How the Mushroom gets made
Mario's adventures are full of whimsy, but they wouldn't be half as fun if they didn't hew to a consistent set of physics. After all, jumping around with precision and speed requires a degree of confidence in Mario's ability to adhere to the rules of gravity. That said, though, dealing with physics is kind of an all or nothing deal.
And the Mushroom Kingdom is full of so many seemingly unanswerable questions (discounting the most obvious theory, anyway). Why does eating a mushroom make Mario grow so big? Why do creatures eaten by Yoshi turn into eggs? Why can Peach glide through the air with no apparent propulsion system? It turns out there's a perfectly logical, scientific explanation for each of them. Let's read and find out!
Toad render by James VanDenBogart
Mario ground pounds through expertly timed flatulence
Mario is a master of aerial acrobatics, but his 'ground pound' ability can't be explained through leg strength and coordination. Far beyond simply altering his trajectory mid-flight, Mario can outright cancel all of his momentum with a 360-degree aerial flip, then send himself plummeting keister-first toward the ground. How on earth does he do that? Well, let's just say there's a reason that he's such a big fan of whole-grain pasta.
First he lifts his legs, angling his rear-end to oppose his current velocity. Then he begins a near-imperceptible series of micro-flatulations that arrest his forward momentum within a split second. The tiny farts send Mario somersaulting through the air, ended by a final tremendous emission, which also speeds his descent to the ground below. It's gross, but you gotta do what you gotta do to clear Bowser's endless death traps You didn't think he kicked up all that dust just from falling, did you?
Peach soars with an aerodynamic petticoat
Peach isn't the first person to imagine that a fancy dress could work like a frilly pink parachute, but she is one of the few to pull it off. Actually, her system works even better than a parachute. Instead of just slowing her fall, Peach can actually float in the air for several seconds, with the remarkable ability to move back and forth at will. It may seem like magical princess stuff, but it's actually quite technical.
You see, Peach's petticoat is lined with thousands and thousands of molecular-scale lift-generating structures. These nanomachines essentially function like a battalion of little plane wings. By the time she appears in Super Smash Bros Melee, in which pervy players quickly discovered she battles sans-slip, the technology was miniaturized even further, to the point where it could be directly applied to the surface of her legs. As for the parasol, have you ever tried to carry one in a strong breeze? It works like a parasol.
Super Mushrooms make Mario expand, not grow
If you want to grow up big and strong, you'd better eat your vegetables. Lots of vegetables, for years. Mario, on the other hand, just needs to consume a single mushroom. How can one Mushroom (oversized though it may be) possibly lend him that much extra mass? Simple: it doesn't. It just creates a thin, symbiotic system of fibers that let his body inflate to twice its normal size without grotesque distortion.
When he runs into an enemy or is otherwise injured, the shock ruptures embiggened Mario's skin. The inert gas, which keeps his frame appearing plump and healthy, rushes out of the wound, producing a distinct sound and causing Mario to shrink back to his normal size. It happens in a heartbeat, but they say if you pause the game at just the right time you can see a horrid, deflating Mario stuck between his two forms
Yoshi's digestive and reproductive systems are one and the same
How do Yoshis reproduce when their egg-laying mechanism also functions as a form of waste disposal? It's actually much simpler than you might think. Both the reproductive and digestive behaviors for a Yoshi begin in the exact same way: they find a victim and slurp it up. If the Yoshi isn't in heat, its powerful stomach acid quickly dissolves its prey into a nutritious slurry. The material which isn't digested is reshaped into an eggshell and expressed from the rectum.
However, while the Yoshi is in heat, its stomach acid is suppressed. In this way it can keep the victim deep in its primordial gut for several months, breaking it down and reshaping it into the deformed polyp commonly referred to as a Baby Yoshi. Once the metamorphosis is complete, the Baby Yoshi is expelled from the adult within a colorful spotted shell, from which it will hatch within a few days. Isn't nature beautiful?
Mario breathes underwater using a follicular apparatus
In most of his adventures, Mario demonstrates the ability to remain underwater for a seemingly unlimited amount of time (or at least as long as the level timer lasts). As you may be aware, normal humans - even humans who can jump really high and have worn the same pair of denim overalls for the last 30-some years - need to breathe regularly to stave off the icy grip of death. It turns out Mario's mysterious ability to remain submerged for extended periods comes from his mustache.
Much like the concept for the Triton rebreather device, Mario's mustache uses the surface area of each individual follicle to filter out the small amounts of oxygen that can be found in most bodies of water. This oxygen is funneled up into his nose, allowing him to inhale and exhale normally. The same goes for Luigi and all other mustachioed plumbers (never know when you'll need to do some wetwork) but why didn't it work in Super Mario 64? Look at his mustache - it's just a flat texture on top of his face. Not enough surface area.
Koopa shells are trying to escape their captors
Have you ever jumped on a turtle? God, I hope not. Turtles are so cute! Alright, let me back up. Let's imagine what happens when you jump on a turtle - either the shell holds up and you fall over and feel like a real asshole, or the shell cracks and you get turtle guts on your shoes and you feel like a real asshole. In neither of these scenarios is the turtle ejected from its shell. So why does it happen when Mario hops on a Koopa Troopa, which is ostensibly a humanoid turtle?
Duh, they're not actually turtles. Koopa Troopas and their shells are actually two separate organisms, the latter of which is not at all pleased to be worn by a creepy lizard guy in a sweat-stained tank top. When Mario smacks a Koopa, the shell takes advantage of the brief shock to pop off, and it secretes an oily substance from all of its orifices to make it more difficult for the Koopa to grab. Mario's wearing specially engineered gloves, so he has no problem picking it up and using its near-frictionless surface for some Koopa bowling.
Mario collects coins so he can live (and die) forever
At first you might think that the Mushroom Kingdom has a somewhat tenuous grasp on the concept of capitalism. Traditionally, money is exchanged between individuals for goods and services, whereas in the Mushroom Kingdom method, it's simply left hanging in mid-air or collected in question-mark stamped blocks. With all these coins hanging around the place, what value could they possibly still have for Mario? Well, as it turns out, all that cloning gets kinda expensive...
...you did know that Mario has thousands of clones, right? Or more accurately had thousands of clones, since all but a few of them are impaled on spikes, burnt up in lava lakes, being digested in the bellies of giant fish, or still falling down bottomless pits. Fortunately, Mario's always just a 100-coin payment away from a fresh new him, ready to live, adventure, and (most importantly) collect more coins. The Mario cloning industry is the economic center of the Mushroom Kingdom, supporting nearly all of its residents and allowing its nobility to live in grand castles and bake fancy cakes. So it works out well for everybody.
See? Nothing unusual about Mario at all. Definitely nothing horrifying going on in the Mushroom Kingdom, no reason to try to blot this out from your memory the next time you start playing. In fact, you might as well submit some of your own favorite Mario eccentricities and their possible explanations in the comments below!