11 ms·
Tears
- urs2102 10y agoCurious if anyone knows anything about the similarities/differences between human crying and dog whining?
- Analemma_ 10y agoDo dogs whine amongst themselves, or is it a behavior they only use around humans? (like meowing in cats: cats don't meow to other, only to get something from people - it's a trait learned from domestication). I image behaviors learned by domestication behave a little differently: the selection pressure is much greater, and they evolve in response to feedback from a completely different species instead of one's own.
- urs2102 10y agoThat's actually a great question. I'm not sure at all. It's definitely really hard to look at a dog's ability to communicate in a vacuum outside human domestication. Couldn't find any papers on whether they whine amongst each other on a quick Google myself.
- rossdavidh 10y agoIn the case of dogs, we should probably look at wolves to see if the whining was a response to domestication. But I don't know if wolves whine, so I'm not much help there.
- thatcat 10y ago>Idk if wolves whine They do
- jaimex2 10y agoDomestication goes both ways, over time we may have developed a response to them whining. I remember a test done where humans had to listen to dog and cat sounds and identify what the animal was communicating (to humans or other animals) and we were quite good at it.
- dragonwriter 10y agoActually, with meowing, adult cats not raised around humans don't do it, but kittens do it; it's a behavior of kittens that continues being rewarded in domestic situations after maturity and so isn't abandoned.
- Symmetry 10y agoNeotenous behavior isn't at all unusual in domesticated animals.
- Jhsto 10y agoAre you sure about the meowing? I have heard and seen cats meowing at magpies and to each other.
- throwanem 10y agoCats will chirp at birds, but it's a hunting behavior and a different sort of sound. I've never seen adult cats meow at one another the way they will at humans.
- gerbilly 10y agoKittens meow (and loudly) to their mothers if left alone for too long. So it's not a behaviour unique to human cat interactions. As is typical, it is a innate behaviour that seems to be repurposed when interacting with humans. Humans are very auditory, and cats faces are not as expressive as dogs are. So cats seems to [1] discover that meowing is a good way to get a human's attention. Behaviourism predicts that when an organism is faced with a 'problem' to solve it will often run through it's behavioural repertoire, trying each behaviour until one seems to trigger the desired outcome. [1] each cat on his own!
- gerbilly 10y agoThere is also another cat sound that to me seems to signal surprise, that sort of 'mrrrrow' sound. If you wake up a cat, or sneak up on it they consistently make that sound.
- cwbrandsma 10y agoOr birds holding a wake for a lost member of the flock. California Quail do that around me. One will get caught by a cat, and next day you will see the flock, right where the other bird died. I remember having a debate in high school about this. There was a very obvious difference between people that grew up on farms around lots of animals, and types of animals, and everyone else (most of which lived in town). Farm kids: yes, animals have emotions and "feel". Town kids: very uncertain. Later I went to a larger city for college in a state not known for agriculture, it amazed me the ignorance of people about animals. Absolutely no clue. And the larger the city I visit, the less people comprehend the outside world.
- 6stringmerc 10y agoNeat summary and contextualization of the topic! Seems simple on the surface, which is why a nice lead through is helpful. Last week at the zoo I watched the Chimpanzee dynamics for a good half hour or so. Very extreme by comparison to us. Loud. Chasing. Urination. I suspect that biologically there's some overlap between Tears in Humans - which Chimps don't seem to possess the capacity to produce - and Defecation as a communication mechanism that Humans have spent a lot of time evolving away from. Each can be quite expressive.
- msluyter 10y agoI recall Scott Alexander (slatestarcodex.com) proposing the tears/bullying hypothesis somewhere, but I can't seem to find it at the moment.
- Analemma_ 10y agoThe subject matter reminded me a lot of his post about guilt, but I don't remember one about tears. Maybe that's what you were thinking of?
- scandox 10y agoI found the preamble a tad confusing. It seems to imply that all our evolutionary behaviours aim at solving a problem. I had understood that they are simply the emergent phenomenon of selection - in other words they are the behaviours associated with successful individuals/groups. Is this just a sort of shorthand - assigning a kind of design _intention_ to Nature as a simpler way of expressing this? If so, isn't it anyway the case that not all selected behaviours do actually solve a problem, but are sometimes just a case of "stuff that became associated with success"? I should say my last encounter with biology was a GCSE some time in the 1990s.
- acomar 10y ago> Is this just a sort of shorthand - assigning a kind of design _intention_ to Nature as a simpler way of expressing this? Yes, and it's a fairly common, if misleading, shorthand. It's easy to communicate and so gets spread quickly and easily but it always takes careful reading to work out if the author is perpetuating a misconception around intelligent design or merely using an easily digestible metaphor. I suspect the author is doing the latter from a cursory reading, but I might be wrong.
- xg15 10y agoLayman here. Wouldn't that metaphor be valid if the "problem" being solved is actually a driving factor of selection? E.g., birds capable of flight have numerous physiological changes which could be seen as "optimizations" for flight. Yet, formally, "flight" doesn't appear anywere in the equation - it's just genetic markup that has been driven in a certain way by recombination and selection. However, for many birds, the ability to fly - and to fly better than their predators or competitors in some aspect - actually highly influences the ability to survive: Therefore genetic markup that results in physiology more capable of flight results in a higher likelihood than markup that worsens the ability to fly. (Of course other factors, such as environment, influence selection. Additionally, certain traits can increase likelihood of survival in a different way - even if they are poor solutions to the original "problem" - and lead to adaptation. So the metaphor is obviously not perfect)
- VLM 10y ago
- bbctol 10y agoThe question of why humans cry is always fascinating, since it's such an instinctive behavior we don't seem to realize how bizarre it is. I tried a little to develop a deliberately insane theory to submit to BAHfest (SMBC's festival of bad scientific hypotheses http://www.bahfest.com http://www.bahfest.com) and proposed that crying exists to blind us during periods of great emotional stress, since we'd otherwise be prone to irrational and dangerous behavior. Unfortunately, compared with the real attempts to explain tears, it seemed a little too plausible to be bad! When the state of research has someone proposing "we cry because of the soot flying into our eyes at prehistoric funeral pyres," it's hard to be deliberately weird. (I eventually came up with a much funnier topic, so swing by if you're in the area shameless plug etc)
- ygaf 10y agoWho doesn't want that trophy?
- tbabb 10y agoTo be fair, I think the soot hypothesis is so terrible it would fit right in at BAHfest. Frankly I'm astonished it has any credibility whatsoever, and if it does, it would severely dim my view of the entire field.
- VLM 10y agoAcross species eye contact is a thing for both carnivore/herbivore dynamics and also dominance hierarchies so if you intentionally wanted to create a weird theory I'd suggest mixing those in weird ways. So if a hunter gets hurt while hunting he could screw up the hunt for everyone by being hurt except for crying messes up his eye to eye stare down so he temporarily falls to the bottom of the dominance hierarchy allowing the overall tribe better luck hunting and more meat for everyone including himself, therefore cry in pain, in the long run equals more delicious meat. Stalking being more a carnivore behavior than herbivore I'd theorize crying is extremely manly and women carried the trait originally rather than directly benefiting by expressing the trait. The vegan types can be very vociferous when presented with commentary about the biology of the human body appearing to have evolved to support meat eating, so be careful, its very politically incorrect to look into things like cross species carnivore eye contact behaviors or apparently evolutionary evidence of stalking and hunting biological technologies.
- gerbilly 10y ago>Humans, unique among all animals, have an instinct to resist aggression even when it's directed toward other members of the group (even non-kin). I'm not convinced that this is a unique to humans.
- abstractbeliefs 10y agoCan you provide some counterexamples?
- throwanem 10y agoI've heard tell of ravens attacking humans who had previously attacked other ravens, sometimes quite a while before; at the moment I'm unable to go hunting a cite, but that might be a place to start.
- Symmetry 10y agoI think it's clear from context that the author meant intra-group aggression. A dispute between a human and a group of ravens isn't really a matter of politics in the way a dispute within a group of humans (or chimps for that matter) is.
- gus_massa 10y agoAfter 5 minutes of googling: * "Buffalo's brutal revenge: Animal gores lion and tosses it into the air after pride attacks its herd and slaughters one of its companions" http://www.dailymail.co.uk/news/article-3518658/Buffalo-s-brutal-revenge-Animal-gores-lion-tosses-air-pride-attacks-herd-slaughters-one-companions.html#ixzz4buQqjhZZ http://www.dailymail.co.uk/news/article-3518658/Buffalo-s-br... * "Rhinos save Buffalo from Hyena Attack" https://www.youtube.com/watch?v=e-cbxLyRN0o https://www.youtube.com/watch?v=e-cbxLyRN0o I guess that wolves and crows will also be good examples, but I don't have a link just now. Also, I live in Argentina and here it's common to have "dogs walkers" that pick a small number of unrelated dogs 5-10 from different owners. I guess that if someone is stupid enough to attack one of the dogs, the other dogs will react.
- 10y ago
- mannigfaltig 10y agoThere seems to be a very interesting book in the making by the same author and in a similar vein of this article. The website says it will be finished at the beginning of 2018: http://elephantinthebrain.com/outline.html http://elephantinthebrain.com/outline.html
- caublestone 10y agoOur expression of grief is probably a result of a mutation that altered the structure of our amygdala so that fear controls brain chemistry less than our primate ancestor. When an animal is in fear, chemical reactions desensitize and suppress brain activity involved in emotional expression to protect the self from being perceived as weak and dedicate brain energy to motor functions. Looking at tears and the neurological development from genetics through adulthood would be a great way to understand what makes us human. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2871162/#!po=29.8450 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2871162/#!po=29...
- blackRust 10y agoHaving recently read "Are We Smart Enough to Know How Smart Animals Are?" [1] by the brilliant primatologist Frans de Waal, the whole introductory paragraph reeks of the "humans only" dogma. Even the link to the Wikipedia article directly contradicts the statement of humans being the only species to bury their dead. How counter-intuitive it is: so many aspects of evolution we accept as continuum with shared phenotypes (and extended phenotypes) all the way through, yet when it comes to our intelligence and specialness, we forget all of this. [1] http://books.wwnorton.com/books/Are-We-Smart-Enough-to-Know-How-Smart-Animals-Are/ http://books.wwnorton.com/books/Are-We-Smart-Enough-to-Know-...
- MaxfordAndSons 10y agoFWIW the author acknowledges in a footnote that some of the "human only" traits are contested. I totally agree that anthropocentrism in a fallacy/trap that we can fall into in all sorts of domains of thought - metaphysics, ethics, behavioral/evolutionary economics or whatever its called, etc. But, to paraphrase Marshall Sahlins, "'Animals are basically people' is a much healthier perspective than 'People are basically animals.'"[1]. Which is to say, I think we can let our biases slide in this case, because even though we're focusing on ourselves because of our misperceived 'specialness', we can still learn broader truths in spite of this because we aren't actually so special or apart from nature. [1] From intro to http://www.prickly-paradigm.com/titles/western-illusion-human-nature.html http://www.prickly-paradigm.com/titles/western-illusion-huma...
- woodandsteel 10y agoI hear what you are saying. But it is also a mistake to simply assume that there is nothing that is unique to human psychology. In particular, we need to explain why humans have been so remarkably successful, including at dominating other species. For instance, in all other social mammals, as far as I know, the social group consists of only the group you directly belong to and are in immediate contact with, and this group is in competition with all other social groups of your species. But in human foraging groups, you band is a member of a larger tribe of many bands that you cooperate with, even though the bands are in no immediate contact most of the time. Now think of all the behaviors and cognitive mechanisms required to make that happen.
- gfosco 10y agoInteresting article, still a lot of unanswered questions and open areas for discussion... Most of my life, I was pretty unemotional. I didn't cry watching movies or TV, and even personal matters never brought me to tears. At some point, just shy of 30 years old, everything changed. I was always empathetic, but, that went in to overdrive... Seeing someone else cry or watching a powerful moment on TV can trigger an instant welling of emotion.
- jawon 10y agoTears aren't excretory or cathartic? Maybe this guy hasn't been through the right kind of situation. When one of my kids was going through a health crisis I did a heck of a lot of lone crying. Each time internal stress and anxiety would build, my guts would get all churned up, then it would reach the point where I would cry and the "symptoms" would all reduce dramatically before starting to build up again. I was amazed at the time that crying had such a noticeable effect on physical symptoms. I thought I must be dumping something, adrenalin?, out my tear ducts. I'm probably wrong, though it's not the kind of set up you can test in a lab.
- mod 10y agoSeems to me like dumping a chemical out of your tear ducts is exactly the type of thing you can test.
- wickawic 10y agoReminds me of all the historic (and continuing!) confusion around women's sexual health.
- Chris2048 10y agoHow so?
- GrinningFool 10y agohttps://en.m.wikipedia.org/wiki/Female_hysteria https://en.m.wikipedia.org/wiki/Female_hysteria
- Chris2048 10y agoI mean what is the link to tears, just "confusion"? Also, Victorian attitudes to female hysteria are confounded by JC attitudes towards female sexuality.
- i336_ 10y agoPossibly tangentially related: http://robinwe.is/explorations/cry.html http://robinwe.is/explorations/cry.html -> https://news.ycombinator.com/item?id=11787083 https://news.ycombinator.com/item?id=11787083
- uptownfunk 10y agoA bit of an odd article. I normally equate crying as grieving, viz a combined physical and psychological reaction to some external distress. Here it seems the author is fundamentally concerned with crying as the purely physical response of 'tearing' which I don't know if it really makes sense to breakdown that way. Nonetheless, an interesting piece and written by a fellow Cal Bear as well.
- applesapl 10y agoFor some reason I just find his articles annoying..his tendency to ascribe a scientific or economic purpose/motive behind everything ..seems too much like positivism and eliminative materialism. Science and economics isn't the answer to everything.
- abvdasker 10y agoYeah the idea that these things can be explained simply by a purposeful guiding force like evolution is an attractive idea not unlike the belief in a higher power. What seems more likely is that many human traits and behaviors are highly complex evolutionary cruft — things accumulated over millions of years that fall into a few categories: 1) evolved "recently" to create a specific advantage for a human population (the author's favored explanation for crying) 2) provided an advantage for a distant ancestral species and stuck around long past the context in which they were advantageous (the human appendix) 3) random interaction between different traits or behaviors initially evolved from 1&2 4) random evolved trait that happened to be part of an evolutionarily successful population (Epicanthic fold) 5) random interaction between evolved traits or behaviors and a novel environment to produce novel behavior (over-eating and obesity caused by an evolutionary preference for high-caloric foods and their now-widespread availability) I tend to not like the speculative aspects of evopsych like the ones in this post because they don't really account for the amount of randomness, complex interaction, and vestigial weirdness that seems to result from evolution.
- dwaltrip 10y agoBut perhaps they are useful for understanding and exploring how things work? As this article was clearly attempting to do.
- gus_massa 10y agoI also find his articles annoying but I have no problem with ascribing a scientific or economic purpose/motive behind everything. The problem is that the explanation has to be solid, based in evidence and experiments. This article is a well written rambling, or to be more clear just an opinion. For example in: > We're also the only creatures who sing from the ground, sing and dance together, bury our dead, point declaratively, enjoy spicy foods, blush, and faint [1] (not to mention all of our weird sexual practices). > [1] human-unique traits. Some of these are contested. [...] And I'm sure there are other examples of similar behaviors enacted by non-human animals. But the basic point stands: We do a lot of things that, if not singularly unique, are nevertheless extremely rare. He cherrypicks a few behaviors and say that they make us unique, and when there is contradicting evidence he just ignore it. Whales can sing, wolves howl (is that similar enough?) and just ignore birds because they are not intelligent enough. Bonobos have a lot of weird sexual practices that are similar to the human one, and other animals have even weirder sexual practices that are unimaginable in humans. And the list of exceptions go on ... It's similar to: from https://xkcd.com/775/ https://xkcd.com/775/ > See, that's just the kind of bullshit sexism that discredits evo-psych. Your "evolutionary histories" always seem tuned to produce 1950's gender roles.
- ldehaan 10y agoMost of the things in this list are not specific to humans. Interesting idea + bad research = fake news this needs to stop so badly.
- wcdolphin 10y agoHow does this theory explain the act of crying in private? The theory explains why someone would want not to cry in front of people (loss of prestige/dominance), but not why someone would want to cry alone, in private.
- Analemma_ 10y agoThat's not how evolution works. If evolution builds a mechanism to make you respond to a certain stimulus in a certain way, then it's more work (and more unlikely) to then make that mechanism only act under certain circumstances. We wouldn't not cry in private unless there were additional fitness advantage to it.
- sillysaurus3 10y agoThe appendix seems to be a counterexample to this philosophy of evolution. Useless body parts exist. What are the chances there are no useless behaviors? (By "useless" I mean "no fitness advantage.")
- cauterized 10y agoNot sure I agree wholly with the GP, but recent theories suggest that the appendix does in fact serve a useful purpose. It can act as a reservoir for gut bacteria that are necessary to our digestive health. It helps repopulate gut flora when they get wiped out by illness (often caused by other bacteria) that causes a bad case of the runs.
- woodandsteel 10y agoI agree that science can't explain everything. But I think that for every individual case, you need to make a sincere attempt to come up with a scientific explanation and then fail, before you can decide it is a mystery.
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- BurningFrog 10y ago
- woodandsteel 10y agoIt seems to me that crying often produces a cognitive process. So I feel sad about something and feel I can't do anything about it and cry, and after a while I don't feel so sad and see the situation in a different perspective where I can go on living. Or something distressing happens, and I talk about it and cry some, and after a while I feel better. This seems to be a different sort of situation than crying to get help with an immediate situation. I wonder if that sort of case evolved first, and then got modified and used for the cognitive processing one.
- throwaway5752 10y agoIs there anyone here that's an actual subject matter expert on this topic? I know 1) that I am not a expert on why people cry 2) I don't believe the author has more than a day's worth of googling more background on the subject than me 3) I suspect there are people that have devoted a whole lot more time than the author to the question of why humans cry. I'm not trying to judge the author, I'm just selfish about and hate wasting my time. This had every hallmark of half-assed pseudo-intellectualism and I don't have a day of time to find out.
- rm999 10y ago>I don't believe the author has more than a day's worth of googling more background on the subject than me There's a certain irony in this accusation considering 30 seconds on his site led me to find out he's writing a book on the subject of social psychology. http://elephantinthebrain.com http://elephantinthebrain.com. The fact that he took the time out of his book writing to write this article probably means he's researched and thought a lot about the subject. He may be a secondary/tertiary source on this matter, but that doesn't mean he has nothing insightful to say about it, or that people who read the article are wasting their time (not to say that the reverse isn't true; maybe he hasn't properly learned the topic, but it's wrong to assume he just wrote this article off the cuff).
- throwaway5752 10y ago"Like all psychology books, The Elephant in the Brain examines many quirks of human cognition. But this book also ventures where others fear to tread: into social critique. The authors show how hidden selfish motives lie at the very heart of venerated institutions like Art, Education, Charity, Medicine, Politics, and Religion. Acknowledging these hidden motives has the potential to upend the usual political debates and cast fatal doubt on many polite fictions. You won't see yourself — or the world — the same after confronting the elephant in the brain." Pardon my skepticism that someone that has a scholarly background in unrelated subject areas and has spent 10 years outside academia is going to do anything but scratch their own itch or vent their own spleen. Nothing wrong with that. But also pardon my false modesty. I'm not what I would consider an expert, but I'm not ignorant about biology, endocrinology, chemistry, evolution, genetics, psychology, history, geology, quantum mechanics, plumbing or any number of other subject areas that any person who wants to be well-rounded in has at their fingertips now. Anyway, I didn't say (and don't think) the article was written off the cuff, I said it's half-assed pseudo-intellectualism. Fisking this thing is beyond by scope of my interest, but: 1. "If evolution devised to make our bodies do something, then the action is unlikely to be a meaningless side effect. There has to be a point to it." extraordinary claim, arguable merit, completely taken for granted 2. "Modern Western culture portrays sadness and tears as inextricably linked" I don't know anybody that thinks this (everyone is aware of happiness, response to beauty, stress, etc), one example of pattern of over- or misstating status quo to boost heterodox bona fides. 3. "There's an idea that we sometimes cry due to extreme happiness, but I think that's a little off the mark. I would rather say that we cry when we feel humbled by something great — something that would otherwise, if it weren't so humbling, cause unbridled happiness" the rare actual example of begging the question (in context of his later claims) 4. "Unfortunately, "stimulus: response" is the wrong frame to use to analyze crying, mostly because it saps the crier of any kind of intelligent agency." another extraordinary claim of arguable merit used to support later argument 5. "Another misconception is that crying is somehow directly therapeutic. Yes, it can feel good to cry, but no:" this whole line of reasoning is ridiculous, why bother to conduct double blind drug trials with placebos, again? Again, core to his thesis, and very flawed. 6. "The fact that we, as receivers, often feel manipulated by someone else's tears is the giveaway that crying is a signal — i.e., because it aims to change our behavior. When someone's tears are making a "request" that we feel is legitimate (and when our interests overlap with the sender's), we're happy to oblige. But we need to make sure we're not getting jerked around, so we're eager to evaluate the situation, to determine how appropriate an episode of crying is. In other words, we can get really judgmental about tears." I see no citation for this, and it doesn't match my experience, so I can only presume this is the author substituting anecdote/personal feelings for fact. Certainly under-supported. 7. "No one contests that these are, in fact, two of the ways we use tears. " I completely contest that human being utilize tears as signals in they way the author claims. It's only because of the rhetorical structure of the piece that this even seems plausible at this point. If I wrote a single sentence article that said "I believe crying is a signal to others of submission/distress instead of an involuntary reflex" the difference in a readers' reaction should indicate the difference between the degree this article is convincing vs the degree to which it has merit. 8. "Why did we evolve yet another way to signal submission or distress?" Arguable merit, lacking support for thesis this is evolved rather than learned. 9. "Tears, in this theory, are a political act, in the same way that tattling, gossiping, and whistleblowing are political" Did anyone even read to this point? How far are we removed from the practical reality of "I cried when I found out a loved one died" reality most of us experience? 10. "The answer is fairly simple. Humans, unique among all animals, have an instinct to resist aggression even when it's directed toward other members of the group (even non-kin)" Really, this could use a citation. There are more, but again, my time is finite. Please don't mistake my prior comment as "I didn't read the article". I read the article and thought it was lacking, an example of someone that starts out with their thesis and backfills with trivia, mediocre citation support, and fancy language to lead you to the intended destination. Since there are presumably actual experts on this out there, though, I was hoping that one of them might read this and volunteer some information about the subject. This just seems like someone read Harari and took away the wrong lessons about pop soft-science writing.
- waderyan 10y agoI have a two year old son. As you can imagine he cries a lot. Lately we have been applying some EQ lessons we've learned and have tried to teach him to be aware of how he feels when he cries. You'd be surprised he's actually pretty good. He starts to cry and then says "I'm crying." We acknowledge that he is crying by saying something like "You seem sad." He generally stops crying at that point and we move on. Its like the signal was sent and received. He feels heard.
- Nomentatus 10y agoI'm toying with the idea that tears are the direct result of excess CSF pressure (i.e. a way to vent that), having observed someone with that condition who tears very easily. Just maybe. This would presumably require that the lacrimal fossa be connected to the inside of the skull, which is certainly possible. Humans, the only upright animal, have unique fluid pressure problems within the skull (except for giraffes - maybe they cry, and nobody's noticed) so crying being unique to humans wouldn't be too surprising. One tiny bit of evidence, a study showing valproic acid ratios (in those taking the drug) are about the same in both CSF fluid and tears: https://www.ncbi.nlm.nih.gov/pubmed/6799283 https://www.ncbi.nlm.nih.gov/pubmed/6799283 Of course, crying being a signaling mechanism is another explanation. Maybe a better one. The only other connection I can make is that migraines are closely correlated with dry eyes (and emotion can trigger migraines.) So people with migraines are sometimes advised to use eyedrops to reduce migraine incidence these days. Lacrimation is also a migraine symptom. If your brain is very active due to emotion, maybe tears help to reduce the chances that migraines result? (Or returning to the first hypothesis, maybe CSF pressure is elevated during migraines.) Not a disproof, but chimps are more socially sacrificing than this article indicates, they will find crippled chimps for long periods, as a group; IIRC not just relatives.
- throwaway5752 10y ago"I'm toying with the idea that tears are the direct result of excess CSF pressure (i.e. a way to vent that)," Don't, it's not. Why don't you thing 1) high CSF pressure is mood altering/predisposing to tear activity 2) high CSF may be the result of an underlying cause also express in lactrimal gland activity? Those are simpler explanations, and not false, like the lacrimal duct/CSF hypothesis. As for valproic acid, you are letting the tail wag the dog (the point of the article was to suggest diagnostic technique, and the drug was present in all tested fluids... the burden of proof would be on your to say why concentration in tears would not correlate well with serum levels, which also correlated as well with csf levels). The only things I could find about migraines and dry eyes were positively correlated, but not strong, and not enough to be causative. Can you share more sources? Also, most source indicates IIH can be comorbid with migraines, but is unrelated, curious if you have sources to share on that, too.
- dwringer 10y agoCould tears be there for some kind of moderating effect on cellular action potentials? Tears are notoriously salty; "salty" has even become synonymous with bitterness, angst, or remorse. I think their production does seem to have a noticeable effect on cognition, but for all I know it's just a coincidence. Certainly they would extract sodium from the body to some degree, I just wonder how much of an effect that would have. EDIT: here is a vaguely-relevant(?) study from 2014 about an infant presenting with inconsolable crying allegedly because of "an alteration of sodium channels inducing neuropathy in small-caliber fibers" (1) EDIT 2: As for why this is something that happens from the eyes specifically, I wonder if it is for a particular local effect on ion channels in the frontal lobes. [1] https://www.ncbi.nlm.nih.gov/pubmed/24468061 https://www.ncbi.nlm.nih.gov/pubmed/24468061
- throwaway5752 10y agoFirst: tears are just as "salty" as blood, so they have no net effect (120–170 mmol/l sodium for tears vs 140 mmol/l in plasma). Even if that was not the case, it would have hardly any effect (5 liters of blood v. a few ml tears). Finally, any effect would be dwarfed by the robust homeostatic system regulated by the hypothalamus. Second: from your study: "Treatment with analgesics and ice packs was established" the infant was crying because the peripheral vascular disease caused them substantial pain. Edit: I guess your "edit 2" is aimed at me? I mean, maybe? It seems like a huge piece of speculation on your part without a particularly well thought out mechanism, so I'd love to see a bit more work on your part before discussing further. I assume you mean that it would be a change in Na+ concentrations propagated by osmotic difference via the optic nerve, because otherwise I don't know how you'd propose that would work (meninges, blood-brain-barrier, and all). Some kind of quantification of the osmotic difference and the rate that would propagate..
- dwringer 10y agoI am not clear on what you mean by "no net effect", and not entirely sure how tears are comparable with blood since tears are expelled from the body; blood (and any sodium it carries away from the brain) hopefully remains in the body (not to mention that blood contains a lot more than just NaCl, compared with tears). I am also curious as to how quickly the hypothalamus would respond to a local drop in sodium ions. What you say is plausible; I do tend to agree with you about the study interpretation. Like you, I really want to hear from an expert in this field. EDIT to reply to your edit: No, my edit 2 above was made before I saw any replies, sorry about that. Yes, it is certainly nothing but speculation. (Thank you for pointing me in the direction of further study - I'm afraid this type of thing is a bit beyond my education when it comes to biology)
- sushobhan 10y agoI hope someday I'll read such detail research on when and how we evolve to lie. It always fascinated me, when this starts and how it propagates from one generation to another. I'm almost sure, it's the most unique human trait.
- haikuginger 10y agoRead "Liars and Outliers" by Bruce Schneier.
- empressplay 10y agoArticle is wrong. Crying is cathartic.
- csomar 10y agoIs he sure that only humans cry? I can perfectly remember my dog (RIP) crying with tears when I lock him up in a cage (sometimes we need to lock him up because he is too friendly to visitors).
- bmelton 10y agoI don't know about the author, but every vet that I've talked to has seemed pretty certain of it. We have an older dog who has begun to get weepy. We first assumed that it was related to resultant pain from her arthritis, but her vet (and three subsequent vets) all assured me that I was definitely wrong. http://www.akc.org/content/dog-care/articles/do-dogs-cry/ http://www.akc.org/content/dog-care/articles/do-dogs-cry/ Is it possible that there's an allergen in or near your dog's cage?
- speby 10y agoDefinitely queues up Terminator 2: https://www.youtube.com/watch?v=eSotD5M3bsY https://www.youtube.com/watch?v=eSotD5M3bsY
- dgreensp 10y agoAs a parent, it seems like a glaring omission that most crying is done by babies. It's right there in the article that humans have the "most dependent babies," and signaling behaviors are often repurposed responses, so it's a good starting point to say that crying (with big inhales and audible sobs) evolved as a "baby in distress" alarm, in which a baby makes a lot of noise because it needs help. We go to that place when we feel small or want the kind of support a parent would give. Babies often don't have tears for the first few months, but I'm not sure that's important. I do think they play a role on the playground, and a lot of the speculation about their effects in social situations sounds right. I don't have any ideas to contribute on why crying is accompanied by tears. In any other species, wearing a signal that advertises, "I recently lost in a dominance challenge," is a strict liability — an invitation for others to pile on, opportunistically, and attack you while you're down (or else to mentally note that you're no longer a good, strong ally). There's no upside, therefore, to using anything other than a quick facial expression or flash of body language, to show your submission only to the aggressor. That sounds like an overly harsh picture of non-humans to me! I'm pretty sure at least certain apes help their potentially-non-kin in distress. Humans aren't the only social mammals.