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Humans have been talking to each other for
hundreds of thousands of years.
And for the most part, researchers have assumed
we’ve all been making the same basic sounds,
no matter what language we’re speaking.
We’re all working with the same equipment,
after all.
But a new study says that that is not the
case.
It claims that back before we developed agriculture,
our teeth and jaws were different
because we were chewing tough, fibrous foods, and
that meant some sounds were harder to make.
Let’s just say early hunter-gatherers weren’t
going around saying “fee fi fo fum” or
“veni, vedi, vici.”
According to this new research, humans have
only recently made “f” and “v” sounds
since they started eating softer foods, so
in the last 10,000 years or so.
This actually isn’t a new idea.
The hypothesis was first proposed by linguist
Charles Hockett in 1985.
You see, scientists have generally assumed
that the language-producing toolbox of humans
hasn’t really changed for about half a million
years.
As a result, you should expect to find roughly
the same sounds in all languages.
The easier a sound is to produce, the more
often it should pop up.
According to linguists, the differences between
the thousands of world languages mostly resulted
from things like tiny pronunciation mistakes
that spread culturally.
Differences could even relate to geography,
as certain sounds are easier to make at higher elevations.
But Charles Hockett put one more explanation
on the table: diet.
He noticed that the languages of modern hunter-gatherer societies lacked labiodentals.
Those are sounds produced by touching or nearly
touching the bottom lip to the upper teeth,
like consonants like f and v in English.
That led him to think differences between
languages might actually come
from how the food we eat affects the way we bite.
Both hominid fossils and modern hunter-gatherers
have what he called an edge bite,
where the top teeth lay directly on top of the bottom
teeth, touching edge-to-edge.
In childhood, humans start out with their top teeth overlapping their bottom teeth in a small overbite,
or what Hockett called a
scissors bite.
But over time, tough foods wear teeth down,
and to compensate for that loss,
the teeth start to drift inward, 
leading to an edge bite.
And if your top and bottom teeth align perfectly,
it’s harder to get your bottom lip into the position where “f” or a “v” sound is possible.
But according to Hockett, agriculture changed
all that.
We started eating less meat and more grains,
and cooking came into the picture.
Softer food meant less wear and therefore helped humans keep their childlike overbite into adulthood.
Scientists at the time didn’t buy Hockett’s
hypothesis.
They didn’t think that wear and tear could
make that big of a difference to the human bite.
Plus, archaeological evidence back then said
that the timeline didn’t add up:
overbites appeared much later than agriculture did.
In the end, Hockett backtracked on the idea,
agreeing that the timing was an issue.
But research since has shown that wear can
change a person’s bite dramatically,
and it’s now well established that overbites
became more common after the rise of agriculture
in the Neolithic era.
But a change in bite doesn’t necessarily
mean a change in language.
You would need more research to make that
connection.
So that’s exactly what an international
team did
for the new study published last week in the journal Science.
First, they created a 3D simulation of the
human mouth and jaw to see if an overbite
really did make labiodentals easier.
It did: it takes about 29% less energy to make an “f” sound with an overbite than  it does with an edge bite.
Next, they created a statistical model that
showed that modern hunter-gatherer societies
only had about 27% as many labiodentals in
their languages as agricultural societies.
And historically, they found that the statistical
likelihood of a language having labiodentals increased over time,
starting several thousand
years ago, around the same time that things
like dairy and cultivated grains became popular.
And they became really common about 2500
years ago,
when industrial milling became a thing in places like Europe.
They also looked at how these sounds appeared
in those languages.
Because a lot of language changes happen by
accident,
they figured that labiodentals would end up replacing sounds that require a similar mouth position.
They put their money on bilabials, sounds
like “p” and “m”
that require you to bring your lips together.
If a culture began speaking their language with an edge bite and then developed an overbite over time,
it’s understandable that a “p” sound might start to become an “f” sound  here and there.
Sure enough, they found a lot of labiodentals
where bilabials had once been.
Like, the Italian “p” is related to the
English “f”,
which in part explains how “padre” became “father.”
Not everyone embraces these findings, though.
Some of the objections echo those from Hockett’s
time, saying that the researchers might be
overstating how much diet can really affect
language.
Others say that it relies on a lot of untested
assumptions,
including the idea that the use of agriculture is a good shorthand for a society’s diet.
But the biggest elephant in this room is the fact that tracing language differences to physical differences
often leads to ethnocentrism
or flat-out racism,
something linguistics has 
had trouble with in the past.
That’s not a reason to abandon the results
entirely,
just a reason to treat them 
with extra care.
The researchers stand by their data, though,
and say their study shows that everything humans do happens in the context of how they live.
They’ve reiterated that they’re not claiming
that physiology is the only predictor of language,
they just think it should get more
credit, like it does for other human traits.
Basically, there’s no reason language and
speech should be an exception.
In this study, the researchers used statistical
models to show that diet probably influences
the sounds we make.
And if you want to really understand the math
that led them to that conclusion,
you might like this course on Probability from Brilliant.org.
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