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When a team of archaeologists
recently came across

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some 15,000 year-old human remains,

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they made an interesting discovery.

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The teeth of those ancient humans
were riddled with holes.

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Their cavities were caused by the same
thing that still plagues us today,

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specific tiny microbes 
that live in our mouths.

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These microbes are with us
soon after birth.

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We typically pick them up as babies
from our mothers' mouths.

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And as our teeth erupt,

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they naturally begin to accumulate
communities of bacteria.

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Depending on what we eat,

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and specifically how much sugar
we consume,

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certain microbes can overpopulate
and cause cavities.

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Diets high in sugary foods cause
an explosion of bacteria

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called mutans streptococci
in our mouths.

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Like humans, these microorganisms
love sugar,

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using it as a molecular building block
and energy source.

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As they consume it,

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the bacteria generate byproducts
in the form of acids,

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such as lactic acid.

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Mutans streptococci are resistant
to this acid,

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but unfortunately, our teeth aren't.

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While each human tooth is coated
in a hardy, protective layer of enamel,

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it's no match for acid.

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That degrades the armor over time,
leaching away its calcium minerals.

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Gradually, acid wears down a pathway
for bacteria

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into the tooth's secondary layer
called the dentin.

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Since blood vessels and nerves
in our teeth are enclosed deep within,

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at this stage, the expanding cavity
doesn't hurt.

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But if the damage extends 
beyond the dentin,

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the bacterial invasion progresses

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causing excruciating pain
as the nerves become exposed.

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Without treatment, the whole tooth
may become infected

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and require removal

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all due to those sugar-loving bacteria.

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The more sugar our food contains,

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the more our teeth are put at risk.

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Those cavemen would hardly
have indulged in sugary treats, however,

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so what caused their cavities?

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In meat-heavy diets, there would have
been a low-risk of cavities developing

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because lean meat 
contains very little sugar,

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but that's not all our early human
ancestors ate.

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Cavemen would also have consumed
root vegetables, nuts, and grains,

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all of which contain carbohydrates.

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When exposed to enzymes in the saliva,

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carbohydrates get broken down
into simpler sugars,

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which can become the fodder
for those ravenous mouth bacteria.

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So while ancient humans did eat
less sugar compared to us,

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their teeth were still exposed to sugars.

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That doesn't mean they were unable
to treat their cavities, though.

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Archaeological remains show that
about 14,000 years ago,

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humans were already using sharpened flint
to remove bits of rotten teeth.

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Ancient humans even made
rudimentary drills

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to smooth out the rough holes left behind

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and beeswax to plug cavities,
like modern-day fillings.

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Today, we have much more sophisticated
techniques and tools,

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which is fortunate because we also need
to contend with our more damaging,

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sugar-guzzling ways.

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After the Industrial Revolution,
the human incidence of cavities surged

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because suddenly 
we had technological advances

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that made refined sugar cheaper
and accessible.

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Today, an incredible 92% of American 
adults have had cavities in their teeth.

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Some people are more susceptible 
to cavities due to genes

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that may cause certain weaknesses,
like softer enamel,

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but for most, high sugar consumption
is to blame.

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However, we have developed other ways
of minimizing cavities

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besides reducing our intake of sugar
and starch.

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In most toothpastes 
and many water supplies,

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we use tiny amounts of fluoride.

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That strengthens teeth and encourages
the growth of enamel crystals

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that build up a tooth's defenses
against acid.

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When cavities do develop,

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we use tooth fillings to fill 
and close off the infected area,

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preventing them from getting worse.

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The best way to avoid a cavity
is still cutting down on sugar intake

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and practicing good oral hygiene

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to get rid of the bacteria 
and their food sources.

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That includes regular tooth brushing,

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flossing,

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and avoiding sugary,

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starchy,

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and sticky foods that cling to your teeth
between meals.

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Gradually, the population of sugar-loving
microbes in your mouth will decline.

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Unlike the cavemen of yesteryear,

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today we have the knowledge required
to avert a cavity calamity.

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We just need to use it.