6 Of Your Most Cringeworthy Questions, Answered By Science

If you have a penis and have ever gone swimming in cold water, you may have noticed that your penis looks similar to the head of a frightened turtle (apologies to Jerry Seinfeld). This is a real thing with some real scientific explanations.

When we are talking about the actual shaft itself, the main explanation is all about blood flow. According to Dr. Abraham Morgentaler, a urologist, clinical professor of urology at Harvard Medical School, and author of Why Men Fake It: The Totally Unexpected Truth About Men and Sex, cold causes a narrowing of the blood vessels (aka vasoconstriction), "so the spongy erectile chambers called the corpora cavernosa become less filled with blood, making them smaller."

A second and related phenomenon happens to the balls. A dude's noble scrotum plays a role in both holding your balls and keeping them at the right temperature. Ideal sperm production occurs at temperatures a bit colder than your body temperature, so it's important that your boys are kept away from your body heat.

"Although the penis essentially functions as a big blood vessel, the same is not true for the scrotum," Morgentaler told BuzzFeed Science. "Rather, its size is determined largely by muscular contraction or relaxation. When it is warm, the scrotum expands, allowing the testicles to hang further away from the body, which is a heat source. When it’s cold, the scrotum contracts, bringing them closer to the heat source."

The vaginia is a gloriously complex microenvironment that houses numerous species of friendly and sometimes not so friendly bacteria. The most common bacteria found down there is called Lactobacilli, and it’s super helpful. It provides the acidic environment needed to kill off unwelcome microbes and keep a vagina healthy.

But environmental conditions sometimes change, and with those changes the whole equilibrium of that fragile ecosystem can shift. The most common example of this is bacterial vaginosis, which occurs when a series of bacterial communities that thrive in low-oxygen environments become more populous than usual. These anaerobic bacteria produce a generally unwelcome “fishy” odor caused by a chemical called trimethylamine.

It is important to note that many other things can also cause fishy odors including trichomoniasis, poor hygiene, and a forgotten tampon.

According to convicted murderer and cannibal Armin Meiwes, "The flesh tastes like pork, a little bit more bitter, stronger.” He also added that “It tastes quite good." Other alleged cannibals have come to different conclusions, describing the meat as veal-like and sweet.

Scientific studies into this question are, understandably and thankfully, pretty much nonexistent. That being said, there is at least one plausible explanation for why human meat might taste a bit like pig meat: Their diet is quite similar to that of a human.

In the early 20th century, Russian scientist Ilya Ivanov attempted to artificially inseminate female humans with chimpanzee sperm and female chimpanzees with human sperm. Stalin was interested in producing an army of ape-men (because Stalin), but Ivanov had no luck. Seeing as chimps are the most closely related animals to humans at the moment, the simple answer is no. This is a good thing.

But...

Arguably, we humans already have done this in our deeper evolutionary past. It depends on where you would draw the line between man and animal. We know that humans and Neanderthals, a closely related but distinct species of early man, and humans interbred regularly and did produce children.

It’s not unheard of for two species to produce offspring. Mules, for example, are produced when a male donkey and a female horse (two different species with differing numbers of chromosomes) mate. And hybrid species between an animal and a human have been created in the lab, but, thankfully, not through actual mating. In 2003, for example, there was great controversy when scientists created an embryo from a combination of material from human cells and rabbit eggs.

If you are nervous, stressed, or terrified, there’s a good chance that you might also have an urgent need to shit. There is a clear connection between stress and bowel movements, so clear that scientists and doctors refer to the “brain-gut axis” when talking about gastrointestinal issues. Studies have shown that people with higher stress levels will be more prone to irritable bowel syndrome and scientists have linked that disease to higher levels of stress hormones produced by your brain.

There could be an evolutionary explanation for this. Many researchers think that your need to shit is part of the system humans have evolved to be vigilant for threats from predators — the fight-or-flight response. Let’s say you are an early human and a marauding, godless bear has come into your cave. Your body wants to put all its energy into fighting or fleeing, which means digestion often stops, and bowels often need to be emptied.

Is it useful for your bowels to pull the eject cord when you are nervous about your next calculus class? Likely not, but evolution is a bitch.