Hiccups are believed to be a leftover trait from our amphibian ancestors. They serve no clear purpose in humans but may be a vestige of a reflex that helped amphibians regulate their breathing while switching between water and air.
When you get goosebumps, it's a vestige of a response that was more relevant when our ancestors had more body hair. When we're cold or experience strong emotions, the tiny muscles at the base of hair follicles contract, causing hair to stand up.
In some rare cases, a person can be born with an extra kidney, which is known as a supernumerary kidney. These additional kidneys can be fully functional, and a person may not even know they have them.
The idea that different areas of the tongue are responsible for detecting different tastes (e.g., sweet, sour, bitter, salty) is a common misconception. In reality, all taste buds can detect all types of tastes.
Hair and nails don't actually continue to grow after you die, despite the common belief. What happens is that as the skin begins to dry and shrink, it may appear that the hair and nails are getting longer.
There are two main types of muscle fibers in the human body: slow-twitch and fast-twitch. Slow-twitch fibers are responsible for endurance activities, while fast-twitch fibers are used for short bursts of strength or speed.
Infants have a reflex called the palmar grasp reflex, which causes them to close their fingers tightly around an object placed in their hand. This reflex disappears after a few months.
The olfactory bulb, which is responsible for the sense of smell, is closely connected to the brain's limbic system, which is associated with emotions and memories. This is why smells can trigger powerful memories and emotions.
While we often associate fingerprints with identification, they also serve a functional purpose. The ridges on our fingers help improve our grip on objects by increasing friction.
The brain itself does not have pain receptors. This means that neurosurgeons can perform surgery on a conscious patient by applying local anesthesia to the scalp and skull.
The stomach lining is constantly exposed to harsh digestive acids, so it has a remarkable ability to regenerate itself every few days.
On average, a person blinks about 15-20 times per minute. This equates to over 28,000 blinks per day! Blinking helps to moisten and clean the surface of the eye.