Evolution is a fascinating and mysterious thing. The concept that all mammals are in some way related – including ourselves – is something so complex that it’s hard to wrap our minds around sometimes. But proof of our ancestral past, evolving from apes to Neanderthals and eventually to the Homo Sapiens we are today, can be found everywhere. A prime spot for evolutionary proof? In our very own bodies!

So many of our internal and external features are simply traits carried down from our ancestors before us. Some of them have essentially no use to us anymore, now that most people are no longer scavenging for food or roaming like nomads from place to place. We still have these seemingly useless features, passed down from a time when they were essential to survival.

For instance, getting the goosebumps isn’t just a random phenomenon. When our mammal ancestors would get cold, goosebumps were a means of expanding their surface area to keep warm. A muscle attached to our arm hairs contracts when we’re cold, pulling the hair upright and causing a bump on the skin.

 

While this doesn’t do much for us nowadays (except making us whine that we should have brought a coat), we can still see modern mammals that revert to this biological instinct when it’s chilly outside. You’ve probably seen a pigeon all puffed up on a cold winter day, expanding its’ feathers to keep it warm. Even if an animal feels threatened – like when you sneak up on your cat – you’ll notice their fur will poof out. This defense mechanism is an ancient one, meant to deceive attackers by increasing ones size.

But one really extraordinary hint of evolution is actually found within our arms. In our tendons, to be specific. There is a tendon that 10 – 15% of our human population has evolved out of, hinting to scientists that we humans are nowhere close to being finished with evolution. This tendon is attached to an ancient muscle called the palmaris longus, which was primarily used by tree-dwelling apes (lemurs and monkeys, for instance) to help them move from branch to branch. Humans and ground-central apes, like gorillas, no longer have a need for this muscle or tendon, so both species have started to lose this internal function.

 

However, evolution is a slow-going process, so almost 90% of humans still have this useless trait carried down from our monkey ancestors.

To see if you have the tendon, lay your forearm down on a table, palm up. Touch your pinky to your thumb and lift your hand just a little off the surface. If you see a raised band in the middle of your wrist, you have the tendon connected to your still-intact palmaris longus.

If you don’t – congrats, you’re evolving.

Whether you have this tendon or not is extremely cool; having this tendon means that you have a link to our ancestral past right there in your body, and not having the tendon means that you are physical proof of further human evolution.

Is your mind blown yet?

What do you think of these cool evolutionary facts? Do you have this arm tendon or not? Share your thoughts in the comments section below.