You have the eyes of your father, the smile of your mother, and the ear muscles of a mammal that lived during the Triassic period.
Vestigial structures are the leftovers of evolution. They are parts of the body that have outlived the situation in which they first arose. Some of the most fun things remind us that we are related to other animals.
They show that the parts that make up the human body have been around for hundreds of millions of years before our species.
42% of Americans say that humans have been the way they are now for less than 10,000 years. This number hasn't changed much since Gallup started asking people about their views on evolution in 1982.
The fossil record, comparative anatomy, and genetics all point to a different story. But you don't have to read all the research to see how we evolved.
For example, our third molars no longer fit in our mouths, which is an example of a vestigial structure. Check out the video above for a few more examples.
Your body is a temple, but it's also a museum of natural history
If you look closely, you can see pieces of our long history. If you press your thumb against your pinky and slightly raise your hand, you'll see a raised band in the middle of your wrist. This is an old muscle that surgeons take out when they are doing reconstructive or cosmetic surgery.
Lemurs and monkeys have the strongest palmaris longus muscles, while chimps, gorillas, and other apes have weaker ones. In one study, when people heard a sudden sound, the muscle cells in their ears became very active. A speaker to the left of the people in the study made the sound.
When we're cold, our "vestigial" body parts tighten, which pulls our body hair up and makes a bump on the skin around it. This keeps us warm and makes some animals look bigger when they feel scared.
A tailbone is a group of vertebrae that are joined together at the end of the spine. It helped hold some of the muscles in the pelvis in place. The human embryo looks a lot like the embryos of other vertebrates. For example, it has a tail with 10–12 vertebrae that are growing.
But in humans, the cells in the tail are programmed to die a few weeks after they appear. Up until they are 6 months old, babies have a palmar grasp reflex that lets them hold their whole weight.