Every now and again friends and relatives call over to my house bearing not gifts, but children. I don’t mind children. Sure they’ll talk back and even kick back, but fill them with sugar in front of the TV and they’re happy. My relatives, however, don’t bring children per se, they bring babies; and babies require total immersion. Ever wonder why that is? Why is it that human infants remain in this inebriated, helpless state for years whereas infants from other species are more or less independent in a fraction of the time? A kitten for example can walk within moments of birth and catch its first mouse within weeks. Human infants on the other hand take their first steps after two years and are reliant on their parents for survival for much longer.
Critically however, human infants go on in life to develop a level of intelligence unequalled on this planet – allowing us to rationalise, reason, learn and adapt to our environment such that we can create and comprehend works of art, launch rockets into space and accomplish just about everything in between. A new study in Current Directions in Psychological Science makes the case that this initial, extended period of helplessness is a decisive factor in allowing us to make the leap from mere animals to fully formed human beings.
The author’s work focuses on an area of the brain called the prefrontal cortex (PFC), located just behind the forehead which is believed to regulate our thoughts and behaviours. In order for this, and indeed any part of our brain to develop and function, electrical junctions called synapses must develop which allow both chemical and electrical signals to be passed between neurons. In just about every animal studied, including our primate ancestors, the PFC develops in line with the other cortical areas, reaching maturity within months. However, in the case of humans, synapses in the PFC develop much more slowly, straggling behind the visual and auditory cortex such that it doesn’t ‘catch up’ until the fourth year of life. Thus, children exhibit “impaired cognitive and behavioural control” in their early years as a result of this slowed PFC maturation and are therefore almost totally reliant upon their parents during this time.
But whereas previous studies have focused on the negative implications of this developmental phenomenon, the authors of the present study assert that while a child’s mind may not be geared for performance, it does appear to be optimised for certain types of learning – in particular, language acquisition. Learning a language involves the understanding of a multitude of conventions from grammar and verbs to conversation. People can converse with each other because we understand what is being said based on a set of conventions we observed and learned when we were infants. Children with immature PFCs are more suited to convention learning than adults with mature PFCs. Illustrating this is the case of Simon, a deaf child who learned sign language as an infant from parents who learned as adults. At age 7, Simon had already acquired an ordered system of rules for understanding the language that far exceeded that of his parents. The authors suggest that this is due to the childs ability to learn and copy only the most frequently observed patterns/conventions and to cut out any alternates/mistakes in the backround. To illustrate, if a child hears the sentence: “Je suis un homme” 60 % of the time and “Je suis une homme” 40% of the time, the child, in general, will only learn the former, simply because it is heard most. Adults, on the other hand, because of their PFC’s greater maturity and flexibility, will learn and repeat both sentences, thus delaying their mastery of the language.
This research conveys the idea that children have actually evolved their frustrating lack of motor skills as a long-tem strategy that allows them to master the linguistic and social conventions required of them at a later stage. So the next time my little three year-old cousins are slobbering their food all over the table, I’ll be a little, just a little, more understanding.
