In Sparta, girls married at around the age of 18 or even a little later, and the boys certainly not before their 20th year, most often between the ages of 25 and 30. This had everything to do with the social organization of Sparta and her system of age classes with collectively imposed obligations on the young and regulation of the private lives of citizens. An unforeseen effect of this system was probably that in Sparta in the Archaic period, in contrast to the rest of Greece, the citizen population did not rise and perhaps had already begun to decline very slowly. The unusually high age of marriage may have had the consequence that the average number of 5.8 live births per woman, which we think were required to sustain population levels in a pre-modern society such as ancient Greece, could not always be attained.
Sparta is an example of a community with a social organization that in the long run handicapped its demographic development. If, as has been presumed sometimes, Dark
Age Greek communities other than Sparta also adhered to the model of an age class society, their populations should probably have stagnated as well, until in the 9th and 8th centuries BC primitive egalitarian structure broke down owing to rising inequalities in property and wealth. Such inequalities caused lineage and property to become more important than marriageable age, and consequently communities permitted marriages at a younger age. This in its turn led to rising birth rates everywhere, except where the age class society was maintained at any cost, as was the case in Sparta. This is, however, a modern reconstruction and is by no means historically proven. But it is a reconstruction that to some extent offers a logical connection between the fragments of historical data that we have. It is a model that, moreover, offers an explanation for the fact that, again in historical Sparta and in Dorian Crete, homosexual relations between boys and unmarried young men were recognized by the state and even encouraged. Perhaps, this “institutionalized” homosexuality also had some roots in ancient initiation practices for boys at puberty, but in historical times it certainly served as a sexual substitute for postponed marriage. In other Greek states, homosexual relations—the normal Greek term was paiderasteia or pederasty—were common as well, but as far as we know they were not institutionalized in the way they were in Sparta (and among the aristocracies of Dorian Crete). In Athens and other cities, since the 6th century BC at the latest, pederasty played an important role in the lives of the aristocratic elites (of the common people we know in general much less in this and other respects). For elite men (not women!), a late age of marriage—the age of 30 was often seen as normal—played a part here too, but probably more important was the idealization of the young male body, fostered by the common practice of athletics in the nude. For boys of free citizen status, the age at which pederastic relationships were allowed was 18 in Athens and most probably elsewhere too—a Greek pederast should not be seen as a pedophile (although slave boys were never protected by the law). In addition, a certain admiration for and hence imitation of Spartan customs probably accounts for the popularity of pederasty in aristocratic circles in the classical age as well. In any case, since the Archaic age, pederasty remained an accepted phenomenon in Greek culture and was often idealized in poetry, philosophy, and art, in marked contrast to many other cultures in Eurasia.