The human body is truly a marvel. A combination of 65% water, 60 elements, 640 to 800 muscles, 206 bones, 12 organ systems, and trillions of cells collaborate to create and sustain you. Advances in medicine and healthcare help us understand the human body like never before. In many ways, the human body remains a vast frontier of discovery though. We are continually striving to understand how each system works in conjunction with one another, reasons certain diseases behave the way they do, and how to advance medical care from treatments to cures.
However, even if you're perfectly healthy, there are seemingly odd things your body does for surprising reasons. We've become medical detectives to crack the code on 4 of them. You might be surprised at these medical mystery explanations!
It Gives Me Goose Bumps!
A scary movie, a chill in the air, an intense emotion – all of these things can cause our skin to pop up in little bumps commonly called "goose bumps" because they look like the skin of a plucked goose. This strange bodily function is a response left over from our ancestors. Once upon a time, our ancestors had much longer body hair than we have today. If cold, goosebumps would cause the hair on your body to stand up and trap air, creating a layer of insulation. As your body warms up, the goosebumps will gradually go away.
Goosebumps may also be a reaction to adrenaline, which occurs when we're scared or having an intense emotional experience. Adrenaline causes muscles on your skin to contract. In our ancestors, goosebumps fluffed up their long hair to make them appear larger to threatening opponents. Animals still benefit from this reaction. Next time your dog feels threatened, notice how its hair stands up. As humans, we lost the long body hair, but we kept the adrenaline reaction we know today as goosebumps.
I Bet You'll Yawn While Reading This
You do it. I do it. Everyone does it – even animals! Yawning is a common phenomenon, but it still has scientists stumped. Theories of why we yawn include:
- Stretching our jaw muscles to increase blood flow to our neck, face, and head
- A way for our lungs to stretch and lubricate themselves while increasing our heart rate, so we're more alert
- An air-conditioning system to cool down hot blood on the surface of the brain
Scientists also recognize that we often experience contagious yawning. This happens when our yawns are triggered by seeing, imagining, or reading about yawning. (Go ahead, you know you want to yawn!) Scientists have no explanation for contagious yawning. However, they have discovered the following facts about contagious yawning:
- Contagious yawning occurs in 50% of adults
- While yawning occurs in many species, contagious yawning is only observed in humans and chimpanzees
- Contagious yawning most often begins at 4 years old
- Autistic children rarely have contagious yawning
For now, yawning remains a true medical mystery!
Cry Me a River
Many species produce tears to flush the eyes of irritants or as a response to pain. However, humans are the only known species to cry as an emotional response. In fact, scientists discovered emotional tears are chemically different than tears we cry to flush our eyes. These tears contain more protein making them stick to the skin and fall more slowly than other types of tears. The exact purpose of emotional crying remains a mystery to scientists though.
One of the strongest theories suggests emotional crying was a way for our ancestors to signal distress or sadness while maintaining safety. Since tears are only visible at a close distance, only people that are near to us and most likely trusted could read the signal. Some scientists believe this up-close and personal signal was a key component of humans developing emotional intelligence.
The brain responds the same way to personal emotion as it does to seeing someone else's emotions. Being able to understand nonverbal emotional cues in one another fosters empathy, compassion, and social bonding. Over time we've developed the ability to even distinguish between the different reasons for crying. Humans are remarkably good at knowing if someone is crying because of joy, sadness, guilt, or shame.
Second Time Around
Have you ever been to a new place, but have the overwhelming feeling that you've been there before? We refer to this sensation as "déjà vu," a French term meaning "already seen." Sixty to eighty percent of people report having déjà vu in their lifetime. The brief feeling can occur at any moment, but scientists aren't sure exactly why. Most neuroscientists believe this sensation is somehow linked to how our brain stores memory in our temporal lobe.
Our brain uses our senses to process information and create memories. A misfiring of these neural pathways may cause the sensation of having experienced a new event or place before. Interestingly, people with epilepsy often report increased déjà vu experiences. The same misfiring that causes seizures, just in a non-harmful way, may be the cause of déjà vu in non-epileptic people.
The human body is truly fascinating. For everything we understand about it, there are many things we're still exploring and striving to understand.