Crying is a waste of perfectly good water. So why we do it? I have no idea, so I would like to hear your ideas. To get the ball rolling, here are eight hypotheses, each surely inadequate and probably false.
(1) Purple Haze: When the tears “well up” under the skin, even before overflowing, the skin changes color, darkening and becoming purplish. Given that our color vision may have evolved for seeing skin color changes (do a Google search of “primate rump” but without the scare quotes to find my paper on this), one wonders whether tears are all about changing the skin’s color while still under the skin. Perhaps the flowing-over of the tears is just a side story. It seems, however, unlikely that the overflowing tears is just a side effect. Why not reabsorb it? And once the tears come out, it is likely the more visually salient feature, not the purple bags of skin under the eyes.
(2) Seen Sheen: Perhaps the water visibly in the eyes and on the face creates a highly salient sheen, and this is the key. We are, indeed, highly sensitive to the signature “glimmer” of water, and perhaps this makes the face’s sad emotion easier to see. But modifying the face via muscle expressions would seem to be even easier to see. And even if tear-sheens are especially visible, why should sadness (and to a lesser extent happiness) be the emotion that utilizes this trick?
(3) Unstoppable: It can be very difficult to control a cry – which is why at the Harley Club Movie Night I go to the bathroom just before Bambi’s mother is shot by hunters – and that kind of uncontrollability is often a virtue for emotions. It let’s the viewer “know” he or she is not being manipulated. This could be part of the story of cries, but we would want to know why color signals (mediated via blood physiological changes under the skin, like blushes and blanches) aren’t enough, because color signals are also out of our control.
(4) Water-Handicap: On the topic of manipulating others, another way to convince others that you’re sad is to sacrifice something important to yourself. Perhaps tears are the sacrifice: by giving up perfectly good precious water, the crier is generally deemed to be more honestly signaling. …because crying is costly.
(5) Salt-Lick: Tears are salty and wet, just the thing animals love to lick. Perhaps tears are put out to attract grooming behaviors and intimacy from loved ones. (…who love you even though they need to be bought off by salt-licks to come to your aid.)
(6) That Wet Feeling: This idea is from my seven year old daughter. “Perhaps,” she said, “tears let us feel how sad we are.” The idea that our facial expressions are crucial in driving our inner emotions – rather than the other way around – has a long history. My daughter wasn’t intending to refer to that, I don’t think, but, rather, that the wet feeling on one’s face helps give one better feedback about how sad one appears to others. Rather than the usual proprioceptive sense of our facial expressions, her point was that the wet feel of tears is a special, extra proprioceptive sense of our sadness expression. The wet skin may even make the muscular facial expression easier to sense (i.e., in addition to the intrinsic wet feel). Why, though, should this extra-powerful proprioceptive sense be especially needed for sadness?
(7) Wet-for-a-While: Once the tears have overflowed, they stick around until they evaporate (or until the last lick of your, ahem, loved ones). To the extent that the tear-glimmer serves to signal sadness, one can keep up the sadness signal without having to put on one’s sad face. Relax your face, and let your water do the fussing on your face for the next ten minutes.
(8) Bucket-O-Tears: Facial expressions due to muscles on the face don’t tell you how long they’ve been being expressed. Tears, on the other hand, are more “additive”. The more you cry, the wetter your face, and eventually your neck, chest and Bowling Enthusiast magazine. Why, though, would this kind of “additivity” matter for sadness and not other expressions?
With the quality of my thinking on this matter out on the table, hopefully you now feel no inhibition whatsoever to propose your own idea. And if we can put together a somewhat coherent one, then we can look into how we might test it.
But don’t be a cry-baby about it.
~~~
This first appeared July 20, 2010, at Science 2.0.
Mark Changizi is Professor of Human Cognition at 2AI, and the author of The Vision Revolution (Benbella Books) and the upcoming book Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man (Benbella Books).
fascinating.. never really thought of this.
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I think maybe because of this we cry: During crying we can’t see well so we can’t see something that had made us to cry and sad. not seeing that bad thing will help us be calmer quickly. :\
Hi Zahra, It would seem, though, that that might be counterproductive. …if the bad thing is still there, and you’re not actually dealing with it appropriately, then wouldn’t it make you worse off? And thus be selected against in evolution? -Mark
For me, crying is showing that the person is feeling the extremity of the emotion. I hate crying because I don’t want people to worry about me, yet there are times when it happens. Usually after a good cry, I’ll feel relaxed. I’m guessing the act of crying is also to allow strong emotions to show in order to deal with them (bad or good as in the case of happy crying) so we may get it out of our system in order to reach a calmer state of mind. To be honest, I’m just throwing ideas out there. Crying is a showing of great emotional response to something, since no one would want to waste their tears on something which has not affected them in any way. As for why, I guess I’m just grasping onto any idea that comes to mind.
That last bit on not wasting tears seems possible. But, even so, why not just evolve to drool instead?!
But seriously! I dunno. Best, -Mark
Hello, I’m one of the kids you spoke to earlier through skype. I go to Summerland Primary school in New Zealand. I was wondering if people can channel their emotions and make themselves cry. If so how?
Hmmm. The “method acting” approach for actors seems to be able to do so — they bring up past scenarios that brought tears. That’s *one* kind of channeling, I suppose. -Mark
Only social animals cry/express distress in a way that makes them look helpless, right? Because if not, then we can’t explain crying just in terms of inter-individual signalization.
Onto the discussion. We don’t just cry tears. We produce more nasal mucus and we salivate, too.
(1) Purple-haze theory: Nasal mucosa swells up and nose starts dripping. We rub the nose to remove the dripping. This stimulates bigger blood flow because of irritation of the skin. Actually, a similar thing might happen during wiping tears away, too. A person’s face is usually more discolored after crying for a while and wiping tears and nose several times than just before the tears spill over. However, a part of that redness could be because of an altered breathing pattern (especially if it’s actually purplish). Also, I can’t explain the salivation in this context other than using anatomy, but even the nucleus salivatorius superior is subdivided into a cranial lacrimo-muco-nasal and a caudal salivatory part and it would be a real waste of water and energy to switch both parts on when just half would do the trick. But that might bring us to…
(4) Water-Handicap: When you add saliva and a runny nose on top of tears, crying just seems all the more expensive. But is the expensive theory enough? All by itself, it just seems a little thin to me. It sounds like you were inspired with the theories about sexual selection breeding disadvantageous traits (peacock’s tail), but we can’t apply the same philosophy to crying. Crying is more of an SOS signal than anything else and it is mostly used by children.
(2), (7), maybe even (8) Seen Sheen, Wet-for-a-while, Bucket of Tears: How is the ammount of tears lost correlated to the ammount of facial hair? Between species, of course.
(3) Unstoppable: Nice idea, but doesn’t strictly apply to tears. They *are* the hardest part to control (and sniffing too, which could be a more subtle signal of distress audible only to those in the near vicinity, like close family members or friends, but not enemies). But facial expressions are also pretty hard to control, and when you lose it once your breathing and vocalizations are all over the place, too.
(5) Salt Lick: But saliva? Again because of the same cranial nerve nucleus? Couldn’t we have dissociated the two parts if we just needed one half that badly?
(7) That Wet Feeling: This is the only one that focuses on what tears do to the cryer instead of the potential help. I don’t really see much sense in reminding myself of how sad I am. Unless I’ve got a super way of controlling my thoughts and ignoring my emotions – like a big prefrontal cortex or someting. But still, how often does one start crying before internally feeling the emotion of sadness?
Or maybe when I get happier later, and the tears dry up, and I smile, I’ll be able to feel my smile better because of the tension-feeling on my skin covered in salt. And feeling my own smile will help my facial expression influence my mood, making me even more happy. Yay! Still, this doesn’t seem very cost-efficient.
However, shifting the focus on how the tears influence the cryer instead of the viewer may open up new possibilities. What exactly is the chemical “recipe” of tears in various situations, anyway?
Can I add another theory?
(9) Inflammation-like: Going all red and puffy and secreting stuff makes you look like you have a disease thing going on, adding to the credibility of your call for help. But that also makes you look kind of repulsive, sometimes… Is this an advantage or a disadvantage?
I like (9)! “I haz disease!” Thanks so much for the comments! -Mark
While I really like the salt lick theory (: I’m thinking that crying is the only emotion expressly requiring aid from others. There are all kinds of things that happen when we really get wailing, but the gist of the whole crying experience is that it’s supposed to draw someone else near, to protect you, comfort you, care for you, and to offer compassion and soothing. It needs to be dramatic, and it needs to require a response, so call my theory the “Wipe Away” theory of tears: they come out so that others will tenderly wipe them away, and in so doing, give us the personal contact and touching that we need. (I guess for the nasal aspects of crying you could add a snot rag adjunct theory…)
Interesting. I like it! In this case, dumping anything that shouldn’t be on the face would suffice.
Exactly!
And tears and snot are already available for cleaning purposes, so it’s an exaptation.
Right. ..and might it also explain why in extreme fear one loses bladder / bowel control?
Probably a skunk-ish reason better explains *this* case.
Ha!