I'm a curious person. Some would say nosy but I think my curiosity is healthy. It leads me to looking things up, learning stuff others might find pointless. My brain seems to store a plethora of useless facts. But I like them there, sitting or standing inside my head, ready to deploy when they are needed: lots of tiny bits of information (and some not so tiny) keeping me company.
Today I want to share a few with you. Let me know what you think or feel or whatever.
VESTIGIAL ORGANS (A partial list)
I.
In plant-eating vertebrates, the appendix is much larger than
in humans. Its main function is to help
digest a largely herbivorous diet. The human appendix is a small pouch attached
to the large intestine where it joins the small intestine and does not directly
assist digestion. Interestingly, it has been noted by paleontologist Alfred
Sherwood Romer in his text “The Vertebrate Body (1949)” that the major
importance of the appendix “would appear to be financial support of the
surgical profession,” referring to, of course, the large number of
appendectomies performed annually. In 2000, in fact, there were nearly 300,000
appendectomies performed in the United
States, and 371 deaths from appendicitis.
Any secondary function that the appendix might perform certainly is not missed
in those who had it removed before it might have ruptured.
II.
The subject of male nipples is a sensitive, and maybe
confusing, topic to many. Those who wish to invalidate evolutionary theory
might pose the question, “Was man descended from woman?” Both men and women have nipples because in
early stages of fetal development, an unborn child is effectively sexless.
Nipples are present in both males and females; it is only in a later stage of
fetal development that testosterone causes sex differentiation in a fetus. All
mammals, male and female, have mammary glands. Male nipples are vestigial; they
may perform a small role in sexual stimulation and a small number of men have
been able to lactate.
III.
With all of the pain, time, and money that are put into
dealing with wisdom teeth, humans have become just a little more than tired of
these remnants from their large jawed ancestors. But regardless of how much
they are despised, the wisdom teeth remain, and force their way into mouths
regardless of the pain inflicted. There are two possible reasons why the wisdom
teeth have become vestigial. The first is that the human jaw has become smaller
than its ancestors – and the wisdom teeth are trying to grow into a jaw that is
much too small. The second reason may have to do with dental hygiene. A few
thousand years ago, it might be common for an 18 year old man to have lost
several, probably most, of his teeth, and the incoming wisdom teeth would prove
useful. Now that humans brush their teeth twice a day, it’s possible to keep one’s
teeth for a lifetime. The drawback is that the wisdom teeth still want to come
in, and when they do, they usually need to be extracted to prevent serious
pain.
IV.
The fused vertebrae are the only vestiges that are left of
the tail that other mammals still use for balance, communication, and in some
primates, as a prehensile limb. As our ancestors were learning to walk upright,
their tail became useless, and it slowly disappeared. It has been suggested
that the coccyx helps to anchor minor muscles and may support pelvic organs. There
have been documented cases of infants born with tails, an extended version of
the tailbone that is composed of extra vertebrae. In those cases, the tailbone has been
surgically removed with little or no adverse effects. Nevertheless, there are no adverse health
effects of such a tail, unless perhaps the child was born in the Dark Ages. In
that case, the child and the mother, would’ve been considered witches and
killed instantly.
V.
The erector pili
are smooth muscle fibers that give humans “goose bumps”. If the erector pili are activated, the hairs
that come out of the nearby follicles stand up and give an animal a larger
appearance that might scare off potential enemies and a coat that is thicker
and warmer. Humans, though, don’t have thick furs like their ancestors did, and
our strategy for several thousand years has been to take the fur off other warm
looking animals to stay warm. It’s ironic actually that an animal, sensing
danger is near, would puff up its coat to look scarier, but the human hunter
would see the puffier coat as a warm prize, leaving the thinner haired weaker
looking animals alone. Of course, some body hair is helpful to humans; eyebrows
can keep sweat out of the eyes and facial hair might influence a woman’s choice
of sexual partner. All the rest of that hair, though, is essentially
useless.
VI.
Your sinuses are basically pockets of air that reside inside
your face. The biological role of sinuses is often a topic of heated debate,
but there is little-to-no-consensus on their actual purpose. One thing everyone
can agree on is that one of the only things worse than a sinus headache is when
your sinuses get infected.
VII.
The human ear has all kinds of strange things going on with
it. For one thing, there’s an entire group of muscles attached to our ears
that, for most monkeys, are used to move the ears like satellite dishes trying
to pick up a signal. For us, however, they just sit there – not moving anything
– suggesting that they’ve lost their biological function. Except, of course,
for those of us who can wiggle our ears, in which case, they serve the purpose
of making you look like a fool. It’s worth pointing out that chimps, like us,
also have these underdeveloped muscles and therefore lack the capacity for
ear-movement, as well. Furthermore, in
about 10% of the population, the outer rim of the ear called the helix has been
known to show signs of vestigial features. In the ear a thickening of the helix
called “Darwin’s
tubercle” occurs at the juncture of the upper and middle thirds of the ear – a
feature common to many mammals.
VIII.
Your plica semilunaris
– what many believe to be a vestigial remnant of your third freaking eyelid –
is the small fold of tissue located on the inside corner of your eye (not the
little bump in the very innermost corner but the small flap next to it). Your plica semilunaris are the vestigial
remnants of what are referred to as “nictitating membranes”, which are most
commonly found in birds, reptiles, and amphibians. In a masked lapwing the
membrane is typically translucent, and serves to moisten the eye, clear debris,
and help stare down weeping angels. Humans, sadly, are not equipped with these
functioning third eyelids, but don’t let that stop you from standing in front
of a mirror and willing yourself to make them move.
