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One of the many fascinating facts I learnt from Matthew Walker's "Why We Sleep" is that the biorhythms of teenagers are shifted to later hours compared to those
by rerx 8y ago
One of the many fascinating facts I learnt from Matthew Walker's "Why We Sleep" is that the biorhythms of teenagers are shifted to later hours compared to those of adults in all human cultures of the globe, even in those rare societies hardly affected by technology. In evolution this was likely beneficial to make it easier for teenagers to socialize among themselves without adult disturbance, which was necessary to drive their tribe out of its ruts, to pioneer innovation and adaptation to changed conditions. In modern society we are stupid to undermine this by depriving the upcoming generation of their sleep.
- sigi45 8y agoInteresting idea :)
- darkerside 8y agoJust as likely that teenagers would then be able to stand watch for predators, attacks by other tribes, or hunt for nocturnal prey.
- rerx 8y agoSure, having some variation in circadian rhythms among the members of a group makes it easier to have guards at most times of day and night. But such variation exists independently of age: There are "owls" and "larks" at all stages of life. I find it interesting that, on top of that, teenagers specifically and consistently have their individual rhythms shifted towards the later hours.
- darkerside 8y agoThat's a really interesting point I hadn't considered. And thanks to evolution's pseudorandom algorithm, it could be that the benefit was obtained in conjunction with another benefit (nighttime socializing), that one came about after the other, or that one exists and one doesn't.
- singularity2001 8y agoCan the purpose of this mechanism not be determined by observing hunter gatherers?
- freeflight 8y agoI don't think there's that many of those left, at least isolated and big enough to serve as an actual testing group.
- RustySpottedCat 8y agoyea but we're not in tribes, are we? People take this evolutionary bullshit way too seriously, like we still run around with sticks and stones. None of that crap matters when we live in a modern society. Teenages are going to "socialize with themselves" whether they sleep in or not, no matter what, because, guess what, that's what people do in modern times. They can choose.
- hrzn 8y agoWhat they meant is that we evolved in a way that made teenagers having shifted cycles, going to sleep later and waking up later. We're not living in tribes anymore, but evolution is slow and we still cary these biological traits. It therefore hurts teenagers to wake up as early as adults. The point here is not about leaving them more time to socialize in the evening.
- mysterydip 8y agoWouldn't accommodating them make evolution slower? Those that have traits making them able to wake up earlier should be "rewarded" if you want to bring change.
- YokoZar 8y agoWell, I didn't come to this thread expecting a eugenics-based argument in favor of medically unsound school start times, but here we are.
- mysterydip 8y agoI was trying to comment on the irony in adapting to our evolution instead of the other way around. I wasn't trying to advocate any solution. Clearly it didn't come out right based on the replies I got.
- Retra 8y agoOur goal is not to control evolution, it is to let people exist within the biological constraints they have.
- lordnacho 8y ago> was necessary to drive their tribe out of its ruts, to pioneer innovation and adaptation to changed conditions Surely teenagers could scheme among themselves while adults were awake? All they'd have to do is walk somewhere else. It's not like the adults would constantly be in their way. Also, those functions may as well be done by adults. For instance startup founders are not all kids right out of college. Anyway, I'm not disagreeing with the idea that teenagers sleep later, just sceptical about why it is so.
- deytempo 8y agoI would argue that this ultimately has to do with one survival trait: who has more sex. I’m guessing that far more teen pregnancy occurs when teens are hanging out without adults around. The ability to shift to different sleep patterns than adults would be among other things, a procreational advantage.
- newnewpdro 8y agoYou're mixing a modern model of family structure and sexual relations with evolutionary timescales. It's very unlikely anyone gave a damn about who was having sex with who and at what age before our population sizes reached levels where paternity mattered.
- chefkoch 8y agoIsn't who has sex with whom the primary issue in most animal groups?
- newnewpdro 8y agoAcross the entire animal kingdom? I'm no expert, but that seems obviously to not be the case. Edit: Just look at our close relative the Bonobo for an interesting example of what human sexuality might have looked like in the past: https://en.wikipedia.org/wiki/Bonobo#Sociosexual_behaviour https://en.wikipedia.org/wiki/Bonobo#Sociosexual_behaviour
- lnanek2 8y agoThere actually have been studies of primitive tribes and cultures where it was showed that they just didn't realize pregnancy happens from a single man's sperm, so children were considered the entire tribe's or to have multiple fathers (with actual language terms for the various fathers). There's also some cultures where men first slept with men while growing up before settling down with women due to thinking sperm was a guy giving up his power and younger ones needing it to grow into warriors. So it wasn't really as clear cut as we know it to be today.
- PurpleBoxDragon 8y agoPerhaps the first question we should answer is if our closest primate relatives have this same behavior among their adolescence? Especially given to what extent adolescence is a social construct and not biological (which seems to clash with the idea this is found to happen in all societies, probably an interesting point to look more into).
- sjg007 8y agoI think it is more of an evolved response to predation. You need people awake to watch for threats. Teenagers could do that while adults tend to young kids etc... young kids and grandparents tend to awaken early etc... adults too wake earlier as they age so you reduce the threat window.
- checkyoursudo 8y agoMaybe, but I wouldn't have put my teenage self on nightwatch. It wouldn't have been pretty. I'm also getting to the point where I don't think I would trust my father to be on early morning lookout. Seems like there are enough adults who are night owls and morning larks to cover an adult-only watchfulness.
- Angostura 8y ago> In evolution this was likely beneficial to make it easier for teenagers to socialize among themselves without adult disturbance, Any evidence to put this down as a 'likelihood'?
- corndoge 8y agoAgreed, seems like a nice theory but without sources of any kind I could come up with another ten such plausible theories
- Reedx 8y ago> easier for teenagers to socialize among themselves without adult disturbance We've also disrupted this with younger kids. They never really get to play without adults in the mix. I think this is actually one of the reasons why Minecraft was so successful, especially with kids. It gave them a way to explore the wilderness (also rare these days) and a way to interact without adult supervision. They got to be masters of their domain and learn how to cooperate and resolve disputes among themselves.
- IC4RUS 8y agoThis sounds like of a 'just so' story, as evolution is not usually considered to act at the group level, but instead at the individual level: https://en.wikipedia.org/wiki/Group_selection https://en.wikipedia.org/wiki/Group_selection And some evolutionary biologists, like Dawkins, argues that it really acts on genes rather than the individual. So, I might be missing some of the claim, but I find it unlikely that teenagers would stay up later to be away from adults and drive the tribe out of its ruts.
- Aeolun 8y agoMaybe so. But if it happens in all cultures across the globe (which is verifiable), then there must be ‘some’ cause. Even if we don’t know it.
- IC4RUS 8y agoThat's true, but the core explanation is not likely to be what the original poster described.
- lamontcg 8y agoYou've misunderstood Dawkins. You can still get completely unselfish individual traits out of selfish gene selection (like the entire chapter on runt gene selection). It looks like group selection, Dawkins only argues that the mechanism is selfish genes. Even he seems to have forgotten he wrote about that though.
- IC4RUS 8y agoThat's true, I just meant to express (over-simplistically) that he argued that the mechanism is at the gene-level, which is even farther away from group-selection mechanisms. The sections about emergent group-level behavior are really fascinating too.
- deleted 8y ago[deleted]
- devxpy 8y agoA better argument is presented by this excerpt from that 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 a.m. The morning larks, on the other hand, would have retired for the night at nine p.m. and woken at five a.m. Consequently, the group as a whole is only collectively vulnerable (i.e., every person asleep) for just four rather than eight hours, despite everyone still getting the chance for eight hours of sleep. That’s potentially a 50 percent increase in survival fitness. Mother Nature would never pass on a biological trait—here, the useful variability in when individuals within a collective tribe go to sleep and wake up—that could enhance the survival safety and thus fitness of a species by this amount. And so she hasn’t. Thanks for giving me the inspiration to read it. This book is just fantastic.