
Tears - urs2102
http://www.meltingasphalt.com/tears/
======
jawon
Tears 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.

~~~
tbabb
I don't think his point is that it _isn 't_ cathartic; he's pointing out that
there is no physiological reason for _crying in particular_ to have evolved to
be cathartic. What have leaking eyes or a quavering respiratory system got to
do with relieving overwhelming emotions? Nothing. And no other animals
experience this.

It's a confusion of cause and effect (or post-hoc fallacy). "I cry because it
makes me feel better" supposes that feeling better is the purpose of crying.
But really it's the other way around: _Crying is the purpose of feeling
better_. Crying is the thing with purpose, because it's an important and
useful social signal. Overpowering urges to succumb to it, and feeling better
after having done so, are evolution's way of coaxing our minds to do something
that's useful to us, just like urges to eat or have sex, and feeling better
after having done them.

~~~
warfangle
Why do we smile when we're happy? Is it because we're happy (we also expose a
similar face when we're scared), or is smiling the purpose of feeling happy?

~~~
tbabb
Not sure if you're arguing for or against my point, but I'd say the purpose of
feeling happy is to reinforce the behavior that got you where you are. Smiling
(and the compulsion to smile, which few other animals have, though they do
feel pleasure) is to signal your state of mind to your peers.

I wouldn't say (and wasn't saying) that the purpose of feeling sad is to cry
or engender social signaling (parallel to happiness, the purpose of sadness is
downregulation of behavior), but the compulsion to cry itself and the relief
afterwards _is_ about signaling.

------
bbctol
The 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)

~~~
VLM
Across 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.

~~~
bbctol
What's the worst that can happen from a vociferous vegan?

------
dgreensp
As 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.

------
scandox
I 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
> 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.

~~~
VLM
You could describe it as bad language. Two physics examples.

A classic momentum problem where a moving railroad car "acts on" a stationary
car making the cars couple and move together, slower. There's no ambiguity
with language like "acts on". I'm sure a very angry physicist could get very
unhappy about the finer details of "acts upon" in that context but mostly
people are pretty tolerant of it.

But what, is acting on what, in a classic quantum mechanics double slit
experiment? Is one slit acting on the other? I mean, you can't even define the
wave/particle as a wave or a particle much less what the whatever it is, is
acting on. A physicist sees it where a wave/particle is interacting with a
system of slits sounds pretty suspect to a non-STEM person even if it is the
weird truth. Or truthier than some other interpretations.

So given the two examples what does "acts on" mean in a physicist sense across
all physics problems? Keeping in mind that the intelligent design people say
things like "God acts on the earth via miracles" now how does that statement
fit in with the two physics thought experiments on the topic of "acts on"?

------
blackRust
Having 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-...](http://books.wwnorton.com/books/Are-We-Smart-Enough-to-Know-How-
Smart-Animals-Are/)

~~~
woodandsteel
I 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.

~~~
xelxebar
Yeah, but I doubt that any non-anthropocentric measure of biological success
puts humans anywhere special:

Biomass: krill dominate

Individual count: bacteria probably soon by a massive landslide

Evolutionary stability: the Goblin shark had been around for millions of years

When people talk about how special H. sapiens is they tend to always say that
we're the only species to have some conjunctive list of traits. But for any
given species there is some list of traits that single it out as unique and
special, so I find those arguments pretty contrived.

However, perhaps humans do win out in the per capita production of waste heat
category.

~~~
VLM
Wideness of niche.

Tardigraves and some lichens can live most anywhere it seems. And then life
forms get more advanced and their range of terrain generally implodes in size,
even migrating birds usually don't cover more than one continent at any given
time.

Then suddenly despite being just another big ole thing you'd expect humans to
be trapped in a dinky little African savannah by a river, but no, here we are
under the ocean and covering the planet pole to pole and under ground and in
the air and in space. If its not possible to live there we import stuff and
live there anyway like Antarctica or space.

No species has a range as large as us, not even close, other than little
microscopic tardigrave critters, and maybe rats. And our internal and external
parasites I guess. You don't see alligators in the arctic or polar bears in
jungles or whales in space stations or dolphins in grasslands.

There is one interesting bean counter type trait where you do something with
the ratio of brain mass to body mass and add a correction factor for total
mass, and we kick butt on that one.

Another one is information bandwidth, we can transmit a couple K visually per
second via reading and a good fraction of a K per second via speech and no
other animals even remotely come close. A human toddler transfers orders of
magnitude more data before kindergarten than the entire lifespan of most
animals, and as far as humans go toddlers rate as pretty dumb.

I'm sure if ants brains were not so small in an absolute sense and if they
could communicate as many bits per second as humans can they'd be teaching us
a thing or two about math and physics, but ...

~~~
xelxebar
Wideness of niche. That's a good one. Once we become trans-planetary, I guess
that will also be quite a distinguishing trait. Also, note my optimism :P

Akin to the brain-to-body-mass ratio that you mention, I wonder if this
wideness of niche idea can be meaingfully quantified.

Would you be able to point me to some sources? I'd like to level up a little
bit on this topic.

------
6stringmerc
Neat 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.

------
throwaway5752
Is 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
>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).

~~~
pricechild
They also say:

> Incidentally, Why Only Humans Weep by Ad Vingerhoets is the most useful book
> I've read about crying.

strongly implying it's not the only reading they've been doing!

~~~
throwaway5752
Ok, well, by way of that example, in less than an hour or so, I was able to
read Vingerhoets last 2 years of selected publications (via his personal
website, [http://www.advingerhoets.com/journal-
articles/](http://www.advingerhoets.com/journal-articles/)) and of particular
note one of the most recent
([http://www.tandfonline.com/doi/full/10.1080/02699931.2016.11...](http://www.tandfonline.com/doi/full/10.1080/02699931.2016.1151402))
was actually rebutting/failing to reproduce the other study cited in this
article by the Israeli group
([http://faculty.washington.edu/beecher/Gelstein_et_al_2011.pd...](http://faculty.washington.edu/beecher/Gelstein_et_al_2011.pdf))
on the chemosignal theory.

It's not just about reading the sources. It the quality of the analysis and
faithful representation of the sources. Don't you think that this major
disagreement between two primary sources would have undermined his thesis
(though captured the actual level of nuance/disagreement that exists in the
research), or at signaled appropriate levels of uncertainty to the reader?

I still think a days worth of Googling (real, concerted, sustained effort)
would leave anyone with a better understanding of the subject matter than
reading this article. If someone wants to read an edgy pop-biology
econometrical/anthrological opinion piece, that's another story.

------
gerbilly
>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
Can you provide some counterexamples?

~~~
throwanem
I'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
I 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.

------
applesapl
For 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
Yeah 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.

------
Nomentatus
I'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
_" 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.

~~~
Nomentatus
I do think "high CSF pressure is mood altering/predisposing to tear activity"
precisely because the CSF pressure needs to be brought down" (in this
hypothesis.) and that high CSF is the result of an underlying cause that also
expresses itself in lactrimal gland activity, due to said pressure. I think
you'd have to do an arabesque to find an underlying cause with two roots from
some underlying cause rather than one (obviously more complex even if you can
think up such a thing) (and it wouldn't explain the study I cited.) But knock
yourself out, suggest such a causal arrangement/pathway.

The I believe very recent study I saw found a high correlation. I've heard
anecdotal reports of eyedrops helping; it's too soon to find studies of
(neutral) eyedrops helping, but you can find preliminary studies of migraine
treatment beta blocker eyedrops at pubmed dot com.

No tail wagging dog - it's common for studies about one thing to discover
something interesting that's consistent with quite another hypothesis (which
is the most evidence can be, qua Popper.) That's all I've claimed in this
case. There was no such correlation with saliva, so it's clear that disproof
was risked - the Popperian litmus test for actual evidence.

------
wcdolphin
How 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_
That'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
The 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
Not 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.

------
caublestone
Our 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...](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2871162/#!po=29.8450)

------
woodandsteel
It 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.

------
waderyan
I 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.

------
gfosco
Interesting 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.

------
msluyter
I recall Scott Alexander (slatestarcodex.com) proposing the tears/bullying
hypothesis somewhere, but I can't seem to find it at the moment.

~~~
Analemma_
The 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?

------
dwringer
Could 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
First: 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
I 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)

~~~
throwaway5752
"No net effect" = tears are produced by the lacrimal glad. I am more of an
interested hack, compared to someone that actually knows something (medical
professional like a neurologist or ophthalmologist), but my educated guess is
that cells in the lacrimal gland produce tears entirely from inputs from the
circulatory system, and because of the circulatory system structure in your
brain v. face, it's actually rather not as local as the physiological
proximity suggests. So the change would be indirect, mediated by blood, and
since the concentration of sodium is the same in each crying wouldn't effect
blood sodium concentration in the first place. You may under-appreciate how
rapid blood moves through the body, too, and quickly any local change would
move to equilibrium.

ps: you're welcome, happy studying! (it's daunting, keep in mind
[https://news.ycombinator.com/item?id=1390027](https://news.ycombinator.com/item?id=1390027),
and remember that some of the smartest people out there become doctors, and
they spend a dozen+ years training in just single areas of study and
indefinite continuing education)

------
mannigfaltig
There 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)

------
urs2102
Curious if anyone knows anything about the similarities/differences between
human crying and dog whining?

~~~
Analemma_
Do 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
That'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
In 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
>Idk if wolves whine

They do

------
speby
Definitely queues up Terminator 2:
[https://www.youtube.com/watch?v=eSotD5M3bsY](https://www.youtube.com/watch?v=eSotD5M3bsY)

------
uptownfunk
A 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.

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i336_
Possibly 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)

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ldehaan
Most of the things in this list are not specific to humans.

Interesting idea + bad research = fake news

this needs to stop so badly.

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sushobhan
I 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
Read "Liars and Outliers" by Bruce Schneier.

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csomar
Is 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
I 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?

~~~
csomar
He just doesn't have tears, he cries out loud and make a sound like he is in
pain.

~~~
bmelton
I believe the howling. Dogs definitely howl, and will happily do so to voice
disapproval, sadness, etc., etc. If there are tears alongside that howling,
then your dog may be an anomaly.

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empressplay
Article is wrong. Crying is cathartic.

