I read that the Greek men did not have anal sex with the pubescent boys they took as lovers, that they instead inserted their penis between their thighs. There is even a term for that kind of sexual contact, though I can’t remember what it is.
As far as people having sex with prepubescent children, I doubt it was much more common as the frequency is going to be limited by the number of people who can be sexually aroused by someone who doesn’t show secondary sexual characteristics. Even if having sex with 8 year olds was accepted and even expected I seriously doubt I would be able to - it’s not societies rules that are holding me back, it’s the nature of my sex drive and what makes it kick in.
To get an idea about how much more or less common pedophilia was we need to understand what prevents the portion of the population that wants to have sex with children from doing so, and decide how those factors have changed over the years. I think there are three things that stop pedophiles from acting upon their desires:
Societies view of such acts and the potential for punishment
The pedophile’s internal morality
The availability of victims
Number 1 is a big factor in modern times. Child molestation is seen as one of the worst crimes imaginable in modern times - most people would rank it above murder and forcible rape as far as heinousness goes. The punishment meted out by our legal system is not the worst there is but the probability of getting caught is probably higher now than it has ever been since most people teach our children enough about the dangers of sexual predators that they would tell someone, and even in cases where the child’s family is passively or even actively condoning the molestation children are generally required by law to spend time with adults outside the family who are trained to see signs of abuse and report it.
Number 2 is a difficult factor to measure. Are pedophiles of today more or less likely to think of what they want to do as wrong and/or recognize the harmful effects acting out their fantasies would have on the victim? One might argue that since we are living in a less religious society that the pedophile would be less likely to fear divine retribution for their acts, but on the other hand a modern man also has a better understanding of the harmful effects of child molestation and the subject is talked about in the open as opposed to being something that you just don’t talk about, so a modern pedophile may have a greater understanding of the wrongness of said acts. This one is a toss-up in my opinion.
Number 3 is a factor where I’m fairly sure modern society is doing a better job of limiting molestation. We are much more protective of our children these days, it’s a lot less common for people to allow their children to spend time alone with adults they do not know well. This doesn’t stop molestation by family members or trusted family friends, but it does cut back on other forms of molestation.
So on two out of three of these factors I think we are doing a better job of stopping child molestation. I think that child molestation is probably a lot less common than it was in the past, and not just the distant past. Since people who were molested as children seem to be more likely to molest as adults there was probably also a larger pool of potential pedophiles in the past before you take into account the limiting factors.