It's no coincidence that the expression "to leave a bitter taste in one's mouth" has a double meaning; people often have strong negative reactions to bitter substances, which, though found in healthful foods like vegetables, can also signify toxicity. For this reason, the ability to sense bitterness likely played an important role in human evolution.
A new study by University of Pennsylvania scientists provides new evidence underlining the significance of bitter taste perception. Their work suggests that a genetic mutation that makes certain people sensitive to the taste of a bitter compound appears to have been advantageous for certain human populations in Africa. Yet the reason why this trait was selected may not have to do with just taste. Instead, the molecular receptor under study may also play important roles in immune response or metabolism.
"We're starting to understand that these taste receptors are involved in so many functions other than just oral sensory perception," said Michael Campbell, lead author on the study and a postdoctoral fellow in Penn's Perelman School of Medicine's Department of Genetics.
The study, published in the journal Molecular Biology and Evolution, represents the first time that this bitter-taste sensing gene, TAS2R16, was studied in a large set of ethnically and culturally diverse African populations.
"Because Africa is the site of origin of all modern humans," said Sarah Tishkoff, the study's senior author and a Penn Integrates Knowledge Professor with appointments in the School of Arts and Sciences' Department of Biology and Penn Medicine's Department of Genetics. "Africans are going to have a large amount of diversity and non-Africans are going to have a subset of that diversity. In Africa, you get an opportunity to observe how these genetic variants are influencing phenotypes that you wouldn't have if you were only studying non-Africans."
Campbell, Tishkoff and oth
|Contact: Katherine Unger Baillie|
University of Pennsylvania