Several months back, I wrote a paper on some ideas of mine, hoping to get it published in a refereed scientific journal. For various reasons, that didn’t work out. However, a site that exists in order to publish scientific articles, “an open access online science publishing platform that employs open post-publication peer review”, The Winnower, has allowed me to publish it: Is the response to calorie restriction purposeful? A challenge to life history theory.
The crux of the article is this: calorie restriction (CR) reliably extends lifespan in virtually all animals tested. Yet how it does so is debated. One school of thought holds that, since growth and longevity are negatively related, the mere cessation of growth causes a decrease in aging. If this is the case, then the response to CR is not purposeful, being merely an artefact (we might say) of growth cessation.
However, another school of thought holds that organisms have been shaped by evolution to respond to periods of less food or even outright famine by allocating resources to anti-aging repair, delaying fertility, strengthening antioxidant defenses, and so on. If this is the case, an organism’s response to CR is purposeful.
Life history theory holds that organisms respond to their environments in such a way as to maximize implicit fitness, that is, to have the maximum number of viable offspring. Life history theory would imply that less food in the environment would produce a response leading to a change in life history strategy. And in fact, CR produces changes that look very much like a change in life history strategy, for instance fewer offspring, delayed fertility, greater anti-aging defenses.
Depending on whether the response to calorie restriction is purposeful or not, then either life history theory or the “quasi-program” theory of aging may need to be modified.
This may be a lot of hooey on my part. But the more I thought about it the more I thought that something had to give, so there it is.