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July 10, 2009
Hungry For Life
Glenn links another calorie restriction study, but I'm skeptical the benefits will extend to humans, even if we develop drugs based on these diets. These studies are all of things that live much shorter lives than we do. Most likely, the diet causes them to express genes that we express regardless of our diet, such as intracellular antioxidant genes that slow down the rate of mitochondrial replication error and other DNA repair mechanisms . This confers an evolutionary advantage for them, because they will survive through lean times and be able to reproduce again when conditions are better; species that did not have this tendency would tend to die out in those lean times. You may have noticed humans have somewhat unusual longevity; there are a few mammals that live longer than we do, but not many. We are also unique in another way: we are one of the few species that survives well past reproductive viability (i.e., post-menopause). We evolved this way because it maximizes the benefit of our primary, peculiar advantage: our brains. We learn, and pass what we learn on to our young. This behavior is so valuable to the species that evolution has a use for us even after we can't reproduce -- so it's likely we are already maxing out this kind of gene expression. I'm as transhumanist as anyone, but I would be very surprised if the benefit was more than 1-2% in humans. Given the pre-existing evolutionary pressure to maximize human lifespan, I don't think we will see significant gene-based extension of human life span until we have the processing power to model protein folding such that we can design artificial genes to splice into ourselves, picking up the design process where Nature left off. posted by Dave on 07.10.09 at 03:55 PM
Comments
Good point. It does seem like it's Nature's way of hibernating till better times, when reproduction is more likely to succeed. Talldave · July 11, 2009 03:35 PM Two different causes of infertility -- starvation diet does not allow the body to produce the hormones necessary for reproduction. Olympic level women athletes aren't on starvation diets, but they are consuming so many calories, their bodies are producing altered levels of hormones. Anyone on a starvation diet isn't going to be running a mile, much less at some record-breaking speed. Although it being nature's way of waiting 'til better times fits both scenarios. One burns a lot more calories fighting and running from enemies, for example. Donna B. · July 11, 2009 03:52 PM Actually, some major athletes do go on near-starvation diets. It's known as a "cutting cycle" in bodybuilding. I don't know if excess calories would produce infertility. I suspect not though; it's telling your body "Food is plentiful! Great time to make babies!" Talldave · July 11, 2009 07:53 PM I meant that not enough calories can cause infertility. Donna B. · July 11, 2009 09:33 PM Post a comment
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It should be noted that people and animals on restricted calorie diets are usually sterile. Women don't ovulate, and mens' sperm production crashes. This has been well known among Olympic level women atheletes for decades.