The Human body is a marvel of natural evolution
with an array of amazing and disgusting abilities, like did you know that humans are the only
animals with chins or that on average you will pass enough wind in a day to inflate
a party balloon. However, despite being around for nearly 200,000
years and being the most intelligent species on the planet, there are plenty of misconceptions
about our own bodies. Here, we’ll look how unique your fingerprints
aren’t, how useful your appendix really is and how your body isn’t very human at
all! Plus a few more mind blowing misconceptions! I’m Stu, this is Debunked, where we sort
the truths from the myths and the facts from the misconceptions. Number 6. The Tongue Taste Map! Many of us will be familiar with this tongue
taste map and some of us might have even been taught it in school. It dates all the way back to Germany in 1901,
when a study was published showing different areas of the tongue to be more sensitive to
tastes than others. Since then, this research has been misinterpreted,
mistranslated and has evolved into the illustrated map you see right here, with different sections
of the tongue dedicated to Sweet, Sour, Salty and Bitter tastes. Aside from the fact that the original map
missed out the fifth distinct taste, umami, the truth of the matter is that your tongue
doesn't determine the taste at all, it’s actually your brain that ascertains
it. Your tongue has up 10,000 taste buds spread
across it, and each of these have 100 taste receptor cells and these respond to different
substances in your food. Up until very recently it was believed that
these taste cells would detect one of the five basic flavours and then send a signal
to our brain that tells us what we’ve tasted. A study in 2015, lead by Charles Zuker at
Columbia University turned this idea on its head. “TASTE, THE WAY YOU AND I THINK OF IT, IS
ULTIMATELY IN THE BRAIN,” “DEDICATED TASTE RECEPTORS IN THE TONGUE
DETECT SWEET OR BITTER AND SO ON, BUT IT’S THE BRAIN THAT AFFORDS MEANING TO THESE CHEMICALS.” In the last decade Dr Zuker has proved that
the tongue has dedicated receptors for each taste, and that each class of receptor sends
a specific signal to the brain. In fact studies have now shown that the brain
can detect tastes like Carbon Dioxide, the distinct taste you get from carbonated water. BUT Zuker’s more recent experiment proved
that each individual taste is sensed by a unique set of brain cells that are located
in the brain’s cortex, which interestingly generates a map of taste qualities in the
brain. So we’ve gone full circle with the taste
map, it’s just now in the brain. In the study Zuker’s team manipulated specific
brain neurons in mice, causing them to taste sweet when they were actually tasting something
bitter and vice versa. They could even activate the neurons to taste
either sweet or bitter when they were simply drinking water. “DEDICATED TASTE RECEPTORS IN THE TONGUE
DETECT SWEET OR BITTER AND SO ON, BUT IT’S THE BRAIN THAT AFFORDS MEANING TO THESE CHEMICALS.” In other words, taste is all in the brain. Number 5. We lose most of our body heat through our
head? You’ll get told it a hundred times as a
kid and you’ll still get told it as an adult, and it was even stated as fact in a US military
field manual claiming... So surely it must hold some weight, right? Well, I’m afraid not. The idea that we lose more heat from our head
than anywhere else, is simply not true. The human head is no more efficient at losing
heat than any other part of the body. A 2006 study by the conducted tests by dunking
test subjects into cold water, with their heads submerged and with their head above
water. The study found that we only lose around 7
to 10% of our body heat through our heads. To us it may feel like your head is colder
as there are five times as many nerves in your head than any other part of your body
making your face more sensitive to the cold But the fact is, if you expose your arms to
the cold, then you will lose more heat from them, as they have a larger surface area from
which to lose heat. According to Dr Daniel Sessler, the myth originated from a military experiment
carried out in the 1950s, where test subjects were dressed in Arctic survival suits and
exposed to low temperatures, the resulting heat loss was then measured. But rather unfairly their heads were uncovered
so naturally this is where they lost most of their heat. Subsequently, the military field manual at
the time stated that we lose 40 to 45% of our body heat through the head. Despite this, seven to ten percent is still
a high enough amount of heat that you don’t want to lose it in cold weather, so it’s
still worth popping a hat on in the winter. Number 4. No Two People Have Identical Fingerprints. We leave fingerprints behind on pretty much
every surface we touch. Why? Because the patterns on the end of your fingers,
called ‘friction ridges’, are connected to sweat glands which secrete sweat to the
skin’s surface. Then when you touch something a pattern of
sweat matching your fingerprint is left behind. Simple. The patterns themselves however, are far more
complicated. You see, fingerprints shape into 3 main patterns:
whorls, loops and arches, with it possible to have all 3 types across all 10 of your
digits. Feel free to take a look at your own, I imagine
that’s what you’re doing anyway. The ridge paths, breaks and forks that you
see there, make up these patterns in countless combinations, hence the concept that ‘no two people have
the same fingerprints’. In fact, they’ve been used to identify individuals
and solve crimes since the late 1800s and, as you well know, they now unlock your phone,
online accounts and personal details, but are they completely unique or could you
end up being the suspect for a crime you didn’t commit? Simon Cole, a professor of criminology, law,
and society at UCI, has identified 22 people who were wrongly convicted in the US because
of their fingerprints since 1920. This wasn’t however because there are 22
pairs of people with identical fingerprints, rather that the print analysis was mistaken. You see for a fingerprint to ‘match’,
they don’t need to be identical but instead need to have a certain number of points of
similarity, and in the US the number of required reference points varies dramatically between
states and examiners, with the average being 12. In fact one judge in California threw fingerprint
evidence out of court when he learned that there wasn’t a standard number of points
to prove a match. A “I DON’T THINK I’M EVER GOING TO USE
FINGERPRINT TESTIMONY AGAIN,” Cole points out that his findings are only
the tip of the iceberg and that when evidence from qualified fingerprint examiners are brought
into the mix, it’s estimated that the average rate of mismatch is 0.8%. So in the sense of fingerprint impressions,
it’s quite possible for your fingerprint to match with someone else's. But what about having a physically identical
match, with indistinguishable patterns? How about identical twins, surely the clue
is in the name? Well, despite inheriting similar size and
shape patterns on their fingerprints, the identifying characteristics are still different. In fact everyone’s fingerprints are completed
a whole 3 months before they’re even born. And incredibly as your entire body grows,
changes and ages, these patterns on your fingertips and thumbs remain the same, they essentially
just scale up. With old age, the ridges can become less prominent,
as your skin loses its elasticity but nonetheless the actual patterns remain the same. There are of course things like scars or burns
that can alter your fingerprints, but even then it can be quite hard to make it a permanent
change. Notorious gangster John Dillinger attempted
to destroy his fingerprints with fire and acid, only to have them grow back mostly the
same. But for some people this wouldn’t be the
case, because if you were born with a condition known as ADERMATOGLYPHIA, you wouldn’t have
any fingerprints to lose in the first place. This rare genetic disorder means that your
fingertips, palms, toes and soles are entirely smooth. But for most, as ‘individual’ as these
identifying ridges seem to be, it has never been proven that they are entirely unique
to each person, and it’s almost impossible to prove either way without having catalogued
the fingerprints of every person that has ever lived. As Forensic Science Regulator Mike Silverman
puts it... “ESSENTIALLY YOU CAN’T PROVE THAT NO TWO
FINGERPRINTS ARE THE SAME. IT’S IMPROBABLE, BUT SO IS WINNING THE LOTTERY,
AND PEOPLE DO THAT EVERY WEEK.” And it was originally estimated that odds
of a match were 1 in 64 billion. Those may sound like some pretty low odds,
but considering there are over 100 billion people that have ever lived on Earth, most
with 10 fingerprints each, that’s around a trillion combinations across human history,
meaning at least 1 pair of those is likely to match. But to counter those odds again, mathematicians
now suggest that when you include details that aren’t even visible to the human eye,
the number of individual finger print configurations would be pretty much countless. Number 3. Your Appendix Is Useless Long believed to be an utterly useless ticking
time bomb waiting to kill you, it has now been discovered that the Appendix
has a reason to exist after all. It has been long established that the appendix
is full of immune system tissues, but it has not been known what these tissues are for. Now, a series of observations and experiments
co-authored between several educational and research bodies has suggested that they are there to protect
good bacteria and provide what is being termed a “safe house” for these beneficial bugs. Assistant Professor William Parker explains
how the appendix comes into its own after a nasty bout of illness. “ONCE THE BOWEL CONTENTS HAVE LEFT THE BODY,
THE GOOD BACTERIA HIDDEN AWAY IN THE APPENDIX CAN EMERGE AND REPOPULATE THE LINING OF THE
INTESTINE BEFORE MORE HARMFUL BACTERIA CAN TAKE UP RESIDENCE," Number 2. The color of your pee indicates whether you’re
dehydrated. It’s likely that you’ve been told that
the darker your urine is the more dehydrated you are, and the lighter and clearer it is
the more hydrated you are. Athletes are even specifically advised “OBSERVE URINE OUTPUT OVER THE COURSE OF
A DAY AND NOTICE CHANGES IN URINE FLOW AND COLOUR. OUTPUT VOLUME AND FREQUENCY SHOULD BE CONSISTENT
AND THE COLOUR SHOULD BE GETTING LIGHTER TOWARDS THE END OF THE DAY, AIMING FOR THE LAST OUTPUTS
OF THE DAY BEING CLOSE TO CLEAR.” So what’s the science behind this theory? Well, when you’re dehydrated a hormone is
released that increases the amount of water your kidneys absorb, this then lowers the
volume of urine when you pee and concentrates the substances left behind, making your pee
appear darker in colour. After this process, less water then needs
to be absorbed, so your urine increases in volume and appears to be more pale and clearer. However, researchers at Oxford discovered
that the science behind this guidance isn’t quite so clear. They looked at 8 studies and found that the
results were very divided, with none of them advocating the use of urine colour as an accurate
measure of hydration. There were 3 studies that suggested it could
be used as ‘a tool to roughly estimate hydration status’ but these also found the problem
that some foods, vitamins, medication and dietary supplements can alter the colour of
your pee. These results have raised concerns that attempts
to achieve the pale clearer colour could instead lead to overhydration and hyponatremia, essentially
the dilution of your body salts, which in extreme cases can be life threatening. Number 1. Your body is 100% Human I would expect most reactions to this to be
along the lines of, get out of here, what nonsense are you talking, if I’m not human
what am I? Now this might make you feel a bit weird,
itchy maybe, but the fact is, every inch of your body is inhabited by little creatures. As Professor Rob Knight puts it: "YOU'RE MORE MICROBE THAN YOU ARE HUMAN." PROF. ROB KNIGHT, UNIVERSITY OF CALIFORNIA, SAN
DIEGO & CO-FOUNDER OF THE AMERICAN GUT PROJECT Because incredibly it’s estimated that only
43% of the body’s cell count is human, the rest is our microbiome made up of organisms
like bacteria, viruses, fungi and archaea. Microbiologist, Professor Sarkis Mazmanian, takes this figure even further and suggests
that genetically we’re outnumbered up to 1000 to 1 "WE DON'T HAVE JUST ONE GENOME, THE GENES
OF OUR MICROBIOME PRESENT ESSENTIALLY A SECOND GENOME WHICH AUGMENT THE ACTIVITY OF OUR OWN. Your first thought may be to grab a scrubbing
brush and make a dash for the shower, but hold up, because you really don’t want to
lose these little guys. Besides a shower wouldn’t do a great deal
because most of them exist inside you, in your guts. "WHAT MAKES US HUMAN IS, IN MY OPINION, THE
COMBINATION OF OUR OWN DNA, PLUS THE DNA OF OUR GUT MICROBES." Although it was originally thought that the
Microbiome’s job was pretty simple - protecting our gut from invaders, synthesising some vitamins
and gobbling up the fibre that our body’s can’t digest. It’s now understood that your Microbiome
regulates your entire immune system, it can influence your mood and it can even affect
your weight. As Dr Michael Mosley puts it: “THE MICROBES CAN DECIDE HOW MUCH ENERGY
YOUR BODY EXTRACTS FROM THE FOOD YOU EAT AND MUCH MORE. CAN YOUR MICROBIOME MAKE YOU FAT?... IT CERTAINLY CAN!” Understanding the incredible world of our
microbiome is a relatively recent process, but it is hoped that Microbial Medicine known
as "bugs as drugs" will become common practice, where you can essentially have a microbiome
transplant, by taking good bacteria from a lean healthy person and inserting them in
to an obese person with either bad or missing bacteria, and making
them lose weight.
