NPR has a blog article in which they highlighted comments about a previous post of theirs on the paleo diet.
One of the highlighted comments was this:
Robert McNealy (wooddragon) wrote: The term "Evolutionary Medicine" is a bit deceptive. Diet is not really influenced by natural selection, since most of the health ailments that show up due to a bad diet show up after breeding age.
Maybe it's late and I need to get some sleep but I'm having a hard time wrapping myself around this statement.
Can someone explain what it means and tell us if it's a valid criticism of paleo?
asked bySol (5828)
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on June 25, 2012
at 01:35 PM
The idea that natural selection only plays a point up to age of reproduction makes sense when it comes to animals that spawn a bunch of offspring and then have served their purpose in life (i.e., propagation of the species). However, humans are a much more complicated species.
Mark's Daily Apple has a relevant post: http://www.marksdailyapple.com/hunter-gatherer-lifespan/#axzz1yoN5YsQS
As Mark notes, "Simply put, it suggests that male and female human longevity is necessary because of the slow, long development of human children. We aren???t like most mammals, who tend to spring forth from the womb with the ability to walk (or swim) and avoid embarrassing themselves; our infants are immobile fleshy bundles. Our children need guidance and instruction from our elders. They need support ??? the community needs material support, since the children consume resources without providing any. And both grandma and grandpa are involved in the teaching process. The emphasis here is on passing on knowledge and wisdom. They???re not just chasing little ones around.
We can???t survive on instinct alone. Our physical gifts aren???t sufficient. And we don???t pop out of the womb with knowledge and wisdom pre-installed. We come out with empty heads full of potential. We have to learn, or, more accurately, we have to be taught. And who teaches us? Experience is a stern, proven tutor, but exogenous instruction from experienced adults, parents, and grandparents ??? from society, really ??? is even more crucial. We need adults to live past reproductive age because human children are unproductive members of society for at least the first 12-15 years of their lives. They are either totally helpless babies (unable to walk, talk, and procure food), extremely annoying toddlers (now able to walk, babble, and get into trouble), or haughty mischief-making pre-teens. And all the while, they are students. They???re learning, watching, observing, and filling their big empty brains with the knowledge and experience that will help them be productive, resourceful adults. But they couldn???t do that if all the adults were dying off by age thirty."
on June 25, 2012
at 02:09 PM
Maybe I'm mistaken, but can't that quote be used to support the paleo diet? Some people want to critique the paleo diet by claiming that there has been enough time for humans to evolve to thrive on grains. But evolution operates through both time and selective pressure. Because humans can survive on grains until reproductive age (and then suffer the health consequences later), there is very little selective pressure, making it less likely that humans have evolved to thrive on grains.
I'm no scientist, but I seem to remember Matt Lalonde explaining this on Cris Kressor's podcast.
on June 25, 2012
at 12:39 PM
This study, albeit small, suggests otherwise: http://www.newscientist.com/article/dn2994
Since Mom's diet affects the fetus and the quality of breast milk, it would seem that diet would create a larger impact than the statement you quoted implies. I would also surmise that Dad's diet would affect sperm quality and motility, thus impacting what is passed on to his offspring. I'll check for other studies when I get a chance this afternoon.
on July 10, 2012
at 11:34 PM
My N=1 pretty much proved to me that this isn't true. I managed to render myself infertile by my mid 20's via diet, but with the removal of grain, and addition of red meat and upping the saturated fat in my early 30's, seem to have brought it back.
on June 25, 2012
at 01:48 PM
I will risk exposing my own ignorance with this response, but I've never really understood this argument to begin with. In times when food was not plentiful, it seems to me that the ability to exploit a new food source would help one survive/thrive better than others even up to child bearing age. Also, it seems better nutrition would increase fertility, reduce miscarriage, reduce infant mortality, etc. Sure, today, health problems related to diet may not affect these things, but I can't imagine the same was true for hunter gatherers during our evolution. What am I missing?
on April 09, 2013
at 11:05 AM
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