The collection of symptoms that strike women in the week or so before their menstrual cycle begins, has been the brunt of countless jokes and has even been suggested as a reason why a woman should not be elected president of the United States. Men, on the other hand, should stop giggling because medicine recognizes the male equivalent known as "irritable male syndrome," a behavioral state defined as "hypersensitivity, frustration, anxiety, and anger that occurs in males and is associated with biochemical changes, hormonal fluctuations, stress, and loss of male identity."

Chronic kidney disease affects over 31 million individuals in the United States and is the tenth largest cause of death, making kidney transplants quite frequent. But did you know that the surgeon doesn't always remove the damaged kidney? The old kidney is usually left in place, and the donor kidney is placed in the lower abdomen on the front side of the body.

There is evidence that pets, as well as insects, can suffer from insomnia. They gain more fat, learn more slowly, and lose their balance, all of which are symptoms of sleep deprivation in humans.

Have you ever been dissatisfied because your freshly cut wet hair appeared to be longer than it was? Then you discovered it had shrunk unexpectedly after the hairstylist had blow-dried it? Don't worry, you're not alone; water causes hair to grow longer than it naturally would!

Hiccups are a relic of our ancient ancestors from 370 million years ago. Because these people used to swim in the water, their bodies were endowed with both gills and lungs (there are still fish in Australia that can breathe using this method). Our forefathers employed the process known as hiccups to protect their lungs from water infiltration.

In situations of inflammation, the vermiform appendix of the cecum has a poor reputation for causing a lot of problems and potentially endangering a person's life. Traditionally, the appendix was thought to be a rudimental organ that provided no practical value. Today's experts, on the other hand, believe it's a safe "home" for beneficial bacteria dwelling in the gut. It stores beneficial germs that will "reload" the bacterial system of the gut and fill it with new beneficial bacteria in the event of a problem.

The ability to put yourself in another person's shoes is an important human trait, but when we're with friends, we take it to the next level. A team from the University of Virginia examined brain scans from 22 different people who were threatened with receiving small electrical shocks to themselves, a friend, or a stranger. Scientists discovered that the brain activity of a person in danger is essentially the same as that of a friend who is in danger.

Did you know that people who are lonely are 50% more likely to die prematurely than those who have healthy social connections? This is due to a number of different factors. For starters, loneliness lowers immunity, increasing the risk of disease. It also causes more inflammation in the body, which, like smoking, contributes to heart disease and other chronic health problems. Being lonely causes stress to affect you more emotionally and mentally, affecting your overall health. So, if you're feeling lonely, make sure you're doing everything you can to avoid isolation. It could mean the difference between life and death!

Expected roles, social norms, and social categorizations are frequently used to shape our perceptions of other people. Because we expect people in certain roles or social groups to behave in certain ways, our first impressions of people frequently rely on mental shortcuts to make quick judgments of how we expect people to behave.

You have more than five senses, despite what you've probably been told. Here's an easy one. Place your hand just a few centimetres away from a hot iron. None of your five senses will alert you to the fact that the iron will burn you. Despite this, you can feel the iron is hot and will not touch it. This is due to the heat sensors in your skin, which function as an additional sense. We can also detect pain and determine if we are upside down.

When the moon is full, you might find yourself sobbing over your first love on the couch. What made you think that? Research dating back to 400 B.C. blamed behavioural changes on the moon's pull. After all, the term "lunatic" was derived from the idea that "mental state changes were related to lunar cycles," according to Healthline. Perhaps this is why, in Shakespeare's Othello, Emelia tells Othello that the moon is too close to Earth, and has driven men insane.

It has an area of 5.4 million square miles. In comparison, the Atlantic Ocean has a surface area of 41.1 million square miles and the Pacific Ocean has a surface area of 62.46 million square miles.

Negativity bias is the consequence of your brain remembering negative over positive. It's also why while getting praise from your customer, you keep thinking about how a coworker ridiculed your clothes. A positive to negative ratio of 5:1 is required for equilibrium.

Do you have a heartbeat that is so quick that it appears to be escaping your body? It is well known that when blood is efficiently pumped through the body, the pressure is so high that it may spew blood up to 30 feet. Wooh!! That is excessive!

No, I'm not talking about terrifying stories, but goosebumps caused by our evolutionary forefathers. When the muscles surrounding the base of each hair contract, the human skin seems weird, especially when we are terrified or have an emotional recollection.

You've probably heard of the Pythagorean Theorem from 10th grade geometry class, but have you heard of Pythagoras' Constant? So, here's the skinny: Pythagoras' Constant is the square root of 2 (1.41). It's also the first irrational number ever discovered.

In Roman numerals, there are a total of zero zeros. While the ancient Greeks were aware of the idea of zero, they did not believe zero to be a number. For example, Aristotle determined that zero was not a number since it could not be divided by zero. To indicate the notion of zero, the Latin term "nulla" would have been used instead of a Roman numeral. There was no need for a numeral to symbolise zero, thus there was no need for one.

The method of record-keeping was widely employed across the Roman Empire for everyday tasks, allowing Romans to quickly price different commodities and services. Roman numerals were continuously employed throughout Europe after the collapse of the Roman Empire. This, however, came to an end around the 1600s. The letters I, V, X, L, C, D, and M are used to represent Roman numerals.

You've probably never considered it, but there is only one number that is spelt with the same amount of letters as itself. Can you figure out which one it is? No? It's 4 o'clock now. Oh, and a calculator's number 4 is made up of four light bars. Tell your friends about this at your next get-together! (However, you might not make many friends.)

A perfect number is a positive integer that is equal to the sum of its positive divisors in number theory. Six is the lowest perfect number, according to this criterion. If you scratched your brow and said, "Huh? The next perfect number is not until 28. It turns out that perfection is really rare...

Have you ever heard that the number 9 is said to be "magical"? No? It is, and here's why: if you multiply a number by 9 and put all of the digits of the new number together, the total will always equal 9.

The number 1 is frequently misidentified as a prime number. However, this is not the case—one does not meet the qualifications to be prime (being divisible by both 1 and itself). 1 divided by 1 equals...1. Nothing has been split.

Because the volume of a cylinder is PI times the radius squared times the height, a pizza with radius "Z" and height "A" has a volume of... PI * z * z * a.