The simple test that proves the theory of evolution: Video explains what a single arm muscle tells us about our development

Many parts of your body are not there because you need them. 

Instead they are there because your animal ancestors did a new video from Washington-based Vox explains. 

From your ears to your tailbone, your body is its own kind of history book, filled with secrets to your evolutionary past. 

This includes the palamaris longus, a muscle in the forearm that not everyone has (pictured).