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One argument I've heard: if evolution could get rid of sleep, it would have a long time ago. There are several survival drawbacks from sleep, as it leaves one v

• BerislavLopac 8y ago
  And it had: https://www.livescience.com/44822-how-do-dolphins-sleep.html https://www.livescience.com/44822-how-do-dolphins-sleep.html
  • pizza234 8y ago
    Based on the article's description, that wouldn't really fit the definition of "getting rid of sleep", as this "half sleep" severely impairs the brain functionality. It does make sense in the context of a somewhat hostile environment, where constant awareness is required, but it wouldn't benefit humans as much.
    • BerislavLopac 8y ago
      The GP didn't mention humans. Also, the ability to be aware of your surroundings 24/7 pretty much fits the description of "no sleep" to me.
      • AstralStorm 8y ago
        No, it does not. These animals fully wake up when they actually have to act.
        • BerislavLopac 8y ago
          So they are sometimes fully awake, and sometimes partially. They are never fully asleep. So they don't sleep.
• imustbeevil 8y ago
  Definitely today sleep prioritizes healing resources over active resources and it certainly seems beneficial to have that happen. But I'd contend that a system that can constantly be active and healing would be an evolutionary improvement that will occur over time. Evolution is kind of like Economics; it's not rational, and it's not currently in equilibrium.
  • omalleyt 8y ago
    That would take extra calories, that's where the balance is
    • deleted 8y ago
      [deleted]
    • abootstrapper 8y ago
      Too bad I can’t spend my calorie surplus on the no sleep extra healing evolution upgrade.
  • gotocake 8y ago
    It may not, if any such system is very energetically taxing, or would confer a host of other issues. Such a system would, downsides taken into account, have to confer a net advantage. It may be that sleep in some form is best system with the fewest downsides.
    • thaumasiotes 8y ago
      The downsides of sleep are more severe for aquatic air-breathers, and, as some other comments have already pointed out, it appears to have already been eliminated in that case.
      • gotocake 8y ago
        It’s not eliminated, it’s bicameral. Dolphins do sleep, they just do so one half of their brain at a time, which is... so cool.
• zaptheimpaler 8y ago
  These kind of evolution arguments are really common but seem super shaky to me. Saying "if it was better, it would've happened already" assumes humans are perfectly evolved right now, and negates any possibility of future evolution. That argument would be just as valid a 5000 years ago as it is now but presumably humans have evolved since then. Genes mutate randomly, selection pressures change, things in our environment might affect the way genes mutate - its much more complex.
  • asdkhadsj 8y ago
    Yea, evolution is just a good enough result based on current stimuli. Even if the output is great and near perfect, the "perfect" is still based on the requirements of the environment.
  • vokep 8y ago
    This isn't about humans though, but life in general. Mostly everything sleeps, theres been a lot of time for something to evolve that would both be intelligent and not need sleep, and yet there isn't. 5000 years isn't remotely close enough for sleeplessness to evolve, more like a few million. Its not so much why do humans sleep, but why do apes? Why does anything?
  • Terr_ 8y ago
    That seems just a little bit of an absolutist straw-man, though. Exaggerating further for effect: Nobody's saying sleep is a universal constant imposed by fundamental timeless physical law. Whatever is going on must be important, and not easy to avoid without serious trade-offs.
• chongli 8y ago
  No, sometimes evolution gets stuck in local extrema. Two examples: 1. The vertebrate retina [1] (cf. the cephalopod retina). 2. The recurrent laryngeal nerve [2], especially in the giraffe [3]. [1] https://en.wikipedia.org/wiki/Retina#Inverted_versus_non-inverted_retina https://en.wikipedia.org/wiki/Retina#Inverted_versus_non-inv... [2] https://en.wikipedia.org/wiki/Recurrent_laryngeal_nerve https://en.wikipedia.org/wiki/Recurrent_laryngeal_nerve [3] http://blog.eternalvigilance.me/wp-content/uploads/2013/04/giraffe-recurrent-laryngeal-nerve.png http://blog.eternalvigilance.me/wp-content/uploads/2013/04/g...
  • oarabbus_ 8y ago
    There is an astronomical difference between vestigial organs/nerves/what have you, and a required biological function which renders the individual totally incapacitates and utterly vulnerable for 6-10 hours. Especially considering the "natural" state of things where even giving the benefit of the doubt you will avoid predators which can kill humans, you may be sleeping under a rock or a tree and susceptible to bugs, rodents, germs, etc. I don't feel that your rebuttal really, well, rebutted his point.
    • chongli 8y ago
      It seems like a big difference but it occurred very early on in the evolution of life, so it's a disadvantage shared by all animals. How about another example: mammalian females giving birth through their pelvises. This caused the deaths of countless women and children throughout human history. It's not as much of a problem for other mammals but it's a huge problem for humans. We've had to advance modern medicine to the point where we can safely perform major surgery (caesarian section) in order to mitigate it.
      • piker 8y ago
        The book Sapiens has a few pages on this. Essentially, the thought seems to be that we're an edge case that's been able to jointly optimize for intellect/large brains and small efficient bodies by overcoming the limits on brain size imposed by vaginal birth. This in part explains our relative immaturity at birth. We're vulnerable and require constant care for the first few years of life. Compare this with other mammals such as calves which are able to walk roughly at birth.
• tha_nose 8y ago
  Actually, sleep would have been evolutionarily beneficial to us since we can't see well at night and it would keep us out of way of predators at night. Sleep wouldn't be a drawback, it would be a benefit to our survival. It's why hamsters are nocturnal. Their predators hunt during the day, so they sleep during the day and play at night. Evolutionary theory would say the hamsters that like to play during the day got eaten so that only those who slept during the day got to mate and pass on their genes, etc. If you think sleep is a drawback for humans, trying visiting a forest at night without a flashlight.
  • afpx 8y ago
    So, why would sleep be benefitial to non-nocturnal animals? That is, I think the parent is saying that sleep must be very important because almost all animals sleep. If sleep wasn’t very important, a lot more animals wouldn’t sleep.
    • asdkhadsj 8y ago
      Depends on what we're debating. Are we debating whether or not humans need sleep? Or simply that beings with similar brain "design" need sleep? Perhaps due to a flaw in our (Animals) common ancestors we developed sleep to overcome other negative traits. Which is to say that sleep is simply one flaw to compensate for another flaw. Given the path evolution takes it seems a stretch to ever consider it best, perfect, good or anything other than "it worked just enough at the time". Just enough being the key. All we know is that sleep didn't disrupt animals enough to entirely fail the evolutionary test. However plenty of garbage features go along with more powerful features. One in isolation is not proof of it's perfection, I would think.
    • tha_nose 8y ago
      There is no denying that sleep is beneficial and I agree with that assertion. I was specifically addressing his point about the drawbacks of sleep - "There are several survival drawbacks from sleep, as it leaves one vulnerable.". Sleep wasn't a liability to our survival, especially our ancestors. It actually aided in our survival. Human beings who were active at night would have been the vulnerable ones as they would attract predators and were more likely to perish as a result. Especially considering out vision would be limited in the dark. In short, sleep kept us away from the dangers at night.
• ggggtez 8y ago
  Maybe, but maybe not. Evolution only has to be better suited to the current environment, but it doesn't necessarily need to result in perfect creatures. Creatures could have developed the day/night awake/resting cycle independent of sleep just because at night you want to conserve energy to stay warm, and it's difficult to hunt at night. Once creature developed day/night modality, taking advantage of that time to run repair processes would be an evolutionary advantage. The question isn't why people sleep, it's why can't creatures run repair processes 24/7? If they could do that, then evolving to not need sleep would be a lot easier.
  • AstralStorm 8y ago
    Most do, but you cannot use certain processes that stop cell metabolism for prolonged time while actually requiring that metabolism. Some organisms have more advanced repair mechanisms than others too. There are trade-offs involved, e.g. immune system.
• nitwit005 8y ago
  Evolution is essentially an optimization algorithm, and like many such algorithms, it can get stuck in localized maximums. Suppose there exists a far better brain design, but all the brain designs that are part way between the current design and that design are far worse. Any mutation that steps toward the better design will be selected against.
  • AstralStorm 8y ago
    Genetic algorithms esp. punctuated equilibrium ones can and will skip over local minima. It might take very specific environmental conditions (fitness function) though, so is not quite guaranteed.
• cortic 8y ago
  There are plenty animals that have all but eliminated sleep; giraffes, elephants, dolphins to name a few, can get away with very short bouts of sleep. Others perfect the Unihemispheric slow-wave sleep, I've even seen studies that humans do this to a lesser degree when sleeping in unfamiliar surroundings. The majority of our hominid evolution was in Africa, where we likely developed night time sleep patterns as a defense to the big cats developing better night vision. Other benefits like social interactions, heat-conservation, even directly procreation; As well as the diminished usefulness of any work, from hunting to building in darkness would all play a roll. I find it fascinating that we likely also developed a fear of the dark as a response to the big cats developing better night vision in exactly the same way gazelles developed better hearing and faster legs.
• LeonB 8y ago
  In the book "Why We Sleep" the author (Dr Matthew Walker) gives such a strong set of reasons that he says the wonder is why we ever bother to be awake. It's a very thorough book and certainly convinces you of the tremendous benefits of sleep.