HUMANS & SOCIE TY
Farming cultivated new speech sounds
Shifting to softer foods may have enabled people to say ‘f’ and ‘v’
BY BRUCE BOWER
Humankind’s gift of gab is not set in stone,
and farming could help explain why.
Over the last 6,000 years or so, farm-
ing societies increasingly have replaced
tougher-to-chew game meat and wild
plants common in hunter-gatherer diets
with processed dairy and grain products.
Switching to softer foods altered peo-
ple’s jaw structure over time, rendering
certain sounds like “f” and “v” easier to
utter and changing languages world-
wide, scientists contend.
People who regularly chew tough foods
experience jaw changes that remove
a slight overbite from childhood. But
people who grow up eating softer foods
retain that overbite into adulthood, say
comparative linguist Damián Blasi of the
University of Zurich and his colleagues.
Computer simulations suggest that
adults with an overbite are better able to
make certain sounds that require touch-
ing the lower lip to the upper teeth, the
team reports in the March 15 Science.
Linguists classify those speech sounds,
found in about half of all current languages, as labiodentals. In reconstructing
language change over time among Indo-European tongues, currently spoken
from Iceland to India and beyond, Blasi’s
team found that the likelihood of using
labiodentals in those languages rose
substantially over the last 6,000 to 7,000
years. That was especially true if foods
The skull of an ancient hunter-gatherer (left) lacks the slight overbite seen in a skull from ancient
Greece (right). Having an overbite in adulthood has been linked to eating soft, processed foods.
such as milled grains and dairy products
started appearing around that time.
“Labiodental sounds emerged
recently in our species and appear more
frequently in populations with long traditions of eating soft foods,” Blasi said
March 12 during a news conference.
Yale University linguist Claire Bowern,
who was not involved in the research,
agrees. If certain sounds become easier to
pronounce, the odds of those sounds getting incorporated into words increases.
But changes in how words are actually
spoken still may not happen, Bowern
says. So evidence of labiodentals’ rapid
incorporation into many languages
comes as a surprise, she says.
Linguists traditionally have thought
that humans have always been capable
of making all sounds used in the roughly
7,000 languages spoken today. Crucial
elements of speech anatomy — such as
a larynx, or voice box, positioned low
in the neck — evolved in Homo species
by 500,000 years ago. So when Homo
sapiens emerged about 300,000 years
ago, humans were prepared to talk.
But in 1985, linguist Charles Hockett
argued that hunter-gatherer languages
virtually never include labiodental
sounds. By young adulthood, heavy tooth
wear from chewing tough foods results in
the upper teeth moving directly on top of
the lower teeth, he contended. A result-
ing “edge-to-edge” tooth arrangement
makes it harder to form labiodental
sounds, Hockett reasoned. If true, his
proposal meant that the introduction
of soft foods in farming societies should
have safeguarded overbites and raised
the likelihood that spoken languages
would include labiodentals.
Computer simulations support
Hockett’s idea. They show that a transition from an edge-to-edge bite to a slight
overbite makes it substantially easier to
utter labiodental sounds.
What’s more, a statistical analysis of
languages and lifestyles for more than
2,400 populations around the world
found that, on average, hunter-gatherers
use about one labiodental sound in their
speech for every four spoken by people in
societies that produce and process food.
A closer examination of hunter-gatherer
languages in Greenland, southern Africa
and Australia found few instances of
labiodental sounds. Historical records
indicate that words with labiodental
sounds were borrowed during contacts
with people from industrialized nations,
the researchers say.
A tendency for some commonly mis-
pronounced sounds to become widely
used can help explain labiodentals’ rapid
incorporation into many languages, says
evolutionary biologist Mark Pagel of
the University of Reading in England. If
labiodentals became easier to pronounce
relatively recently, making them more
likely to be spoken by chance, the sounds
could have quickly become embedded in
lots of native tongues, he speculates.
Robert Corruccini, a biological anthro-
pologist at Southern Illinois University
in Carbondale, says the findings are “fun-
damentally correct.” But human overbite
increased much more after the Industrial
Revolution, which began in England in
the late 1700s, than after the introduc-
tion of agriculture, he says.
Industrialized food processing and
canning— and perhaps the adoption
of forks in Western societies, so that
food could be held down with a fork,
not gripped with the front teeth, while
the other hand cut the food with a
knife — played big roles in preserving
overbites, Corruccini contends. s