New York, Jan 31: In a surprising revelation, researchers have found that babies as young as six-month old know that plants are food sources.
But it comes only after an adult shows them that the food is safe to eat.
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 six and 18-months of age preferentially identify the plant as 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.
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 behaviour,” added Wertz.
The researchers hypothesised that instead of imitating an adult’s behaviour outright, children tend to go for specific types of entities – in this case, plants – but only when an adult does so first.
In an experiment, 18-month old infants 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.
The fruits were then taken off the plant and the artifact and the infants were asked, “Which one can you eat?”
The infants showed a clear preference for the fruits that came from the plant, despite the fact that they saw the same social information – the experimenter “eating” the fruit – applied to both objects.
Six-month-old infants looked longer at in-mouth actions when they were performed with fruits from the artifact, suggesting that this violated their expectations for edibility.
“Together, the experiments show that infants use social information from adults to rapidly and selectively identify plants as food sources,” said Wertz.
This suggests that humans, unlike some other non-human primates, don’t simply consider anything that goes into the mouth to be food. Instead, they also take the type of object into consideration, concluded the study published in Psychological Science.