"He's so smart! He said his first word at seven months!" How often do we moms hear (and say) things like this? Whether it's accurate or not, we strongly associate earlier acquisition of infant milestones with higher intelligence. The baby who sits up, walks, babbles, and talks sooner than his same-age peers is-- at least by his own parents-- assumed to be brighter than average. After all, isn't precocious learning the defining characteristic of intelligence?
Intelligence in infants is actually quite a bit more complicated than we tend to assume. While we can easily guess an older child's intelligence based on his development-- assuming, for example, that an eight-year-old who reads Shakespeare is very bright-- an infant's developmental milestones are far less telling. In fact, there appears to be only a slight connection between infant developmental milestones and intelligence in later life.
In 2007, the University of Cambridge published the results of a long-term study investigating the intelligence of 5,362 children from birth until age 53. They found that babies who reached certain milestones earlier than average had slightly higher IQs. For example, for every month earlier that a baby learned to stand, the scientists documented an increase of about one half of one IQ point at age eight.
By ages 26 and 53, the correlation was no longer apparent-- suggesting that a baby who who stands at six months is no more likely to be a genius than one who stands at ten months of age. Other physical milestones, such as walking and crawling, seemed to be completely unrelated to a child's intelligence.
The scientists found that speech milestones were slightly more indicative of later intelligence than physical milestones. Babies who babbled, spoke words, and formed sentences earlier had slightly higher IQs on average and were slightly more likely to attain higher education in adulthood. So, while your baby's early walking may not be a sign of brilliance, early talking is more likely to signal that she'll be bright later on.
Ultimately, you can't assume that your child is or isn't more intelligent than average based on milestones in infancy. A baby who talks and walks earlier than his peers may be of completely average intelligence, while the late bloomer down the road may turn out to be incredibly gifted. Early milestones are only slight predictors of a child's later intelligence.
Exceptions to these predictions do exist when a baby is notably delayed in reaching key developmental milestones. Milestones primarily exist to alert parents and practitioners when a child is not experiencing normal cognitive or physical development. If a child's development is dramatically behind schedule and he has been diagnosed with a developmental delay, this could be a sign that he has a cognitive disability. While your baby's early speech may not be a sign that he is a genius, severe, diagnosed delays could be a sign of a problem. Get in touch with your pediatrician if you have any questions about your baby's development. Otherwise, relax in the knowledge that she is developing at her own natural pace.