Paleo

Dump the Paleo Diet and Do a Little Family Research

Everyone has one: the friend doing the Paleo diet who comes for dinner and eats all the meat meant to feed six people and leaves the starch. Well, next time, before you invite Pete Meathog over, have him read this book:

Because author Nabhan points out that, when archaeologists sift through the soil of early hominid camps,

they seem less certain that there is a single discernible dietary pattern evident among excavated sites. Some scholars have begun to doubt whether Java Man or other populations of Homo ever kept to a uniform diet; some even wonder if ancestral diets contained more or less the same proportions of fats, proteins, sugars, and fiber.

Heck, even the primate populations living today "less than one hundred miles away from one another" demonstrate considerable dietary and genetic variation, so who's to say what Paleolithic man ate?

Nabhan builds a stronger case that diet and genetics have had an active interplay over the last several thousand years, resulting in different ethnic groups evolving in response to their typical diets and in response to environmental pressures (e.g., prevalence of malaria, rate of meat spoilage near the equator, etc.). Folks used to believe evolution took eons, but now we understand that natural selection can operate much more quickly, making significant changes in a few hundred generations. Of course, not everyone lives in the land of their ancestors anymore, eating what their ancestors had developed to eat, and

the forcing of ethnic populations to abandon either their homelands or their traditional diets has inevitably led to epidemic rises in diabetes, heart disease, cancer, and allergies, among other maladies. Because some people have been untethered from the foods to which their metabolisms are best adapted, some 3 to 4 billion of your neighbors on this planet now suffer nutritional-related diseases (italics his). 

Sure, let's be friends--just don't try to poison me with your food

The studies and cases covered by the book are fascinating. Why do some Sardinians suffer from seasonal symptoms, when fava bean pollen is adrift? Why do the highland Cretans eat three times the fat of Americans, but the Americans sampled had a coronary death rate forty times higher? Why are some families more prone to alcoholism than others? Why do many ethnic populations who shift to a "Western" diet see their diabetes levels skyrocket?

A lot of what Nabhan had to say about the both medicinal and toxic effects of plant chemicals dovetailed well with Mark Schatzker's book THE DORITO EFFECT, which I talked about here.


I only wish Nabhan concluded with a giant map of "traditional" diets across the world. What would be his best guess for what different ethnicities should be eating, if you weren't one of the few groups discussed in the book? Some diet company could tap into a goldmine here. They could run a genetic test on clients and then hand them a printout of the diet their body is tailored to. Anyone? Anyone?

As it is, I'm left to do some sleuthing on my own. (I'm no scientist, so nobody quote me!) But, as a person of Chinese ethnicity, I notice a few things:

  • According to the American Diabetes Association, of the 29+million Americans who had diabetes in 2012, only 4.4% were Chinese.
  • In 2010, according to the CDC, rates for coronary heart disease were lowest among Asians/Pacific Islanders (3.9%).
  • While Asian/Pacific Islanders have only the second-lowest number of cancer incidents among the ethnic groups, they have the lowest death rate from cancer.
These things suggest some possibilities: either Chinese-Americans don't do so horribly on the Western diet; or Chinese-Americans continue to eat a higher proportion of their traditional foods, even in America; or some combination of the two. In our household, we only eat Chinese-ish food maybe once a week, and, apart from Sugar-Free January, we eat probably half the sugar a typical American family eats. (That is, we eat dinner dessert but don't drink soda or eat sugary cereal or pack cookies in the lunchbox.) So I'm going to guess Chinese-Americans are evolutionarily suited to survive the Western diet, which is heavy on grains, and they are further benefited by liking things a little less sweet than other tasting groups. (Sadly, I don't seem to have passed this latter characteristic to my half-Chinese kids. I can't bear to eat my husband's Christmas fudge--too sweet!--but my kids like it just fine.)

So I did a little research on traditional Chinese agriculture on the internet and discovered the legend of the Five Grains, mythical stories that explained the dawn of agriculture in China, about 9500 years ago. While accounts differ on the original five grains, some main contenders pop up: millet, rice, wheat, soybeans, hemp, adzuki beans, and barley. Which means my body has benefited from thousands of years of evolutionary adjustment to those items. Score! 

Now I just need to figure out how to keep the hub and kids alive, they being much more genetic mutts. This might mean I have to pull out that genealogy from crazy Great-Grandpa Dudley, who once traced the family back to the Virgin Mary. Yes, you read that right.

I'll keep you posted.

Are We Evolved Enough to Eat That?

Great job selecting for desirable traits, early farmers!

If you've read books that mention the history of agriculture, you've learned by now that wild maize bore little resemblance to the crunchy, sweet, essence-of-summer corn we now enjoy. Nah--the wild stuff had few kernels on tiny ears and required plenty of scavenging before you could make a meal of it, much less a bowl of tortilla chips and a gallon of high-fructose corn syrup.

Our hunter-gatherer forbears spent up to six hours a day to accumulate enough calories to feed their small bands, and they ate a diet made up largely of fruits, tubers, nuts, seeds, and wild game. As a result they got plenty of physical exercise, fiber, and enough of a chewing workout to make their jaws grow large enough to fit their teeth--all their teeth. They were also seasonal eaters by default and not too subject to widespread famine, since they could always move on elsewhere or put up with less choice offerings, like rabbits having to eat grass after they're already devoured your pea plants.

After millenia and millenia of such a diet, it only makes sense that natural selection favored bodies that processed such food best, and this story would all have had a happy ending, except that humans decided to start sticking around in one place and farming.

I've been reading again.

Really it was the "health and disease" part of this book that interested me, since I've been wondering about all the different diets and nutritional advice out there. It seemed best to listen to an evolutionary biologist to figure out what exactly are we designed to be eating?

The short answer is: not what we're currently eating. Lieberman classifies many of our modern illnesses as "mismatch diseases," meaning, our bodies now encounter foods and environmental circumstances which are different from what our bodies have come to expect after so many gabillion years, so we get sick. Examples of mismatches:

  • Obesity. Most of us in the developed world experience an energy surplus of food. Our bodies have been designed to sock away fat, so we have a continuous supply of energy to fuel our giant, energy-sucking brains. But we used to experience lean times as well as bonanzas, and now all we have are bonanzas.
  • Type 2 diabetes. Remember that bit about the hunter-gatherer diet? It included hardly any sugar (all pre-agriculture fruits were about the sweetness of a carrot) or simple starches. The carbs we ate had lots of fiber and therefore made our bodies work hard to get energy out of them. Which meant, no sugar spikes in the blood and no insulin spikes and no consequent insulin resistance.
  • Myopia! (Lieberman gave many, many disease examples, but I include this one because I always wondered how nearsighted people could've survived the caveman era.) Back in ye old hunter-gatherer days we were mostly outside and never spent hours with our eyes frozen in flexed position, staring at books and screens. It turns out that the teeny muscles holding up the lenses in our eyes get to relax when they look far away, but nowadays we hold the poor muscles clenched up, focusing close up, with sad, contact-lens-wearing results. Among the few hunter-gatherer populations remaining on earth, you don't find many needing lasik.
There's much much more to the book, but the lifestyle advice is familiar and straightforward. Prevent mismatch diseases by avoiding "stimuli that are too much, too little or too new." 
  • Too much = sugar, simple starches, overly processed foods.
  • Too little = fiber and physical activity (walking is just fine--that's what we're designed to do, along with a little running on our arched, springy feet, when necessary)
  • Too new = environmental pollutants, weird foods like transfats (our bodies are like, what the heck?), high-heeled shoes, sitting for hours
Our bodies are trying to catch up with the crazy brave new world--there's already some selection happening for people to produce more insulin--but all the changes happened so very fast, evolutionarily speaking, that we aren't going to turn those mismatches into matches anytime soon.

So grab extra of those fruits and vegetables and pastured meats at the Market this week, and park your car in the furthest spot in the lot. Oh, and read this book!