Today’s Wonder of the Day was inspired by Gia. Gia Wonders, “Can we live without any body parts?” Thanks for WONDERing with us, Gia!

We have a song stuck in our head today. Maybe you know it! Lots of kids sing it when they’re young. It goes like this: “Head, shoulders, knees, and toes. Knees and toes!” Do you recognize it? If so, you might be tempted to point to each part of your body as you sing. You might even go on to point to your “eyes and ears and mouth and nose.” 

This song helps young kids learn the parts of their bodies. But not all body parts are included in the song. Why is that? Are some body parts more important than others?

As a matter of fact, yes! And actually, there are many human body parts that are pretty unnecessary altogether. So why do we have them? In most cases, these body parts once served a purpose. But, as people evolved and became more advanced, the body parts became less useful.

One example is the tailbone. It starts as a tail—that’s right, an actual tail!--on the human embryo. As the embryo grows, though, the tail vertebrae fuse together and become the tailbone. Or at least, that’s usually what happens. Each year, a few human babies are born with very small tails still attached! In the distant past, tails may have helped human ancestors stay balanced. Today, the tailbone serves no known purpose for people.

Where can you find the next unnecessary body part? Just look in the mirror! Specifically, look closely at your own eyes. There—in the corner of each eye. Do you see it? There’s a small pink membrane in the corner of the human eye that anyone could live without. It doesn’t seem to serve any purpose today. However, experts believe that past humans may have had a third eyelid, as many other mammals do. This extra membrane is likely leftover from that.

Of course, the appendix is probably the best-known of all unnecessary human body parts. Or is it? For many years, doctors have called the appendix unnecessary because it doesn’t seem to serve any purpose—but it does cause problems like appendicitis! However, some experts today believe it may help the human immune system in some way. Could that be true? Possibly. But many people live without an appendix after having it removed, so people can certainly live without it.

If you’re like many kids, you probably pay close attention to your teeth. You brush them. You notice when new ones grow in. And you definitely get excited when your baby teeth fall out! One day soon, you might notice some large teeth growing in the very back of your mouth. These are your wisdom teeth. Do they make you wiser? Not necessarily! And they don’t do much else, either. Wisdom teeth are leftover from when primitive humans had to tear apart raw meat to eat. Today, they just take up room in your mouth. Many people have their wisdom teeth removed as teenagers or young adults. 

Of course, there are plenty of other body parts people can live without. People live with fewer fingers and toes all the time. Many have their tonsils and gallbladders removed. Some people are born without a hand, foot, or plenty of other body parts. Many people lose body parts throughout their lives, too. This can be due to accidents, disease, and plenty of other things. This might make some activities more difficult, but living without these body parts is definitely possible!

Lots of other animals have unnecessary body parts, too. Did you know some snakes have leg bones? It’s true! And the blind tetra fish even have eyes—unnecessary ones, as tetra fish have been blind for thousands of years. What other body parts can you think of that people can live without?

Standards: NGSS.LS1.A, NGSS.LS3.A, NGSS.LS3.B, NGSS.LS4.B, NGSS.LS4.D, CCRA.R.4, CCRA.L.3, CCRA.L.6, CCRA.R.10, CCRA.W.7, CCRA.SL.1, CCRA.W.2, CCRA.L.1, CCRA.L.2

Wonder What's Next?

We WOOD definitely check out tomorrow’s Wonder of the Day if we were you!