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Disclaimers / Notes
♡ This is like, super estimated. The ages I chose are what I found through Google, but obviously different sources use different measurements and study approaches and whatever else. And yes, I did NOT use one site, (bc I couldn’t even if I wanted to (and I wanted too TwT)), so I chose sources that seemed to have a good approximation.
♡ Some sources would say the lifespan of some of the turtle species could reach extreme numbers like 100 and I was like “okay but some humans can age to 120 and we don’t say that’s the average human lifespan” so I didn’t include extremes, just what people would report are typical averages.
♡ For the estimated sexual maturity I just used what @shotaconned found since that is what inspired me to calculate all of this in the first place XD
♡ Also, I suck at math (part of why this ended up taking so long), so if you see smth wrong pls let me know!
♡ I plan to make a second chapter comparing puberty rates with any iteration that has a canon species.
Here is the math for the ages the Rise turtles would have been when they had hit sexual maturity if they developed at the rate real turtles do. I used a ratio calculator to figure this out (cause fuck doing that myself).
Brief analysis: Only Mikey would have still been sexually maturing in the Rise series. But, he would be reaching the end of puberty. Raph would have just finished his own puberty. Considering post-movie ages all of them would be over the age of sexual maturity. See the bottom for further analysis on a more sociological level, as it can be applied here as well and I don't wanna repeat everything.
However, turtles mature at a rate much faster than humans. The turtles COULD age that quickly, and conversely, they could also mature at the rate humans do. But, if their rate of development is perfect 50:50 then their rate of development would be the average of the two.
So...
Calculating Average Puberty Amounts Between Turtles and Humans
Lol this required more math. Had to use the quadratic formula. y = mx + b
In this equation, y = average lifespan, m = rate of development, which would have to be averaged between humans and each turtles species, x = estimated age, and b = 0 since we are measuring development since birth. If we went from start of puberty to the end it would require knowing when each turtle species “starts puberty” in a more official way and that’d be pretty difficult to find XD
Anyway, so I had to calculate the average human cis-male rate of sexual maturity. Then each individual turtle species' maturity rate. Then I averaged it. Then I repeated for the high end of their ranges and the low end of their ranges. Finally, I used ratios to find the start of puberty using data I found through Google.
So basically I decided to take the rate through which each turtle species reaches sexual maturity, and averaged it with how quickly humans develop to sexual maturity so that we could see what a theoretical half-human, half-turtle mutant’s puberty will look like. Then I found when each turtle would have theoretically begun puberty from there.
Don’t be intimidated by all the subscripts, it looks all serious and sciencey but it’s not XD It's pretty much the quadratic equation used repeatedly lol. I just used subscripts to tell the difference with each repeated variable. I also used ratios toward the end to calculate the start of puberty using a ratio calculator.
Here’s the math:
(The last box is meant to say "complete puberty example," I do not recommend just viewing it as if that's the official results cause that's boring and doesn't allow flexible interpretations. It's just meant to kinda get an idea of how their puberty could look in a more direct sense)
And here's a graph I made to help visualize everything. And since there are age differences between the turtles, I bumped Raph down a year and Mikey up a year so we can get an accurate look at them timeline-wise.
Analysis: I like thinking this is more of a canon age range for their puberty since it averages out the turtle and human rates of development. This means in the series Raph could possibly still be going through puberty, though he could also be completed with it. He is definitely completed with it by the movie. Mikey is for sure going through puberty in the series, and he is just barely sexually mature in the movie.
♡ Donnie and Raph start puberty at similar times, though Raph could start a bit later.
♡ Donnie’s puberty span tends to be shorter than Raph’s, potentially by a significant amount, which would be interesting if they started around the same time.
♡ Even if Raph’s a late bloomer Mikey and Raph still can’t start quite together, but their puberty could intersect.
♥ ((I love the idea of the twins helping out their “innocent” siblings with puberty lol))
♡ Raph can intersect with Leo as well if he starts puberty early. So basically whether he’s an early bloomer or a late bloomer Raph will be experiencing puberty together with at least of his bros, if not multiple.
♡ Leo, Raph, and Donnie can start puberty together theoretically. But only if both Donnie and Raph are early bloomers and Leo’s a late bloomer. And Raph would still end a year later than Leo and Donnie.
♡ Leo and Donnie have very rapid puberties, which kind of makes up for how early they start.
♡ Mikey’s puberty is very close to a regular human’s puberty in both length and timing.
♡ Even at Leo’s latest possible puberty onset and Mikey’s earliest the two will never have intersecting puberties.
Remember though that this is if you half their human and turtle DNA. If you have them be more turtle than human, then their sexual maturity range will be somewhere between the first table and the one above. (I know a lot of ppl like to have Raph be more turtle-like, for example, and that could mean his range can be lower than the above table). If they are more human than turtle their range will be somewhere between this table and the human range (so if you don’t like how early Leo’s is you can make his puberty process more human-like XDD).
Also, remember this is the rate of sexual maturity. Sexual maturity does not, however, speak to brain development, which, based on the show’s characterizations of the turtles, follows typical human development in a lot of ways, even if they are theoretically sexually mature.
As for when they are official “adults,” adulthood is a social label that has more to do with a person’s legal capabilities in their country rather than anything biologically related. It is not assigned based on sexual factors, and as proof of this, male and female humans become adults at the same time despite females on average becoming sexually mature earlier than males, so it has nothing to do with sexual maturity and is more vaguely about general maturity. (This makes it sound like it's a bad thing, but it's actually good because it means no matter how young a person is when they begin sexually developing, nor how sexually active they are, they still have the same rights and protections as their peers).
If the turtles were to comply with America's standard of what’s considered an “adult,” the turtles wouldn’t be adults until 18. If they wait to have sex until then, that is a long time during their teen years where they are sexually mature enough to have sex but aren’t having any (lol heavy sexual frustration).
Adulthood could be a completely different situation with youkai. It’s free reign. So adulthood can start at a strict age if you want it to, but it could also be based on different species(?) of youkai, meaning it could theoretically have age-laws more suited to the turtles’ development rates. (Personally, if I were to go this route I would just slap a year on Mikey’s 15 and claim that’s the law for turtles, parallel to humans XD).
However, considering youkai probably age a LOT slower it might be another situation where the turtles are sexually mature for forever before a youkai is willing to sleep with them (unless they’re a creep lol).
I personally feel that the turtles are more likely to follow youkai laws regarding adulthood since that is the world they engage with as themselves most often and without hiding, and because if it is personalized to species, youkai turtles presumably are going to have similar development rates to our mutant turtles, so our turtles may be more inclined to follow whatever age laws are in place for youkai turtles. Of course, this is assuming they care about following laws in the first place XDD
Anyway, Raph is a surprisingly later bloomer than I thought he’d be, Leo was destined to be a cherry bomb slut since childhood, and will probably rub it in Donnie’s face whenever he sees changes happening to his body first, and poor Mikey is born to be an innocent little babe compared to his brothers (TvT my own HCs are now squashed).