreading that trait further than those who naturally followed a more daytime rhythm during teenage years.

Or it could just be random chance. Either way, it's fun to discuss. We don't have to dismiss all fun discussion because it may be conjecture. It is only the comments section of HN, not a respected scientific publication. Time and place.

Also, when your jobs are a) finding berries and hunting mammoths and b) having sex, it is not implausible that doing a) during the day and b) during the night gives you more reproductive success than vice versa.

It is fun speculation, but still, OP's self-assured "this is so trivial" tone was not called for.

I mean, my impression from reading 19th century novels is that people used to just slip into a convenient glen or wooded area, it wasn't that hard before the industrial era.

I, and I assume most guys (and gals) in their puberty were horny most of the time, but my being a night owl I don't think factored into that at all. I studied much better at night, I was a lot more creative (music mostly) at night, and everything was more peaceful at night. I was horny too, I guess, but that was more of a 24/7 thing.

Same here. I don't think it's a stretch to say that increased teen sexual energy, inextricably bound to increased general energy, was a big part of that, whether sexually active or not. In fact sublimated sexual desire/energy can be extremely helpful in creative endeavors. It's the essence of creativity, the creation of a new human life is pretty hard to top power-wise.

I'm still a night owl, wired for very late.

    > ...no competing theory that does have hard evidence has been proposed, so current behavior is actually the first rationalization.

I think it would be even more reasonable to investigate WHY this is being discovered now rather than a long time ago. What has changed in the lives of teens now compared to 3 or 4 decades ago?

I suspect one thing is a much higher percentage of "structured time". Teens today seem to have far more time obligations than my generation did. As a result, socializing and free-time ends up getting pushed to interstitial times, late at night _and_ online.

Young people need unstructured time for ad-hoc socializing and discovering who they are and there is less opportunity for that now so it happens later at night when their obligations have been met and the time is their own. That's a simpler explanation than primate sexual urges.

Very slight digression. I can't stop thinking that modern 'college' oriented societies forgot to take biology into account.

IMO teenage perception of the world, which triggers the frenzy need to act, create, be seen; this is how I interpret pseudonyms and graffiti for instance.

A century ago, the average independance was ~16, similarly some religion have rites of passage in mid teens to signal a change of status. I think they did notice there was a need for teens to change lifestyle.

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