In animation and comics, animal characters develop and age like humans. In reality, they tend to have much different lifespans ranging, from mere weeks to centuries longer than any human could hope to live. In addition, they usually develop quite differently and sometimes have life stages that are completely alien to humans.
This trope takes on three different forms, human-like lifespan and longevity, human-like aging process, and human-like developmental process.
Human-like Lifespan/Longevity: This is when an animal character has the same longevity as a human, that is, live as long as a human. Depending on the species this is either accomplished by shortening or lengthening their life span.
Human-like Aging Process: This is when an animal character shows their age in the way that a human does. Examples of this include gray hair or fur even on a non-mammal character, wrinkles, liver spots, bushy eyebrows, balding head, and sagging Non-Mammal Mammaries.
Human-like Development Process: This is when an animal character develops in the way or at the pace that a human does.
Human-like Baby Animal Body Proportions: This is when baby animal is inaccurately given body proportions like those of human babies. For example, real-life calves, fawns, and foals have long legs, so that they can stand shortly after birth and reach to suckle.
Averting or lampshading this trope is sometimes done as a Furry Reminder.
Human-like Lifespan/Longevity Subversions, Lampshades, and Exceptions:
"[You're] eleven? That's what, two in human years?"
In the first Madagascar when Marty the zebra turns 10, it's hinted that he is middle aged at that age.
It's enforced in the case of The Secret of NIMH, where the rats and mice who were experimented on at NIMH were given long lifespans. It's mentioned that Johnathan Brisby would have far outlived his wife, a simple field mouse, had he not been killed by a cat first.
Mentioned but not elaborated upon in The Beginning, the last book of the Animorphs series. Tobias, a human trapped in morph as a red-tailed hawk, briefly mentions that he's old for a red-tail, but he has absolutely no idea how much time he has left.
Justified in Harry Potter and the Prisoner of Azkaban in regards to Scabbers, Ron's pet rat that had been alive for at least 12 years and had belonged to Ron's older brother before him. Ron is told by a magical pet shop owner that a plain country rat such as Scabbers generally doesn't live more than a few years, but of course it's revealed that Scabbers is really Peter Pettigrew, a traitor and presumed dead wizard in disguise.
Originally averted by Garfield, who mentions on his second birthday that the human equivalent of fourteen, and complains about aging ever since he turned four. Later played straight, as he's still relatively healthy and active over 30, though the average lifespan of a housecat is 12-14 years at the least and 20 years at the most. While there are unconfirmed reports of cats living longer, the oldest cat ever recorded was 36, who died a few weeks later.
If Garfield's 30, then Jon's what, in his fifties? The relevant point is that the characters in Garfield, like most comic strips, just don't age. (If we take Garfield's comments about the length of time since the strip started being his age literally, he was never a kitten.)
In the Phineas and Ferb episode "Phineas and Ferb's Quantum Boogaloo" Candace travels 20 years into the future where Perry is still alive, though old. In reality, platypodes only live for 10 years.
The lifespan part of this trope is averted with Brian Griffin the dog from Family Guy as occasional references are made to his age (seven) and longevity. Also, Peter also addressed the fact that Brian will only live a fraction of the time Peter will.
One episode of Pinky and the Brain hinted at the lifespan of real mice, which is 2-4 years. Brain says that at 2 years old, he's lived half his life.
This isn't mentioned, but it's strongly implied in Chip 'n Dale Rescue Rangers. In the pilot, when Gadget is added to the group, it's mostly because she is the daughter of a friend of one of the protagonists, and she is the only one who can fly his plane now that he is dead. It is mentioned that said friend and protagonist fought together in "The Great War", which seems to be an expy war for World War II. For any of this part of the pilot to work, either,
a) Gadget was born about a decade or so after the real actual WWII, making her actually anywhere from 20-30 something at the time of the pilot
b) The Great War isn't an expy for WWII, but a more recent conflict such as Vietnam, and Gadget is actually 12, and demonstrating a "puberty = adulthood" trope
c) Gadget and every other animal is aging just like they should, The Great War happened in the past 3 or 4 years, is not an expy for any human war, and is an expy for a covert black ops action instead
d) It's not the late 80's in the show
As all the visual evidence, parody, and inferences point to a) (right down to the plane they fly), and in the show, it's clearly the late 80's, this trope has to be in play.
In One Piece, the Fishmen (a Fish People, not a Half-Human Hybrid) ages not unlike humans. Evidenced in Hody Jones and his New Fishman Pirates, who, after a steroid-induced Rapid Aging, are shown with wrinkles, saggy eyesockets, gray beards and teeth loss.
Rufus the cat from The Rescuers has a grey moustache that indicates his old age.
Jock the Scottish Terrier from Lady and the Tramp has a grey moustache and bushy grey eyebrows.
While he certainly has a far longer than human lifespan, some of the clues to Yoda's advanced age include wisps of gray hair and the fact that he is almost always seen either walking with a cane or in a scifi version of a wheelchair.
In "The Old Gray Hare," after a Flash Forward to the year 2000, a 70-or-so-year-old Bugs Bunny is shown with white chin whiskers.
The Tom and Jerry cartoon "The Missing Mouse" has Jerry Mouse pose as an escaped lab mouse filled with a volatile explosive. Jerry's ruse dissolves, however, and Jerry gets booted out of the house. Tom soon captures another mouse, thinking Jerry is repeating the trick. When Jerry shows himself elsewhere, though, Tom realizes that he's abusing the explosive mouse. This realization ages Tom dramatically: white eyebrows, white ear-hairs, baggy skin, collapsed posture. He looks like a centenarian.
Human-like Development Process Subversions, Lampshades, and Exceptions:
In the Redwall series most animals seem to use "seasons" as a substitute for years, Tagg for example is stated to be an adult at 16 seasons. They seem to equate one season to one year, and that's still far too slow. In the example that's given of Tagg, to be realistic he would have had to have been an adult by around 13 months, or just over four seasons. Also, the mice ought to be fully grown in well under one season.
Examples of Human-like Baby Animal Body Proportions:
Averted with the fawns in Bambi as they have long, ungainly legs like real fawns.
Minecraft features calves (baby cows) with large heads and stubby legs.
Averted in Warrior Cats. Aside from a few inaccuracies, they age and develop just like real cats do. The exceptions to the lifespan rule are the clan leaders, who have 9 lives. They measure age for kittens as "moons".
The episode "The Cutie Mark Chronicles" reveals, in a flashback, that Fluttershy as a filly resembled a real filly with long legs, compared to the others which are just smaller versions of their adult forms. Presumably, this was to illustrate what a late bloomer she was. Alternatively, it's to illustrate that she's older because she looks taller than the others.
Author's note: As to the probable age of Wally Gator, I offer the following formulations: In terms of developmental progression, anyone above the age of 12 is said to be in Jean Piaget's Formal Operational stage, defined by the ability to think in the abstract. Wally has a defined idea of the difference between freedom and captivity. Erik Erickson would likely place Wally in the Intimacy vs. Isolation stage; Wally yearns for the intimacy of societal contact, not the isolation of the zoo. This stage is typified by young adulthood. A biological examination reveals the average lifespan of the male American alligator to be roughly 40 years in the wild. The average lifespan of the human male is 76 years. Thus, one alligator year is equal to about two human years. It is probable that Wally Gator at least 12 in alligator years, since he evidences abstract thought. This makes Wally at least 24 in human years. This age demographic would fit neatly into the Ericksonian stage of Intimacy vs. Isolation. In watching Wally Gator, who does appear to be in his younger years, we can assume that Wally Gator's chronological age is 12 at the least and 14 at the most. I hope you know that I stayed up all night working on this, since I never seem to get much sleep anyway.
Five hats means that five tropers think it is ready to publish.
You are saying that you think this draft is ready to be published. That means the description is not ambiguous,
it doesn't duplicate an existing trope, there are at least three examples, and the title makes sense.
Is that what you meant to do?
You are saying this draft has a ready-to-publish hat it does not deserve and you are taking it back.