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Hydras suggest that sleep evolved before brains
- Fellshard 5y agoAlternatively: God Himself is one who rests, and He built a pattern of rest into His creation. (Genesis - 'on the seventh day He rested'; Deuteronomy 5:13 - 'Six days you shall labor and do all your work, but the seventh day is a sabbath of the Lord your God; in it you shall not do any work, you or your son or your daughter or your male servant or your female servant or your ox or your donkey or any of your cattle or your sojourner who stays with you, so that your male servant and your female servant may rest as well as you.') Why is that important? God cares for His creation and gave rest as a good gift to be enjoyed as He commands. But He also used it to point to Christ, and to eternal life! Hebrews 4 talks about a final 'Sabbath rest for the people of God', one that you may enter into, no longer having to strive and toil to accomplish things. Why the theology lesson on HN? There's always a dual to what evolutionary hypothesis tends to claim in its discoveries. Genetic links between different species that are better explained as common components from the same designer than mutual ancestry, for example.
- ceejayoz 5y agoIn your rush to inject religion, you've mixed up rest and sleep.
- chownie 5y agoThat, and if genome similarities were to be explained away by an intelligent designer using the same "toolbox" (so to speak) then why would he create crabs multiple times without using those same widgets? Leaps of faith seem to introduce more questions than they're able to answer.
- slver 5y ago> That, and if genome similarities were to be explained away by an intelligent designer using the same "toolbox" (so to speak) then why would he create crabs multiple times without using those same widgets? I also don't know why I keep writing StringUtils every few months, but I just... like it. Guess God likes crab-like things and it's too annoying to merge from old codebases.
- forgotmypw17 5y agoSleep is a whole-body process of repair and optimization. Many cultures chastise sleepers as lazy, but every time you sleep, it's like a big reconstruction process in your body. I think that sleep and allowing adequate time for it is the lowest hanging fruit for most people's health. Us site readers usually get enough to eat, and sometimes more, yet when was the last time you allowed yourself to sleep as much as you want to, without limit?
- kevmo314 5y ago> when was the last time you allowed yourself to sleep as much as you want to, without limit? I was told premature optimization was the root of all evil.
- the_local_host 5y ago> Many cultures chastise sleepers as lazy, but every time you sleep, it's like a big reconstruction process in your body. The morning alarm is society telling you "stop reconstructing yourself, start working on our problems."
- have_faith 5y agoNot using an alarm clock 90% of the time is one of the greatest privileges I experience in life. One which I wish more people were fortunate to share.
- falcor84 5y agoAs a parent of a young child, I'd welcome the routine tyranny of an alarm clock
- alostpuppy 5y agoOh man. You aren’t kidding.
- fullstop 5y agoEventually the human alarm clocks do grow up. Part of the problem is that children occupy a lot of your time. After you get them in bed, it's tempting to stay up later than one usually would in order to have some personal time. This doesn't change the time that the human alarm clocks go off, though, and it can quickly spiral out of control. It gets better. When they are older you can include them into your passion projects, or whatever sort of hobbies you have. This part is great because you are both teaching them and having fun at the same time. I say this all the time because it showcases how little time you have with them, but you only have about 1,000 weekends with them until they are adults. It all happens so fast. I enjoy the time that I spent with them, especially over the last year when we were all together as a family for so many months. I, myself, am nearing the end of those 1,000 weekends with my oldest and I miss some of those human alarm clock days when they were up early and just wanted to play together.
- coliveira 5y agoThis gives additional evidence to my personal hypothesis that the normal state of living beings is sleeping. The awake state only appeared as a survival strategy, to better adapt to the natural environment.
- TylerLives 5y agoWhat do you mean by "the normal state of living beings"?
- serverholic 5y agoSurely you understand that most people consider being awake to be our default state and sleeping is just something that we need to do sometimes
- slver 5y agoThe way you phrased is reminded me how blindly we walk through life, doing things that our body forces us to do, because despite all our bravado about how smart we are... we really have no clue what we do and why we do it most of the time.
- vmception 5y agoIt means that being aware of surroundings with continual sensory input and influence is the aberration. This matches some other theories as well, where humans and a few other always awake organisms are the extreme, due to selective pressures. For example, humans "feel bored" because having nothing pressing to do for survival is usually the wrong option. Whereas that isn't true for many other organisms and they likely wouldn't have an opinion about staying still in the same place for prolonged periods of time.
- deleted 5y ago[deleted]
- wfn 5y agoThis is basically what Matthew Walker (https://en.wikipedia.org/wiki/Matthew_Walker_(scientist) https://en.wikipedia.org/wiki/Matthew_Walker_(scientist)) sort of alludes to in his book, "Why we sleep". It's a good book. He specifically mentions hydras as well (iirc)... he's a neuroscientist who is a crazy maniac about sleep and he cites newest research and delivers a very clear message of urgency. Lots of fascinating stuff there, highly recommend if you're interested.
- amelius 5y agoproof -> evidence Evolution has reinvented many things in different ways.
- periheli0n 5y agoThe evolution of sleep may or may not predate the evolution of brains. It might have evolved twice, once in predecessors of hydras and once in predecessors of beings with brains.
- vmception 5y agoagreed, divergent evolution is very common
- dragonwriter 5y agoThe upthread suggestion is actually of convergent, not divergent, evolution.
- vmception 5y agothats funny because I googled it before I wrote it and still wrote the wrong one
- jfengel 5y agoIt's amazing how bad our brains can be, even after a few million years of evolution. They're capable of flying a helicopter on Mars and cranking out a vaccine within months, as well as developing vast machines containing zettabytes of information -- and still can't retain a word for 15 seconds.
- periheli0n 5y agoAll the amazing capabilities you mention are the result of cooperation between dozens, hundreds or even thousands of humans. Without doubt, individual people made millions of errors in the process, and each time some other contributor caught it. Single brains can only do that much, great things are the product of cooperation between humans.
- wombatmobile 5y agoHydras, like c. elegans, cockroaches, fruit flies, humans, sponges and all the other animals named in TFA are eukaryotes. What about prokaryotes? Do they sleep?
- _Microft 5y agoHere is something on cyanobacteria showing sleep-like behaviour during which they do not divide. https://phys.org/news/2010-03-cell-division-cyanobacteria-kind-circadian.html https://phys.org/news/2010-03-cell-division-cyanobacteria-ki...
- Sniffnoy 5y agoI mean, they're all animals. Prokaryotes are far less related to animals than e.g. fungi or plants would be.
- wombatmobile 5y agoYou would know that eukaryotes evolved from prokaryotes. So, the interesting point of the question is whether sleep is something that occurs at the cellular level or the organism level. See the article linked to in the comment above, about cyanobacteria. > Cyanobacteria maintain their circadian rhythms even when isolated from the naturally occurring daily light-dark cycles of the sun, just as humans do. The researchers found that under conditions of moderate constant light, the cyanobacteria undergo cell division about once per day, and the divisions take place mostly at the midpoint of the 24-hour cycle.
- unparagoned 5y agoSleep occurs at both the cellular and organism level. Sleep is probably like getting a car serviced and cleaned. Sleep isn't just blowing up the tires, or changing the oil or cleaning the screen, it's all of it.
- sateesh 5y agoCan you please be specific when you say sleep occurs at cellular level. Definitely bodily systems (circulatory, respiratory etc.) don't go to sleep, even when we are sleeping.
- stevenalowe 5y agoEvery complex mechanism requires some form of downtime for maintenance
- papito 5y agoI mean, do you want to live in a world where no one ever sleeps?
- Phenomenit 5y agoI would rather say all forms of combustion produces pollutant that needs to be dealt with.
- kens 5y agoThe article describes how sleep has been found in simpler and simpler animals. But I wonder if you could go further: do plants sleep? It seems like an absurd idea, but on the other hand there was an article a few months ago, "Anesthesia works on plants too, and we don’t know why". https://news.ycombinator.com/item?id=25591443 https://news.ycombinator.com/item?id=25591443
- xxpor 5y agoI don't know if you could call it "sleep" per se, but there are certainly plenty of plants that need a daily period of darkness to grow properly. This comes up when growing indoor plants when people say you shouldn't run a grow light 24/7.
- grawprog 5y agoPlants increase their respiration at night and stop photosynthesizing. https://www.bbc.co.uk/bitesize/guides/zxtcwmn/revision/1 https://www.bbc.co.uk/bitesize/guides/zxtcwmn/revision/1 It seems kind of like sleeping to me.
- ASalazarMX 5y agoAlthough without sunlight, they have no choice but to stop photosynthesizing. Then we have plants like the dracaena fragans, whose flowers remain closed at day, but open and release their delicious fragrance all night. I'm not sure how sleep would work for her. https://en.wikipedia.org/wiki/Dracaena_fragrans https://en.wikipedia.org/wiki/Dracaena_fragrans
- periheli0n 5y agoDaytime sleeping is not unheard of.
- einpoklum 5y agoNitpicking: "stop photosynthesizing" is just a direct consequence of the lack of ambient light. People stop getting sunburn at night, that's not part of "sleeping". Other than that: +1.
- papito 5y agoMan, working from home has the advantage of a power nap, or a "coffee power nap", which basically makes you feel like it's the second morning of the day. https://www.vox.com/2014/8/28/6074177/coffee-naps-caffeine-science https://www.vox.com/2014/8/28/6074177/coffee-naps-caffeine-s...
- jimmytucson 5y ago> She distilled a set of behavioral criteria to identify sleep without the EEG. A sleeping animal does not move around. It is harder to rouse than one that’s simply resting. It may take on a different pose than when awake, or it may seek out a specific location for sleep. Once awakened it behaves normally rather than sluggishly. ... A sleeping animal that has been disturbed will later sleep longer or more deeply than usual, a phenomenon called sleep homeostasis. When you define "sleep" this way, without reference to the brain or consciousness, it's not all that surprising that animals without brains can "sleep". If you take out the criteria having to do with locomotion, so as not to exclude organisms that don't need it, plants probably sleep too...
- Sniffnoy 5y agoReally? Certainly it's not surprising that animals without brains might go without movement for periods of time, but why would you expect them a priori to have a state that meets all these criteria?
- deleted 5y ago[deleted]
- manquer 5y agoThis is not surprising, for consciousness to awaken, it has to be asleep first !
- dandare 5y agoShout out to the beautiful design of this web. The loop video of the hydra at the beginning is meaningful and super informative!
- lethologica 5y agoI came here to say this as well. The video is so crisp and detailed that it is mesmerising. And being able to view it from the comfort of my iPad screen? Wow. Technology really is amazing. It’s funny (and maybe sad) that it took something as small as a quality video loop for me to really appreciate all of the things involved in the process of me being able to view that video.
- mark_l_watson 5y agoInteresting that sleep has functionality for resting the body as well as then brain. Off topic, sorry, but: hydras and rotifers were my favorite pond creatures to look at under my microscope when I was a little kid. Hydras were much more difficult to find.
- ajdude 5y agoI wouldn't be surprised if sleep is an aspect of a nervous system in general. Last year an article came out about how even artificial neural networks benefited from sleep. Perhaps it's the nature of the beast. https://news.ycombinator.com/item?id=24018131 https://news.ycombinator.com/item?id=24018131
- it 5y agoThis is evidence in favor of the hypothesis that consciousness happens in microtubules. https://en.wikipedia.org/wiki/Orchestrated_objective_reduction https://en.wikipedia.org/wiki/Orchestrated_objective_reducti...
- sva_ 5y agoI feel like this article touches a lot more on the definition of what sleep is, rather than what people commonly refer to as sleep. I mean, what really defines sleep? I would've thought it is the temporary absence of consciousness in an otherwise conscious being. Or something along those lines. Of course that wouldn't make a lot of sense with medical comas and such. So maybe sleep is just a, perhaps regular, phase in which an organism is 'inactive', that is, doesn't perform a lot of actions or waste energy. Energy is limited after all. From an evolutionary perspective, it might make sense to have an organism not be dependent on a permanently available power source. It'd be better to alternate between using a lot of energy and using less energy, because permanent sources of energy are rare or even non-existing. Depending on such a permanent source would starve the organism to death and hence it wouldn't evolve. So you get those intervals and they'll naturally evolve to synchronize to the phases of their energy source. And that's supposedly the sleep cycle?
- DoreenMichele 5y agoSleep might have helped to maintain the first sleeper’s rudimentary nervous system, but it could just as easily have been for the benefits of its metabolism or digestion. “Before we had a brain, we had a gut,” he said. I will note that the nervous system of the human gut is so complex that some people speak of it as "a second brain" and there is growing evidence that the gut biome and what we eat significantly impact brain chemistry. If jellyfish sleep, that suggests sleep may have evolved more than 1 billion years ago This is sort of off topic. When me and my adult sons were first homeless, we spent a month in Port Aransas. While we were there, there was a big storm and this storm left a lot of jellyfish stranded on the beach. My oldest son set out to rescue some of them. He would take a plastic container and plastic utensils and flip them into the container so they couldn't sting him. He would get five or six of them into the container and in his first attempt, he just walked out into the water and dropped them in the water and then he had to get the hell out of the way so they wouldn't wash into his legs and sting his legs. So he began walking out onto the jetty so he could drop them into the water while standing on a rock. That way he was in no danger of being stung because he wasn't standing in the water he was dropping them into. The other reason he began going out onto the jetty is because they were getting washed back up onto the beach. He felt it wasn't working at all. And he told me that the jellyfish stranded on the beach all closed themselves up as best they could, as if trying to conserve water while on dry land in hopes of surviving long enough to wash back out to sea. He reads really fast and has always been interested in science. He knows more about science than I ever will and he told me he had never read anything like that about jellyfish behavior. Once he dumped them in the water, they "uncurled" and began to pump immediately. So perhaps they were sort of "asleep" or hibernating while on land and once they were in water and safe from this harsh environment that was threatening to be the death of them, they would revive and resume pumping. He went on a bit about that. He thought it was really exciting and interesting stuff. I think he saved a few dozen jellyfish over the course of about three days. Edited for accuracy after fact checking with my son. In talking with him, he said that at first he thought it was coincidence that they were kind of closed up. But after seeing them all immediately open up and start pumping, he decided "No, I think this is deliberate." Additional update: He quit trying to rescue ones that were flat and a different color because he concluded they were dead. Those didn't pump when they went back in the water. The ones that were curled up were still alive. (Read by my son, edited in accordance with his wishes and signed off by him as an acceptable telling of the story. There should be no further edits after this.)
- ncmncm 5y agoMy question is whether ctenophores sleep. These are the critters we used to call "comb jellies", and thought they were related to jellyfish. But it appears, according to some biologists, that they invented nerves independently of the other animals; they use different molecules for the job, controlled by different genes. For an eye-opening introduction to ctenophores, look up some youtube sequences of Beroe eating other ctenophores. https://www.youtube.com/watch?v=1xkNPp6mzzI https://www.youtube.com/watch?v=1xkNPp6mzzI , e.g., at 37s in, or https://www.youtube.com/watch?v=eDS_NMrPPKc https://www.youtube.com/watch?v=eDS_NMrPPKc at 2:50. I don't know if anybody has studied ctenophore sleep. You could be the first!
- andrewprock 5y agoGiven that the default state of being is "not awake" it's reasonable to suppose that sleep evolved first, and then wakefulness.
- TeeMassive 5y agoThey do not seem to have considered convergent evolution, like the article about trees that was on the front page a few days ago.
- Geee 5y agoThe simplest universe is a repeating binary sequence. Night and day. The simplest intelligence learns to predict this pattern and switches on/off to maximize its energy input and minimize its energy output. So, a sleeping brain is probably the simplest brain there is.
- ranprieur 5y agoEveryone is wondering how sleep serves life. Maybe it's the other way around: the purpose of being awake is to find nutrients and a safe place to enable sleeping.
- exo-pla-net 5y agoI mean, that's a fun and trippy idea. But we're vessels for propagating genes. Can't do that while you're sleeping, so one would have to construct an exceedingly strange model of the universe to make sleeping central to our existence.
- maiqthefalse 5y agoI always thought sleep didn't make sense evolutionarily speaking - I mean wouldn't carnivores be selected for learning how to function with no sleep, to prey on the sleeping herbivores? I mean I would assume carnivores because herbivores have to spend a long time eating - but a carnivore just needs one lucky break, and the likelihood skyrockets with a diminishing sleep schedule.
- VortexDream 5y agoWell, clearly there are negative aspects to getting less sleep, so there is no (or insufficient compared to the benefits) evolutionary pressure in that direction.
- hackflip 5y agoYour are describing nocturnal animals.