COLLEGE PARK, Md., July 15 (UPI) -- One mouse can learn from another mouse what foods are good to eat and safe to eat -- by smelling its breath, researchers say.
For rodents, any food smell combined with breath odor sends an irresistible "eat this" message to the brain, ScienceNews.org reported Thursday.
Carbon disulfide, a metabolic byproduct found in the breath of many mammals, stimulates specialized cells in the mouse nose, scientists report in the journal Current Biology.
These cells send a signal to specialized structures within the mouse brain that links an incoming odor with food that's safe to eat, researchers said.
"One mouse is saying, 'My friend here just ate some food that smells like this -- and he's still breathing, he's alive -- so it must be safe," study coauthor Steven Munger of the University of Maryland said.
For humans, food preferences are mostly learned visually. But for nocturnal creatures such as rodents, visual cues are limited, so it makes sense that there's a scent signal, neuroscientist Emily Liman of UCLA said.
In human, the specialized scent cells no longer function, though they appears to work in dogs and presumably many other mammals, Liman said.
This loss of specialized cells may have coincided with other changes in the primate lifestyle, including a shift to daytime activity and improved eyesight, which made vision as important as smell for evaluating food, she said.