It's no-brainer that you need your brain and your heart, and you wouldn't last long if your liver failed.But. the lungs and kidneys come in pairs, so you could survive if one of then failed. people who have lost their spleens in accidents have gone on to live healthy lives. The tonsils and appendix, meanwhile and practically useless and rare routinely removed when they become inflamed.
Why do I have eyebrows???
Humans have evolved to become less hairy in the past six million years or so, but we still have those clumps of fur above eyes. Beyond their role in our facial expressions, eyebrows act like natural sweatbands, preventing rain and sweat from running directly into our eyes.
Why are some body parts pointless? ?
Called "vestigial" organs, these useless body parts are leftovers from our evolutionary encestors, who actually needed them. Take your wisdom teeth, for example. Today they crowd our mouth and often need to get yanked by the dentist, but our primate ancestors had large jaws and needed the extra choppers in case some rotted away in the days before tartar-control toothpaste. Our tailbone or coccyx, is a leftover from animals that needed tails For balance or grasping tree branches.
Why do men have nipples???
They were there before you were even born. Human eyebrows in the womb develop according to a blueprint that is the same for males and females. Eventually the eyebrows begins to take on features specific to their sex, but not until after they have already developed nipples. Later in life, chemicals called hormones trigger changes in females so that they can nurse their young. Males don't have those hormones, so they are stuck with nipples that are nothing more that chest accessories. Most male mammals have nipples. Nipples don't cause males any harm, which is probably why evolution hasn't given them the heave-ho.
Why do I have a BABY BUTTON?
For the same reason dolphins,cats, dogs, chimps, bats, and other "placental mammels"- animals nourished inside their mothers before birth-- have navels. In other words you can thank your mother for that lint collector on our stomach. Before you were born, when you were still developing on the womb, you were hooked up to your life-support system through a special cord that plugged into your navel. Through this "umbilical cord " you received food and oxygen and passed waste. The day you were born, you let out a cry and began breathing on your own. That let the doctor know he or she could cut off the umbilical cord, leaving you with a belly button as a souvenir. Whether it's an "innie" or an "outie", we all have one.
Why do people get goose bumps??
Like your wisdom teeth and your tailbone, goose bumps serve no purpose in modern humans. They were created by itty-bitty muscles in our hair follicles, which raise the bumps as a reflex reaction to a sudden drop in temptature or feeling of panic, anger or extreme fear. Goose bumps fluffed up the body hair of our much furrier ancestors to help trap heat or make them look larger to the threatening animals. Today goose bumps just make you need to borrow a sweater.
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