Did you know the hardest part of our body isn’t our bones, but the enamel that covers
our teeth?
And now scientists are on the cusp of figuring out where this enamel came from!
Hint: it once lurked in the briny deep during the Silurian period!
Hello!
It’s Natalia Reagan for DNews and I’m ready to take a bite a out of some science.
Teeth- they are amazing!
They can tell us so much about someone’s diet, background, overall health, their hygiene
(or lack thereof)!
Heck!
Teeth aren’t just for eating- We can even tell if our ancestors used their teeth to
make tools- how great is that!
But human teeth also contain the hardest mineral in the body- enamel!
And nearly all tetrapods- or 4 limbed land dwelling animals- have enamel on their teeth,
too.
But what exactly IS enamel?
Tooth enamel is the hardest tissue in the human body and it's comprised mostly of a
mineral fittingly called hydroxyapatite, which is crystalline calcium phosphate.
This is the part of the tooth that dentists are most concerned with preserving since it
protects it from cavities and other dental maladies.
Even though it’s the top layer of the tooth, it’s not responsible for the tooth’s color
as it’s transparent.
But how did enamel get there in the first place?!
Well, scientists have found that an ancient fish might hold clues to how enamel came to
cover our chompers.
This fierce wee minipredator called Psarolepis romeri cruised the seas 410 to 415 million
years ago.
Scientists dissected the fossilized skull of this minipredator and found that parts
of their scales and skull were comprised of an enamel-like substance called ganoine.
Their teeth, on the other hand, did not have the enamel-like ganoine and were comprised
of naked dentine.
Similarly, some living fish do not have enamel on their teeth but some recognizable fish
like piranhas, grunts, and those ravenous cartilaginous fish like this guy (point to
shirt) do!
Yes, shark teeth are also made with a hard mineral called fluoroapatite or fluorinated
calcium phosphate which is very similar to hydroxyapatite, except with the added protection
of fluoride.
That’s why sharks don’t get cavities!
So, how did enamel GET to our teeth from the scales of ancient fish?
Time to get to the root of the problem!
Some scientists have surmised that the armored scales on ancient fish evolved to become teeth.
And if those scales had enamel on them, that would explain how enamel made it’s way on
our teeth.
But, upon further analysis of Psarolepis romeri’s fossilized skull and scales, it was clear
that the distribution of ganoine was not a uniformed layer; the enamel was scattered.
So perhaps the scales didn’t re-situate themselves to become enamel covered teeth,
but maybe the enamel production shifted south to the teeth?
Hmmmm….
That’s when scientists decided to look at the genome of the modern-day spotted gar to
understand the genetic building blocks of enamel production.
Researchers already knew that the gar, like the ancient Psarolepis romeri, produces the
hard enamel-like mineral called ganoine that covers their scales.
And when they looked at their genome they found that the gar produces 2 of the 3 proteins
that comprise enamel, further supporting the evidence that ganoine coated scales are like
the enamel coating of teeth.
This discovery is making scientists rethink the evolutionary process of how our teeth
became covered in enamel.
Originally, researchers assumed that the enamel-coated scales of fish shifted and eventually became
teeth, but these new findings suggest that perhaps the actual body part did not move
from one place to another but that it was just the enamel production that shifted from
one area of the body to another.
But more research is needed...
So what’s the molar of the story?
We can learn a lot about our evolution from some unexpected places and that teeth are
some of the coolest parts of our anatomy!
Now you know a little more about teeth...did you know that teeth can grow in tumors or
cyst?
Check out this video to find out more!
What do you think about this fish tale?
Tell us in the comments below and subscribe for more DNews.