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Dogs’ Eyes Have Changed Since Humans Befriended Them

theatlantic.com

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Re: Dogs’ Eyes Have Changed Since Humans Befriended Them

#11

Post by barry-cotter »

ralusek wrote: post #4

> 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?

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.

Re: Dogs’ Eyes Have Changed Since Humans Befriended Them

#12

Post by sunstone »

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.

Re: Dogs’ Eyes Have Changed Since Humans Befriended Them

#13

Post by philwelch »

Raticide wrote: post #9
ralusek wrote: post #4

> 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?

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.

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.

Re: Dogs’ Eyes Have Changed Since Humans Befriended Them

#14

Post by barry-cotter »

Raticide wrote: post #9
ralusek wrote: post #4

> 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?

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.

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.

Re: Dogs’ Eyes Have Changed Since Humans Befriended Them

#15

Post by NeedMoreTea »

barry-cotter wrote: post #14
Raticide wrote: post #9

Earlier quoted context omitted.

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.

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 tha…

Floppy ears are just pointed ears that failed to rise - perhaps because they became too big. A German Shepherd pup has floppy ears and they eventually start to stick up, after going through a phase where they can't decide.

There is something impressive that a Chihuahua can instantly somehow recognise the Great Dane or Pekingese as of type dog, even at great distance upwind. Yet can react differently to cat, sheep, fox or squirrel at similar range.

Re: Dogs’ Eyes Have Changed Since Humans Befriended Them

#18

Post by onemoresoop »

sunstone wrote: post #12

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.

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.

Re: Dogs’ Eyes Have Changed Since Humans Befriended Them

#19

Post by notatoad »

tlb wrote: post #6
NeedMoreTea wrote: post #2

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.

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

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.

Re: Dogs’ Eyes Have Changed Since Humans Befriended Them

#20

Post by grawprog »

philwelch wrote: post #13
Raticide wrote: post #9

Earlier quoted context omitted.

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.

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.

The order all bats are part of, Chiroptera, translates to hand-wing because of this webbed hand wing structure.
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