Does your tongue have a sense of smell?

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By Maria Cohut 

Fact checked by Isabel Godfrey

Many animals taste and smell
their environment through the same part of their body, but can the same be true
about humans? New research suggests that this might indeed be the case and that
we may have smell receptors on our tongues.

Unlike humans and other
mammals, not all animals have noses with smell receptors, but this does not
mean that they have no sense of smell.
For instance, crabs capture
smells through the sensory bristles on their antennae, while snakes, although
they do have nostrils, actually smell better through their mouths,
“fishing” for scents with their forked tongues.
However, smell and taste
usually work together in allowing animals to navigate the world. This
collaboration is obvious in snails, for instance, whose lower tentacles allow
them to smell and taste their environment.
Taste and smell also work as
complementary senses in humans. Olfactory (smell) inputs from the nostrils and gustatory
(taste) inputs from the tongue interact in the brain to create a complete
picture of what, for example, a person is preparing to eat or drink.
Nevertheless, so far,
researchers have tended to believe that the senses of taste and smell operate
individually in humans and other mammals.
However, a study that Current
Biology published earlier this year found that when scientists removed the
taste cortex from the brains of rats, this affected not only the animals’
ability to perceive taste but also their sense of smell.
Similar research has now led
Dr. Mehmet Hakan Ozdener and colleagues from the Monell Center in Philadelphia,
PA, to investigate whether mammals — including humans — can also smell with
their tongues.
Taste cells could both taste
and smell

In the new study, the results
of which appear in the journal Chemical Senses, Dr. Ozdener and team used both
genetic and biochemical techniques to determine whether the taste buds of mice,
called mouse taste papilla cells, might be able to respond to odor molecules.
They then tested laboratory cultures of human fungiform taste papilla cells.
First, the researchers found
that mouse taste papilla cells actually contained olfactory receptors and that
the same was true of the cultured human taste cells.
Following this, the team used
a scientific technique called calcium imaging to assess how the cultured taste
cells responded to odor molecules, which revealed that the taste cells
interacted with them in a very similar way to regular smell receptor cells.
Further experiments then also
showed, for the first time, that one taste cell can contain receptors for both
smell and taste. This discovery could help shed new light on just how closely
taste and smell work together to alert us to the desirability of a particular
food, for instance.
“The presence of olfactory
receptors and taste receptors in the same cell will provide us with exciting
opportunities to study interactions between odor and taste stimuli on the
Dr. Mehmet Hakan Ozdener

“Our research may help
explain how odor molecules modulate taste perception,” Dr. Ozdener also
notes, adding that it “may lead to the development of odor-based taste
modifiers that can help combat the excess salt, sugar, and fat intake
associated with diet-related diseases, such as obesity and diabetes.”
In the future, the research
team hopes to find out whether only certain taste cells contain smell receptors
and to what extent the odor molecules that taste cells capture can change how
an individual perceives specific tastes.

Kayode Ojo
Kayode Emmanuel Ojo is the Co-Founder and Managing Director at SHEFFA Limited. He is presently studying Computer Science at the National Open University, Victoria Island, Lagos.