Sunday, August 26, 2012

The Cheapest Calories

When we visited Maui recently, I saw sugar cane for the first time--


Sugar cane came to the Hawaiian Islands with the Polynesians in the range of 300-800 AD.  It was a part of a complex and sophisticated lifestyle.  As the Hawaiian version of the industrialization of agriculture, the plantation owners of the 19th century started large-scale cultivation and the importation of sugar to the United States.  Massive, industrial scale sugar production has enormous human and environmental health impacts.  William Banting wrote about this almost 150 years ago.  The issue gets much less attention than it should.  As we ride down the back side of the petroleum curve, the effects may actually worsen.

I started to comprehend the human effects about 11 years ago.  In 2001, a friend of mine started the Atkins Diet.  Atkins is a low-carbohydrate diet.  He lost weight, which puzzled me.  I had been running marathons and further since 1978.  Except for trying to eat a vaguely (as I imagined) balanced diet, I ate what I pleased with some allowances for avoiding sugar crashes in endurance bouts.  I sort of bought into the low fat, calorie management conventional diet concepts.  As it turned out, I wasn't thinking like an evolutionary biologist, despite my degrees in the field.


Mt. Lemmon Marathon, 2010
Fortunately, I came across Gary Taubes' article in Science Magazine, The Soft Science of Dietary Fat.  Gary did an excellent job of explaining the problems with studies of metabolism and health.  He unmasked sugar as the real cause of weight gain, which hadn't been a problem for me.  But in my 40s, my knees started bothering me and I couldn't exercise at my normal level--I was pudging up.  I cut carbohydrates (molecules of one to several sugars) and lost a couple of pounds.  In 2003, I discovered cycling, with a nudge from a local orthotics builder a bunch of us go to.  I was able to crank up my exercise levels to normal and heal up my knees to boot.  "Normal" is at least 8 hours per week of something strenuous and aerobic you like doing.  At the peak of Death Ride training, I was doing over 200 miles a week on the bike, over half of those miles up and down Mt. Lemmon Highway.  I gained weight and people said I looked thinner as my body changed from a runner's body to a (slow) cyclist's body (Cyclists use more strength than runners to pedal hard.).

Ebbets Pass in the 2009 Death Ride

I read a couple more of Gary's articles, such as "What If It's All Been a Big Fat Lie?", but didn't pay close attention until this summer when I heard Gary on Talk of the Nation.  Gary has some definite ideas about what one should eat, with emphasis on (way) less sugar and more animal tissue.  Since the looming end of cheap oil will have big effects on agriculture and the food supply, I was curious to know if he had thought about the matter.  I tracked Gary down and started a dialogue.  I ended up reading his book, Why We Get Fat, and giving copies to others.  Gary doesn't seem to see much point in exercise.  That said, I strongly recommend Why We Get Fat if you want a better understanding of your body, what you should eat, and how that relates to your weight and health.  I'm going to weave his ideas into my own interpretation, leading up to the age of petroleum and the cheapest of cheap calories.

We're Homo sapiens.  Genus Homo turned up perhaps 2 million years ago.  In 2004, Dennis Bramble and Daniel Lieberman published an article in Nature, Endurance running and the evolution of Homo.  They claim the fossil skeletons show that Homo was a distance runner.  I've known for decades that current people were good at distance running compared to other mammals.  In 2007 Bramble and Lieberman wrote an article for Sports Medicine, The Evolution of Marathon Running.  They point out that we can run at speeds that are uncomfortable for other animals to sustain for extended periods, especially in warmer climates.  I already knew we could out-sweat all other animals.  They say th ability to run at a strong pace and not overheat allowed humans to chase prey until it dropped from exhaustion and overheating, then come in for the kill.  We could also be day-active scavengers, stealing other predators' kills, during the heat of the day when the big cats and such were laying low and staying cool.  I'll go into more detail on these topics in another post.  Here's a BBCEarth video of the hunt--


Not everyone agrees about the exact diet of our ancestors, but it's clear we did something involving hunting, scavenging, and foraging for a couple of million years.   That would have been a diet with some amount of animal tissue (Gary says the fatty tissue as much as possible.).  We would have foraged for vegetables, roots, nuts, etc.  When we came across fruits or berries in season we would have gorged on those.  The sugar in the fruits and berries would be quickly converted to a bit of extra body fat, since that would be the only way to store those calories.  Most of the time we weren't eating sugars in an easily digestible form.  Read Gary's book for more details, but when we consume sugars, or carbohydrates that digest quickly to sugars, our blood sugar rises.  Our insulin elevates to signal our liver to take up the sugars and convert them to the storage molecules glycogen or triglycerides.  We can only store about 2000 calories worth of glycogen.  Meanwhile, the fat cells are being signaled by the insulin to stop releasing fatty acids and take up the triglycerides; i.e. store fat.

We started agriculture about 10,000-12,000 years ago.  That meant a diet heavy on high carbohydrate content grains and much less animal tissue. Carbohydrates consist of various combinations of sugar molecules, some more easily digested than others.  We quickly figured out that making a slurry of grain and water was a perfect medium for yeasts, which fermented a lot of the sugar into alcohol.  That actually made it easier for people to live in larger groups and have drinkable water--the fermentation killed the microbes that could make us sick.  There are some side-effects to drinking the yeasty water.  But was this transition to agriculture a good thing?

From Jared Diamond's 
Discovery May 1987

Diamond assembles information I've seen elsewhere.  When people switched from hunter-gather existence to agriculture, they got smaller and less healthy.  And a lot more numerous.  We had more calories from growing grains and other crops, but the nutritional quality was much poorer.  If you haven't read this article, you really should. Twenty five years later, it's still on track.  Gary talks about this topic somewhat in his book as well.

What Jared Diamond doesn't really address are more recent ideas about why this occurred.  I apologize, but in the interests of getting this post out, I'm going to forgo my usual style of adding supporting links for every key point.  I've read about this for years and can't put my mouse cursor on all the articles quickly.  I may come back and add links.  And not just Wikipedia...

Our species has been around for about 100,000 years, our genus for about 2 million.  We're one of the primates, most of whom are forest dwellers.  When the world began to get colder and dryer starting 50 million years ago, the grasslands started to form, and some primates moved into those from the forests.  They mostly ate plants.  We turned up approximately when the latest series of ice ages began, 2 million years or so ago.  The ice age pattern is one of oscillation--ice caps grow, glaciers form and flow, and cover much of the earth, then shrink and we have an interglacial period.  Colder during the glacials.  Human civilization has only existed during the interglacial following the most recent glaciation, which ended 12,000 years ago.  The fabulous u-shaped glacial valley of Yosemite was carved out by the mountain glaciers of the Sierra Nevada.

Looking up Yosemite Valley. El Capitan on the left, Half Dome in the distance.
We didn't start scratching the ground because it was a better way.  Either we caught and ate the food, or other factors killed off the large herbivores that we and other predators liked.  Unlike the other predators, who tended to go extinct, we're smart, omnivorous and very, very adaptable.  The calories from scratching the ground weren't as good for us, but we could survive.  In enormous numbers as it has turned out.

Let's just gloss over thousands of years of agrarian civilizations.  All the major grains, plus sugar cane, have been used since the early days.  The Industrial Revolution started about 250 years ago.  It's also the Hydrocarbon Age.  We learned to burn coal, liquid hydrocarbons (especially petroleum, beginning in 1859), and gaseous hydrocarbons to power fabulous machines that fill factories, carry us around the world in less than a day, and light and heat our structures.  From what I gleaned at the Sugar Museum on Maui, steam engines allowed sugar cane to be processed on a truly massive scale, squeezing out the juice and cooking it down to almost pure sucrose (table sugar) and molasses.

The HCS sugar factory across from the Sugar Museum.
Techniques of mechanized production, harvesting, and industrial processing have been used with all the other crops as well, especially corn.  However, sugar cane is the 1000 pound gorilla of crops at this point.  I've seen production figures ranging from 1300-1700 million metric tonnes per year.  Brazil is by far the largest producer.  Corn, wheat, and rice are in the 600-700 million metric tonnes ranges each. (http://en.wikipedia.org/wiki/Agriculture).  That isn't quite the same thing as yield of food and/or energy.  I've read that sugar cane contains 11-16% sucrose by weight (11% in 2010 in Louisana).   A brochure from Iowa State claims that a bushel of corn yields 33 pounds of corn sweetener, which works out to 47-59% depending on whether it's shelled (70 lbs) or ear (56 lbs).  Corn sweetener is the basis of high-fructose corn syrup, which has 2.81 calories/gram versus 3.87 for table sugar.  Pediatrician Robert Lustig characterizes fructose as the worst contributor to obesity.  Table sugar is a disaccharide, one glucose and one fructose molecule.  High fructose corn syrup is a mixture of fructose and glucose varying from 42 to 55% fructose depending on what it's used for.

There's another source of pure sugar, the sugar beet.  The sugar beet is the new kid on the block relative  to the history of agriculture.  In Europe in the mid-18th century, people experimented with breeding common beets (Beta vulgaris L.) for higher sucrose content and figured out how to process the beets to extract the sugar.  Before the era of cheap oil and transportation, sugar was a prized, expensive, and exotic commodity imported from the tropics at great expense.  Beets are temperate climate crops, which European, and later Americans, could grow to produce sugar domestically.  I've seen estimates of 20 to 35 percent for how much of the world's sugar comes from sugar beets.

There's an argument to be made that sugar is addictive.  It makes sense that we would gorge on the sugary sweet fruit of a tree and store the calories as a bit of fat, since there was no way for the hunter-gatherers to process and store sugar like we do.  Notice that nothing except ants want to have anything to do with dried sugar crystals.  No nutrition, just pure calories.  We love the stuff.  I'll focus on sugar itself in another post.  Fructose and glucose are metabolized somewhat differently, but both can contribute to fat storage.  Dr. Lustig says that fructose has directly toxic effects when consumed in significant amounts.

The petroleum age is the era of industrial agricultural, including the production of pure sugar.  On the website, I explain how mechanized agriculture, powered by oil, has allowed both a factor of ten increase in corn yields, and more acreage of crops plowed by tractors instead of horses.  The global population explosion is undoubtedly the result of the industrial revolution, especially the past 150 years of the petroleum age.  We're past 7 billion people now.  Feeding them takes a lot of calories, plus a lot of nutrition.  We're not so good on the nutrition side.

The pressure to feed people something, somehow will grow.  Our energy resources will become more expensive and our economies will shrink.  I've said I'm confident we'll adapt assuming we don't have a large-scale nuclear exchange.  Assuming there are anthropologist and archeologist equivalents in the world of the future, will they mark this time as the transition point to the lowest common denominator of cheap calories and poor nutrition as we attempt to feed the billions?  Will we have to depend on the cheapest calories?  Here are some guesses regarding agriculture and food supply.

What crops depend most on cheap oil?  I learned that most sugar cane is cultivated and harvested by hand, despite what I saw in Maui at the Sugar Museum where they used machines throughout.  As is common elsewhere, they burned the "bagasse" cane waste to generate a large part of the steam that powers the mill.  Looking up rice, I learned that rice cultivation is very labor intensive.  These two crops dominate tropical agriculture.  Conversely, in the temperate regions, like the United States, we've used mechanical systems, fertilizers, and petrochemicals to dramatically boost crop yields.  One or a few people drive big machines across hundreds of acres of fields.  They also take out big loans every year to pay for the crop's planting, cultivation, and harvesting.  This makes me think temperate zone agriculture could suffer relatively worse impacts from expensive oil.

Wheat, corn, and sugar beets are the big carbohydrate and sugar-containing crops of the temperate latitudes.  Wheat is mostly used to feed people; the bread of the world.  It's also the crop exported from country to country in greater volume than all other crops put together.  I wonder if part of that is because wheat stores and travels really well, maybe even better than rice and corn.  Corn, at least in this country, goes mostly to feed animals and make ethanol fuel, although we do export about 20% of the crop.  Only 1.7% actually gets eaten as corn and corn-based foods here in the U.S.  Four times as much gets made into "corn sweetener", i.e. sugar. (From the Iowa State brochure again...)

You would think that as oil gets more expensive, making production and transport more expensive, that there would be considerable pressure to use the food crops we have to feed people, not animals.  Likewise, there's debate regarding whether making corn into ethanol is actually cost-effective without cheap oil.  That suggests a shift toward using the corn production that we can sustain to feed people.  Will it be cheaper to process the corn into corn sweetener and other products and ship that to cities?  I don't know.  Wheat stores and travels just fine.  Sugar beets needs to be quickly processed into sugar, which can be stored indefinitely.

After researching the details, I think it's unclear whether the shifts in agriculture will in themselves force more sugar consumption as a proportion of diet.  What may matter more is what foodstuffs are cheap and accessible for the millions of people in the big metropolitan areas of the world as the economy shrinks and hardship spreads.  Historically what's been most accessible to poor people with limited mobility has been cheap starchy carbohydrates and sugars.  Gary Taubes' Why We Get Fat documents multiple instances of poor populations that become obese on these diets.  A couple of books I've read talk about agriculture moving back closer to the metropolitan areas, but there will be some amount of dislocation along the way.

There's good evidence that on the front side of the Hydrocarbon/Industrial Age, we've dramatically increased our consumption of sugar, going from 6.3 pounds per person per year in 1822 to a peak of 107.7 lb/person/year in 1999 in this country by one esitimate.  It's dropped off a bit since (a trend?).  Perhaps this is the Sugar Age, too.  Gary Taubes and Robert Lustig argue persuasively that adding body fat and consuming sugar products are intimately linked.  Before Gary's book made me think about the matter in better detail, I had vaguely assumed that with some amount of pain and suffering people would get thinner as the economy shrink.  We may in fact see a higher incidence of obesity combined with poor nutrition, which won't help people adapt to a more difficult world.

We need to ask what we can grow and distribute that will sustain people.  That's a different issue that what's cheap and available, isn't it?









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