What are the origins of this fun-filled festive custom?
A cervical rib, or neck rib, is not very common, but a small percentage of people do have it. Some reptiles have them too.
About 20% of humans don't have this triangle-shaped muscle located in the rectus sheath of the abdomen.
The vomeronasal organ is used by some animals to detect pheromones through smell, so it has an important role in reproduction. We actually had vomeronasal cavities, and some humans still have vestiges of them, although they're non-functional.
Blue eyes are a genetic mutation that happened later in our evolutionary timeline. Until 6,000 to 10,000 years ago, all humans had brown eyes.
This muscle, which stretches from the shoulder to the first rib, was pretty useful when we walked on all fours. Now, not so much. Again, not everyone has this muscle. And those who do might only have it on one side.
While most of our body is hairless, we still naturally grow armpit hair. It has been suggested that it might have played a role in holding odor, which would consequently be helpful in attracting a mate.
These are part of our lymphatic system and do play a role in defending our body from infections, but we can easily live without them. In fact, many people do, without affecting their immune system.
Not everyone has a lumbar, or 13th rib. In fact, it's estimated that just about 8% of us do. Lumbar ribs are, however, present in primates such as chimpanzees and gorillas.
While useless today, this vestigial organ used to play a role in our ancestors' digestive system.
Sources: (Reader's Digest) (List25) (Discover Magazine)
See also: Body parts that you can live without
This is a sort of undeveloped remnant of a male uterus. So much so that it's also known as the vagina masculina or uterus masculinus.
Like others mammals and vertebrates, we also used to have a third eyelid. Located in the corner of our eyes, the plica semilunaris is essentially a leftover part of a nictitating membrane.
It's pretty clear why women have them, but men? Well, they are formed during gestation before the switch from female to male is made. While they have no use, in evolutionary terms, they do no harm either, so there is no benefit in getting rid of them.
Wouldn't it be funny if we had whiskers, like other mammals do? Well, we certainly still have small vestigial muscles to move them.
We can observe the same reflex on other animals, except they have fur, and the result is an extra layer of protection. We kept this from our ancestors, even though we're pretty much hairless now.
Press your thumb against your pinky and flex your wrist, and you'll see your palmaris longus tendon popping out. This tendon was helpful in our primate days, but it no longer has an effect on grip strength. It's estimated that around 16% of people don't have it.
There are many theories as to why we dropped the hair, unlike our primate relatives. Though it probably had something to do with our environment.
Our jaws used to be bigger, but we evolved, and with fire and cooked foods we no longer needed the large jaws. We did keep the extra molars though.
The coccyx, also known as the tailbone, is indeed a vestige of where our tails would grow from.
Like most mammals, humans used to be able to produce their own vitamin C through the enzyme L-gulonolactone oxidase. We've lost this, but we still have the disabled gene in our DNA.
Our pinky toes are pretty much useless. They might have played a part when all our toes were longer, but not anymore. It's even possible that we might evolve to get rid of them completely.
We might have muscles around our ears, but they're weaker now and we no longer move them, because we don't need to move our ears. It's a cool party trick though!
While this nerve plays a role in controlling the contraction of the diaphragm, it's not anatomically placed in an advantageous place. It runs from the skull, down the neck, and through the chest, which makes it quite vulnerable.
This muscle can be found in our feet and it was quite useful to grip objects. It goes without saying we no longer use it, or indeed need it.
The groove on the area between the mouth and nose develops during gestation. Many primates also have it. As for its function, it had something to do with our olfactory system.
Newborn babies can use quite a lot of strength when they grab a finger. It's believed this comes from our primate ancestors, who would grip on to their mother's hair.
We've all had these annoying spasms, but do you know where the reaction comes from? Well, it's believed hiccupping has its roots in our amphibian ancestors.
This small bump on the outer part of our ears is also a sign of evolution. Many primates have pointed ears, and this is our inheritance.
Have you ever wondered why you have goosebumps? Or, unlike many other mammals, you are virtually hairless? Well, the answer might lie somewhere in the timeline of our evolution as a species. According to the theory of evolution, humans have evolved and adapted over millions of years. But don't just take our word for it: you can actually find vestiges of this in and on your own body.
Browse through the following gallery and discover the physical signs of evolution.
Signs of evolution you can find on your body
Got goosebumps yet?
LIFESTYLE Humans
Have you ever wondered why you have goosebumps? Or, unlike many other mammals, you are virtually hairless? Well, the answer might lie somewhere in the timeline of our evolution as a species. According to the theory of evolution, humans have evolved and adapted over millions of years. But don't just take our word for it: you can actually find vestiges of this in and on your own body.
Browse through the following gallery and discover the physical signs of evolution.