Over the course of the next 40 days, the brain-baby migrates from its father's head to his chest to his belly to ... well, you know where this is headed. Once the baby has reached its father's junk, there's a period of a little more than a week where he's a loose cannon, ready to shoot a tiny baby into any willing female companion. This is when the sexy happens, and the baby takes a ride through its father's dong and into its mother's body, just like that tunnel in Space Mountain.

You'll note that the male pregnancy ends with an orgasm, while the female pregnancy ends with hours of labor. This proves that life isn't fair, and class is now dismissed.

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"This is BULLSHIT!"

So Why Do They Believe It?

If we're going to look at these weird-ass beliefs from various cultures around the world, we should take a moment to figure out why anyone believes them. After all, most weird beliefs exist because, well, they work.

In this case, it solves a problem that the actual scientific understanding of pregnancy brings: that the responsibility for a pregnancy is on the woman alone. Women have to take prenatal vitamins, avoid alcohol, eat responsibly, give up smoking ... while guys could squirt and bolt, and it wouldn't affect the baby one bit. Physically, anyway. Whereas the Malay belief says to the man, "You also carried this baby for over a month."

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And after so long, it just doesn't fit back in. So no refunds.

The man is said to even have cravings during his part of the pregnancy, just as his wife does after he passes the baby to her. And after his 40 days are through, he's still involved in the fetus' well-being -- he's not just moral support, but actually part of the pregnancy. Malay pregnancy rituals require just as much fastidious behavior from the man as from the woman. That's right: There's no wham, bam, thank you ma'am in Malay pregnancies. Instead, it's baby-making as a team effort. It's almost sweet, in a bizarre brain-baby sort of way.

Now, the Tiwi didn't completely miss the intercourse-baby connection. Tiwi women, at least, were well aware that sex with a man was part of baby-making -- but while the guy who did the horizontal tango "helped" make the baby, that didn't necessarily mean he was the father. That's because while sex might have jump-started the pregnancy, the kid wouldn't exist if it hadn't been dreamed up -- and it was always a woman's husband who did that dreaming. No matter whom she'd been banging, when a woman got pregnant, her husband was the father. Under the Tiwi understanding of conception, Maury Povich is a scientific impossibility.

Now, you might be wondering how they explained single mothers, and for that the Tiwi had a simple answer: There were no single women. Tiwi women married very early -- in fact, they were often promised in marriage before they were even born. Every Tiwi woman was perpetually married, so her kids always had a father.

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"You take a nap, we'll take your wife out. And in the morning: baby!"

So Why Do They Believe It?

For Tiwi women, being married from birth probably wasn't super awesome, at least not on its own. But here's the thing: Since the Tiwis saw intercourse as irrelevant to paternity, female extramarital sex was completely accepted. After all, no matter how many guys you'd been screwing around with, your child was still legitimate. And while they didn't get to pick their husbands, women did get to pick their lovers -- and they didn't catch any flak for it, lose any social status, or have to cope with violent jealousy.

But in the midst of this orgiastic free-for-all, every baby was also born into a stable family unit: Its mother and its "father" were married for life. Turns out if you believe in dream-babies, you wind up with a society of stable nuclear families and free love, man.

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"You can't tell me what to do! You're not my dream dad!"

As any teenage boy can tell you, you can't get pregnant from having sex just once. But your average horny teenager's got nothing on Papua New Guinean cultures like the Huli and the Arapesh, because they firmly believed that babies were the product of repeated intercourse. Repeated a lot. They didn't even know it was possible for a single sweaty night to lead to a baby -- they thought it took way more work than that.

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"Just 20 more minutes -- the ritual is almost complete!"

For the most part, Huli and Arapesh beliefs were pretty close to being biologically accurate. They understood that sex led to pregnancy, and that babies were the result of man-juice meeting up with something inside the woman's body. So far, so good. The trouble was, they figured infants were actually constructed bit by bit out of sperm and menstrual blood. The man's sperm built the child's skin and bones, while the woman's blood took care of the internal bits. To be honest, Papua New Guinean pregnancies are just a bit too similar to Hellraiser for our comfort.

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"The box. You opened it. I came."

Now, if you figure that your average newborn is somewhere around 7 pounds -- and even if you figure that the woman takes care of the internal half -- holy s**t that's still a lot of raw building materials for the man to provide. Clearly one night of bangin' isn't going to even come close to cutting it -- instead, these cultures believed that you had to have sex pretty much as often as the man could manage until you had squished together a healthy, viable sperm-and-blood baby.

The Arapesh themselves weren't necessarily all that happy about this situation. They said that there were two kinds of sex: the fun kind, and the kind you had when you wanted to get pregnant. Baby-making was an awful lot of work -- no matter how tired you were, or how not in the mood, you still had to get down to business. And they didn't even have candles and Marvin Gaye to help them out.

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"Get up, p***y, you have work to do. Dick work."

So Why Do They Believe It?

This one is obvious. Despite all of those health class lessons about how just one sex act can get a woman pregnant (and it totally can), in general the odds aren't that heavily in favor of a less fertile couple that wants kids. Maybe the guy has lazy sperm, you just don't know. So if you really want to keep the tribe going (and happen to live in a culture where things like fertility tests are some kind of sci-fi sorcery), nonstop humping actually isn't all that crazy of a strategy.

So Why Do They Believe It?

The crazy thing -- crazy to Western minds, at least -- is that having more than one dad was totally cool. There was no scandal, and dads weren't angsty about who was more the father. Mothers weren't ashamed, husbands didn't mind, and kids ... hell, the kids loved it. Two dads means twice as many birthday presents and that you get twice as good at playing catch. Or rather, two dads means that there are two men giving you and your mom food when food is scarce, and two dads means that if one of them dies, you have a spare.

No, seriously. These are actual benefits observed by actual researchers (except for the parts we made up). Science has finally proven '80s sitcoms right: Having two dads is awesome.

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"Don't worry, just aim for Daddy Jim -- he'll catch you if you suck."

As for the ladies ... well, first off, they get to choose their sex partners. It may not sound like much, but think about it -- much of human history has seen women having very little say in who they screw, so you've got to give any system that corrects that problem props. And not only do they get to choose; they get the added benefit of having two or more men providing for their kids.

And for guys, it's a giant stress reliever. Anthropologists used to think that no culture anywhere had men who "shared" wives without freaking out about it, but Amazonian cultures proved them wrong. Under the multiple-dad system, paternity is never challenged, just added to, so everybody calms the hell down: They sleep with whomever they want, joke about sex all the time, and don't go around getting into duels over who slept with whom. If some guy slept with your wife, he just has to help take care of the kid -- who is still your kid, too.

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"Honey, do you think you could narrow down your standards? Every dinner is becoming a full-on festival."

If that just sounds like standard reincarnation, here's the important part: This whole process was completely unrelated to sex, and no (living) man was involved in the baby-making in any way. According to baffled anthropologists, Trobrianders genuinely had no understanding that intercourse could make you pregnant -- pregnancy was 100 percent thanks to Casper the Vagina-Crawling-Up Ghost.

So Why Do They Believe It?

You can't exactly blame the Trobianders for coming up with such a supernatural explanation when they were practically living on contraceptive yams (yes, apparently that's a thing). It turns out that if you're unintentionally on birth control most of your life, it's actually pretty hard to make the sex-pregnancy connection, and ghosts start to make a whole lot more sense.

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"Ew, that kid is dressed as a fetus!"

Also -- and there's no delicate way to put this next part, so we're just going to come right out and say it -- Trobrianders started having sex as kids, and kept right on keeping on as they grew older. Teen sex with no consequences, group sex on the regular, partner-swapping like it's no big deal -- anthropologists said that Trobrianders "begin their sexual life young, lead it indefatigably, and mix their lovers freely." That's right, indefatigably. Their life was one epic, never-ending Spring Break.

After all, when you don't think of sex as part of procreation, there's really only one explanation left as to why we have these weird dangly bits: They're fun! The Trobrianders thought of sex as a sort of universal hobby and a way to pass the time. Ghosts took care of the baby-making, and there were no population explosions thanks to the Morning After Yams, leaving the islanders free to have, like, all the sex, all the time.

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"Who ordered dongs?"

Believe it or not, most cultures understood that babies come from sex. In Elizabethan England, however, they thought that babies only came from a particular kind of sex ... good sex. If the gentleman was ye lumpish two-pump lout who left ye lady unsatisfied, there was no chance she'd end up in the family way.

It's pretty obvious that the male orgasm is crucial to conception, but today we look on the female orgasm as sort of the cake-topper of baby-making -- a great and wonderful thing, sure, but completely extraneous (of course, there is some contention on the subject). But back in Shakespeare's day, people assumed that the female orgasm released a "female seed" that was absolutely essential to conception. The c**toris was viewed as a sort of inside-out wang that, just like the male equivalent, released a seed into the womb during orgasm. That's the sort of logic you get from people wearing ruff collars.

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"'Tis true!"

Oh, and remember when Todd Akin said that women can't get pregnant if they're raped? Yeah, Elizabethan England was basically teeming with Todd Akins, because if a woman ended up pregnant, she obviously enjoyed it. So you can imagine how your average rape trial turned out. And of course, some women who were having terrible sex were still getting pregnant, so they tended to blame it on demons.

And this wasn't just a superstition propagated by the unwashed masses -- it was seriously in all the medical books of the day. You'd think all it would take to disprove such a harebrained theory would be the aftermath of a single Elizabethan prom night, but hey, maybe Shakespeare and his bros were just that good.

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"To tongue, or not to tongue. There's only one answer to that question."

So Why Do They Believe It?

At the time, England was pushing to increase its population to counteract all the plagues and general filth and stuff. And if you're trying to convince your population to do way more boning, which woman is more likely to drop her farthingale: one who's looking forward to a face-melting orgasm, or one who's lying back and taking it for England?

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"Get back here and finish this s**t off ... I'm tired of being called barren!"

From now on when we picture Elizabethan England, it's just female orgasms, everywhere. Elizabethan ideas of conception might have been biologically wrong, but for approximately half the population, they were oh, oh, oh so right.

For more from the realm of boning, check out 6 Depraved Sexual Fetishes That Are Older Than You Think and 5 Inspiring Religions That Worship Penises.