It might sound a little offensive, but your body is a museum, full of ancient relics no one really needs anymore. From your wisdom teeth to that weird way some of us can wiggle our ears, so much of how we ended up as humans reflects what our animal ancestors needed for survival.
As this video by Vox explains, these strange remnants, that stuck around only because they're not 'costly' enough to have disappeared across many millennia, only make sense within the framework of evolution by natural selection.
Here's one you can see for yourself right now: if you hold your arm out, and touch your thumb to your pinky, you'll probably see a raised tendon in the middle of your wrist.
Right? If you don't have that, lucky you - you're among the 10-15 percent of humans on Earth who were born without this prominent feature in one or both of their arms.
This tendon connects to the palmaris longus, a muscle that most of us have, but there seems to be no real reason for it being there. As the video explains, research has found that the presence of this muscle in our forearms does not give us any more discernible arm or grip strength than people born without the muscle.
In fact, it's so inconsequential, surgeons often remove it and use it for reconstructive or plastic surgery procedures elsewhere on the body.
So why did we end up with such a useless piece of tissue? Scientists have found that, while palmaris longus is present in many species of mammals today, it's most developed in those that use their forearms to move around - such as lemurs and monkeys.
Here's another one: have you figured out how to manipulate the three muscles around the base of your ear so you can wriggle it ever-so-slightly?
Good job - you're demonstrating how another evolutionary remnant has transitioned from an essential piece of equipment for our animal ancestors to a party trick no one cares about in humans.
Just like many nocturnal animals today - such as rabbits, gazelles, and cats - rely on the wide range of angles their ears can turn and face to better locate the origin of a sound, the creatures we've evolved from would have used the same trick millions of years ago.
And we haven't completely lost all of the 'equipment' they would have used.
As Vox points out, not only did humans retain three of the muscles involved in ear movement, studies have shown that these muscles still respond to sound. They don't respond strongly enough to make our ears move anymore, but they appear to give it their best shot.
From goosebumps and tailbones, to that adorable thing babies do when they grasp whatever you put in front of their tiny fingers, there are plenty of other examples of weird things our bodies have that hint at the abilities of our ancient ancestors.
I'll let the Vox video above explain those to you, but let's just say there's a good reason for why you always get chills when you listen to Adele.