We have long known that our sense of taste is associated with smell, but new research indicates that human tongues can actually smell.
Research conducted at the Monell Chemical Senses Center in Philadelphia revealed that taste cells in the human tongue contain the same smell receptors found in noses, American Association for the Advancement of Science reported.
Taste and smell have been considered independent sensory systems, but cell biologist Mehmet Hakan Ozdener began to ponder this assumption when his 12-year-old son asked him if snakes extended their tongues so they could smell.
Scientists would later set out to dig into this mystery. They reportedly grew living human taste cells in a lab. What they discovered was that human taste cells contain many key molecules known to be present in olfactory receptors.
The scientists also used a method known as “calcium imaging” to show that the cultured taste cells responded to odor molecules in the same way that olfactory receptor cells do.
Other tests showed that a single taste cell on the tongue “can contain both taste and smell receptors.”
The findings suggest that the primary components of flavor may begin on the tongue and not in the brain, as many have previously believed. In addition, it appears that flavor may come more from smell that we once thought.
“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 tongue,” Hakan Ozdener said.
The research also suggests that human taste cells are probably more complicated than once believed. Taste has long been divided into five categories: sweet, salty, sour, bitter, and savory. Scientists have believed that these categories were combined, or integrated, with smell in the brain. However, the new research suggests that the integration could happen before any sensory input has time to reach the brain.
“This 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,” Ozdener said.
In addition, the research could provide insight into a new way in which scientists study how humans smell things. As it is, scientists do not know which molecules activate the majority of the 400 different types of smell receptors humans possess.
Future research will seek to determine where particular olfactory receptors are located. Other studies will also explore how odor molecules alter taste cell responses, and how humans perceive taste.