Jesse Bering

Stimulating conversation … popular-science writer and psychologist Jesse Bering doesn't like things left unsaid. Photo: Mitchell Bach

Jesse Bering has a big problem with the elephant in the room. Not, however, with a chimpanzee in his bed or a gorilla being serenaded by musicians, but more on them later.

Bering, a developmental psychologist and popular-science writer, has made his name engaging with some of the more vexing influences on the human condition - namely religion, sexuality and, more recently, sexual perversion.

''I don't like things unspoken,'' he says. ''To me, having these elephants in the room is the most uncomfortable thing, and it's always been that way.''

The author of The Belief Instinct and Why Is the Penis Shaped Like That? can not only draw a connection between his seemingly disparate fields of research, but also between his coolly rational treatment of these topics and the personal experiences that piqued his curiosity in them.

''I've always felt an affinity with the underdog - I guess being gay and shy and being an introvert,'' he says.

''Growing up, I never trusted the majority. I always suspected that whenever there's consensus, there's probably something wrong.''

Bering will visit Sydney this month, from his home in upstate New York, to speak at the Festival of Dangerous Ideas, with the bold assertion ''We Are All Sexual Perverts''.

He understands, of course, that most people's response to this will be ''speak for yourself!'', but he calmly defends his position. ''I think if we look critically, unmercifully enough at our own arousal patterns, we'll all find something that sets us apart from the vast majority,'' he says. ''It might not be as significant as a full-blown paraphilia, but in terms of our empirically measurable arousal responses and what turns us on and off, I think we've all got something that somebody else would consider us to be a pervert.''

Some of his candid investigations can be found in ''the penis book'', which includes essays on zoophilia, paedophilia, foot fetishists and rubber enthusiasts alongside considerations on genitalia, cannibalism, masturbation and even suicide. They're all delivered with the same combination of scientific gravitas and sly humour he exercises in conversation.

Did you know, for example, that the cultural eroticisation of the female foot has, historically, coincided with the presence of sexually transmitted epidemics? Or that Italian decadent poet Gabriele d'Annunzio is said to have had a rib removed to aid the act of auto-fellatio? Or did you ever wonder what will become of the creativity of today's teenagers, who need not exercise any erotic mental representational skills in this age of internet pornography?

''There are probably a disproportionate number of people in their 20s that have never masturbated without using porn, which is bizarre when you think about it,'' he says. ''Nobody really knows the long-term consequences of this.''

Bering arrived at his current preoccupations via an ''atypical, unusual, strange career'', which has included a serious commitment to primatology, a tenured professorship in psychology and directorship of the Institute of Cognition and Culture at Queens University Belfast, before leaping with some trepidation into a full-time literary career.

Surprisingly, he describes himself as unfocused at school; he was distracted by his closeted homosexuality and the breakdown of his parents' marriage. But a move to Florida from Ohio after graduation led to voluntary work at a chimpanzee sanctuary, where he became the care giver for a chimp named Noelle, with whom he spent every night.

''I grew up in a sort of religious environment in the middle of Ohio and was never exposed in high school, for example, to evolutionary theory,'' he says. ''Interacting with these chimps and seeing their physical similarities, not to mention their behavioural similarities, hit me at the time in my life when I needed that philosophical world view.''

Bering launched into an academic career specialising in primate cognition, working first with a former circus gorilla, King, who had ''a very storied life''. King had been housed alone and consequently developed behavioural problems, including repetitive rocking and compulsive regurgitation. ''My whole idealistic plan was to try to make him more comfortable, eliminate some of these problem behaviours, so I invited these music therapists to come and sing him songs, interact with him with instruments and play him different types of music,'' he says, dismissing the plan now as ''silly''. (Both Noelle - who he visited recently - and King are doing well, Bering says.)

When it came time to undertake a PhD, Bering found himself back in Florida to be with his mother, who was losing a seven-year battle with cancer. Now engaged in many conversations about dying and the afterlife, and having acquired a taste for existential literature - ''a lot of Camus and Sartre and Dostoevsky and Gide and Genet'' - Bering abandoned primate cognition and began a series of investigations that would take him to academic postings in Arkansas and Belfast, and were ultimately summed up in The Belief Instinct, in which he argues that the tendency to believe in gods gave humans an early evolutionary advantage they no longer require. Three years after arriving at Queens University, however, he felt burnt out. ''I had exhausted my interest in religion - I felt like I'd put the story together in a way that made sense to me.''

The subject of sex appeared to shimmer with possibility, as did a return to the US. Bering's next book, due next year, will be devoted to paraphilias, of which an astonishing 547 are formally classified. ''A fetish is … something that will facilitate sexual arousal but you're not dependent on that for your orgasm,'' Bering says. ''[For] a paraphilia, you need a particular, very well-defined, circumscribed trigger or erotic target to have any kind of satisfactory sexual response.'' Lesser-known focuses of erotic interest include forniphilia (turning a human into a piece of furniture) and agalmatophilia (statues and mannequins).

At a personal level, Bering's newer research has inspired an entirely fresh curiosity about female sexuality (''growing up gay, I had to pretend I was interested in women when I felt no arousal, so I think I avoided it for many personal reasons''), as well as incurring the wrath of members of the transsexual community (''an area I'm very worried about touching with a 10-foot pole'') and asexuals (''I doubted their existence''). In his line of work, there is always going to be, he says, a ''third rail'', or highly charged topic: ''Probably more than the God book, it's going to be interesting to see how that pans out.''

He understands the tension created when the scientific community - with its theories and taxonomies - inevitably runs up against sexual minorities for whom these are socio-political and personal issues, but finds solace in intellectualisation. Bering says: ''I can't construct a reality that, simply because it's palatable to them, I'm going to endorse.

''I might not always be right about what the truth is, but getting closer to that or making a concerted effort to get at that - and doing it in a way that our emotions don't cloud that attempt - is humane. And that can only be a good thing.''

Jesse Bering will present ''We Are All Sexual Perverts'' at the Festival of Dangerous Ideas and take part in the panel ''How to Solve All the World's Problems in an Hour'', Sydney Opera House, September 30.

Paraphilias 101

Thalpotentiginy A psychological term applied to sexual arousal from heat or warm weather.

Agalmatophilia Statues, dolls and mannequins.

Dendrophilia (also arborphilia or dendrophily) Trees.

Formicophilia The desire to be crawled upon or nibbled by insects, such as ants.

Macrophilia Giants.

Mechaphilia (also mechanophilia) Machines such as bicycles, automobiles, helicopters and aeroplanes.

Plushophilia Stuffed animal toys.