Dogs’ Eyes Have Changed Since Humans Befriended Them

https://www.theatlantic.com/article/591868/

by gilad • 7 years ago

251 117 7 years ago

Dogs' eyes don't generally look sad, especially if they're quizzically raising one eyebrow. Why change the title from the much more interesting, and accurate original?

"Dogs’ Eyes Have Changed Since Humans Befriended Them"

I was actually expecting a dire clickbait sort of article, when it actually turns out to be substantive and interesting.

tlb• 7 years ago

Title changed from "Why do dogs look sad", thanks.

notatoad• 7 years ago

thanks for leaving a comment that includes the old title.

it's always confusing when the title gets silently changed, and then there's comments complaining about a title that's no longer the title.

gilad2• 7 years ago

[poster here]: Interesting find - my phone showed the title as 'Why Do Dogs Look So Sad?', where the actual article's title is different. Looking at the page's source code under the <title> tag shows these are different. I chose the shorter version (nevermind dropping the 'so' in 'so sad' cause that's really click-bait-y). My assumption was that readers would know that the source (the Atlantic) is a reputable publication and assume the article is of substance. It's interesting that even the Atlantic needs to resort to changing the title to get those coveted clicks. In the future, i'll strictly post the _actual title_ over to HN submission.

NeedMoreTea4• 7 years ago

Hm, never knew Atlantic played that game too. I know Ars A/B tests titles, and that a few of the buzzfeed type publications put a social title (ie clickbait fest) for the first day or two while a piece does the rounds of Facebook and Twitter, and replace with a sane "forever" search engine title later.

At the other extreme there's the odd dry-as-dust titled technical article that really needs some editorialising or at least posting on sub-head to have any chance of interest.

ken• 7 years ago

The "Sad" version is in the <title>. That usually means that is the original, and they changed the <h1>.

taneq• 7 years ago

They're talking a lot about the LAOM muscle which raises the eyebrow - I always thought it made dogs look more anxious than sad when they tense it - but they don't really talk about the RAOL muscle much.

With dogs, Horowitz points out, we’re so driven to connect that we often search for “smiles” in the shapes of dogs’ mouths.

I think a lot of the "smile" facial expression you see on dogs is produced, not by the mouth, but by the RAOL muscle pulling the corners of the eyes out slightly to mimic the way humans' eyes squint slightly when we smile.

In any case, it'd be surprising if dogs didn't have some behavioural / communicative adaptations, given that their role in our lives has historically been a collaborative one. Look at all of the dramatic cosmetic changes we've made in selecting different breeds of dog. Surely selecting for increased utility as a hunting or farming animal would exert even more pressure?

ralusek• 7 years ago

By evolutionary standards, the time since this split [from wolves] has been remarkably short for two new facial muscles to have developed.

2 facial muscles? What about Chihuahuas to Great Danes, is that not a more impressive evolution than 2 facial muscles?

Raticide• 7 years ago

I think it's because chihuahuas and great danes have all the same bits, just with different scales/shapes. Where as entirely new muscles take a lot more work to evolve.

philwelch• 7 years ago

And bone structure, just forget it. Mammals have mostly the same sets of bones attached the same way--a bat's wings are just gigantic hands with webbed fingers in skeletal terms.

barry-cotter3• 7 years ago

I'd be very surprised if Chihuahuas and Great Danes literally have all the same bits. Canines are the most morphologically diverse animal, surpassing even humans. If there aren’t dog breeds that all have or lack a particular muscle, type of hair or bone I’ll be very surprised. Poodles have webbed feet for one, or just consider how some breeds have floppy and others pointed ears.

It’s reasonably likely the muscles that are universal among dogs existed among wolves at very low frequency and just exploded in frequency once they started hanging around humans. These kinds of hard sweeps happen when there’s either a very useful de novo mutation or a new environment makes a previously irrelevant or disadvantageous allele or trait beneficial. In humans think lactase persistence which was pretty much nonexistent 5,000 years ago or the Tibetan altitude adaptations which derive from the Denisovans who were living on the Tibetan plateau over a million years ago.

barry-cotter3• 7 years ago

Artificial selection versus natural selection. New facial muscles emerging without design or intent is quite different from two separate groups of people trying to see how big/small they can breed a dog to be.

Selective breeding works incredibly fast on evolutionary timescales. You can get a selected population to no overlap with the parent population on your variable of interest in seven generations quite easily.

lurquer• 7 years ago

They examined four dead wolves. Four. Each had muscle fibers and a tendon at the appropriate place. Just not as pronounced. Where the wolves related? Apparently a pair was obtained from a taxidermist and a pair from Michigan. That is, this is hardly a representative sample of wolves.

Spinning a saga about dog evolution from examining 4 dead wolves is stretching...

hermitdev2• 7 years ago

In my experience, the dogs ive been around dont generally look sad. The totality of their facial expressions show their emotion.

Ive a one year old pup, border collie/labrador mix. I can take a quick glance at his face and know exactly how he's feeling. Probably 80% of the time, its pure joy. Happy to run around, chew on toys, jump on the furniture and try and play (unrequitedly) with our cats. About another 10%, he's scared of other animals he can see out of the Windows of our townhouse and barks incessantly. The other 10%, I have no idea.

Eyes on a dog don't tell the whole story. Need to look at eyes, ears, back position, tail and legs to tell.

As I write this, my dog is laying against me, calm amd near sleep. Depending on perspective, I could see his face as seeming sad, but I know he's just sleepy. He's only awake because I am and I've not put him to bed yet. But his face says to me he's calm and content. His breathing is also slowing. His favorite chew toy is inches from his mouth and against my arm and he's content to let it stay there; that's how I know he's tired. If you were to just look at a photo of my dogs face right now, he might appear sad, but I know hes just calm and sleepy.

NetOpWibby3• 7 years ago

Damn, I cannot wait to have a dog.

jyriand• 7 years ago

Getting a dog should not be an emotional decision. I have a dog and sometimes it's a lot of work. Feeding, pooping, pissing, neverending fur in the house and on my clothes, vet, constant attention seeking etc. Just to mention a few things. And if you need to travel you need a babysitter for your dog. It's easier if you have a backyard where the dog can chill.

mschuster912• 7 years ago

Think about a cat instead ;)

Seriously, dogs are a shitload of work and especially, no matter how fucked the weather outside is, you gotta take the dog to walks so that the dog can take a dump. In addition, many of the larger breeds are working dogs which means that they require massive amounts of attention and daily exercise so they don't literally go mad. Please do proper research upon the characteristics of your desired breed, and don't take in a rescue dog as your first dog either. Rescue dogs can and will have psychological issues.

skunkworker• 7 years ago

I swear this article was timed perfectly with a top reddit /r/aww post earlier today. Being able to deduce intent and an expression from a dog's glance.

https://www.reddit.com/r/aww/comments/c1qt1x/doggos_polite_a...

https://gfycat.com/healthyfaintbilby

_bxg12• 7 years ago

One of my favorite factoids is that the human-dog symbiosis evolved twice, in two unrelated corners of the world, at around the same time. It was meant to be.

henryackerman• 7 years ago

Got a source on that? Seems like an interesting read.

_bxg12• 7 years ago

https://science.sciencemag.org/content/352/6290/1228

sunstone• 7 years ago

I wouldn't be surprised if humans haven't changed too since dogs befriended them. I imagine it's really a symbiotic relationship in the wild.

Both are social animals. Dogs have the speed and the teeth. Humans have the brain power, stone throwing and cooking. Dogs can mind the human young to a large extent and humans can feed the baby dogs cooked food. It's win win and a fearsome combination.

onemoresoop• 7 years ago

I’ve had the exact thoughts. And in fact all domesticated animals change and we change with them as well. Im not only thinking about pets but the all animals that live in (an unfair) symbiosis with humans.

GorgeRonde• 7 years ago

I watched a documentary about domestication a while back. Turns out there are many "corollary features" to being domesticated: for instance, ears falling down are also to be found in domesticated fox.

One of the most common feature across domesticated species was tighter jaws.

Source: https://www.youtube.com/watch?v=_6Zep-GhQYU

Causality1• 7 years ago

It would be interesting to look for genetic differences between human populations with a history of intensive domestication like the Maasai and populations that have no or only recent domestication like aboriginal Australians.

rags2riches• 7 years ago

Adults that can digest lactose is one trait obviously related to animal husbandry.

olalonde• 7 years ago

objectively cuter

For sure.

ekianjo• 7 years ago

It’s the first biological evidence scientists have found that domesticated dogs might have evolved a specialized ability used expressly to communicate better with humans.

It could be the other way around: when that kind of ability appeared humans have very selectively decided to prefer dogs that had that trait. Dogs are pretty much a human creation (through centuries of selective breeding) so it's not really evolution rather selection when it comes to this particular example.

MarcScott• 7 years ago

Isn't this better described as selective breeding, rather than evolution?

Maybe we haven't consciously bred the trait into dogs, but we might have selected such dogs for breeding, over litter mates that never made eye contact.

arnarbi• 7 years ago

For the dog, it's just evolution under some environmental factors. One of the factors just happens to be human behavior.

(But it's typical and common human hubris to not call nature nature when it includes us.)

Retra• 7 years ago

Selective breeding is still evolution.

Joakal• 7 years ago

This is a good opportunity to educate the general [HN] community about dogs:

1. They can only see blue/yellow. Not like humans' RGB.

2. They are short sighted. For far away objects, their sight is like a T-Rex, they can see moving objects, not stationary objects. Remain still, and they can't see you. Then again, they can smell you, especially if it's downwind.

3. Their flicker fusion threshold is higher than humans. If you show them a cute mobile picture of a baby, they'll see a lot of flickering. As well, did you know lights have a flicker? If you think it's bad, it's even worse for dogs which can lead to stress.

https://dog-vision.com/

https://www.dogwalkersmelbourne.com.au/articles-dog-walking-...

sl1ck731• 7 years ago

The flickering thing has always made me feel bad for my dog and dogs in general. My entire office room is monitors/TVs and I can only imagine what she sees, like a rave 24/7. But she will still sleep in here when she can go anywhere else in the house.

interfixus2• 7 years ago

My 12 year old labrador is in excellent shape, but his hearing is no longer quite up to scratch, and to avoid embarrassing levels of shouting when we are out and about, I increasingly use pointing and other signs at my end of our communication. Also, his left eye has been problematic for many years, and apparently only registers the haziest of outlines these days.

And yet, he contantly amazes me by the range and precision of his vision. Downwards pointing with my left arm means come here at once, which he will reliably register at a distance more than a hundred meters. Other dogs he will recognize at distances further than that, and he will unerringly home in on thrown stick bobbing on the water, as long as it's on the right, where his good eye can see.

Clearly, there's more to it than just they are short sighted.

dunstad• 7 years ago

As a nearsighted human who didn't get glasses as early as he should have, I used to use people's gait or clothing to recognize them at long distances. You know your dog best, just saying there can be ways to compensate.

jacobush• 7 years ago

I have noticed my dog scans people visually at a great distance. (Looking for people he might know, I imagine.)

miahi• 7 years ago

3. The flicker fusion issue mostly applies to cathode ray displays and moving pictures. Many LCDs use flickering light (PWM) for backlight, but usually at more than 200Hz. Better LCDs use linear current sources for backlight, so there's no flicker at all. An LCD should be fine even for dogs when static images are displayed.

quaa55• 7 years ago

well now i’m curious, since we have a handful of LED bulbs throughout the house. they flicker no doubt, detectable through the slow motion setting on my phone camera.

any suggestions on what energy efficient bulbs to replace them with?!

Frondo• 7 years ago

Cheap LED bulbs actually flicker significantly, which I realized when I filmed using my camera's "slow motion" capture at 240 frames per second.

In our bedroom, I put in some LEDs, not realizing there could possibly be a difference between cheap and expensive ones. One night I filmed my cat doing something dumb in slow motion, and when I looked at the playback the whole room was strobing.

It was pretty wild. I might even still have the video, and could see about posting it somewhere.

rhinoceraptor• 7 years ago

My dog will watch my LCD TV, she likes watching Minecraft and dog videos.

vanderZwan3• 7 years ago

As well, did you know lights have a flicker? If you think it's bad, it's even worse for dogs which can lead to stress.

As someone who notices and gets really tired from the stroboscopic effects of cheap LEDs, I can only imagine how terrible that must be for dogs

tw04• 7 years ago

I'll take that over florescent any day of the week.

vectorEQ• 7 years ago

try candles. natural light for me gives me least issues. most electric lights are exhausting...

tzs2• 7 years ago

Another dog sense I've wondered about is hearing. What is our music like to them?

Let's consider live music, first. A lot of instruments have significant harmonics well above 20 KHz. So let's say you are practicing your violin or trumpet, and your dog is in the room. The maker of your instrument took great care to get the sound right, which mainly consists of making sure that the various harmonics are at the right relative amplitudes.

Does the instrument maker take any care to get the harmonics above 20 KHz right? They don't affect how the instrument sounds to humans, so I'd expect not. That could mean that your beautiful violin has a horrible screech that only your dog hears.

How about recorded music? If my guess is right and our instruments sound bad above 20 KHz, recorded music may be an improvement from the dog's point of view, because we filter out those highs when recording.

But if live instruments do actually sound OK above 20 KHz, then to a dog our record are going to seem limited at best.

throwitaway9• 7 years ago

That's interesting. We switched to LED bulbs in our living room and after that our eldest dog would not settle, I thought maybe the bulbs had a low humming noise he didn't like but it could have been a flicker instead. We switched back and he was fine again.

clairity2• 7 years ago

hmmm, the first 2 months of my (rescued) dog being in my home (a year ago) were anxiety-filled for her, and now i wonder if it was due to the led bulbs. she’s mostly settled now, realizing that home is good for sleep, though still gets nervous here and there. she likes being outside more but that seems to be true of dogs in general.

WorldMaker• 7 years ago

Or both. Some cheap LEDs have terrible high-pitched humming noises from bad AC to DC converters/transformers.

(A big reason that there's a growing movement questioning if we should have more dedicated DC wires/plugs/sockets in our homes and do AC to DC conversion once for entire circuits instead at the socket/in the plug "wall wart" for every single device. Also interesting that USB A sockets are probably the closest we have to a ubiquitous home standard actually moving in that direction.)

Shivetya• 7 years ago

So, is fluorescent lighting in an area with dogs would be bad, or not? Is there method to determine which type of lighting is best? I expect even LED bulbs could flicker based on quality of the line.

Am I wrong in assuming incandescent bulbs would be better

ubercow132• 7 years ago

LEDs can be very bad, depending on the circuitry, to the extent that it's uncomfortable for peoples. Incandescent bulbs won't flicker.

b_tterc_p• 7 years ago

I don’t think T-Rexes actually suffered from that problem.

Insanity• 7 years ago

I think that was a "myth" indeed. But the OPs point is still valid. :)

xsace• 7 years ago

today I learn dogs see us as Simpsons characters

lelima• 7 years ago

The dog Image Processing Tool is pretty awesome, thanks for the link!

I wonder if is possible design glasses with the same goal.

sandworm101• 7 years ago

>> Then again, they can smell you, especially if it's downwind.

Only if the dog is downwind. Contrary to repeated myths about bears, no animal can air-scent objects downwind of themselves.

saltcured• 7 years ago

But, they might find your latent scent on the ground or on objects and follow that to you. So, being downwind at the moment is different from having a downwind approach to a new area...

sfaxon• 7 years ago

I actually got curious about this a year ago when I got a dog and she was watching me paint a wall. I made an iOS app* that allows you to see the color spectrum a dog sees, as well as take video and photos.

Some weekend I hope to make enough time to add something to represent the short sightedness using image depth data as well as a few other features I would like to add.

I actually had not heard about the flicker fusion threshold being different, thanks for the links!

* https://itunes.apple.com/us/app/dog-optics/id1447069492?ls=1...

stronglikedan• 7 years ago

I fully believe that they can also "see" scents, like a cartoon character floating to a pie on a window sill following a path of inhaled visible scent fumes, but I have no evidence of that.

hnick• 7 years ago

The funny thing with my dog, who we've done some scent work with, is that his nose seems to need to be focused and 'switched on' to really work.

If I throw him a treat and he misses it, he will default to looking around with his eyes and missing it until I point it out. But give him the ready cue, and he can find a tiny piece of food or odour hidden in a drawer in a room in under a minute.

So my take on that is it takes a lot of processing power to run the nose, and after a search session it's definitely nap time.

And side note, I'd like to see AI efforts aiming at the level of a dog before we go for humans. It's amazing what they can do but it takes so long to train them and you have to start from scratch each time.

mattlondon• 7 years ago

The article (and others at e.g. the BBC) seem to say dogs "evolved" this capability in "a remarkably short time".

Is it not fairer to suggest that this is not evolution/natural selection at work here, but rather just selective breeding? I can't think of another species of animal that has been so widely twisted and manipulated in appearance by human's selective breeding than dogs.

Seems odd to suggest that this part of a dogs' body was due to evolution, but that rest of the crazy variety in dogs' body is not? A trait like this that humans like seems like is an obvious thing to get selected surely?

Or is there some strong evidence to suggest that this was really was nothing to do with selective breeding?

hoseja• 7 years ago

What else is selective breeding than evolution where fitness is strongly influenced by a hairless ape?

viscanti• 7 years ago

The article mentions that the trait is observable at only 4 weeks old. It might not be crazy to think that Humans are more likely to select the puppies that demonstrate the trait. It might not be "natural" selection, but if Humans are making a substantial amount of the breeding decisions for dogs then it could still be a form of evolution.

NeedMoreTea4• 7 years ago

I'm mostly comfortable with thinking it's evolution as crazy variety and selective breeding came very late to the party. Most in the last few hundred years - lots of the breeds we know are from the 17th, 18th and 19th centuries.

I would guess that for most of our co-existence breeding was up to the dog to figure out, which might explain the oldest breeds being of a particular region. Task breeds came very much later.

Edit: Also, how do you selectively breed for muscles that didn't previously exist?

silvestrov• 7 years ago

selective breeding came very late to the party

I think that breeding before 17th century was focused on the dogs job such as hunting wolves (Wolfhounds), sheep herding (Border Collies), watch dogs.

When you don't breed for apperance and only have a low number of different kinds of jobs for dogs, then you only need very few breeds.

The Irish Wolfhounds were out of jobs in 1786 (no more wolves in Ireland) and the breed practically died out.

noiv• 7 years ago

Well, humans are part of the environment of dogs - selecting or not.

WhompingWindows• 7 years ago

It comes down to definition of terms, English words to sub-optimally describe a genetic process... How do you define selective breeding - if humans are selecting for short legs and long torso and small and short hair, over time you will get a Daschund-type shape and look. If selective breeding can include discarding/disliking puppies/young dogs without responsive eyes, then most likely humans did selectively breed dogs for desirable "eye contact" traits. It's quite reasonable given we "chose" dogs for many less physically obvious qualities like temperament, utility, and intelligence.

In the end, we are using words to describe genetic processes. The genetics of dogs have changed remarkably both over the last 200k years and over the last 500 years. In my view, it's a combination of natural selection, unconscious selection, and conscious selection of breeding individuals.

brazzy• 7 years ago

https://www.smbc-comics.com/comic/wolves

hjk05• 7 years ago

As first reading the title I thought: “Really, that’s very interesting” Then I realized that almost everything about dogs have changed since humans befriended them. They literally went from wolves to pugs. Taking that into consideration it’s not at all surprising that the eyes changed too. Of cause it’s still interesting to dive in exactly how they’ve changed.

jumpinalake• 7 years ago

I wish this article included photos comparing the look of a dog face when using vs not using the cited muscles.

thebeefytaco• 7 years ago

Direct link to the study referenced: https://www.pnas.org/content/early/2019/06/11/1820653116

bmurphy1976• 7 years ago

I always found dog eyes interesting. Some dogs have eyes that very animal like. I grew up around Miniature Schnauzers and their eyes are eerily human. The biggest difference is that the iris is a little too big. Were it not for that, I'd have a hard time distinguishing their eyes from ours.

I find that to be rather astounding actually. Given the wide variety of expressions Schnauzers at least are capable of emoting, it's pretty amazing how easy it is for two unrelated species to communicate on such a level. They speak a lot with their eyes. Look closely, you'll be amazed.

Dogs’ Eyes Have Changed Since Humans Befriended Them

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