2022---evolutionary-remnants--we-carry-on-5-traces-of-the-past -

"Perfect timing," Dr. Aris smiled, pointing to Leo's forearm. "There is number five: [1]. When you get cold or scared, tiny muscles at the base of your hair follicles contract [1]. For a furry mammal or a bird, this puffs up their coat or feathers [1]. It traps a layer of air to keep them warm, or makes them look much bigger and fiercer to a threatening predator [1]. Since we lost most of our thick body hair, the reflex does absolutely nothing to keep us warm or scare off enemies. It just makes our skin look like a plucked chicken [1]."

"Wait, so I have a monkey muscle in my arm?" Leo laughed, flexing his wrist. "Perfect timing," Dr

"Those are your [2]. For mammals like cats, dogs, and our early primate ancestors, those muscles are vital [2]. They allow them to pivot their ears toward a sound without moving their heavy heads, helping them pinpoint predators or prey [2]. We have larger, more flexible necks now, so we just turn our heads. Most of us lost the neural wiring to use those muscles, but the physical remnants are still there [2]." When you get cold or scared, tiny muscles

"Well, let's start with a classic," Dr. Aris said. "Rest your arm on the table, palm up. Now, touch your pinky to your thumb and tip your hand up slightly." Since we lost most of our thick body

"Okay, that makes a lot of sense," Leo admitted. "The dentist doesn't seem so mean now."