To be fair, the mammals “born able to run within hours” are the terrestrial ungulate mammals. They are newcomers and parvenus and they die when they step on a bee. They only showed up when grasslands became common, the meme-loving fucks - they’re all matcha lattes and YEET. Like, okay, we get it, hoofed ungulates: you’re vegan, you really like synthpop, you’ve “discovered” a “new” continent, you ran fifteen miles this morning, your baby walked within eight hours of birth, sure. Fine. You’re cute, diversity is important, you can stay. We need something to eat, after all.
But ungulate mammals are REALLY poor representation of Mammalia.The ancestral Mammal, rodentlike, that gave rise to Placentals and Marsupials, would have been more like - well, more like today’s Placentals and Marsupials. More like us. More like badgers and dogs and monkeys and hamsters. Born blind and naked, and hidden discreetly from polite society, until the horrible alien thing looks more like a Real Animal.
Consider the mouse: born completely naked, hairless, blind, deaf, helpless, only able to drag itself to a nipple with terrific effort. Consider the cat: born as a thinly furred sausage with eyes and ears glued shut for weeks. Consider the newborn dog. Big cats. Rats. Bears. Squirrels. Sure, consider the marsupials; also, weasels and rabbits and porcupines and pangolins. All the mammals that aren’t the bloody ungulates.
Rodents are born practically fetal, their limbs mere buds, their skin see-through, their eyes bulging in their transparent skulls. Their bones aren’t even opaque! You can see their dark livers, the white milk in their bellies! Their eyelids are welded shut, their heads too large to raise. They are a lot more alien than a human baby - a liminal animal indeed. Certainly, rodents grow quickly, because they die so young. Their helpless childhood is still proportionately a large chunk of their life - nearly the same proportion as ours, actually. But they are born like uncooked eggs. I would add a picture of a newborn rat pup here, but young and impressionable children read this blog.
And we are not the weakest of the Furry Mammal clan, if we zoom out. It takes about two weeks for a kitten to open their eyes. It takes about four weeks for their hearing to come online. This is because these senses are still developing. They’re born undercooked, too!
By contrast with many mammals, human babies come out with their senses active (unless that specific baby is blind or deaf or has another sensory disability)*. It takes a while for human babies to focus their eyes, because we usually have a lot of apps installed (color vision, facial recognition) that take forever to boot up the first time, and focusing requires muscle control - but human babies are goggling at the world with open eyes, and processing what they see, as soon as they come out. Human babies come out able to hear, if hearing is included with that specific baby. We are born able to record and process sensory information, where our other mammalian cousins can’t.
I mean, I am so guilty of this trope too, I love it to pieces and use it all the time. Even more hypocritically, I personally agree with the “Fourth Trimester” theory, which is that human babies need about three months to adjust themselves to life outside the womb. Thus, the first three months are the “Fourth Trimester,” where you just carry the baby around, and it boggles helplessly at the world and goes “ugh!!” That is the part that makes sense when you look at the birth canal etc, and you go “oh, we’re so undeveloped,” and you mope because you can’t see yourself ever getting your life back. But the first three months is only a small piece of the longer story of human babyhood, and the “weak, helpless” stage is not particularly unusual among our mammalian family. It just seems so terribly long because we compare it to horses and rats, which is unfair on everyone. And at some point we get our lives back, and can’t remember where the time went. And it isn’t as bad as it could be. I mean, we can usually shit on our own. So that’s something!
No, it really is something. Many baby mammals cannot excrete on their own. Cats, for example; the mama cat must lick certain areas of the baby to stimulate it to poo and pee. They can’t do it by themselves. Mama cat must lick them religiously, to make their bowels and bladder work, or the waste will back up and the kitten/cub will die. This is relatively common among the Furry Mammals. Every kitten on Earth had to be forcibly poo’ed for the first three weeks of its life. Every tiger took six weeks (!!) before it could pee by itself. And that’s just the felids. Don’t talk to me about werewolf cubs unless you’re ready to make the decision on whether they need diapers, you cowards.
Humans, though, are born perfectly capable of shitting by ourselves. Which is rather nice, when you consider the alternative.
So if you take us in context of the other baffling and amazing animals on Earth, we are not really particularly “undeveloped,” taken as a whole. Not particularly in comparison to our cousins, whom an alien would find just as strange and foreign. We humans are simply hitting milestones at our own pace - sometimes faster, sometimes slower, always legitimate, always because an ancestor dodged death once by doing something slightly different. Our infants are for carrying in our arms, so it doesn’t matter that they can’t hold their heads up - but they are born shitting, and boggling with their enormous eyes.
Anyway, aliens would probably regard all this nonsense in the same way as the dinosaurs did - “Lord, what fools these mammals be,” at first, and then “OH FUCK THE MAMMALS DID WHAT?”
“Parenting is important,” reply the badgers and the bears and the humans, aggressively cuddling something they call a baby, although they might be taking the piss: “Really, we will bond with and nurture ANYTHING that meets our vague criteria. Isn’t cuteness just the best thing you’ve ever seen? Don’t your hormones just SQUISH when you see something with specific proportions? You know what’s inherently rewarding? HOLDING SMALL THINGS AND MAKING A SOUND ABOUT IT.”
“Erm, I guess?” replies the alien or the dinosaur. “I guess… I guess your baby…. thing…. is very …. important? To you??”
“YES I LOVE IT A LOT”
“I …. see that you do. It’s … cute.”
“Cuteness is a powerful weapon,” the mammal says seriously. “Oh, also? This is our planet now.”
* Many humans are born without the ability to hear, see, see in color, eliminate, socialize, process sensory information, etc. Or they may lose these abilities later. They are valid, human and loved. These “space Australian” posts are about generalising humans, so I generalise here, but I don’t want to make anyone feel bad.