The human diet—a result of increased meat consumption, cooking and agriculture—has led to stark differences in the saliva of humans compared to that of other primates, US researchers have found.
Saliva is a crucial bodily secretion in humans. The fluid helps digest food, protects tooth enamel, polices microbes in the mouth, and forms a first line of defence against pathogens. Saliva plays an important role in speech and taste as well.
Spit’s many functions can be credited to the salivary proteome, which are the thousands of proteins within the fluid. These proteins may also reveal clues to how humanity diverged from the great apes throughout its evolution.
Researchers from the University at Buffalo, New York, compared the salivary proteins of humans and our closest evolutionary relatives: gorillas and chimpanzees. Macaques—who share a common, more distant ancestor with humans and great apes—were examined as well.
Their findings—published in Molecular Biology and Evolution—came as a big surprise since humans are known to be genetically close relatives of the great apes, chimpanzees and gorillas.
“Salivary proteins in humans and other primates could be overlooked hotbeds of evolutionary activity,” Stefan Ruhl said.
“We knew already that evolutionary adaptations to a human-specific diet have resulted in obvious changes to jaws and teeth, as well as the oral microbiome.
“Our findings now open up the possibility that dietary differences and pathogenic pressures may have also shaped a distinct saliva in humans.”