WHY DO WE YAWN AND WHY IS IT CONTAGIOUS?

 It has traditionally been thought that yawning is an involuntary reflex that draws more oxygen into our bloodstream and removes a buildup of carbon dioxide. This theory was fueled by the notion that when people are bored or tired, their breathing slows, resulting in a lack of oxygen, which causes them to yawn.

However, research based on exercise suggests that this theory is incorrect. In tests, it was discovered that people’s yawning rates were not altered during exercise, despite an increase in the breathing rate and levels of oxygen in the bloodstream. In addition, athletes often yawn before big events, which is unlikely to be as a result of boredom or a reduced level of breathing. It has also been found that fetuses yawn in the womb, even though they don’t breathe oxygen into their lungs until after birth.

It has been suggested that people yawn to stretch the lungs, jaw and facial muscles, which increases the heart rate and makes a person feel more awake, although this suggestion is largely posited on the fact that a stifled yawn that does not stretch the jaw is unsatisfying. Other theories are that yawning is used to regulate body temperature or is caused by a variation in certain chemicals, such as dopamine, in the brain. It is now accepted that the exact reasons why we yawn are unknown. It’s also not known why yawning is contagious.

One theory is that we have evolved to yawn when others around us do because our early ancestors used yawning to coordinate social behavior or to build rapport in a group. When one person yawned to signal something, such as it being time to sleep, the rest of the group also yawned in agreement and the members’ activities were synchronized.

Yawning might also have been used to bare the teeth to intimidate enemies, so that, when one member of the group yawned, the rest followed suit. This has carried through to modern times, when the suggestive power of yawning is still contagious. Lending weight to this theory is the fact that babies, who are unaware of social codes, don’t yawn contagiously until they’re about one year old.

WHAT IS THE PURPOSE OF PUBIC HAIR AND WHY IS IT CURLY?

 

The purpose of pubic hair is something that has been argued about for years Even today, scientists are still unsure of its function.

One view is that pubic hair protects against friction during sexual intercourse, and it provides cushioning for the pelvis in that area Another view is that it provided insulation for our ancestors, although this is not widely held because of the lack of significant hair over the rest of our bodies However, there is some support for the idea that the hair helps to regulate body temperature in the genital area, which is particularly important for the production of sperm in men.

Pubic hair also performs two other possible functions The first is that it indicates that the person is sexually mature and able to procreate; indeed, some anthropologists have suggested that pubic hair in males might have been an ancient way of impressing and deterring other males who were in competition with them, performing the same function as a mane on a lion The second proposed function is that it helps to trap and retain the pheromones that are secreted from sweat glands in the pubic area, which are thought to serve as a powerful aphrodisiac to the opposite gender 

Pubic hair is curly because for some reason our sex hormones turn the hair follicles in that area into an oval shape, which in turn makes the hair oval in shape, causing it to bend Straight hair grows from round follicles and is less prone to curliness.

-What did we use before toiler paper? by Andrew Thompson