Weird Things Humans Do Every Day, and Why

Find below some of the things we do (or that happen to us daily).

1. Pins and Needles

Hitting your funny bone isn't very funny. Neither is crossing your legs for too long, or waking up at night with a dead-seeming hand that gradually tingles back to life. What causes that horrible "pins and needles" sensation?
It happens when you apply too much extra weight or pressure on a nerve, temporarily inhibiting its function, and then remove the pressure. As the nerve gradually returns to normal, our brain somehow interprets its activity as a tingling sensation pins and needles.

2. See in 3D

Hey, wait a second... how do two eyes produce 3-D vision?

It's actually a trick of the mind (or three tricks, to be exact). First, our brains utilize "binocular disparity" the slight difference between the images seen by our left and right eyes. Our brains use the two skewed versions of a scene to reconstruct its depth.

For a close-up object, the brain registers the "convergence" of our eyes, or the angle they swing through to focus on the object, to decide how far away it is.

When glancing at things on the go, we subconsciously gauge distance by registering "parallax." That's the difference in speed at which closer and farther objects seem to move as you pass them.

3. Blink

It's not that strange that we blink: The tenth-of-a-second-long activity clears away dust particles and spreads lubricating fluids across the eyeball. What is strange, though, is that we fail to notice the world plunging into darkness every two to 10 seconds!

Scientists have found that the human brain has a talent for ignoring the momentary blackout. The very act of blinking suppresses activity in several areas of the brain responsible for detecting environmental changes, so that you experience the world around you as continuous.

4. Fart

The answer may stink, but everything we eat or drink gives us gas. In fact, it's normal to fart up to half a gallon (1.9 liters), or about 15 to 20 toots worth of gas each day.

Particularly fragrant flatulence, however, comes from colonies of bacteria shacked up inside our lower intestinal tract. In the process of converting our meals into useful nutrients, these food-munching microbes produce a smelly by-product of hydrogen sulfide gasthe same stench that emanates from rotten eggs.

Just like the rest of us, the bacteria like munching on sugary foods best. The types of sugar naturally present in milk, fruit and, of course, beans produce the most farts .

5. Kiss

It's weird, when you think about it, that swapping spit seems romantic. Turns out it's a biological instinct.

Kissing allows people to use smell and taste to assess each other as potential mates. People's breath and saliva carry chemical signals as to whether they are healthy or sick, and in the case of females, whether they're ovulating all important messages for potential partners in reproduction.

Furthermore, the skin around peoples' noses and mouths is coated with oils that contain pheromones, chemicals that broadcast information about a person's biological makeup. When people pick up each other's pheromones during a sloppy kiss, they'll subconsciously become either more or less sexually attracted to each other depending on what they detect.

Alongside the chemosensory cues exchanged during kisses, psychologists also believe the actual physical act of kissing helps couples bond. This theory is supported by the fact that oxytocin a hormone that increases most peoples' feelings of sociality, love and trust floods brains when mouths kiss.

6. Hiccups

Hiccups are involuntary spasms of the diaphragm the muscular membrane in your chest that figures importantly in breathing. A spell of them ensues when that muscle gets irritated, often by the presence of too much food in the stomach, or too little.

Weirdly, though, hiccups are as useless as they are annoying; they serve no apparent purpose. One hypothesis suggests they may be a remnant of a primitive sucking reflex. Whatever the ancient function, they are little more than a nuisance now something to be gotten rid of via a variety of creative folk remedies.

7. Cry

How odd that sadness causes water to spill from our eyes! Among all animals, we alone cry tears of emotion.

Not only do they serve the purpose of communicating feelings of distress, scientists believe tears also carry certain undesirable hormones and other proteins that are produced during periods of stress out of the body, which may explain the cathartic effect of "a good cry."

Culled from Livescience