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High-school student undermines our "famine-food longevity" hypothesis, maybe

Back in 2009, I suggested that, to the extent that organic foods provide greater health benefits, this might be due to tradeoffs with reproduction. See my original post for a more-detailed explanation. Since then, I've seen at least one paper on a diet that increases both longevity and reproduction in some species, but there were no data on the timing of reproduction, which is key to our hypothesis.

This week, however, high school student Ria Chhabra and colleagues published a paper in PLoS One reporting both greater longevity and increased egg-laying at all ages, in fruit flies fed various organic foods. It's not inconceivable that some conventionally-grown produce could be so poor, nutritionally, that it would reduce both lifespan and reproduction. But their data seem inconsistent with our hypothesis that organic-vs-conventional differences were mainly differences in toxins (synthetic in conventional, natural in organic) and that natural toxins mainly acted as environmental cues, switching physiology towards longevity at the expense of reproduction.

I'd like to see this experiment repeated by a different lab, however, before drawing firm conclusions. There are a couple of strange things in their data. First, as noted in the paper, survival curves for Drosophila are usually sigmoidal, whereas theirs are more linear. Also, their peak egg-laying rate was reportedly at an age of 1 day. Other studies I've seen show essentially no egg-laying that early, with peaks at day 5 or so. See this paper or this open-access one.

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