• The science behind the sexy. (Toronto Star)Source: Toronto Star
From beer goggles to bacteria.
Chloe Warren

2 Mar 2017 - 10:36 AM  UPDATED 2 Mar 2017 - 2:48 PM

Dim the lights and ignite your Bunsen burner – let’s get down to the science behind the sexy.

1. The microbiome – our bacterial bunk-mates

For a long time, people weren’t all too keen on bacteria.

While it’s true that some microorganisms can cause infection and disease, many of them are harmless - and some even helpful.

Enter the modern fascination with the microbiome – that’s the assortment of bacteria that live on and inside us all the time.

While you might have heard that your microbiome can affect your digestion and immunity, did you know it’s probably affecting your hormones, too?

In humans, hormones regulate many different things, including sleep, mood, our immune systems – and our sex drive.

Amazingly, performing a fecal transplant (or ‘transpoosion’) from male to female mice has been seen to increase testosterone levels in the receptive females – which suggests that our microbiome is sex-specific. It also suggests that we might be able to modify our live-in bacterial buddies to optimise how they interact with our sex hormones.

Women on antibiotics might have noticed unusual changes in their sexual appetite.

That’s because antibiotics have the potential tointerfere with ALL of the bacteria in or bodies – not just the infection causing ones. Disruption of the microbiome in this way has been shown to decrease estrogen levels.

2. Periodic perceptions (sorry)

It’s no surprise that where a woman is in her menstrual cycle - characterised by fluctuations in sex hormones – can affect her sexual desire.

But scientists who tracked sex hormones in 33 women in heterosexual relationships also found interesting links between these levels and how attractive the women perceived men to be.

Women were found to be most attracted to their partner during the week before their period (i.e. when their levels of progesterone peaked).

However, estradiol (which peaks around two weeks after a period) predicted greater attraction to other men relative to the women’s current partner – showing that sex hormones don't just influence women’s sexual desire, but upon whom this desire is projected.

3. Seeing red

There are lots of evolutionary hints as to why the colour red is associated with sexiness.

Plenty of studies have found that dressing in red, wearing red lipstick and even just being in framed in red can alter how others perceive your attractiveness – and even competency.

In some primates, the colour red can be a sign of fertility. In human females too, vasodilation (increased blood flow to the skin) and reddening of the skin increases in response to some sex hormones.

But advertisers and fashion consultants have long been aware of these associations – meaning our perception of red as sexy has been influenced by social conditioning, too.

4. The sweet smell of genetic diversity

When it comes to choosing a mate in the animal kingdom, females need to be reassured that their baby daddy is healthy. Healthy offspring survive, healthy offspring go on to procreate, healthy offspring of healthy offspring survive – and so on.

One of the ways to ensure a baby is strong and healthy is to give it a good immune system.

The HLA is a group of genes coding for proteins which detect potential threats (viruses, bacteria) to the body. The proteins point threats out to the immune system so they can be destroyed.

The more threats an organism is capable of detecting, the better. It makes sense that animals would want to cash in on as many threat-detection mechanisms that they don’t already have from a mating partner – so that they can pass them onto their offspring.

But what’s this got to do with smell? And humans?

While scent in the animal kingdom plays a much bigger role than it does in ours, multiple studies have shown that humans can get subconscious clues about each other’s HLA fingerprint from smell alone.

The science is controversial – there aren’t any studies which show that people chose long term partners based on their scent (not exactly surprising), but there is plenty of evidence suggesting that our initial attraction to a person is influenced by the way they smell and how different their HLA fingerprint is to ours.

5. Booze-y behaviour

Whether it be from personal experience or not, we’re all very much aware that drinking alcohol can lead to somewhat silly behaviour.

It’s the same reason why we can get a bit frisky once we’ve had a few.

Scientists call it ‘alcohol myopia’ – and it means that only the most salient or obvious cues are processed before committing to a decision.

That means that we won’t necessarily dwell on the consequences of sex before actually doing it.

Scientists have also found evidence that the ‘beer goggle effect’ is real – drinking alcohol really does make you perceive others being more attractive compared to when you’re sober.


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SBS will be streaming the 2017 Sydney Gay and Lesbian Mardi Gras parade live on Saturday, March 4 on SBS On Demand, and will then air our Mardi Gras special event - with commentary from our hosts, behind-the-scenes action and exclusive interviews - on Sunday March 5. In the meantime, you can keep up with all our Mardi Gras content here.