Our bodies are remarkable examples of natural evolution, often taken for granted in our daily lives. When we pause to reflect, it’s incredible to consider that we’ve evolved from beings similar to modern chimpanzees into highly advanced, society-building creatures capable of exploring other planets—all in what feels like a blink of an eye, at least on the scale of the universe’s timeline.

One fascinating aspect of our evolution is how little our physical form has changed over the past 20,000 years, even though we now inhabit a world vastly different from the one our ancestors knew. Even more intriguing is the fact that evolution is still happening, albeit at a pace so gradual that we rarely notice its effects within a single lifetime.

This brings us to a curious link between evolution and a seemingly insignificant tendon in your wrist, tied to humanity’s ongoing evolutionary journey.

The Palmaris Longus Tendon and Evolution
The tendon in question connects to the palmaris longus, an ancient muscle that has been gradually disappearing in 10-15% of the human population. This muscle plays a critical role in animals that rely on their forearms for movement, such as lemurs and monkeys. For these creatures, it aids in swinging from branch to branch, making it an essential part of their anatomy.

However, as ground-dwelling apes like gorillas shifted away from using their forearms for locomotion, the palmaris longus muscle became less necessary and began to fade from their anatomy. Similarly, in humans, the tendon associated with this muscle has been slowly disappearing.

While the process is gradual, studies show that nearly 90% of humans still possess the palmaris longus tendon. Nevertheless, evidence suggests it is steadily being phased out, a subtle but fascinating example of evolution in action as humanity continues to adapt to new environments and lifestyles.

You can easily check if you still have this tendon with a simple test at home. Start by resting your forearm on a flat surface, palm facing up. Next, touch your pinky finger to your thumb and gently lift your hand off the surface.

If a prominent band appears in the middle of your wrist, that’s the tendon in question. If not, you’re likely part of the small percentage of people who no longer have it—a fascinating nod to human evolution in action.

Did you find the tendon? Share your results in the comments, and don’t forget to share this article with friends and family so they can try it too!