In fact, being able to distinguish between friend or foe could be an important survival skill. "It's important to tell who is going to be helpful, who is going to be threatening," Hamlin noted.
But that's the evolutionary argument, and not one everyone would agree with it, Dennis pointed out.
"Even though these authors make a good argument that very young infants don't have a lot of time to learn, even some basic observation of people cooperating might be enough to make some learning take place," Dennis said. "It's important, but it's a study that people are going to debate about."
More information
Read up on child development at the U.S. Centers for Disease Control and Prevention.
