Most animated characters look the way they do for a plethora of boring reasons, like being easier to identify, a more attractive appearance, or just plain freaking the shit out of children. But the illustrators and animators don't usually take into account the weird side effects which would befall their creations if they were real. I do, though, because I'm paid to think about weird shit.
#6. Four Fingers Would Lead To Weird Numbers
Many cartoon characters have four digits per hand instead of the five we have, because four fingers are far easier to animate than five and actually look less weird and crowded when the character is holding or manipulating something.
But there would be an unintended consequence of evolving only eight fingers. Any such cartoon civilization would have an octal system of counting, or base eight. This means that the fictional worlds in which they lived would be ruled by completely different numbers than our own.
Important values would be based on powers of eight, so that the octal number ten would represent eight in decimal. 100 would be 8x8, or 64. 1,000 would be 8x8x8, or 512. This would lead to some really bizarre math for any human unfortunate enough to cross over into 2D four-fingered land, and those scores in Space Jam would make no damned sense to Jordan.
Base eight, base ten, letters, hieroglyphics, whatever. Everything about that movie is ridiculous.
Those important numbers would be most evident in the screwy way they would measure time. The year 2014 in our world becomes 3736 in base 8 in Toon Town, since the equivalent of a century has 64 years, and the equivalent of a millennium just 512. The base eight year 3000 happened in our base ten year of 1536, and the octal world's next millennium at the year 4000 will be coming up in our year 2048. The same amount of time will have passed; it's just represented by different digits.
Then there's the money. As Andy Kiersz of Business Insider says: "One dollar in base ten would convert over to $1.44 in base eight, and $0.84 in base twelve. Conversely, what we'd call a dollar in our world with eight fingers -- $1.00 in base eight -- would translate to just $0.64 in our base ten world." So any intra-world trading going down in Who Framed Roger Rabbit? would be fraught with the kinds of difficulties that would make our stock exchange look like an abacus.
He's just realized he has no clue how much to tip.
The most interesting thing would be the fact that base eight would make it far easier for the 'toons to read binary, since any three-digit 0/1 sequence can be broken down into multiples of two, whereas we struggle because of our shitty extra fingers. That means there's a very real possibility that these characters would have invented computers way earlier than our base ten selves. Which might go some way to explaining the quantum tunneling technology in Monsters, Inc., or how the Roadrunner is able to break the fourth wall and escape all of Wile E. Coyote's traps.
#5. Bigger Eyes Means Way Better Vision
Most good characters have big eyes to make us care for them, fall in love with them, or sob uncontrollably when they die (damn you, Bambi). But those giant-ass pupils would also allow in a crapload more light than ours, meaning they will have far better night vision than we do. Any situation in which a bug-eyed Disney princess is stuck in utter darkness wouldn't actually be that bad, as they basically have cat vision. And it'd help any monsters working at Monsters, Inc. when they're sneaking into children's bedrooms at night to scare the piss out of them. Bigger eyes would also mean these characters could see much farther into the distance than us, discerning tiny shapes from vast distances away, like an even more femininely attractive version of Legolas.
This applies right across the board, from the Powerpuff Girls to Bing, from Rapunzel in Tangled to every anime character ever. Those giant honestly-I'm-not-high pupils make every adorable cartoon character a freakin' superhero.
The best example is Mike Wazowski from Monsters, Inc./University. He is essentially an eye with limbs.
And a killer smile.
Assuming the diameter of his eye is about a foot, this means that his pupil would be about seven centimeters wide. Using the most important equation in astronomy, we can calculate the angular resolution of Mikey's eye. In real-world terms, it means he could read your name badge from miles away.
Of course, this means their brains would use way more processing power for their vision -- the same problem which might have caused the extinction of the Neanderthals. But hey, nobody's perfect.
On the other hand, any animated characters that are much smaller than we are but have the same giant eyes we know and love will struggle to see anything any real distance away. So all the ants in Antz and A Bug's Life (who, in our world, have compound / non-cantaloupe-sized eyes for this very reason) would struggle to see anything in focus, because the wavelength of light isn't small enough when you get down to bug height. Basically, real ants would kick the shit out of the ants from Antz. Yes, even Sylvester Stallone's character.
"Are you saying no one can appreciate my bitchin' hat?"
Additionally, an overwhelming number of cartoon characters in shows like The Simpsons, Family Guy, South Park, Scooby-Doo, Adventure Time, and Looney Tunes do not have irises -- only a pupil in the center of a vast cornea. This is a problem, because the iris isn't just there to look pretty; it is a muscle tissue which allows us to expand or contract the size of the pupil. Without this, these characters would not be able to regulate how much light reaches the retina, and therefore would struggle to see anything in very bright or very dark environments.
#4. Huge Heads And No Hips Lead To Maternal Death
Just like big eyes, big heads are cute and make us go awwwwww. Well, up to a certain point. Proportionally speaking, humans have the biggest heads of the animal kingdom. Taking into account our encephalization quotient (EQ -- head size in relation to the body's size) of 7.5, compared with dolphins at 5.3 and a mouse at 0.5, it's clear that the bigger the brain, the better.
It may mean that we're really smart (well, up to a certain point), but it also means that we have to be born far sooner than other mammals. Otherwise, our giant skulls would kill our mothers during childbirth.
Many of the characters with giant heads must have either been born at a very early stage of development (which comes with risks for the baby) via a cartoon version of a c-section (I'm thinking maybe a zip in the stomach), or just flat-out killed their mothers on the way out.
But even giving birth to normal-headed babies, cartoon mothers would almost certainly have problems during childbirth. Just look at the slew of wasp-waisted female characters there are out there. Many of the animators don't seem to understand that women have rib cages, hips, or, fuck it, skeletons. It may look "more elegant" or sexier, but many of those girls wouldn't survive their second trimester, let alone pushing a baby out.
Either there must be a huge demand for cesareans in cartoon hospitals, or it goes some way to explaining why so many Disney princesses have evil stepmothers: Their hourglass-figured moms died giving birth to them.