Grown up at 26?
"In every mammalian species, immediately upon reaching puberty, animals function as adults, often having offspring," says psychologist Robert Epstein, author of The Case Against Adolescence. "We call our offspring 'children' well past puberty. The trend started a hundred years ago and now extends childhood well into the twenties. The age at which Americans reach adulthood is increasing - 30 is the new 20 - and most Americans now believe a person isn't an adult until age 26."
Source: Psychology Today
Although, one has to also remember that most animals can walk (and even escape predators) within a few hours of being born. Humans are kinda useless for quite a while. Unless drool can be considered a deterrent to predators, then they are pretty much helpless.