7 Body Parts That Are More or Less Useless The human body contains around 600 muscles, more than 200 bones, and all sorts of tendons, fascia, and organs — but some of them are pretty much obsolete, even if they make for decent party tricks. A few body parts have even started to disappear already, and are only present in certain segments of the population. In extreme cases, as people who have had appendectomies or wisdom tooth extractions can attest, it seems like some of these body parts exist only to hurt us.
Are you
missing a mostly useless arm muscle? What muscles are key for dogs, but not
particularly handy for us? These seven body parts are pretty much just along
for the ride.
Appendix
- The
appendix, a small pouch attached to the large intestine,
is perhaps the best-known useless organ, doing little except occasionally
getting infected. However, it turns out that it might not be entirely useless.
Scientific theories have been floating around since 2007 that the appendix
might actually serve as a “safe house” for beneficial gut
bacteria, storing it to replenish it in the rest of the gut if it gets wiped
out by illness (or, in modern times, antibiotics).
If this
turns out to be accurate, it’s still not a particularly important organ, and if
it gets severely infected, you still need to get it removed.
Don’t worry: Hundreds of thousands of people get them taken out every year and
are doing just fine.
Tailbone (Coccyx) - Humans
don’t need tails, but our ancestors sure did —
and tailbones, also known as coccyxes, are the last remaining part of them,
consisting of three to five vertebrae that
aren’t connected to the spine. The coccyx is not a functional tail, but it
is woven in with the ligaments,
tendons, and muscles in the area. Occasionally, it gets rid of itself by fusing
with the sacrum, another lower back bone. In cases of
extreme pain that don’t resolve with any other treatment, people can get
their coccyx surgically removed,
but it’s unnecessary in the vast majority of cases. Occasionally a baby will be
born with an actual tail — and human embryos
generally form with a tail that later disappears as it grows
into the tailbone — but it’s extremely rare.
Wisdom Teeth - Wisdom
teeth, a third set of molars, have made dental surgery a rite of passage. For
those who get them — many people don’t — they
usually start emerging between the ages of 17 and 21. Often, there’s no room
in the jaw, and the teeth end up trapped. When that happens, they need to be
surgically extracted. Occasionally they grow in without incident and just
become extra teeth.
It’s a lot
of trouble for a set of teeth that we don’t even need. One theory is that our
ancestors, who ate harder-to-chew things and didn’t have dentists, needed them as backup teeth.
Modern science has gotten pretty good at just replacing teeth as they fall out,
but wisdom teeth could still replace
damaged molars in a pinch.
External Ear-Orienting System - If
you have a pet dog or cat, you’ve probably noticed their ears snapping to
attention at an interesting or startling noise. Humans still
have those muscles and, likely, the brain circuits
associated with them. In one study, researchers observed tiny, involuntary
movements in the directions of interesting sounds. For one part of the study,
they had participants read a boring text while they played attention-grabbing
sounds like crying babies and footsteps. Next, they had participants try to
listen to a podcast while a second podcast played in the background. Those ear
muscles fired up in both cases — they’re just obsolete for modern human beings.
Some humans can still wiggle their ears, which does serve one purpose: It’s a
cool party trick.
Goosebump Muscles
Human ancestors were much furrier than us, and
sometimes needed to fluff up their hair for warmth or to look bigger and more fearsome.
They had tiny muscles attached to their hair follicles, called arrector pili muscles, that
would shift each hair up into a vertical position.
Today, in our much more hairless state, those muscles give us goosebumps, also
known as goose pimples, when we get chilly, scared, or excited.
Some
emerging research suggests these muscles may have a role in combating
hair loss — and without them, we wouldn’t have a name for
the iconic children’s horror series Goosebumps — but as far as
basic survival goes, the arrectores pilorum are pretty much useless.
Third Eyelid
Most animals have a third eyelid, also called the
nictitating membrane, which serves as a kind of windshield wiper that
distributes tears and clears debris from the eye. This trait evolved out of
human beings and some apes, but we still have a tiny vestigial remnant in the
inner corners of our eyes. It’s a bit of eye tissue just inside that fleshy
pink eye bump. In exceedingly rare cases — only two have
ever been reported — humans can have a more developed
nictitating membrane that covers a larger portion of the eye.
So why did
we lose ours? One theory is that, unlike animals that still have them, we’re
not typically sticking our faces directly into bushes or other animals to
forage for food, so we have less debris to push out of our eyes.
Palmaris Longus Muscle
The palmaris longus is a muscle stretching the length
of our forearm that’s evolving away before our very eyes, literally — because
it’s visible when you hold your hand and wrist a certain way, you can
actually tell whether you still have yours on
sight. It’s already missing in a significant portion of the population, and
different studies around the world have observed its disappearance in anywhere
between 1.5% and 63.9% of participants.
The muscle
helps with wrist flexion in those who still have it, but it’s getting progressively
weaker as other muscles take over its duties. If you don’t
have one, you can still do all the same things as someone who does have it.
While it’s unnecessary as is, the palmaris longus is pretty useful as
a donor tendon for plastic surgery.
