Five Signs of Evolution in Modern Mankind
by Guy McCardle
November 21, 2011
Have you ever seen a picture of a blind cave fish? Over many millenia, in response to their pitch black environment, their eyes have dwindled down to mere vestigial organs. Humans, too, have developed vestigial body parts during the course of our evolution. Read on to find out more about five examples of this phenomenon.
Extra ear muscles: These are also known as auriculares muscles or extrinsic ear muscles. Many mammals, such as dogs and horses, are able to move their ears independently of their bodies thanks to this set of muscles. This became an evolutionary advantage for them as it allowed for directional hearing when searching for prey or protecting against predators. As humans, most of us cannot move our ears at all. Our ear muscles now have become so feeble that only a few of us can manage a little wiggle.
Wisdom teeth: A long time ago our jaws could readily accommodate all 32 teeth. Early man's jaws were larger and more prominent because teeth played a vital role in their survival. Our ancestors subsisted on a tough and chewy diet of leaves, roots and raw meat. Third molars, what we today call wisdom teeth, might have played an important backup role when teeth were lost or worn down. As evolution made its selections, our diets changed and our jaws grew smaller. Third molars were no longer necessary and for the most part would no longer fit in our new, smaller jaws. This is why today they are often impacted or missing altogether.
Darwin's point: No, this isn't a make-out spot in the Galapagos. Darwin's point is a pointy protuberance on the upper aspect of the ear. It is present in a majority of mammals, including a little over 10% of the human population. It has been postulated that its function is to aid in directing sound into the ear canal. Some people say that having a visible Darwin's point is a sign of intelligence, but of course this is just an old wives tale.
Third eyelid: We've all awakened with "crust" or "sleep" in our eyes from time to time. We have our third eyelid, or plica semilunaris to thank for this. These are rare in mammals. If you closely watch a cat blink, you can see the third eyelid sweep across the eye clearing it of debris. In humans you can see a small vestigial remnant of this membrane in the corner of your eye.
Bonus: If you are so inclined, google "bush reptoid eyes" to see more photos and videos used by conspiracy theorists to argue that former President Bush is really an alien reptoid. The images supposedly show him to have a full third eyelid, a reptilian characteristic.
Goose bumps: I suppose geese have bumps or something. I've never gotten close enough to one to really tell. The medical term is cutis anserine. Humans get goose bumps when they are cold, frightened, angry, or in awe. The act of producing goose bumps is known as the pilomotor reflex. This occurs in many mammals besides humans, a good example being porcupines. In response to fear, goose bumps make an animal look larger. In the case of the porcupine, they raise the quills. Humans no longer benefit from goose bumps. They are simply left over from our past when we were not clothed and needed a way to scare our enemies. Natural selection removed our thick hair but left behind the mechanism for controlling it.
by Guy McCardle
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