Male crickets need to load up on carbs, and female crickets do better on their version of the Atkins diet. That鈥檚 the conclusion of a new insect study that raises the possibility that humans male and females may also have different dietary requirements.
Evolutionary biologist of the University of New South Wales in Sydney, Australia, and colleagues measured life span and reproduction in hundreds of male and female black field crickets (Teleogryllus commodus).
The insects were all individually housed, and fed one of a range of diets. The male鈥檚 houses were fitted with microphones.
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The crickets lived longest when fed a diet of eight parts carbohydrate to one part protein 鈥� up to 55 days for females, and up to 70 days for males.
The same high carbohydrate, low protein diet also led to the greatest potential for reproductive success for the males, as judged by the increased duration of their night-time mating chirps or 鈥渁dvertisement calls鈥�. Listen to crickets singing
But females laid far more eggs if they consumed a diet far higher in protein, with a ratio one part carbohydrate to one part protein.
Energy v eggs
鈥淚f you are female on the high-protein diet, you are producing about 300 eggs over a lifetime, even though your lifespan is only 40 days. On a high-carb diet, you are making only about one hundred,鈥� says team member , director of the Evolution and Ecology Research Centre at the university.
The most likely explanation for the sex differences is that male crickets need to carbo-load to provide easily accessible calories for energy for calling. Females, on the other hand, need protein to make eggs.
Despite the clear reproductive advantage for males and female crickets to consume different diets, in a surprise finding, the team also found that when given a choice, both sexes opt for the same diet 鈥� eating roughly three times as much carbs as proteins.
Pregnancy advice
It seems that what is best for female reproduction 鈥� a high protein diet 鈥� is sacrificed by evolution for what is best for males.
鈥淚t suggests that the genes for diet choice can鈥檛 be segregated between the two sexes, so that we are lumbered with a rather poor compromise,鈥� says of the University of Melbourne, also in Australia.
But it could still be possible to alter human diet to maximise human life spans and reproductive success, suggest Brooks.
鈥淒uring pregnancy women get told which micronutrients to eat. But they may also benefit if they ate different amounts of proteins and carbohydrates,鈥� he says. 鈥淲e need to understand the ways our evolutionary history has shaped our diet preferences and how they might lead us astray鈥�.
Journal reference: (DOI: 10.1016/j.cub.2008.06.059)
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