Use to not be, but it appears to have become that way with the younger set.
I hate to burst your bubble, Its been mainstream for eons.
The Ancient Greeks weren't the only peoples to have had a mania for portraying sex acts in clay.
Between 100AD and 800AD in Northern Peru, the Moche culture production of pottery exploded.
Archaeologists have unearthed 10,000 pots. The vessels baffled scholars who tried to tackle their subject matter. Here's why: there's so much anal sex.
Explanations for their mania range from showing a form of birth control to the pots making sense of new political power structures.
In this instance, contraception isn't necessarily the driving factor behind entering through the rear. As we've seen before, a correlation between vaginal sex and pregnancy isn't always made by participants.
A pot depicting a couple engaged in anal sex while the mother breastfeeds her child points in another direction. It's possible that the Moche held similar beliefs as the people of the modern day Sambia. Semen was viewed as an important life force and this pot might suggest that they believed that receiving spunk via the mother's rectum produced milk. The sperm would be channeled through the mother's seemingly magical body to the breasts. Let's hope we never find evidence that any father's considered skipping the middle man. It's not convincing that this belief could be held among the entire population and survive outside influences over such a long time period.
The second reason - that anal sex might be a way of the need to make sense of new political power structures - isn't much more plausible. The nearby Recuay people also made sex pots in the same era but they depicted good ol' fashioned penis and vagina sex.
Their society was to some degree much more equal than the cosmopolitan Moche. This has led to the evaluation that the anal sex pots are trying to communicate the notion that "in every relationship, one partner has to suffer discomfort to give pleasure to the other." Hmm. Well, maybe. But this ignores the evidence that
anal sex can be bags of fun.