The human body is full of mysteries — fascinating, functional, and sometimes just… leftovers from evolution. One curious little feature that some of us have (and others don’t) is quietly hiding in your forearm, waiting to reveal something interesting about your evolutionary past.
Hold your arm out, palm facing up. Now, touch your thumb to your pinky finger. Do you see a raised tendon pop up in the center of your wrist?
If yes — you’re in the majority. But if you don’t see anything, congratulations! You’re among the 10–15% of the population who don’t have a palmaris longus muscle.
This tendon is completely harmless — and totally optional. In fact, whether you have it or not has no effect on grip strength, arm function, or athletic ability.
The palmaris longus is a long, thin tendon that runs from your elbow to your palm. It’s believed to be a vestigial muscle, meaning it’s a leftover from evolutionary history — possibly when our ancestors used their limbs for climbing and swinging.
Today, this muscle serves no functional purpose in modern humans, which is why many people never develop it at all. In some medical studies, it’s even removed and used in tendon graft surgeries, with zero impact on arm function.
Genetics play a big role. The presence (or absence) of this tendon varies not just by individual, but even between the two arms of the same person. It’s not linked to health risks or developmental issues — just a quirky genetic trait.
It’s the same kind of thing as wisdom teeth, goosebumps, or even the appendix — evolutionary leftovers with little modern use.
Surgeons often use the palmaris longus tendon in reconstructive surgery. Because it’s expendable, it can be removed and used to replace damaged tendons in the hand or elsewhere. That makes it something of a “bonus part” if you ever need tendon repair.
Vestigial muscle meaning
Palmaris longus muscle function
Forearm tendon missing
Do I need the palmaris longus?
Signs of muscle evolution
Human body curiosities
High CPC health topics
Evolutionary muscle examples
source: 22 Words / YouTube/Vox
Whether you have that tendon or not, it doesn’t make you more or less capable — just another interesting chapter in the story of human evolution. It’s a fun party trick, a cool anatomy fact, and a reminder that our bodies still carry traces of our wild, ancient past.
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