Women’s bodies are extraordinary—few other species have such a difference in body composition between males and females. Amanda Smith takes a look at why men’s and women’s bodies are so different, and asks why so many women have fraught relationships with their curves.

As a teenager and young woman, Taryn Brumfitt would sometimes try the latest diet, or complain about the size of her thighs.

With the birth of each of her three children, however, she became more and more unhappy about how she looked: 'I would say things to myself like, "Ugh, you're disgusting and you're fat and you're ugly, you're gross.” I felt alone at the time but now I know that I'm not alone.’

This thirty-something Adelaide mum has now become an advocate for positive body image, but for years struggled with her own perception that her body was disgusting.

Fat gets a really bad press, but actually it's a wonderful and very complex tissue and it's saved our ancestors many, many times. David Bainbridge, biologist and zoologist

'Lots of women talk like this about themselves, or give themselves a really hard time before they walk out of the house, or on the beach wearing bathers they sit down and they feel their tummy scrunch up with rolls,’ she says. ‘This is a very, very familiar story.’

That familiar story intrigues and perplexes UK reproductive biologist and zoologist David Bainbridge.

'It just seems that women think about their bodies in much more complicated ways than men do, and that's kind of bewildering when you're a man,’ he says.

Apart from mere curiosity, Bainbridge has a professional interest: 'I'd always thought it was strange that humans are the one species where our females are curvy—you don't really see that in other species'.

He addresses that question in his book: Curvology: The Origins and Power of Female Body Shape.

At birth, he writes, human babies are around 12 per cent fat by weight. Throughout childhood that average fat level remains consistent between boys and girls. However, by the end of puberty girls of average weight will have have a body composition of 24 to 30 per cent fat, while boys hardly change at all.

‘There is a very spectacular stacking on of adipose tissue during those years, and of course that's what makes women such a distinctive shape compared to men,' says Bainbridge. 'Men have got the same as most animals, it's women that are absolutely exceptional.’

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Anatomically as well as physiologically, human females are unusual. For example, women have a very large pelvis compared to other primates. Bainbridge says that when we started walking upright, the shape of the human pelvis departed from that of other primates. The female pelvis then changed even further in order to be able to give birth to babies with large human brains.

Then there's the extra adipose tissue on women’s hips, buttocks and thighs. Fat is not something that we tend to speak positively about in this day and age, but in an evolutionary sense, Bainbridge is keen to sing its praises.

'Fat gets a really bad press, but actually it's a wonderful and very complex tissue and it's saved our ancestors many, many times,’ he says.

While visceral fat around your belly is understood to contribute to heart disease and diabetes, according to Bainbridge fat on the buttocks and thighs may actually be protective against those diseases.

Yet when it comes to weight loss, female buttock and thigh fat is often regarded as 'stubborn'. This gluteofemoral fat, however, is a resource is there to be called upon after a woman has had a child and needs up to 750 extra calories a day in order to breastfeed.

‘That's suddenly when that fat in the buttocks and the thighs gets mobilised into the bloodstream, into the breast milk, and straight into the baby,’ says Bainbridge. ‘This stuff is really waiting there for breastfeeding to drive that baby brain growth.’

In Taryn Brumfitt’s case, it was her children that made her rethink her poor body image. As her loathing of her body intensified, she even got to the point of booking surgery, before having an epiphany while watching her daughter play.

'I thought to myself, how am I going to teach Michaela to love her body if I can't love my body? What sort of role model am I going to be for her if I have surgery? I decided against the surgery at that point,’ she says.

Instead, Brumfitt entered a fitness modelling competition, training for months before walking onstage in nothing but a bikini and high heels. In most self-transformation narratives, that would have been the end of the story, but that’s not how it was for Brumfitt.

‘I did this non-traditional before and after photo and posted that on social media,’ she says.

In the first image, taken during competition, Brumfitt is slender and taut. In the second, taken afterwards, she has a much fuller and curvier body.

'I just did it because I thought it might help some people, but it had millions of hits and likes and all of that stuff. I had the US media ringing me, Good Morning America and Today, saying, "Can we interview you? We want to talk to you about this photograph.”

'No one could believe that a woman could love her body afterwards. It really shocked a lot of people.'

Curve theory Sunday 22 March 2015 Listen to the full episode of The Body Sphere to discover more about the evolutionary origins of the shape of women's bodies. More This [series episode segment] has image, and transcript

It also brought criticism, however, and the accusation that she was promoting obesity, a charge she refutes: 'I was healthier in that after photograph because I was a more balanced person.

'During the training and when I was on stage with that body, all I could think about was a gym session or food to eat, I wasn't a balanced human being, I was so self-obsessed to look a certain way.

'My children would say, "Hey, Mum, could we go to the park?" I'd be like, "I will, but I've got to go do half a day at the gym first and then obsess about my food for the next 24 hours.”’

Why do so many women have a negative or distorted image of their body? David Bainbridge believes constant exposure to images of other bodies is a major factor.

'In the evolutionary sense, that's a completely unnatural thing to have happen,' he says. 'Ten thousand years ago you probably knew about 50 women and probably never saw any others and you certainly never saw any images of them.

‘The way that we perceive our bodies is so utterly different, especially over the last 150 years.'

For her part, Taryn Brumfitt is working to foster positive body image in girls.

'When girls say, "Do I look pretty in this dress?" I say, "What are you going to do in that dress?" So it becomes less about what they look like, and more about their achievements and what they're going to do,’ she says.

Brumfitt believes the advice is good for adult women too: 'It's like training, it's like exercising, it's like climbing a mountain—do that because it feels good and the endorphins are flowing through your body; don't exercise just to count calories. We need to focus more on how we feel and less about how we look.’

Focusing on the physical, The Body Sphere is about the ways we use our bodies to create and compete, nurture and abuse, display and conceal.

