The reason some women love spanking so much has nothing to do with Fifty Shades of Grey.

The erotic act of spanking predates the Fifty Shades phenomenon by centuries. One need not look any further than Ancient Rome circa 800 BC.

The famous Tomb of the Floggings features frescoes depicting a naked woman bent over, while two men spank her from behind. From Ancient Egypt, to tribal drawings, to the Kama Sutra, to Victorian era erotica, the sadomasochistic act has been explored and represented, fascinating men and women alike.

This week on The Recap, we discussed the – er – ins and outs of Fifty Shades Darker. Post continues… 

In a study published this year titled “Sensual, Erotic, ad Sexual Behaviours of Women,” published in the Archives if Sexual Behaviour, researchers surveyed 1,580 women from all over the world. It was determined that 95 per cent of all participants enjoyed being spanked, and ranked the practice third out of 126 sexual behaviours.

So, why is the act being slapped on the butt by a hand or foreign object, a source of pleasure for so many women? What’s the psychology behind it? Wendy Strgar writes for The Huffington Post that the relationship between pain and pleasure in human sexuality is “as profound as it is complex”.

“It is a polarity that lives in each of us and deserves our curiosity… love, sex, pain and violence all stimulate the release of similar chemicals and hormones in the human body. Endorphins that are released in painful experiences are often perceived as pleasurable,” she says.

Biologically, she says spanking can release epinephrine and norepinephrine - both of which are pain chemicals, but can elicit a pleasurable 'rush'. Strgar says that when it comes to sex, pleasure and pain may be "one in the same" using examples of the runner's high and the complex "facial expressions during orgasmic release" - which, without context, could be mistake for pain.

Strgar also argues that the themes of sexual dominance and submission run deep within human sexuality, and have underpinned sexual rituals since the beginning of time. Dr. Rebecca Plante has an additional theory about why men and women enjoy erotic spanking. Simply, it feels good.

"You're talking about this fairly well-protected muscular region of the body that's right at the base of the spine, where there are quite a bit of nerves, so it's sensitive," she told Broadly.

Dr Gloria Brame agrees, "I think it has more to do with the delightful sting and the delightful warmth and the delightful vibrations that it sends through the whole region," she says.

The part of the body where most people enjoy being smacked is a tender zone that stimulates blood flow and physiologically arouses the neighbouring genitals. It makes sense that the person being spanked would find it arousing. Of course, not everyone enjoys this practice, nor should they feel compelled to.