Obesity And Longevity: It’s All About Sex
Everything in our lives ““ our life expectancy, behavior, choice of diet and even our vulnerability to obesity has to do with sex, says Professor Robert Brooks who will receive the Australian Academy of Science’s 2010 Fenner Medal at an award ceremony tomorrow.
‘We may think that the high obesity rates are a disease of wealthy nations ““ but you’ll find that the people who are most at risk for obesity are the poor women in wealthy countries and the wealthier women in poor countries,’ Professor Brooks says. ‘Although one of the reasons is that these women can afford only enough high energy food to get obese, but not enough food with high protein, we also found that far more women are obese than men.’
‘Thus gender is another cause. As these women have been found to be highly fertile, the high ability to reproduce combined with socioeconomic and educational factors play a major role in causing obesity.’
Obesity is only one facet in our lives that can be influenced by sex. Professor Brooks mentions that longevity is also associated with reproduction and the rules seem to apply broadly in nature. Species with high fertility may have a shorter lifespan than those with lower fertility.
Professor Brooks has demonstrated in his research into sex using the Australian Black Field Cricket that male crickets with good diet and high fertility call out more to attract female crickets. Although their chances of mating are higher than the other crickets, their lives are constantly threatened by predators attracted by the calls and the amount of energy they spend in making in the calls.
‘They live fast and die young’,’ he laughs. ‘This is what we call the “˜economics of reproduction’ ““ the energy and cost that we invest in sex.’
Similar factors also affect humans, for example women in countries hit by famine, he says. ‘When there’s a famine, women often stop ovulating and lose reproductive condition. For women whose bodies find a way to remain fertile, they produce more babies but tend to have shorter lives than others,’ Professor Brooks says.
‘You have to take into account the energy that they spend carrying their offspring, feeding them through their placentas and then producing milk ““ all the energy that goes into this stage can’t be spent elsewhere. Something has to give, eventually.’
Professor Rob Brooks will receive the 2010 Fenner Medal for research in biology for his outstanding achievements in changing the way scientists and the public think about the complex yet fascinating relationships between sex, death and diet. His research involves the intersection of evolution, genetics, ecology and behavior.
His presentation will be made at the Shine Dome in Canberra on Thursday 6 May 2010 at 11.15am, as part of the Academy’s annual Science at the Shine Dome meeting. Media are welcome to attend and interview participants.
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