I know evolution is governed by chance and it is random but does it make sense to "ruin" sleep if there's light? I mean normally, outside, you never have pure darkness, there are the moon and stars even at night. In certain zones of the Earth we also have long periods of no sunshine and long periods of only sunshine....
I study circadian rhythms (the process that is responsible for getting us to sleep in the night). Specifically, how circadian rhythms influence how easily we catch diseases, but that part is less relevant to the question.
So since Earth rotates and has day/night cycles, life on Earth evolved to try to predict when the day and night comes. That's what circadian rhythms do. This is really important, since day and night aren't just associated with lightness/darkness. Day and night are associated with a ton of different environmental differences. For instance, it's colder at night, so animals need a way of keeping warm at night. There's more UV light at day, so animals need a way of resisting DNA damage in the day. There's some evidence that the bacteria in the air are different at day vs. at night, so animals will need to have different levels of immune system alertness.
We as humans live in artificial houses with artificial lighting, so we can lose track of why this is really important. But if you've ever went camping or tried to stay out at night you'll probably understand why it's really important for animals to be able to predict the time.
Circadian rhythms end up getting reinforced on a community level, since if it's easier to see in the day, an animal is more likely to forage in the day. Then predators will notice that prey is more plentiful in the day, so it will also be more likely for predators to hunt in the day as well.
Anyways, the end result of all of this is that animals have a huge evolutionary pressure to pick either the day or night to be their active period, which is the time where they look for food and in general just be awake. And whatever they don't pick, that's their rest period, the time where they sleep and recover.
But how do animals know that their circadian rhythms are predicting the correct time? Imagine a mouse in its burrow - it wouldn't be able to tell what time it is just by looking at the sky. And even just stepping out for a second to check would be very dangerous if it ended up being the wrong time. Animals need a way of reading what time it is when their out and about and then correcting their circadian rhythms if the rhythm is inaccurate. There's a lot of different measurements that animals use to read the time, but the key here is that the measurements that they pick must change significantly between day and night. In other words, it must be a very obvious signal, like "oh, I see this signal, so there is no doubt that the time is day."
Vast majority of the time, the most obvious signal ends up behind light. And it makes sense - if you see bright light, that is the clearest indication that it is day outside. So for many animals, light is the primary measure that animals use to read the time.
So to wrap back around to your question, it's not necessarily that light ruins sleep because evolution just decided to go "nae nae," it's because predicting time is incredibly important for keeping animals and humans alive, and up until very recently, light has simply been the easiest and best proxy for the time
And to answer your bonus question, yes, other animals have their sleep messed up by light too
This is untrue - we have explicitly evolved to sleep in the dark. Sleeping in the light is a learned behavior that's more or less an exploitation of a loophole in the circadian clock
Ah, so this goes more into the nuance of what exactly determines the time of the circadian clock. It is very well documented that animals in the arctic circle still have circadian clocks even if it's perpetual light or dark. I left out for simplicity that the level of light matters - that is to say, if there's a time where it's slightly dimmer and a time that's slightly brighter, that is enough to adjust the circadian clock to the correct time. The adjustment process will be slower and weaker than usual, but it does happen.
Also, I hinted that animals do take in multiple measurements to determine the correct time, and that plays a role in this case. In general, light tends to be the measurement that animals will default to, but where light variation doesn't exist, animals can and do utilize other measurements to determine the time. Eating (among other things) turns out to be a relatively strong signal, so circadian rhythms end up being somewhat self-reinforcing. After all, I would expect that you only eat when you're awake.
But in general, circadian rhythms and the ways that animals adjust their rhythms to the correct time is a huge rabbithole
No need to use quotation marks - it is scientifically confirmed that night owls and early birds exist (among a number of other, less-well-known circadian types). We call them chronotypes, and it's an active field of study. Unfortunately it's not something that I specialize in, so I can't comment too much on it.
However, it is very well acknowledged in the field that modern society is built on an early bird schedule and that completely screws over night owls. (To my memory, night owls tend to score lower on tests, pursue higher education less than early birds, tend to be less promoted and generally less successful than early birds. Inversely, night owls tend to do better in evening classes than early birds.)
I'm pretty sure that's the general hypothesis in the field, but as you might imagine, it'll be very difficult to prove. There was a study done sometime (I don't fully remember when) where researchers collected data on when people go to sleep and when they wake up, and they found that there was a remarkably normal distribution in the population for when people wake up and sleep.
My personal interpretation is that chronotypes (what you call early birds and night owls) are genetic in some way, but I don't specialize in this area, so don't take my word for it
Yes, but your wikipedia link doesn't prove that animals are only sensitive to blue light, only that they are more sensitive to blue light. That is a very well-documented phenomenon. But there is plenty of evidence that red light can entrain circadian rhythms as well, dating well back to the 80's. There has even been a study that identified different mechanisms of entrainment to low-wavelength and high-wavelength light in bacteria, which you can find below. My point is that it is very scientifically irresponsible, and in fact, blatantly wrong, to claim that humans are sensitive only to particular wavelengths of light, when in fact humans and other animals are sensitive to all wavelengths of visible light.
Beyond that, I don't necessarily know why you seem to be claiming that the intensity of the ambient light does not matter for photic entrainment, when this is a highly documented and, in fact, highly studied phenomenon in the circadian field. Yes, the moon reflects light, but this is dim enough that mammalian SCN's can interpret the difference between that and the full daylight. See below for some papers that look into light intensity and their effects on entrainment.
You're right, I can't give medical advice. But having abnormally long or short circadian days is a known thing - called circadian diseases. It's not really my specialty, so I can't comment too much on it, but my understanding is that many of them are genetic. These genetic variations can cause the circadian clock to run slower or faster than normal (which happens to be adjacent to what I study, so I can talk about it in excruciating detail if desired)
The Familial Advanced Sleep Phase Syndrome (FASP) is one such genetic circadian disease that gets a lot of attention among the circadian field, but you almost certainly don't have it, since FASP makes your clock run shorter than 24 hours, whereas you seem to imply that yours runs longer.
The key thing to remember is that the circadian clock is not psychological. There is an actual, physical, molecular clock running in your brain and in nearly all the cells in your body. If this clock has imperfections, then that will directly lead to consequences in your circadian rhythms and your sleep cycle. The circadian clock is a real thing that people with the right equipment can measure and read. It wouldn't even be particularly hard - just a blood sample or a swab would be sufficient. To be honest, I myself would like to study your cells to see if there really is anything out of place, but that would probably break so many research and ethics rules.
Anyways, to answer your question, I would recommend getting a medical opinion - it might be worth specifically bringing up that you suspect you have a circadian disease. I'm not too sure about treatment options, since my impression has generally been that we kind of don't have any treatments for circadian diseases. But it's not really my specialty, so maybe there is. My memory is that melatonin is a masking cue, which basically means that it makes you sleep but it doesn't actually affect your circadian clock (which probably explains your poor experience with melatonin).
Yeah, crepuscular animals are weird. They have circadian rhythms (the circadian clock is incredibly well conserved across vertebrates and to a lesser extent, across invertebrates), but I'm not actually entirely sure how their circadian clock work to get them to wake up at dawn/dusk
Yeah, sure! This happens to be my field of research.
So I was referring to this particular paper, which unfortunately (to my knowledge) didn't get much follow-up.
Tangentially, there is much other evidence that circadian rhythms have evolved in part to deal with differences in microbial pathogens at the day vs. at night. However, whether it's because the composition of bacteria in the atmosphere is different, or because animals are more likely to get themselves exposed to pathogens when they're foraging, or a mix of both, is unclear. My favorite paper that demonstrates this effect is this one, where the circadian clock affects how strongly the immune system responds to bacteria in the lungs. I'll also include the seminal paper here that first kickstarted the idea that immunology is fundamentally circadian, although frankly I didn't like how the paper was written. It looked at how mice responded to Salmonella infection at the day vs. at night and found a difference in immune response that then led to a difference in how severe the infection got.
To my knowledge, a similar study has never been repeated with other biomes. Which is a shame, since I can almost guarantee that a similar diel cycle exists in virtually every biome.
Could we, in theory, use something like CRISPR to give a new baby replacement super-kidneys (or whatever organ it is that makes drinking saltwater be a bad time)? It seems like if we cracked that, we’d be set as a species....
Not a direct answer, but I want to point out that if you’re considering a technology that will help improve poor people’s lives, you must also consider that technology is prone to the same issues that caused the wealth disparity in the first place. Namely, that only rich people can afford new technologies. Suppose if we really are able to edit human genes to let people drink salt water. Would poor people (the people who may actually need this technology) be able to afford it? Or will it end up just becoming a gimmick for rich people?
As others have pointed out, there’s really no need to be able to drink salt water, since we already have the technology to desalinate water. It’s only that poorer areas don’t have the funding to build desalination plants. You can start to see that it’s the same issue as what I said above - there’s a new technology that would theoretically help poor areas, but then it ends up not benefiting poor people because they can’t afford the technology.
All of this is not to say that new technology is bad. It’s simply that we already have solutions for a lot of societal issues, and the reason we still have those problems is simply because we as a society don’t care enough to distribute the benefits of those solutions fairly
Disclaimer: I’m not a physicist, but I am a scientist. Science as a whole is usually taught in school as though we already know everything there is to know. That’s not really accurate.
Science is really sort of a black box system. We know that if you do this particular thing at this particular time, then we get this particular response. Why does that response happen? Nobody really knows. There’s a lot of “vague” or unknown things in all of science, physics included. And to be clear, that’s not invalidating science. Most of the time, just knowing that we’ll get a consistent response is enough for us to build cool technologies.
One of the strangest things I’ve heard about in physics is the quantum eraser experiment, and as far as I’m aware, to this day nobody really knows why it happens. PBS Spacetime did a cool video on it: youtu.be/8ORLN_KwAgs?si=XqjFEjDfmnZX31Mn
I am generally somewhat skeptical about your comment. Sure, I hadn’t heard about Sabine’s video about the quantum eraser, but I don’t necessarily think that it disproves the idea that physics is never vague or unknown.
Perhaps it is different in physics than my own field, but if you read enough primary papers, enough lit reviews, at least in my field, you’ll see some common themes come up. Things such as “further research is required to determine this mechanism,” “the factors that are involved are unknown,” “it is unclear why this occurs.” Actually, your suggestion that nothing is vague is entirely counter to my entire field of science. When we introduce ourselves in our field, we start off with a sentence about what we do not know. And perhaps it is my bias, having worked in my field, but I cannot see how any scientist could possibly say that nothing is vague.
To me, my interpretation is that “science is not vague” is itself a symptom of popular science. “Science is mystical” is simply a symptom of a slightly different disease - the disease of poor popular science communication. But I think that’s distinctly different from the question, which is asking if anything was vague. I’d love to hear your thoughts on the matter.
Thank you for the thoughtful response. I see that we interpreted the question differently, based on what we thought was the issue of science communication. Which I think is really interesting!
I see what you mean - the people who impose their fantasies onto the science, who seemingly think there is some sort of “science god” who determines what fact is true on which days. Certainly, they are a problem. My experiences with non-scientific folk have actually usually been something of the opposite. They think that science is overly rigid and unchanging. They believe that science is merely a collection of facts to be memorized and models to be applied. Perhaps this is just the flip side of the same problem (maybe these people interpret changes in our knowledge to be evidence that there is no such thing as true facts?)
The difference in interpretation might stem from a difference in our fields. I assume you study physics. And I must assume that scientific rigor in physics depends on being certain about your discoveries. In my field (disease and pathogenesis), the biggest challenge is, surprisingly enough, convincing people that diseases are important things that need to be studied. Or perhaps that’s not a big surprise, given the public’s response to COVID-19. Even grant readers have to be convinced that there is merit in studying your disease of interest.
When I speak of my research to non-scientific people, a lot of the times the response is simply, “why not just use antibiotics? Why do we care about how diseases happen when we can just treat it?” A lot of my field, even in undergraduate programs, is dedicated to breaking down the notion that “we know enough, so don’t bother looking deeper.” I think there’s a very strong mental undercurrent in my field that we know next to nothing, and that we need to very quickly expand our knowledge before conventional medical science, especially our overreliance on antibiotics, gives out and fails. For instance, did you know that one of the most fundamental infection-detecting systems in our bodies (pattern recognition receptors) was discovered in mammals just over 20 years ago? The idea of pattern recognition receptors is literally only college-age.
So I actually find it interesting that you interpret the question so differently. It’s a testament to how anti-science rhetoric manifests in different ways to different fields
I grew up in an evangelical household and went to a Christian school where they only taught creationism (and a little “micro evolution” but not much)....
Scishow is good for up-to-date info about a variety of scientific fields. If you want to check if your scientific knowledge is up to date (or if you want to keep it up to date), I highly recommend checking them out. As for evolution in particular, I can’t really say. Biology is an umbrella term for a vast number of incredibly niche sub-fields, and even something that would seem straightforward, like evolution, can be broken up into multiple fields of study. For instance, I know people who study evolutionary microbiology, which is the study of how bacteria evolve.
I’m not sure if you’re looking for general knowledge of scientific concepts or if you’re looking for in-depth analysis of leading-edge, niche scientific concepts. If it’s the former, I’m sure that videos from even 10 years ago is probably fine. World-changing breakthroughs don’t happen that often. And while maybe there might be minor inaccuracies, overall it’ll still be accurate enough to get a general understanding. If it’s the latter, you’ll unfortunately have to learn how to read scientific literature
I was thinking about vaccines and their usefulness, when it occurred to me that, in using vaccines, we’ve sort of pigeonholed viruses into behaving the way covid does. Haven’t we?...
So, I’m not a virologist, so I can’t answer about viruses. But I am a bacterial microbiologist, so I can talk a bit about pathogenic bacteria. Short answer: yes. Long answer: yes, kind of.
It really depends on what the vaccine is targeting and what the pathogen is. My favorite pathogen is Streptococcus pneumoniae, the leading cause of pneumonia. So let’s look at it from that perspective. There are vaccines for S. pneumo, but the vaccines only target certain stains of S. pneumo. And every 5 or so years, we make a new version of the vaccine because the types of S. pneumo that are causing disease keeps shifting. If the vaccine accounts for type A, then type B starts to cause more disease. If the vaccine accounts for types A and B, then type C starts to cause more disease. If the vaccine amounts for types A through C, then type D starts to cause more disease. Repeat ad nauseum.
So yes, we can cause shifts in pathogen populations through vaccines. This is evolution, in its strictest definition. That being said, there’s a lot of caveats. First, that doesn’t mean that vaccines are bad. Maybe we want to shift the population (for instance, toward a milder form of the disease). Or maybe it doesn’t strictly matter if the shift occurs (if we can just keep making new vaccine versions, a la S. pneumo).
Second, even though vaccines may be shifting the population, that doesn’t mean that it doesn’t work. The S. pneumo vaccine significantly decreased infection and mortality from pneumonia. And while a lot of people still die from pneumonia today, it’s nothing compared to the mortality before modern medical science.
Third, it really depends on the vaccine. Specifically, how hard is it for the pathogen to mutate that portion that the vaccine is attempting to mimic? There are certain proteins that are more difficult to mutate than others. For instance, there are certain proteins that are involved in binding to and attacking the host. These proteins tend to be somewhat difficult to mutate, since mutating those proteins tend to also make the pathogen less efficient at attacking the host. If the vaccine trains the immune system to recognize these proteins, it can be really difficult for pathogens to evolve away from these proteins. Not to say that it’s impossible for pathogens to evolve anyways (pathogens are surprisingly tricky), but a well-designed vaccine, along with good adoption in the population, can significantly hinder a disease.
It’s really fine if nobody shows up. If anything, you could always just post or cross post something every once in a while to help the community pick up steam. What you should be concerned about is too many people showing up. The reddit admins (as well as certain sections of redditors, it seems) have forgotten that moderating is pretty tedious and not everyone has the time or energy to spend on moderating. If I were you, make your moderating policy clear from the start and stick to it as objectively as possible. When changes to that policy has to be made, clearly communicate to your community what changes are made and why. Some changes will not be accepted by the community, and you should do your best to remind yourself that it’s not a personal attack on your values if they disagree.
Starting from a molecule on up, to cells and beyond, at what system level is a being actually making a decision rather than reacting to their chemical environment based on purely chemical laws? For example, the molecules in a cells are solely reacting to their environment based on chemical fundamentals. However, a person thinks...
Frankly, the decisions that we make are chemical reactions. The difference is in the complexity of the decisions that we can make. At that point, though, in order to answer your question, we would need to argue about what one would consider to be a decision that’s complex enough and a decision that’s not complex enough, and that leans much more into philosophy and ethics rather than science.
I can only tell you that, from a mechanistic point of view, there’s not really much distinguishing our decision making process from, say, the decision making of a flatworm
Regarding sleep quality, why did humans evolve to require full darkness?
I know evolution is governed by chance and it is random but does it make sense to "ruin" sleep if there's light? I mean normally, outside, you never have pure darkness, there are the moon and stars even at night. In certain zones of the Earth we also have long periods of no sunshine and long periods of only sunshine....
Hypothetically speaking, what alterations to our biology/genome would need to occur in order for us to be able to safely drink saltwater?
Could we, in theory, use something like CRISPR to give a new baby replacement super-kidneys (or whatever organ it is that makes drinking saltwater be a bad time)? It seems like if we cracked that, we’d be set as a species....
Does physics ever get vague?
As in, are there some parts of physics that aren’t as clear-cut as they usually are? If so, what are they?
Sources to learn about recent evolutionary discoveries?
I grew up in an evangelical household and went to a Christian school where they only taught creationism (and a little “micro evolution” but not much)....
Is humanity accidentally selecting for vaccine-resistant traits in viruses?
I was thinking about vaccines and their usefulness, when it occurred to me that, in using vaccines, we’ve sort of pigeonholed viruses into behaving the way covid does. Haven’t we?...
Reddit is a dead site running ( dbzer0.com )
At what systemic level do we start to see living beings making decisions rather than purely chemical reactions?
Starting from a molecule on up, to cells and beyond, at what system level is a being actually making a decision rather than reacting to their chemical environment based on purely chemical laws? For example, the molecules in a cells are solely reacting to their environment based on chemical fundamentals. However, a person thinks...