9. Platysma muscle
Can you see it? Yup, it’s a superficial muscle that’s in the front of our neck and that reaches our chest. Is it useful? Not really, no. It’s mostly aesthetic and it can help make some facial expressions, especially in our mouth, more noticeable. When it contracts, it makes the corner of the mouth move down and that makes us look “sad.” It also helps to open our mouth and jaw a bit more than if we didn’t have it. It’s speculated that it is actually a vestige of the panniculus carnosus (a fancy name for the thing that makes animals twitch their whiskers) that some animals use for clearer purposes, like preventing birds and insects from perching on them.
We not only have organs left behind by evolution, but also a few behavioral responses that our bodies use in specific situations. Most of the time they are spontaneous, but not necessarily useful. Think about goosebumps, for example, when you’re feeling cold or tense. For our ancestors, pulling up body hair was a useful ability to have if they wanted to look bigger and scare away predators. That’s something cats still do, by the way. Lifting hair in that way also keeps animals warmer. But today humans have lost a great deal of that hair and don’t really need that skill anymore, so it has become obsolete.
Even the palmar grasp reflex in babies who are a few months old, who hold tightly to a finger or object that touches their palm, probably comes from a reflex we inherited from our ancestors. We still see newborn animals that make use of this grasp reflex to increase their chances of survival when being transported in their mother’s fur.
Are you one of those people who can move their ears? Were you able to find Darwin’s tubercle on your ears? How about the long palmar muscle? Feel free to share what other outdated parts you’ve found in your own body, including your wisdom teeth.