- Handedness. Other animals, in-
cluding polar bears and chimpanzees,
also have handedness, but those spe-
cies are split 50/50 between right and
left. Humans are the only ones that
show a distinct bias as a species to-
ward one hand (90 percent of us are
right-handed), and scientists have no
idea why. - The appendix. Charles Darwin
theorized that the appendix was the
useless evolutionary remains of a
larger structure that housed bacteria
our plant-eating ancestors needed
to digest stubborn plant tissues such
as tree bark. Modern scientists aren’t
convinced. Some think that the tube-
like organ actually promotes the
growth of some kinds of good gut
bacteria. - Fingerprints. Our fingerprints
are unique, though they do come in
a few broad patterns: loops, whorls,
and arches. Researchers have found
that some patterns are associated
with certain diseases—people with
loop prints have a higher incidence
of bronchial asthma and dementia,
for instance. What we don’t know is
why fingers have these swirly patterns
in the first place. For many years, sci-
entists thought they helped us grip
things, but fingerprints actually allow
less of our skin to come into contact
with objects. Another theory: They
somehow protect our fingers or pro-
vide touch sensitivity.
38.The mesentery. In November
2016, researchers officially added
another organ to anatomy textbooks.
Scientists used to think the mesen-
tery was a few unconnected sections
of tissue scattered in the intestines.
But after peeling back layers of the
gut, they now realize it’s a single or-
gan: a double fold of membrane in
the digestive system that holds up
the intestines; connects them to the
abdomen; and has a distinct, two-
foot-long structure that spreads out
like a Chinese fan. Its function? They
still aren’t sure.You’ll Be Amazed
to Know That ...
- Only one in ten cells in your body
is actually human. Of the 100 trillion
cells in our bodies, the majority are
microorganisms such as bacteria and
viruses. In fact, the National Institutes
of Health Human Microbiome Proj-
ect found that microorganisms make
up about 1 to 3 percent of the body’s
mass, or as much as six pounds of
bacteria in a 200-pound adult. - Your salivary glands produce
one to two quarts of spit every day.
Saliva breaks down food and keeps
the mouth infection-free. Plus, with-
out saliva, you wouldn’t be able to
taste anything! Food molecules need
to dissolve in saliva for taste buds to
recognize them.
64 june 2019
Reader’s Digest