The human body is a complex machine full of wondrous—and sometimes downright bizarre—functions. Even though we think we know our bodies inside out, some features continue to surprise us. From unexplained reflexes to strange survival mechanisms: the body has several traits that seem useless at first glance, but secretly hide deep evolutionary secrets.
1. Your skin glows in the dark
Although we can’t see it with the naked eye, our skin emits a faint glow. Japanese researchers discovered using special cameras that humans have subtle bioluminescence visible in the dark. This comes from chemical reactions in the body that emit energy. Why do we have this? No one knows for sure—but it secretly makes us a little glow-in-the-dark.
2. Your body can charge itself electrically
Humans generate electricity—and quite a bit of it. Our nervous system runs on electrical signals, and our skin can even build up static electricity. That’s why you sometimes get shocked when touching a doorknob. Theoretically, we could charge small devices using our own body’s current.
3. Your brain predicts the future (sort of)
Our brain has a built-in prediction system. For example, if you throw a ball at someone, the brain automatically calculates where it will land, allowing you to catch it without thinking. This also works with music—your brain anticipates the next note in a melody.
4. Your stomach has a second, smaller brain
In the walls of your intestines lives a vast network of neurons called the enteric nervous system. This ‘gut brain’ operates mostly independently and influences your mood and emotions. It’s even thought to play a role in depression and anxiety, as it regulates neurotransmitters like serotonin.
5. Your body creates tumors every day (and destroys them immediately)
Every day, your body generates cancerous cells. But thankfully, your immune system is tuned to eliminate them immediately before they become problematic. Only when this process is disrupted can tumors begin to grow.
6. Your body ‘forgets’ pain
When you go through something painful—like childbirth or major surgery—your brain eventually forgets just how bad it was. This partly prevents trauma and partly ensures we’re not too afraid to repeat certain life experiences.
7. You have a built-in sense of time
Ever woken up on time without an alarm clock? That’s because your body has an internal clock based on hormone signals and light levels. This also explains why you get jet lag after a long flight—your internal clock is no longer in sync with the sun.
8. Your bones are surprisingly strong (and constantly renew themselves)
Bones seem solid and unchanging, but your skeleton is constantly renewing itself. Every ten years or so, you have a completely new skeleton. Also, bones are stronger than you might think: a piece of bone the size of a matchbox can support around 9,000 kilograms.
9. Your body ‘sees’ sound
People with synesthesia experience sound as colors, but even those without it can have a cross-sensory experience. Brain scans show that the part of our brain responsible for visual processing also activates in response to certain sounds—especially unexpected ones. This explains why sudden loud noises often make us jump.
10. You have an ancient survival reflex (that you’ll probably never need)
When you fall into cold water, the dive reflex kicks in. Your heart rate slows, blood vessels constrict, and your oxygen usage drops dramatically to protect vital organs. This is a remnant of our evolutionary past and also occurs in marine mammals like whales and dolphins.
