Take a moment to remember Laura Joffe Numeroff’s children’s story, If You Give a Mouse a Cookie. It’s the feel-good tale of a boy who offers a chocolate chip cookie to a mouse, who in turn asks for a glass of milk and a series of other items.
But what would happen if you actually gave a mouse a cookie? We asked Northwestern professor Dr. Robert Linsenmeier, who teaches a class on animal physiology, to deconstruct the logistics of this illustrated classic.
Based on the book’s drawings, Linsenmeier guesses the mouse is eating a Famous Amos cookie, which has about 37 Calories. Estimating the mouse to weigh about 25 grams, Linsenmeier says he would have a metabolic rate of about 7.3 Calories per day.
Do the math and that cookie would fuel the mouse for five days—and that’s without the glass of milk. Eight ounces of low-fat milk contain about 103 Calories, bringing the total to 140 Calories. That would take the mouse about 20 days to burn.
The mouse does perform several activities, however, like sweeping every room in the house and washing the floors. “He’s working pretty hard, so maybe he could use 10 Calories [instead of the original 7.3],” Linsenmeier says. Still, the cookie and glass of milk would last the mouse two weeks.
Plus, the mouse's lack of opposable thumbs means he probably couldn’t hold the broom or any other item. He might be able to latch onto the straw he requests for his milk—that action is similar to post-natal breastfeeding—but he likely couldn’t generate enough physical force to actually suck the milk up the straw, Linsenmeier says.
The odds of finding a mouse with a sweet tooth on a sunny afternoon are pretty low any- way. “Mice are nocturnal,” Linsenmeier says. “They’re not going to be roaming around outside with their backpacks on looking for adventures.”
Despite the various scientific impossibilities, the book’s depiction of rodent fashion might puzzle Linsenmeier the most.
“Where did he get this pair of overalls?”