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80 votes

Why shouldn't dogs eat chocolate?

The reason is simple: Chocolate contains cocoa which contains Theobromine. The darker the chocolate is (meaning the more cocoa it contains) the more theobromine it contains. This is a bitter alkaloid ...
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25 votes

Why shouldn't dogs eat chocolate?

The toxic ingredient in chocolate is in the mythylxanine class, a substance called theobromine. It is much like theophylline; overdoses of theophylline used to be very common before the advent of ...
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17 votes
Accepted

Why do human eyes glow red on a photo and dog's eyes green?

Short answer In humans it is basically the red choroid plexus in the back of the eye you are seeing on a flashed photo, while it is the green-reflecting tapetum lucidum in dogs. Background The red-...
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12 votes
Accepted

Why do these 2 dots frequently occur in dogs' eyebrows? Does it serve/served any advantage?

I suspect but can't prove that these markings are not adaptive, but are accidents or epiphenomena of the general genetic system that determines coat colour. On the one hand, an Australian Broadcasting ...
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10 votes

Best colour for a dog to track an object against green background

Dogs are a dichromatic species, featuring only a long wavelength (L) and a short wavelength (S) cone (source: Smithsonian). As such, they are thought to perceive mainly blues and yellowish hues (Fig. ...
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6 votes

Why do dogs try to cover their poop?

I cannot find any definite articles on why there would be a reason for this behaviour other than the same ones that you have mentioned in your article. It could be because it wants to mark its ...
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5 votes
Accepted

Do wolves bury food like dogs?

The habit of burying food in modern dogs is an instinct that came from the grey wolf (Canis lupus) long ago, and originates from a phenomenon called surplus killing, where a carnivore would kill more ...
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  • 3,687
4 votes

Dogs bark at familiar person in Santa costume. Why? Don't dogs trust smell over vision?

The dog was probably freaked out by the weird costume. Humans do it all the time (I've been seeing Halloween decorations for sale since early August, which is terrifying) but we generally comprehend ...
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  • 9,702
4 votes

When did the most recent common ancestor of all living domestic dogs live?

From the wikipedia article you linked: The origin of the domestic dog (Canis lupus familiaris or Canis familiaris) is not clear. Whole genome sequencing indicates that the dog, the gray wolf, and ...
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3 votes

Could we breed a dog to the size of a thumb?

As mentioned above the inbreeding required to select smaller and smaller dogs would be problematic because of the myriad of health problems that would be associated with it (see inbreeding depression)....
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3 votes

Why shouldn't dogs eat chocolate?

I had a chocolate loving dog. She was 12 lbs. The vet said she could have it, provided she wasn't given too much. So his rule of thumb was not to feed her more than I would allow the average 2 year ...
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  • 141
3 votes

Evolutionary advantages of wet nose of cats and dogs?

Why did it evolve ? Mammals with rhinaria tend to have more acute olfaction, and the loss of the rhinarium in the haplorrhine primates is related to their decreased reliance on olfaction, being ...
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3 votes
Accepted

When did the most recent common ancestor of all living domestic dogs live?

As Remi.b points out, the where and when of the ancestor of the domesticated dog is not well known. Based on a review by Morell (2015), the ancestor of the domesticated dog (canis familiaris) was a ...
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  • 51.1k
3 votes

Can canines communicate with each other using gaze direction?

It is hypothesized that the starkness of white sclera against darker colors of the pupil and iris is a unique mutation in primates that have become prevalent in human beings because it enhanced our ...
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  • 1,634
2 votes

Can canines communicate with each other using gaze direction?

A new study published in the journal PLoS One compared facial characteristics, gazing behaviors, and sociality of 26 different canid species (including wolves, bush dogs, and Arctic foxes). The ...
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2 votes

Can any species be bred selectively/engineered to become as diverse looking as dogs?

Not a mammal. But goldfish have also been modified both in shape and colour http://40.media.tumblr.com/ef8838366e4b7a51646b74b5330238e3/tumblr_mi60i8S52c1rmp9qqo1_1280.jpg
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  • 2,876
2 votes

Do any dogs have blue iris - not just sclera?

I have no idea why you cannot find reputable sites that discuss eye color in dogs. Dog breeds with blue eyes should satisfy you; I can't see that they would have any reason to dissemble. In case it ...
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2 votes

Why do these 2 dots frequently occur in dogs' eyebrows? Does it serve/served any advantage?

Dogs are actually not prey animals and are pretty high up on the food chain, so the theory that the eye dots are "decoy eyes" doesn't make a whole lot of sense. Realistically speaking, dogs are pack ...
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2 votes

Did Darwin explain why he believed that domestic dogs descend from several distinct species of ancestor?

It seems that this was based on arguments in 1780 by Pyotr Simon Pallas that most domestic animals had descended from two or more aboriginal species that had since become mixed by interbreeding. Here'...
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2 votes
Accepted

What advantage do dogs have in clearly disclosing whether they are afraid or unafraid in a conflict?

It is better for animals to broadcast their qualities, and size one-another up before risking injury in conflict. As pack animals, dogs are particularly sensitive to where they are placed in a ...
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  • 7,569
2 votes

Do animals' facial expressions have similar meanings to humans'?

I would say no, facial expressions in humans do not generally relate to facial expressions in other animals. Even though there are some cases (as described in the comments an previous answers) that ...
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  • 2,877
2 votes

How many teeth can "African wild dogs" have?

I found conflicting information on different websites with a humanima article stating that they have 4 toes and 40 teeth (reference). However, multiple sources state that they have 42 teeth (reference ...
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1 vote

Can a dog run 150 km non-stop?

There are 100, 200 and 1000 mile races for huskies, we can check the speeds of the winners of the races: http://www.eaglecapextreme.com/index.php/the-race/race-times 97 miles run in 17.23 hours, ...
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1 vote

Nature versus nurture regarding aggression in specific dog breeds

There is another study, in addition to that cited by @TumbiSapichu, that establishes a genetic component in canine aggression. This is: Zapata et al. (2016) BMC Genomics 17:572 and is entitled Genetic ...
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1 vote

Nature versus nurture regarding aggression in specific dog breeds

It seems that there are some important differences in dog aggression depending on the dog breed (towards strangers, owners, and other dogs): That being said, it seems that a significant proportion of ...
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1 vote

Do animals' facial expressions have similar meanings to humans'?

Get to know dogs' facial expressions and you will find that there are comparable facial expressions of a canine with that of humans.
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1 vote

Do animals' facial expressions have similar meanings to humans'?

Our cousins in the primate world share the same base facial expressions as we do, happy, sad, disgust, etc; it would make sense that other mammals are capable of facially displaying emotional ...
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  • 127
1 vote

Do pet animals and humans perceive good and bad smells differently

TL; DR Mostly no. On a molecular basis, cats' and dogs' noses look quite similar to ours. Most of what we know about smell comes from studies on non-human mammals, and is supposed to apply to humans ...
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