פירוש על קידושין 59:1

The Beraisa taught: to teach him Torah. From where do we know this? That it says in the Pasuk: That you should teach your sons. If someone was not taught by his father, he should teach himself, as the Pasuk says: and you should learn. How do I know the mother is not obligated to teach Torah?... Since the word “you shall teach” can also be written “you shall learn”: those who are required to learn torah are required to teach torah; those who are not required to learn are not required to teach. How do I know that she doesn't have an obligation to teach torah to herself? Since the word “you shall teach” can also be written “you shall learn”: those whom others are required to teach are required to teach themselves; those whom others are not required to teach are not required to teach themselves. A woman does not have to learn Torah because no one has to teach her. And where do we know this? Because it says in the Pasuk your sons, and not your daughters. The Rabbanan taught: If he can learn OR his son, he comes before his son. Rabbi Yehuda says:If your son is an interested person, smart, and has a good memory, then your son comes before you.

Here we can get a sense of why the rabbis urge men (boys) to marry so early—to ward off “Satan.” This is probably a way of expressing the sexual urge. Unmarried boys over the age of puberty will almost certainly either masturbate or engage in illicit sex, both activities the rabbis did not condone. To prevent this, it would be best to marry as young as 14. But again, this does not mean that people actually did so.

This source debates whether men should marry between the ages of 16-22 or 18-24. Note that these ages are slightly older than those above.