You've probably learned about vestigial organs in Biology class by now. There are a lot of things that aren't important to humans any more but we've still held onto them in some way. If you've ever seen someone wiggle their ears, it's obvious. 

This video shows some of those unnecessary parts and why we used to have them. It also goes into detail about the way that some humans have actually lost those extra pieces. 



That's evolution at work.