I’ve always thought of myself as a fairly enlightened, refined, modern man. As it turns out, I more closely resemble a jungle animal than I care to admit. But there’s a chance you may have shed a primitive physical feature that I still have. One way to know if you’re further along the evolution chain is with a quick examination of your wrist.
Lay your forearm on a table with your palm facing up. Then touch your thumb to your pinky and lift your hand slightly. Do you see a raised tendon in the center of your wrist? If so, welcome to the monkey house. That narrow muscle is called palmaris longus and it’s more prominent in primates that still use their arms or forelimbs to walk. In humans, palmaris longus is classified as a vestigial muscle. In other words, it’s useless to us. In fact, almost 15% of the human population doesn’t have it anymore. The rest of us must be holding onto it for sentimental reasons.
This is not really as big of a deal as I’m making it out to be. I just never liked being picked last for the kickball team in school. At least I’m not walking around with a tail. You can see more signs of our evolving anatomy in this video: