Infants as young as six months old tend to expect that plants are food sources, but only after an adult shows them that the food is safe to eat, according to new research published in Psychological Science
, a journal of the Association for Psychological Science.
The findings show that, after watching an adult put part of a plant and part of a man-made object in her mouth, infants at 6- and 18-months of age preferentially identify the plant as the food source.
"Plants are often peripheral to modern life, but they were central to fundamental problems of determining what is food and what is fatal across evolutionary time," says psychological scientist and study author Annie Wertz of Yale University. "Humans relied on gathered plant resources for food, but many plants are toxic and potentially deadly."
So how do babies learn what's good to eat and what's not?
"Young children's decisions about what to eat are, famously, not determined by simply copying adult behavior," Wertz and co-author Karen Wynn note.
Wertz and Wynn hypothesized that, instead of imitating an adult's behavior outright, children tend to go for specific types of entities - in this case, plants - but only when an adult does so first
. They tested their hypothesis in four experiments.
Full-term 18-month-olds were presented with a realistic-looking artificial plant and an obviously man-made artifact, each of which had dried fruits attached. The infants watched an experimenter take one fruit off each object - the plant and the artifact - and place it in her mouth as if eating it.
This experiment touches on several important issues. First, it means that on an instinctual level infants don't immediately recognize plants as a possible food source. And for a good reason, since plants, even the ones we eat on a daily basis, contain many anti-nutrients and toxins
. This experiment also shows how important it is for parents to teach their children about the types of food that carry the greatest benefit for their health. And plant food isn't one of them. In fact, human beings appear to thrive
on a high fat/low carb diet.