At one point or another, most parents have remarked that their young one is like a little monkey – scrambling around on all fours, climbing on the coffee table, hooting and banging blocks together. Indeed, kids do bear a striking resemblance to our furry ancestors. The similarities go well beyond their general ape-like behavior, though. Scientists are seeing more and more that primates and babies both enter into the world with similar wiring, sporting impressive knowledge of things like basic physics and math. The fact that our infants share so much with the tree-dwellers is helping researchers make the case that nature has pre-packaged us with much of what we need to hit the ground running.
Research with non-human primates has taught us a lot about what makes children tick. We nuzzle skin-to skin with our newborns in the delivery room and tuck them into baby slings thanks in large part to Harry Harlow’s famous monkey experiments of the 1950s. In Harlow’s research, rhesus monkeys were separated from their moms and given two inanimate mommies – one made of wire and one terrycloth. The majority of infant monkeys clung to the soft terrycloth moms. When they were scared, they bee-lined for the soft mom even when the wire mother was the one with the bottle. Harlow’s monkey findings inspired psychologists to look more closely at the role of contact in the parent-child bond, laying the groundwork for attachment theory.
Research with non-human primates has taught us a lot about what makes children tick. But studying other primates also shines light on our hard-wired capabilities. If we share certain skills and behaviors with monkeys, the reasoning goes, it is pretty likely that those traits are innate – passed down over millions of years from our common ancestors. One of the most clear and certainly the most endearing example of this is the newborn grabbing reflex. Babies automatically wrap their tiny fingers around anything that goes in their hand (usually mom or dad’s finger). Laurie Santos, Professor of Psychology at Yale, says this behavior is a vestige of our evolutionary ancestors, probably left over from when we had fur and a baby would need to hold on to mom while she moved around.
Santos and her team of primate scientists often pair up with infant researchers to answer questions that go beyond behavior and look at how our cognitive machinery has evolved. One of the main lines of research is testing “core knowledge” – the idea that babies are born with sophisticated mental abilities. Developed by the influential psychologist Elizabeth Spelke, core knowledge has been a revelation in infant development. Before this, infants were assumed to basically be blank slates, born with their senses and crude motor skills, but no real knowledge of how the world works. For example, most moms are told that their baby will not develop “object permanence” until the end of her first year, meaning that when she can’t see an object, she forgets about it completely. We now know this is kind of an old-school notion. Jean Piaget proposed this concept in the 1950’s based on studies he did with his own children. When he hid a toy, his infant daughter would not search for it, leading him to conclude that young babies have no ability to mentally represent objects if they are out of sight.
Modern scientists realized that Piaget’s findings were more a reflection of babies’ fledgling motor skills than their mental power. The core knowledge folks bypass motor skills and use eye movements to determine what babies know. When eye movements are used, they see that the tiniest babies have a lot more going on upstairs than previously thought. Spelke believes that even newborns know that objects exist when they’re out of sight. As young as 2.5 months, babies know a lot about how the physical world works; for example, that inanimate objects don’t move unless something comes in contact with them, and that objects move in continuous paths and stop only when something is in their way – both important Physics 101 lessons.
In her lab at Yale, Santos puts Rhesus monkeys and Lemurs through similar tests and the primates grasp the same concepts as babies – more support for the idea that this knowledge is innate. Evolution has basically given us a head start, explains Santos, so babies don’t resort to sheer trial and error to figure the world out. She notes that even though this knowledge is very basic, it drastically alters the way that babies see the world.
Physics isn’t the only subject built in by natural selection. Infants and primates have been shown to do simple math too. If you show a five-month-old baby one doll, put it behind a screen and then add another doll, she knows that when the screen is lifted there should be two dolls back there (object permanence and 1+1=2 already in effect). Babies are surprised when the screen is lifted to show only one doll. Rhesus monkeys can do similar addition with small numbers (but both babies and primates seem to fall off after four). Santos explains that this counting ability would have given our primate ancestors a leg up in fighting situations. Imagine you’re deciding whether to be aggressive – you’d be well served to know if you’re facing two, three, or four opponents.
We’re not just given a jumpstart on our MIT applications. Young babies already have systems in place to help them make social judgments as well. Katherine Kinzler, a former graduate student of Spelke and now a professor at the University of Chicago, has been asking how babies use language to guide social interactions and their preferences for people. At five months, babies prefer to look at speakers of their native language, even when they’re not actually talking anymore. Older babies are more likely to take a toy from someone who speaks their language. One of the explanations for this could be that babies are born with an ability to tell “this person is like me” versus “this person is different.” As Kinzler explains, “We may be set up to prefer individuals who are members of our native group.”
Step away from the flashcards, B.F. Skinner.Step away from the flashcards, B.F. Skinner. A similar study used baby food choices to test the same concept. Kinzler and her colleague Kristin Shutts enrolled one-year-olds in the research because they are notoriously indiscriminate about what they put in their mouths. This may seem like a poor strategy for evolutionary fitness, but Kinzler explains that traditionally moms would breast feed until two or three years of age. It’s no coincidence, from an evolutionary standpoint, that this is just the age when most kids put their pickiness into high gear. In the study, researchers showed babies in the U.S. two people, an English speaker and a French speaker, eating two different sauces that were alike in every way except that one was green and the other purple. When the babies were given a choice of which to eat, they chose the one that the English speaker had been chomping on.
It’s all fun and games to think of babies as little engineers, but are they really born with social biases? If babies are already cozying up to people like them and dissing the ones who are different, does that mean we’re destined for an “us versus them” mentality? Does it start with green sauce and end up as gender inequality and Prop 8? Kinzler points to some optimistic findings in her work. She says that when she tests twelve-month-old babies to see if they prefer people of their own race, they do not. But at five years old, they do. Even then, kids seem to pay attention more to language then they do to race. “It shows that something like race-based preferences, even though they can become robust in our society later on, they’re not necessarily mandatory, or even present until later in development.”
It may seem daunting, in a way, that babies are born so knowledgeable. Does this mean we have to up the ante as parents and take greater advantage of our infants’ precocious brain development? Nope. Step away from the flashcards, B.F. Skinner. The core knowledge theory tells us that babies already have systems in place to help them learn. As long as we give them plenty of opportunity to explore and some tools to do this with, their brains cannot help but develop. But one of the best brain boosters out there, as we know from Harlow’s monkeys, is still a good old-fashioned cuddle. And next time you’ve got your child wrapped up tight in your arms and you’re gazing lovingly at each other, think about what’s going on just behind those eyes, and how millions of years of primate evolution have brought you two together.