"Studies have found that those with higher I.Q.s, for example, enjoy a longer stretch of time during which new synapses continue to proliferate" this assertion

"Studies have found that those with higher I.Q.s, for example, enjoy a longer stretch of time during which new synapses continue to proliferate" this assertion that there is empirical evidence for this hypothesis is almost certainly false. We just don't have the technology to do this experiment on human beings - the only species for which this statement can make sense. I know of some studies which have observed synapse formation in vitro, perhaps one in vivo in animals kept alive through strenuous means, but all in mice and with no simultaneous behavioral examination.