_Salt_ isn't awful but it's not my cuppa in the sense that I prefer books that have some kind of narrative. Taubes' _Good Calories, Bad Calories_ is a freakin' door stop of a book, and while I was already very familiar with the basic thesis, Taubes seemed overly zealous in some places -- in spite of that fact that, I, of all people ought to be pissed as all gittout right along with Tabues. As Taubes points out, all this advice was dished out, supposedly to save families like mine, only for it to turn out to have been not just misinformed but actually dietary advice that was not just misinformed, but harmful and actually more dangerous to my family, than if we'd just kept right on eating lard biscuits, full fat milk, and yummy seared gristle. :)
By far, the best book was _The End of Food_. Last fall, I'd mentioned that the second chapter is a really good overview what Paul Roberts calls the human food economy. AT the time I read it, I mentioned it here and was going to post an excerpt from chapter 2, which I'd scanned. Lo! this conversation reminded me that I should post it. Rereading this, it's basically an argument for the centrality of meat eating to our evolutionary past. Roberts points out that he is _not_ arguing for a determinist reading, however.
Years ago, I read these basic arguments in scientific journals (fam tends to pay more attn than yer avg bears). In my estimation Roberts' chapter a pretty succinct overview of what I've read elsewhere:
http://www.cleandraws.com/EndofFood.pdf
<quote> By the early twentieth century, meat - the food that humans were built for and certainly the food we crave - was still so scarce that populations in Asia, Europe, and even parts of the United States suffered physical and mental stunting, and by the end of World War 11, experts were predicting global famine.
...
By most accounts, that narrative started about three million years ago, with Australopithecus, a diminutive ancestor who lived in the prehistoric African forest and ate mainly what could be found there - fruits, leaves, larvae, and bugs. Australopithecus surely ate some meat (probably scavenged from carcasses, as he was too small to do much hunting), but most of his calories came from plants, and this herbivorous strategy was reflected in every element of Australopithecus's being. His brain and sensory organs were likely optimized to home in on the colors and shapes of edible (and poisonous) plants. His large teeth, powerful jaws, and oversize gut were all adapted to coarse, fibrous plant matter, which is hard to chew and even harder to digest. Even his small size -he stood barely four feet tall and weighed forty pounds - was ideal for harvesting fruit among the branches.
So perfectly did Australopithecus match his herbaceous diet that our story might well have ended there. Instead, between 3 million and 2.4 million years ago, Australopithecus got a shove: the climate began to cool and dry out, and the primeval jungle fragmented into a mosaic of forest and grasslands, which forced our ancestors out of the trees and into a radically new food strategy. In this more open environment, early humans would have found far less in the way of fruits and vegetables but far more in the way of animals, some of which ate our ancestors, and some of which our ancestors began to eat. This still wasn't really hunting, but scavenging carcasses left by other predators3 -yet now with an important difference: our ancestors were using stone tools to crack open the leg bones or skulls, which other predators typically left intact, to get at the calorie-rich, highly nutritious marrow and brains4 Gradually, their feeding strategies improved.
By around 500,000 years ago, the larger, more upright Homo erectus was using crude weapons to hunt rodents, reptiles, even small deer. Erectus was still an omnivore and ate wild fruit, tubers, eggs, bugs, and anything else he could find.5 But animal food - muscle, fat, and the soft tissues like brains and organs - now made up as much as 65 percent of his total calories, almost the dietary mirror image of Australopithecus. On one level, this shift away from plants and toward animal food was simple adaptation. All creatures choose feeding strategies that yield the most calories for the least effort (anthropologists call this optimal foraging behavior), and with fewer plant calories available, our ancestors naturally turned to animal foods as the simplest way to replace those calories. But what is significant is this: even if the move toward meat began out of necessity, the consequences went far beyond replacing lost calories.
In the economics of digestion, animal foods give a far greater caloric return on investment than plants do. It might take more calories to chase down a frisky antelope on the veldt than to pluck fruit in the forest. But for that extra investment, Homo erectus earned more calories - far more. Fat and muscle are more calorie dense than plants are and thus offer more energy per mouthful. Animal foods are also easier to digest, so their calories can be extracted faster. In all, meat provided more calories, and thus more energy, that could then be used for hunting, fighting, territorial defense, and certainly mating. Meat was also a more reliable food source; by shifting to meat, prehistoric man could migrate from Africa to Europe, where colder winters and lack of year-round edible vegetation would have made an herbivorous diet imp~ssible.~
But meat's real significance to human evolution was probably not the quantity of calories it contained but the quality of these new calories. Because animal and human tissues have the same sixteen amino acids (whereas most plant-based proteins contain just eight), animal converts readily into human: meat is the ideal building block for meat. That's why bodybuilders eat a lot of meat; it also helps explain why, as our ancestors ate more animal foods, their bodies grew larger. Whereas Australopithecus stood four feet tall, Homo erectus was a strapping six feet in height, and much stronger, which made him better at eluding predators and hunting.* As important, Homo erectus's skull was a third larger than that of Australopithecus, and the brain inside vastly more developed - an adaptation known as encephalization that was also related to the meatier diet. Just as muscle grows best on a diet of meat, brains thrive on the fatty acids, and especially on two long-chain fatty acids, the omega-3 fat docosahexaenoic acid (DHA) and the omega-6 fat arachidonic acid (AA), which are abundant in animal fats and soft tissues.' Plants have omega-3 and omega-6 fatty acids, too, but these are shorter forms and can't provide the same nutritional benefits. Fatty acids were just the start.
The brain is what's known as expensive tissue - not only does it need lots of DHA to grow so large, it also needs lots of calories to create all the chemical neurotransmitters upon which mental activity depends. The bigger the brain, the more calories it requires, which is why across the zoological spectrum, bigger brains tend to be found with bigger bodies. A sperm whale, for example, can support a twenty-pound brain mainly because it also has a massive stomach and heart. But humans defied this brain-body pattern. In the millions of years between Australopithecus and Homo erectus, brain size nearly tripled, yet body size barely doubled. Somehow, the human body was fueling a very large brain with a relatively small set of body organs. How? Again, the likely answer was meat. Recall that meat is more calorie dense and easier to digest than plants. According to paleoanthropologist Leslie Aiello, coauthor of the expensive-tissue theory, as our ancestors ate more meat and fewer plants, they no longer needed the large primate gut to digest all the plant matter. Over time, the gut shrank to about 60 percent of the size of other primates' - a critical development, as digestive systems themselves consume lots of energy and having a smaller gut meant more available calories for larger brains. (In a similar development, because we weren't required to grind up so much plant matter, our jaws and teeth became smaller.) This is not a claim for dietary determinism: meat didn't "make" monkeys human. Many factors interacting in complex ways spurred the changes in our ancestors' physiology that ultimately produced modern humans. But it's also clear that without more animal foods, their bodies and brains couldn't have gotten larger. And without those bigger bodies and brains, they couldn't have become the intelligent, tool-using, highly effective hunters who were able to spread so quickly from Africa to the Middle East, Asia, and finally Europe. It's probably not entirely coincidental that the several offshoots of Australopithecus that remained herbivorous became extinct.
In any case, by around 180,ooo years ago, as the first of the four ice ages began, animal foods dominated and defined the human food strategy. Neanderthals and, later, the Cro-Magnons, the first anatomically modern humans, were primarily hunters. Each had its own strategies, but both relied heavily on the mastodon, bison, woolly rhinoceros, and other arctic megafauna that had been driven southward into human territory by expanding glaciers. To prehistoric hunters, these big animals were walking meat markets - risky to hunt, but offering a huge payoff. By some estimates, Cro-Magnon hunters were earning as much as fifteen thousand calories per hour - far more than their predecessors. In fact, although Cro-Magnon foraged for plants and tubers, eggs, insects, fruits, and honey, two-thirds of their calories came from animal foods, making their diet, as Mike Richards at Oxford University has shown, nearly identical to that of bears, wolves, and other "top-level carnivores." By the start of the last Ice Age, eighteen hundred years ago, big-game hunting had become the brutally efficient practice that was celebrated in cave paintings - and that elevated humans to a kind of dietary elitism. Daily life must still have been solitary, poor, nasty, brutish, and short: infant mortality was high, work was dangerous, and treatment for injury or infection was nonexistent, which helps explain why the average life expectancy may have been eighteen years. That, coupled with low birthrates (in part because infants couldn't digest meat and unprocessed plants and so had to be breastfed longer, which delayed subsequent pregnancies), kept population growth nearly flat. By some estimates, world population cycled at around one million for tens of thousands of years. Still, from the strict standpoint of food economics - that is, the quantity and quality of available calories - Cro-Magnon was fabulously wealthy. Indeed, so ideally matched were these ancestors to their diets that those who did survive childhood trauma and hunting accidents were probably healthier than most of their modern decedents: according to Neil Mann, an expert in paleonutrition at RMIT University in Melbourne, Australia, fossil remains from this early period show none of the diet-related chronic diseases that plague us t~day.~
The good times couldn't last. ... </quote>
the rest is here,
Paul Roberts The End of Food Chapter 2: STarving for Progress -- http://www.cleandraws.com/EndofFood.pdf
"let's be civil and nice, but not to the point of obeying the rules of debate as defined by liberal blackmail (in which, discomfort caused by a challenge is seen as some vague form of harassment)."
-- Dwayne Monroe, 11/19/08
-- http://cleandraws.com Wear Clean Draws