True Story: The first book ever printed was the Gutenberg bible. The second was porn.

We're no archaeologists, but we'll bet porn goes back even further, and that if you decode the hieroglyphs on some Pharaoh's tomb you'll find plenty of naughty bits mixed in with all the prayers and poems about the deceased's prowess in battle.

But today in our on-demand digital age, when porn is available almost instantly anywhere through devices that fit in a coat pocket, when virtual reality porn is the entertainment industry's hottest niche, our obsession with porn may be starting to catching up with us. A new study of men with a stated preference for pornography over The Real Thing shows them likely unable to perform sexually when the opportunity presents itself. These men are more likely to suffer from dysfunction and are less likely to be satisfied with sexual intercourse.

The Naval Medical Center in San Diego surveyed 312 men, aged 20 to 40, who visited a San Diego urology clinic for treatment. Despite only 3.4 percent of the men saying they preferred masturbating to pornography over sexual intercourse, the results betrayed a statistical relationship between porn addiction and sexual dysfunction.

Regular watchers of porn, like regular users of narcotics, find that their tolerance is increased – it takes more and more of the product to get the same results. The real world, it seems, just can't keep up with a pornhound's demand. It certainly doesn't help when porn is legitimately, officially, addicting.

"Sexual behavior activates the same 'reward system' circuitry in the brain as addictive drugs, such as cocaine and methamphetamines, which can result in self-reinforcing activity, or recurrent behaviors," said lead researcher Dr. Matthew Christman.

"Internet pornography, specifically, has been shown to be a supernormal stimulus of this circuitry, which may be due to the ability to continuously and instantaneously self-select novel and more sexually arousing images," he added.

Another problem is the anxiety that befalls porn aficionados when they step into the world of real sex and realize they cannot do all the things that porn stars do on the screen. “Kids,” the disclaimer ought to read, “these people are trained professionals. Do not try this at home.”

"The rates of organic causes of erectile dysfunction in this age cohort are extremely low, so the increase in erectile dysfunction that we have seen over time for this group needs to be explained," Christman said. "We believe that pornography use may be one piece to that puzzle. Our data does not suggest that it is the only explanation, however."

Fortunately, the effects of too much porn viewing on men appears to be reversible. Some reports have shown that sexual function can improve if an affected man stops viewing pornography.

The research was presented at the American Urological Association's 2017 meeting, in Boston.