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People Break Down Which Biological Facts About 'The Other Sex' They Only Just Learned

Reddit user pragmail124 asked: 'What biological fact about the other sex did you not know until quite recently?'

cutaway human anatomy figure
Nhia Moua on Unsplash

Sex in humans is usually categorized as female, male, or intersex.

There are wide variations in the biological attributes comprising human sex and in how those attributes are expressed.

Sex is determined by anatomical, physiological, genetic, and physical attributes and is not binary.

An individual can have the genetic coding for a male but develop the anatomy and physiology of a female.

Gender refers to the socially constructed roles, behaviors, expressions, and identities of girls/women, boys/men, nonbinary, agender, and gender-fluid people.

This article deals only with binary sexes—female and male—and not intersex people or anything related to gender.

Reddit user pragmail124 asked:

"What biological fact about the other sex did you not know until quite recently?"

Required Reading

"The comments in this thread are a must-read by all sexes."

"There is a ton of educational feedback, some of which is eye-opening."

~ Echo71Niner

"Yeah, I’ve already learned a few things already."

~ Xingxingting


"Surgical tech here who just witnessed their first pneumoscrotum!"

"When you have a laparoscopic or robotic procedure as a gentleman, and you have a hernia in the right spot, the gas used to inflate your abdomen can leak into your scrotum and fill it to an alarming size."

"The doctor said it’s nothing to be worried about, but it sure looks concerning."

~ Naive-Climate


"Penises float in the bath."

"I had no idea they were buoyant!"

~ SuspiciousFrogs

Vaginal Fluid

"A woman's vagina secretes a fluid—vagina's naturally acidic pH—which can bleach their underwear."

~ Previous_Film9786

"Can actually put holes in the underwear over enough time."

~ bothwatchxfiles

Prostate Purpose

"The prostate exists to make seminal fluid more alkaline, otherwise the acid inside the vaginal canal would just kill all the sperm."

~ wanderfae

Signs Of A Heart Attack

"Women experience significantly different symptoms from a heart attack than men do."

~ surfex

"This was something I learned a few years ago and it came in handy when my aunt had a heart attack last month! In the case of my aunt, she had pain in her left breast, which is common for females who have heart issues or are currently having a heart attack."

"She experienced fatigue and just generally felt awful in a way that she struggled to put into words. When my mom called me and told me what was happening, I told her to rush her to the hospital because it sounded like a heart attack."

"Lo and behold, it was a minor one but a heart attack nonetheless. She’s okay, but knowing that there is a difference between male symptoms compared to female can really save someone!"

~ oinkszoinks


"Women have, by far, the greatest propensity for iron deficiency/anemia, mainly because of periods, pregnancy, etc..."

"I've recently heard that ladies generally make up about 95% of anemia cases. It's not that men can't get it too, but usually, if a man has it, there's likely another underlining condition."

"I guess it never dawned on me, being a man, that all this blood loss causes such likelihood of iron deficiency. I mean, I know women lose blood, but it didn't click that this can cause them problems."

~ llcucf80

Refractory Period

"Until a few weeks ago, my wife didn’t know guys needed recharge time after sex."

"So if she was ready to go again straight away and I said ‘give me a minute’ she was taking it personally. I never explained because I thought it was a well-known fact!"

"We’ve been together for 10 years."

~ StrangledByTheAux

Generation To Generation

"That women are born with all the egg cells they need and do not reproduce/create new ones."

~ collapsedbook

"What’s even crazier is that things that happened to grandma even before she’s pregnant can impact how genes are expressed in her offspring, and the offspring can pass it on to their kids, too."

"There have been studies on people who experienced famine as children and the health of their children and grandchildren long term. I can’t remember the exact findings, but basically, the children and grandchildren showed more instances of a specific issue than the control group."

"We also know that extreme mental stress can have an impact on the body and how genes are expressed—kinda puts generational trauma into perspective. Sh*t is literally passed on through genes."

~ what_the_a

Descended Testicles

"OK, this is embarrassing, but when guys talk about puberty and their 'balls dropping', I thought it was this explosive thing."

"Like one day you're walking down the street, and BAM! your balls just come hurtling down."

"Yes, I know that testicles descend within the first few months of a boy's life."

"My mistaken impression was based on the expression 'balls dropping' to describe puberty. Obviously, I've since learned that this doesn't happen during puberty."

~ sharknado_18


"My wife and I are BOTH learning things about menopause and have been for the last five years. Which is the first thing we've learned about menopause, how LONG it can last."

"Also hot flashes aren't just 'weird', they actively suck. Also, hormonally, you can be quite f*cked, like forever-PMS f*cked. All kinds of medium-grade stress, mood and energy problems."

"There are treatment options, but they are poorly understood and poorly explained. It's quite confusing."

"Lots of girls are never taught about sexuality and periods, but we are realizing NO ONE is taught about menopause."

~ procrastablasta


"That both urine and sperm use the same piping/plumbing."

"Somehow I never thought about that."

"Because women have two separate systems, I thought it was the same with dudes."

~ schwarzmalerin

"They’re the same pipes, but there’s a switch at one of the junctions to go from one to the other."

"If a guy just had an orgasm, it’s unlikely he could pee right away. It has to relax and switch back."

~ Cien_fuegos

False Menses

"Newborn girl babies can have periods due to hormones still in their system from the mother."

"It's called a false period."

~ lilyboocakes

Urethral Sphincter

"Guys control their urethra from the base of their penis. Not the tip. THAT’S WHY THEY HAVE TO SHAKE IT OUT."

"As a girl, this blew my mind. When we turn the faucet on, then the exit point is right there. Dudes have to go through a hose that they can only control from the base!"

"I learned this in medical school when I was about 35. Suddenly all this talk about shaking things out made sense!"

"I think most women just haven’t given it much thought and that’s why it’s so surprising."

~ SeeLeavesOnTheTrees

My Mother was a registered nurse.

She worked labor and delivery in hospitals, then as a school nurse for K-12.

My education on biological sex was fairly comprehensive, so I can't say there were any surprises by the time I was 11 or 12.

Was there anything you learned later in life about "the other sex"?