mismatch disease

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May 6, 2014 by scratchtype1

Earlier this year, I read Daniel Lieberman’s book, The Story of the Human Body and found it a bit dry but mostly good reading. I might quibble some about his characterization of type 2 diabetes being a mismatch disease or at least how much it is one…

Wait, you say. What’s a mismatch disease? It’s one of the important ideas in the book, the idea that it’s possible for a species to become mismatched to its environment if the environment changes. Maybe that’s not surprising, it’s one of the ideas of evolution, that changes in the environment will often cause species to adapt over time to become better matched to their environments. Lieberman argues that type 2 diabetes is a result of mismatch that stems from the fact we’ve now developed a food environment of lots of quick, easily-ingested carbohydrate and a lifestyle environment where we don’t have to labor much physically to obtain our food. This puts a greater strain on the endocrine system our species evolved and this helps to drive the increasing rate of type 2 diabetes that we are now seeing in the world.

I’m not entirely sure if all cases of type 2 diabetes are caused by this. I suspect there has likely always been at least some level of type 2 diabetics in the human population, but that probably most of those who did become type 2 diabetic didn’t do so until after their years of reproductive capability were by them. But that would mean it was a disease just on or outside the margins of having significant enough effect on reproduction, and it’s maybe even possible that having some susceptibility to type 2 diabetes could offer some level of reproductive fitness or survival fitness while one is able to reproduce. That’s only hypothesis of course, but as long as it isn’t falsified, is worth considering.

Anyhow, I’ve been thinking in other lines about this idea of mismatch, in particular with regard to how shoe-wearing has become so dominant in most societies with enough affluence. Why is it? Why have we developed a culture where we stick kids in shoes as soon as possible almost? I’ve begun to think that there is an instinct in us that has helped to drive it, and it’s a very basic instinct just as much as our instincts in a carbohydrate-rich environment have helped to drive the rise in type 2 diabetes.

It’s fairly uncontroversial (although potentially wrong and perhaps one day could be falsified by as yet unknown evidence) that human beings crave sweet things. It seems that this is a good instinct in an environment where there aren’t many sweets, if you’re living in such an environment, you take any chance you can get to consume easy carbs and have energy to do all that you need to do to survive and reproduce. But maybe that’s not such a great instinct to have nowadays and as a result, people tend to eat too many sweet and easy carbs.

Now here’s my thinking about feet. Consider that crucial period of human evolution, when we were persistence hunters, and we used our bare feet to chase down large prey. For that reason, our feet developed tremendous sensitivity with which to evaluate what was underfoot and also protect those feet from injury. Injuring the feet might have been our ancestors’ worst nightmare. One thing I’ve noticed is that just because I go around barefoot a lot now and have considerably tougher plantar skin than most people, I still think constantly about possible dangers and ways to injure my feet. Another thing I’ve noticed is that when people hear of the concept of running barefoot for the first time, their first instinctive reaction is about scenarios of injuring the feet — broken glass! Sharp rocks! Its observations like those that make me think a protect-the-feet instinct is deeply wired into all of us.

Now if I recall correctly from Lieberman’s book and it seems to also be supported by a couple of links I googled, the first human footwear was developed around 40 to 45,000 years ago. The oldest surviving footwear that’s been recovered is around 10,000 years old. Persistence hunting itself showed up around 2,000,000 years ago, so footwear is still just an eyeblink on the time scale. But anyhow, once footwear became easily mass-produced and cheaply available, it’s really no wonder that nearly continuous shoe-wearing took over and has now taken over so completely that many of us today don’t even have memories of spending prolonged childhood periods barefoot. A little side-story, some weeks ago, I was hiking in Cheslen Preserve and encountered a couple of horse-riders. We talked for a few minutes with one of the subjects being about me being barefoot. They were an older couple, in their 60s or 70s, and I talked about how much I enjoyed the sensation of the ground under my bare feet. The woman, who had grown up in Alabama, ended up recalling the fact that when she was a youngster, she spent her whole summers barefoot except for church. That contrasted starkly with me. I don’t have childhood memories of being barefoot except for when I was at the beach or at the swimming pool. Other than that, if I went outside to play, I had to wear shoes.

So my basic contention is that we have a deeply-wired instinct to protect our feet and this pairs up with the laziness instinct that we all possess. It’s important to understand that laziness can offer survival benefits, it’s important to do enough to survive, but it’s also important not to expend too much. When our brains and instincts encounter the cost-benefit analysis of footwear, it’s maybe not surprising that so many think that shoes are the correct choice. Wearing shoes helps to minimize scraping or cutting the feet, and we’re instinctively guarded against that. That’s an immediate benefit, much like eating something sweet immediately awards us with wonderful flavor and feelings. We can do those short-term analyses quite well. Long-term analyses we’re not so good at. We’re not immediately cognizant of how even slightly elevated heels alter our posture or how wearing cushioned soles affect our gait, causing us to walk unnaturally. We’re also immediately aware of how shoes serve as fashion choices in our societies and it’s probably not controversial that there is an emphasis on how women’s shoes are used with indications of sexuality and physical attractiveness, but the facts of how forcing the feet into such unnatural positions can cause deformities such as corns and bunions and hammer toes, or that high heels can shorten the Achilles tendon will get little immediate thought and usually only get immediate thought once those problems arise, long after the initial choices were made years before.

Plus also at this time wearing shoes immediately keeps you from standing out from the crowd in a way that can be uncomfortable. As it is now, most of us are only aware of the immediate benefits of nearly-continuous shoe wearing and only a few are aware of the longer-term effects. Again this parallels the rise of type 2 diabetes, where human beings have great difficulty seeing how the instinctive choices they make lead to long-term drawbacks.

The other item that I would like to bring up in regard to this and will perhaps go into greater depth for another blog entry is that perhaps all this shoe-wearing is impeding how many of us develop into runners. Perhaps I overestimate it because of my own experience and story, but I really didn’t fall in love with running and feel like I became a runner until I began to run barefoot. Without all the feedback from the soles of my feet, I didn’t realize just how human it felt to run. For me, that was critical, but am willing to concede it might not be necessary in everyone, although I would still urge those that run in shoes and love running at least consider the idea of trying some short distances of barefoot running, and seeing if they feel something even greater in doing so. They’ll never know if they don’t try.

But I wonder how much did wearing shoes as a kid keep me away from running? Is it possible that if I had grown up barefoot I might have always run some throughout my life? Is it possible that if I had been a barefoot runner, I would have been able to continue to run during 2011 to 2013 while my heart grieved and healed? There’s no way of knowing certain answers to those questions.

Apart from that, running has been going really well right now for me. I haven’t had any more upper respiratory infections and the weather has been much more favorable. I ran consecutive weeks of 36.6, 32.4, and 25.4 miles, first time ever I’ve run 25+ miles for 3 straight weeks. I’m not feeling any aches or twinges. Most of those miles have been easy or recovery pace, with a little bit of fartlek, one session of 3 hill repeats, some 8 to 10 second hill sprints, and 8 mailbox dashes as I call them, when I run from a neighbor’s mailbox to my home mailbox almost as fast as I can. After this morning’s run, I’ve run 25 consecutive days and 111.5 miles in that time. 33.1 of those miles have been barefoot and the other 78.4 in the Xeros. I’d like get to where I’m doing about half my miles barefoot.

The funny thing is right now is I don’t know if I’m really training for any sort of race. I’m running just because I’m enjoying it, it makes me feel better usually and happier. I suppose at some point I might look for a good 5K race to do and take that run at a new PR and going under 25 minutes in the 5K. I feel very confident that I should be able to do that if healthy and properly rested to have good springy legs.


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