Have you ever wondered why you have eyebrows, or whether yawning is actually contagious? If you are one of those curious types who like to be in- the- know, Dr Cassy Richmond unravels a few little mysteries about your body.
Why do you have eyebrows?
Your eyebrows sit in a smack-bang position above your eyes, and help you to convey a variety of expressions, including surprise, anger and confusion. However, some experts say that these little hairy patches actually played a significant role in protecting early man’s survival.
Because eyebrows help to keep the eyes dry from rain and sweat, they prevented vision from being impeded during a heavy rainstorm (shelter wasn’t always so easy to come by back then) or whilst sweating profusely (which was likely to occur when being hunted by a predator).
Nowadays, they continue to protect our eyes during inclement weather, and keep out salty sweat, which may irritate or sting our peepers.
Is yawning contagious?
Have you ever noticed that when someone in the room yawns, you find yourself yawning as well? This yawning domino effect is called “contagious yawning”. It can also occur when you hear someone yawn (for example, over the telephone), or even when reading about the subject-matter. Chances are, you are probably yawning yourself right now!
Contagious yawning is believed to be a subconscious expression of empathy. And some experts believe that those with greater empathy (who are able to understand, and sometimes share, others’ feelings) are more susceptible to engaging in the phenomenon.
And now a recent study has used brain imaging techniques to show that certain brain cells, called mirror neurons, are involved in the process. These neurons are believed to be the driving force for imitation so that when someone sees or hears a yawn, they may mimic or “catch” the yawn themselves.
Why do you lose your taste when your nose is blocked?
Your tongue contains thousands of taste buds to enable you to perceive the five different types of tastes, namely sweet, sour, bitter, salty and umani (this is a newly recognised taste -and basically means savouriness).
But did you know that up to 75 percent of what you perceive as taste actually comes from your ability to smell?
Your nose contains millions of olfactory nerve receptors. When you eat, odour molecules from food bind to some of these receptors. This causes the release of chemical signalling to the brain, and enables your nose to distinguish hundreds of different smells and flavours.
Given the crucial role that your nose plays in perceiving taste, it makes sense that food becomes tasteless when your nose is blocked (from a cold, for example). It may also explain why kids subconsciously scrunch their noses in disgust when told that they have to eat their Brussels sprouts at dinner-time.
Can you keep your eyes open when you sneeze?
A sneeze is a quick and forceful, involuntary process. It occurs automatically to expel dust, pollen, and other allergens from your respiratory tract.
It is common to sneeze when you have a cold because the inside of your nasal cavity becomes swollen and inflamed and more sensitive to irritants than usual. Some people also sneeze when they see a bright light.
Most people find that their eyes close during a sneeze. This is not (as folklore will have you believe) to keep your eyes from popping out of your head. Shutting your eyes while you sneeze is simply a reflex similar to the reflex that causes your leg to kick out when your knee is tapped with a tendon hammer.