Our ancestors hunted big game for the same reasons some of us drive fancy cars or carry a designer handbag: status. The hunters were hungry for prestige, and the meat was a bonus.
Hallam L. Movius, Jr. Public Lecture by John D. Speth
Professor of Anthropology in the Department of Anthropology and Curator of North American Archaeology in the Museum of Anthropology, University of Michigan
Since its inception, paleoanthropology has been closely wedded to the idea that big-game hunting by our ancestors arose primarily as a means for acquiring energy and vital nutrients, with prestige and social standing an additional bonus. This assumption has rarely been questioned, and seems intuitively obvious—meat is a nutrient-rich food, and big animals provide meat in large, convenient packages.
John Speth provides a strong argument that the primary goals of big-game hunting were actually social and political—increasing the hunter’s prestige and social standing—and that the nutritional component was the added bonus. Dr. Speth reevaluates the role of big-game hunting among some of our best known modern hunters and gatherers: the San of southern Africa, the Hadza of eastern Africa, and Ache of South America. With an examination of the historical and current perceptions of protein as an important nutrient source and the biological impact of a high-protein diet, Speth challenges the long-standing view that big-game hunting evolved primarily as a means of putting food on the table.
Recorded on Thursday, March 10, 2011
About Hallam L. Movius, Jr.
Hallam L. Movius was a Paleolithic archaeologist at Harvard, and a member of the department of anthropology for many years, as well as being a long-time curator in the Museum. Being chosen as the Movius lecturer is considered an honor in the field he helped advance for many years.
Dr. Ofer Bar-Yosef 0:01
It is my pleasure to introduce an old friend, John Speth from the University of Michigan. We know each other for 30 years, 40, maybe 100 — from the Paleolithic. And, and some of our encounters were, when in 1982, I was in there spending a sabbatical year in Michigan, and we were going jogging together and discussing different issues. This was the time when John was publishing his first volume on, on bison kills and where he became very interested in nutrition. So from this year onwards, you can see his contribution to the issues of not just hunting but also the nutrition. But before this, he had an interesting history too, as a scholar. He started the — because he was interested in the Middle East, and he went digging a cave that was tested by Ken Flannery and Frank Hole, but he found that it's full of holes made by these porcupines, probably, or some other burrowing animals and came back to Michigan and did his his PhD on subjects related to stone tools, like napping glass, and finding all about how you make flakes and so on and so forth. And when he finished, he was called to, not surprisingly, to take a job in Hunter College in New York. And then, one day alma mater called him back to Michigan, so he went back. Well they said, "You have to — you're interested in the southwest of Asia? How about replacing it with southwest of the United States?" And he agreed. So where did he go digging? In Roswell, New Mexico. I don't think he was looking for aliens. Instead of this, he found some of the most interesting discoveries that led him to these issues of the big game hunting that on which he will be talking today. But I never gave up and after '82 and '85, we asked him to come and work with us in the excavation of Kabbalah cave, where he is doing the analysis for the bones and therefore animal bones. It's a cave with about, according to him, about 1 million pieces of bones. So it will keep him busy for a few more years. But I think he shows exactly the kind of integration of different subjects, of not just being a zooarchaeologist, but as an anthropologist, and also looking at the nutritional aspects that which play a major role in his forthcoming lecture. And without further ado, it's we are all yours, John.
Dr. John Speth 2:49
See if I — is the mic on? Now, I think I've got it — is that a little better? Okay.
Well, thank you all for — thank you to the people who, family and friends, who created this whole series. For me, it's a tremendous honor and pleasure to be able to, to give the Hallam Movius talk tonight. I thought I would just indicate my — I met Hallam Movius once after he retired, was living in France. But so I you know, in terms of personal familiarity, it was rather limited, although we had a really enjoyable visit. But when I was a graduate student, he was a household name. And so it was amazing to actually meet the person. And I just put two things on this slide to indicate things that are actually still very much talked about, discussed, debated today. And he did many other things. But, for example, the famous Movius — is called the Movius line — has been debated in the literature for years, the idea that hand axes tend to be most common to the west and southwest of that line in Africa and Europe, and Western Asia. And that to the east, you have very different types of stone tool assemblages during during the Paleolithic, and the reasons behind this are still very actively debated today. So how Movius focused in on an issue among many others that that are still very central in discussions today about human adaptations in the Pleistocene, and what the significance of this transition or boundary or whatever between the western part of Asia and Europe and Africa and Central and Eastern in Asia. And then the other thing that he's very famous for is the work at the site of Abri Pataud. And I think even today, every graduate student reads about it, knows about it. It's one of the classic series of studies on an Upper Paleolithic site in Western Europe. So it's it's really an honor for me to be able to make a presentation in that in this Movius speaker series. What I want to talk about tonight is somewhat unorthodox. And I can say right up front that I'm not sure I believe what I'm going to say tonight; I'm not sure I believe it entirely myself — I'm still trying to convince myself. I think there's enough interesting issues out there that it's worth talking about. And I will try to give you some flavor, some sense of what these arguments and issues are. I've been interested in hunter-gatherers since the beginning of graduate school. I can't tell you why, but I've always been fascinated with them. And two books came out at more or less the same time in 1968. One was this book called Man the Hunter by Richard Lee and Irven DeVore. And the other was Lou Binford and Sally Binford, called New Perspectives in Archaeology, and maybe exaggerating slightly, the new perspectives generated a giant yawn for me. And this, this was for me, the the eye-popping eye-opener book. And it was a tremendous shot of adrenaline, if you like; it got me really interested in hunter-gatherers. And despite the fact that a lot of what's in there we have since rejected in various ways, it had so much positive impact on the field that it's one of those contributions that I think advanced hunter-gatherer studies tremendously. And at a very important time, because hunter-gatherers were rapidly disappearing. And it generated I think, so much interest that that interest continues today. Now, what I want to question or challenge, in a way, is what is sort of fondly known as the hunting hypothesis. And it's been with us, certainly since Darwin, and I'm sure you could find it in Aristotle. It's it's an argument that has been around for a long time, that hunting played a key role in our evolution, that in some ways, it made us human. Some of the extremes — if you look in Man the Hunter, there's a famous article by Lancaster, that, and Washburn that, perhaps doing it a bit of injustice, attributes everything to men hunting: language, culture, you name it, and it's hunting.
What I'm going to look at tonight are where this, just very briefly, where this view comes from, and we trace it back, as I say, you could probably go back to Aristotle, and maybe before, but in terms of, of scientific and academic writing, it clearly goes back to Darwin, who was very explicit about the role of hunting in, in his view, at least of human evolution, and his arguments, with refinements and changes and labels, and so forth, actually still remains with us. It's undergone a lot of change. But in a sense, the core of it from Darwin is still with us today. Then I want to talk about some of the newer views, that stem in large part out of work by an area of study that was often referred to as behavioral ecology. People who, particularly that that area of it, focused on hunters and gatherers, that look at, in a much more quantitative way, and a much more hypothesis-driven way, at what hunter-gatherers do, what the selective advantages of certain behaviors are. One of the — there are many different branches of this. One of them focuses on what foods people eat, when they chew, when do they choose to eat a specific food or bypass it to look for another food and so forth. And then what I want to look at are some of the current views, problems with some of these earlier views, and ultimately end up arguing, and I'll tell you the punchline right now, that big game hunting, I'm talking I'm not talking about all hunting now, but the focus of hunter-gatherers on the biggest critters available on the landscape. And I'm going to try to argue that this is driven more by politics than it is by nutrition. I don't want to give you the idea that I'm rejecting nutrition; it has definitely has nutritional value. But the traditional view is that that really is what lay behind the evolution of big hunting and big game hunting. And that over the course of human evolution, we got better and better and better at killing bigger and bigger animals, the driving force, through technology, through organization, and so forth, that led humans towards this push. And the typical underlying assumption is that it's food and particularly protein that drove this. And so what I'm going to do is go through some of these arguments, starting with the classic hunter-gatherer model that grew out of the Man the Hunter period, look briefly at Darwin, and then look at some of the problems, as newer studies have come about, with this focus on on big game hunting. The traditional view, the Man the Hunter view, is that there's a division of labor: men hunt, women gather. Hunting large game makes sense, because it's come — first of all, meat is a high quality food because it has, we need protein; meat provides protein and abundance, with the right mix of amino acids in the right proportions, and so forth. The division of labor: What men provide complements what women provide. So this is a very logical, cooperative kind of system. The traditional model that goes to Dickley — it actually goes back much further — is that there's a kind of risk pooling involved in this, that hunting is risky, so risky, not so much in the danger side of it, but in success or failure side. So today, I am successful in a hunt; I share with you. You may be unsuccessful, so you get you get food from me, you get this high quality food. Tomorrow or whenever I fail, but somebody else succeeds, you share and then I benefit. And the idea is that over the long term, this averages out, it pools the risk in a way. The idea of big game hunting is it makes a lot of sense. It's a high quality food, particularly the protein it supplies. It comes in large efficient packages. So if you have the technology and the organizational skills to kill large animals, it makes sense to go after, let's say a wildebeest. It makes more sense to go after a wildebeest than it does to go after a bunny. Alright, let's go back very briefly to Darwin. He very carefully avoided human evolution in The Origin of Species. But with The Descent of Man in 1871, he tackled it head on, and a large part of the argument revolves around hunting.
And he, in looking at what made humans — modern humans —human, the most obvious to Darwin and to others is the big brain: We have an unusually large brain. We are very tool-using, tool dependent; we obviously make very heavy use of tools. Hunting, he viewed as, for non agricultural or pre agricultural people, that's what life was all about, was was hunting. And he focused on bipedalism, two legged locomotion, as being a key part of this. And he developed a feedback, or what we often now refer to as a feedback model, in which these are linked together, and emphasis on one puts positive selection for others of these traits. For example, tool using is more effective if you're bipedal and can free the hands. You can hunt more effectively if you use tools; tool use is favored by a large brain. And all of these things can be linked in a feedback model. The only negative or reducing component of this would be the canines: the argument that the canines reduced as we relied more and more on cultural means of killing animals. Now, the pieces of the argument fit very well with the archaeological and human fossil data. And I would say, certainly when I was a grad student, and more recently, that variants of this feedback model were certainly what I learned, and I'm sure it was pretty common globally — variants of this this basic Darwinian model. The fossil record shows the brain size increased very nicely. The archaeological record shows not only that we got real interested in, in animals, but that stone tools were used for this. We have, I don't know if you can see this, but they're cut marks on the bone. So we have direct evidence that humans were exploiting the meat of these animals. And there are lots of big ones. If you look at the Olduvai Gorge data, particularly a site called FLK Zinj, we have really good evidence of exploiting mostly larger animals, wildebeest-sized and larger, and using stone tools to do this. We are arguing ad nauseum about whether these were killed or scavenged. And this debate will go on for some time. But there's very little disagreement in the academic world about what it was all about. They were after meat. And the usual argument until let's say the last maybe 10 to 15 years was primarily because of its protein content. That was the the focus, and we had a love affair with protein. And I'll show you a little bit of the history of that love affair. Bipedalism — we had great evidence of bipedalism. These are the Laetoli footprints at roughly three and a half million: very human like foot with an arch, a big toe in line with the rest of the foot, basically useless except for walking and kicking a soccer ball. So that that part of the puzzle was there as well.
But it began to, in certain ways, fall apart. We found that bipedalism — and this is fairly recent — that bipedalism evolved long before the brain size, before brain size increased, and that a lot of the bipedalism may have developed in more forested habitats, not out in the savannas, as was once envisioned. So all that happened in a way in the field was we simply shifted it up in time: The Darwinian feedback model may not apply to the origins of hominids — that is, of the earliest relatives of ourselves — but it may have just shifted up in time to the origin of our genus, Homo. So instead of being five or six million years ago, the feedback model applies very nicely, and is still used for explaining, what happened in human evolution at roughly two and a half million. So we just got bipedalism out of the picture, the rest of the feedback model still hangs on very much intact. Now, there are other arguments that fit very nicely with this. And one of them is the recognition that humans have very large brains. But they basically have a metabolic basal metabolic rate that is what you predict from a any primate of the same body size. In other words, we have a very costly organ, the brain, which today uses about 20% of your resting energy. So we have this huge, expensive organ. And yet, given our body size, our basal metabolism, metabolism is not elevated, compared to smaller-brain primates of the same or roughly equivalent body size. So a woman named Leslie Aiello and colleagues of hers developed a very influential and very interesting model, which is often referred to as the expensive tissue hypothesis. And in brief, that argument is that here's the basal metabolic rate, and given our brain size, this should be up here somewhere. And it's it's, it's not. So what Aiello and her colleagues argue, is that something else had to have to go, had to shrink. And they postulate that it was gut size, which is another very expensive organ. So in order to achieve and support a large brain without changing your basal energy requirements, something else had to reduce its energy requirements. And arguing from a lot of data about the gut sizes of different primates and so forth, they zeroed in on that as the most likely organ that was reduced. And one of the logical consequences of that suggestion is that in order to maintain your your nutrient input with a shorter gut means that the food has to be of higher quality. Now, Aiello and colleagues were very explicit in saying it does not have to be meat, but most people in the field glommed on to meat as the most likely. All right? So this also fit in a way that — here's another argument: large brain but without increasing basal metabolic requirements, shrinking gut means higher quality food. What's the obvious high quality food? Protein. Okay? So that was another piece. Now what I'm going to start out with here then is to look at a number of problems with protein. Now, my again, I gotta emphasize that I'm not trying to argue that protein is irrelevant or unneeded or that meat is irrelevant and has no nutritional value. It's it's very relevant. But what I want to show you briefly is that it's not the magic elixir that the profession for a long time made it out to be, that high protein presents problems. And much of the emphasis in the field in nutrition, as well as in anthropology, for years was lack of protein, insufficient protein; very few people looked at too much protein. So let's very briefly look at some of these issues. First is looking at the the origins of this love affair. It starts in 1935 with the recognition of kwashiorkor, protein deficiency syndrome or disease, and it was recognized by a woman named Cecily Williams in the 1930s, in what used to be the Gold Coast, is now Ghana. She identified childhood kwashiorkor, recognized that it was a protein deficiency, cured it by supplementing protein.
So that was not a problem, and this is not a critique of Cicely Williams. What happened was that starting around World War II, the World Health Organization glommed on to protein as the major source of nutritional shortage worldwide, and they wrote a series of manifestos, if you like, about the the world crisis that we faced if we didn't deal with this protein deficiency, and in fact, it became part of the Cold War. This is in part, the export of milk by the US, particularly skim milk, was in part a political tool to fight this supposed protein worldwide protein deficiency. Once the milk supplies went, when we no longer — for a while, we were dumping it in the ocean, then we started using it as a tool, as a political tool, to to take care of this worldwide protein deficiency. When milk surpluses began to disappear, we started coming up with substitutes, protein substitutes: soy, skim milk, and, and so forth. In the 1970s, this love affair finally collapsed in nutrition. But that's just about when anthropology started. And I'll give you a couple of quotes, and if you have problems reading, I can read them to you. This is the end in a way, the end or the beginning of the end, of the protein love affair in the nutritional fields. And this is Donald McLaren in 1974. "The concept of the much-publicized world protein gap crisis or problem arose from the description of kwashiorkor in Africa in the 1930s and the assumption, which has turned out to be wrong, that malnutrition in children takes this form throughout the world. As a result, measures to detect protein deficiency and treat and prevent it by dietary means have been pursued until the present time, the 1970s. The price that has had to be paid for these mistakes is only beginning to be realized." Now this is one of the most extreme statements, but I love it — another nutritional statement. "Let's answer that last question with a categorical piece of provocation, that of all the disasters caused by the misapplication of science in this century, including the development of the atom bomb, none has caused more human misery or a greater misuse of resources, or a more pernicious perversion of policy and action, than the nutritionist exaggeration of protein requirements." And here's one of our own, Marvin Harris, who, towards the end of his career had an incredible love affair with protein. "Among the less developed countries today, the problem has always been that of too, little rather than too much, protein. Individuals and populations are therefore well advised to pursue a production strategy aimed at maximizing protein intake and at resisting any lowering of per capita norms. When one does not know what is a safe minimum, it is best to strive for the highest sustainable rate of consumption possible under given ecological circumstances." All right, this is the end of the 70s. And you can see this when you look at the literature in paleoanthropology, for example in the 70s and 80s. That love affair spills right into there, into the field, and a lot of the literature talks about the need for protein to feed our large brain. And as I will try to show you, the brain has very little protein in it. This is what needs the protein. And the brain — you know, you call somebody a fat head, there's a good reason for it. The brain is mostly fat and water. There are special kinds of fat and that becomes a separate, interesting issue.
All right, some of the literature is filled with statements like this. These are from explorers, military officers, and so forth of the 18th and 19th century. This guy is Randolph Marcy. He was stranded in southwestern Wyoming and in midwinter, ran out of supplies. For those of you who know the geography of Wyoming, Colorado, New Mexico, you can imagine: midwinter, out of food, southwestern Wyoming. He marches with oxen, horses, and soldiers to Santa Fe, New Mexico, to get resupplied. And his experience was: "We tried to meat a horse, colt, and mules, all of which were in a starved condition — and of course, not very tender, juicy or nutritious. We consumed the enormous amount of from five to six pounds of this meat per man daily, but continued to grow weak and thin, until at the expiration of 12 days, we were able to perform but little labor, and were continually craving for fat meat." I have since then pulled out literally hundreds of these kinds of comments from all parts of the world, from Sub-Saharan Africa, from Australia, from throughout North and South America. When I started getting interested in this issue and went to nutritionists, they looked at this and said, "This is utter nonsense. Nobody eats from five to six pounds of meat." And it was simply not part of the training right up into the 80s in nutritional studies and in the medical world to look at hunter-gatherers, to look at issues of high protein intakes. Everybody was still worried about low protein intakes. What finally, I think, legitimized hunter-gatherer studies in the medical and nutritional fields was the beginning interest in the omega-3 fatty acids. And when they started looking at Eskimo diets, realizing that 75% of a traditional Eskimo diet was fat, and yet they didn't have any of the so-called diseases of civilization: strokes, heart attacks, and so forth caused by or at least linked to the the modern lifestyle, modern diet, and so forth. At that point, it became fashionable to start looking at hunter-gatherers as part of humanity, that maybe we could learn something about nutrition from, from looking at hunter-gatherers. So what's wrong with protein? Obviously, if you have too little, there are all kinds of problems. But there are also problems with too much. And too much — and I'll show you some data on this in a moment — too much is typically expressed as a percentage of total calories, roughly 35% of calories. Now, most of us don't get close to this, although with Atkins diets, now finally the medical profession is taking another look at the dangers of high protein diets, because there are consequences that had not been explored. And suddenly, there were people abusing the Atkins diet in ways that were really dangerous. These are some of the typical symptoms if you are put on a diet where roughly more than 35% of your calories comes from protein. Now, you might say for most of us, other than being on an Atkins diet or something like that, we would never approach that. When I was a grad student athletes were protein-loaded; then they finally moved to carbohydrate loading. But you know, when you look at their diets, even though they were gross, their protein intakes probably were seldom in excess of 15% of calories. But when you look at hunter-gatherer literature, at least seasonally, many hunter-gatherers exceed 50% of calories, and they lose weight. They're on an Atkins diet. And it's not something that they necessarily need or want. Depending on how high the level of your protein intake is, it can lead to death — in the shortest, two weeks. Typically, if you're not way over this threshold, the length of time may be on the order of a month, month and a half. And what Randolph Marcy described: If you're just over this threshold, you become lethargic, you can't work. You read some of these early explorer accounts and they'll say, "I was so weak I couldn't even crawl out of the river bank to get out of the river subsisting on jerky, basically." All right, there's a limit. And it varies with body size. Now, the typical sort of modern Western individual is around 70 kilograms. If you look at the body weights of most modern hunter gatherers, they're down around 40 to 50 kilograms. So the limit for them is much, is much lower.
For a 50 kilogram individual, the daily as a 24 hour maximum is about 180 grams of protein — that's not grams of meat now, but grams of protein. That would translate into a little under a kilo of meat. So the use of the as I say, the typical values, about 35% of calories percentage, however, is misleading because it's an actual threshold. And percentage implies that, well, if I eat more fat or carbohydrates, then I can eat more protein, so long as I keep that value at 35%. But it's actually a ceiling; you can adapt to it. So it's not rigid. And we don't have enough studies of just how much flexibility there is in it. But that ceiling, let's say, is roughly a kilo of meat per day. Now, one reason for emphasizing this, think of what do you do with a giraffe? You know, we go out and hunt a giraffe. And people say, "Well, you get much more meat that way." What are you gonna do with it? Because you're, you're generating, even if you share it with a hell of a lot of people, you're generating so much protein that if you were to consume it, it's toxic. So it raises — and this I'll keep coming back to this from many different points of view — it raises some real questions about why hunter-gatherers spent so much of their life chasing big animals.
So the problem, explained very briefly, what the problem is with too much protein: it contains a lot of nitrogen, nitrogen forms ammonia, you have enzymes in the liver that have to de-ammonize the protein, break it down, and generate urea that you then excrete. And that is rate limited, even though there's some flexibility in it and, surprisingly, amazingly few studies of it. Basically, you can't get rid of the nitrogen fast enough, once you exceed that threshold, and you develop ammonia toxicity. And there are various other symptoms that go along with it. At low levels above that threshold, you can persist, but you get these symptoms of lethargy, bloated stomach, diarrhea; I mean, these explorers knew exactly what was happening. And they're very explicit. They don't talk about protein and enzymes and liver, and so forth. But they knew when they were pushing that threshold because they couldn't function anymore. And if you if you get high levels of this excess, you ultimately die of this ammonia toxicity. The early explorers called it protein poisoning. And when I first started talking to nutritionists about this, they looked at me like I was nuts. Now there's a whole literature on it. So it's finally, finally coming. Actually, let me back up here. One of the things to realize is that African — we're going to talk about human evolution in Africa — African antelope are among the leanest animals as a group on the planet, even in peak prime condition. And this is just one of hundreds of quotes that I was able — I'm having a love affair with Google because all of these 18th and 19th century volumes that used to be locked up and you had to wear special gloves to look at them and so forth, and there was no way to keyword search — they're all there now. And it's just incredible. So I just picked out one nice short quote from Teddy Roosevelt, one of many white hunters who like to go and kill just about anything that moves. And he sums up the the African antelope very nicely: "There's only one antelope, one major species that almost consistently has high fat levels, and that's the eland." And that is a sacred animal for the Bushmen. And there's — I'm not going to attribute every aspect of why it's sacred to the fact that they're fat. But the eland fat is a highly sacred item among Bushmen: it's used in rituals, you get smeared with it and so forth. Obviously they consume it as well. A lot of their rock art is about eland; a lot of their ceremonies are about eland. And it's no wonder every single white great white hunter that went out and blasted everything that moved, that was the first thing they went after. If they could get an eland that was it; a hippo is another one. But for many hunter-gatherers, hippos are probably too hard to kill. However, they're great to scavenge because it's like a barrel of oil sitting there. Another one, which is probably beyond the capacity of a lot of early hunter-gatherers, would be the giraffe. And interestingly enough, the zebra, and interestingly, not the wildebeest. And it's when you look at the literature on the Hadza, one of the major well-studied hunter-gatherer groups in Africa today. They have lots of wildebeests, and they don't like them. They go after zebra. And you look at the the white hunters and missionaries and explorers in Africa, and they all talk about loving the zebra. It has a lot of yellow fat right here. And that's what they targeted. Why didn't they like the wildebeest? The fat coagulates in your mouth, sticks between your teeth, there isn't much fat there. And whenever they could avoid it, they did. So it's it's it's really kind of intriguing. At any rate, African ungulates are exceedingly lean. They are basically, in many cases, walking shoe leather. And every one of these explorers describes them that way. And when they can get fat, they would target it. And if they could get an eland, they'd go after it. If they could get a zebra, they'd go after it. If they could shoot a hippo, that's what they would would target.
So this is another question then: why would African hunter-gatherers spend a lot of time chasing these bundles of protein that don't have all that much fat in them? Now, gradually, paleoanthropology has come to recognize this as a problem. And so what they've done is to shift emphasis and say they were after the brain and the marrow. But when you start quantifying this, it's an incredibly costly enterprise to get that amount of fat. So — and we'll come back to that in a variety of other ways. Protein is a very expensive nutrient. Fat produces nine calories, roughly nine calories per gram; fat — and excuse me — carbohydrate and protein, around four, or four and a half. Now, but there's another aspect to it. And that is, it requires a lot of energy, much more energy, to digest a gram of protein than it does to digest a gram of fat or carbohydrate. So when you eat fat, you need an additional 0 to 3%. So let's say you you eat 100 calories of fat: You need anywhere from 0 to 3% additional calories to metabolize it. Carbohydrate varies, but from roughly 5 to 10, and protein 20 to 30%. So it's a terribly inefficient way, if getting energy from this is what you're trying to do, it's a very inefficient way of doing it. One of the most interesting set of studies was done by a guy named David Rush. He's in Tufts, right here in Boston. I don't know if he's retired now. He may well be. He looked at pregnancy and protein and found — again, think back to the love affair with protein. We had women growing up in urban ghettos, underweight births, low birth weight babies, babies with all kinds of cognitive problems and so forth that were linked to nutrition. What did they do? Supplemented it with protein, skim milk, and so forth. But they didn't do follow-up studies. It was so — they were so convinced that protein was was was an elixir in a way that they simply supplemented the diet of pregnant women with skim milk and things like that. Rush went back retroactively, retrospectively or whatever, to look at these early studies. And he found a very interesting thing: that below about somewhere between six and 10% of calories, protein deficiencies led to problems, but above about 25% of calories, it also went downhill. In other words, there were increases in cognitive deficiencies, decreases in birth weight, much more infant morbidity, disease, and so forth and higher death rates, mortality rates when protein exceeded 25% of calories. They're now finding in studies of in vitro fertilization and so forth that the protein content of the media, the medium, in which the ovum is raised, in the embryo is raised, is extremely important because if you if the protein level gets up above a certain threshold, and it's it's below this 25%, it generates ammonia, and that's toxic to the to the embryo. It's sort of intriguing — well actually we'll come to this next point later. Let's look at protein in the brain. The brain needs anywhere from 20 to 25% of total resting energy just to support that organ. So it's much higher than in other primates. And if you look at the composition of the brain, it's about 8%, protein, 10%, fat and the rest water. Look at muscle. It's muscle that needs protein, not the brain. I'm not saying it doesn't need any protein. But the idea — you'll find it right up to 2000, probably 2011 — I stopped looking, but certainly through 2010 study after study in paleoanthropology that talks about the evolution of human hunting to provide protein for the brain. What the brain needs as an energy source is glucose or ketone bodies, which come from breaking down fat. It does not thrive well on protein; it's a very inefficient way of providing energy to the brain. One indication of this is looking at human breast milk compared to other breast milks: it's the lowest protein milk on the planet, which is really intriguing.
If protein were so important to the development of the brain of the human infant, the human fetus and beyond, then it should this should be reflected in the breast milk. And it's not. What babies are caching is fat. And I call this, you know, the little Michelin Tire Man. Humans have incredibly fat babies. I don't know how well you can see this, but the chimp infant looks like a prune. So humans have this unusual capacity, human infants, to store fat. And I don't know whether you can see this in the back. This is the percent fat at birth. And you can see the humans are well above seals. Really, really interesting: what what human infants are targeting here is fat. And there's a lot of debate about which fats, but basically, it's not protein. We're not — again, I got to emphasize I'm not saying that protein is unnecessary; it's obviously necessary. There are lots of studies that show that it is, but it's not what's driving this. Some of the most interesting things, and very understudied, are cross-cultural looks at food taboos and food aversions. And meat is at the top of the list. And it's interesting, it's especially — and often the staple, so-called, of a particular culture, pregnant and nursing women are often tabooed access to it. And there are all kinds of reasons: you can look at gender politics as part of this, but part of it may have to do with the toxicity to the fetus, to the embryo, and even to the newborn of excessive levels of protein. Others have argued that it's the heavy metals that get into the fats; this could also — the the fats in animal meat — this could also be a variable. This doesn't explain it all as protein, but I think it's very much part of the the picture. Alright, so what's happened is the whole emphasis has shifted in the field. I think paleoanthro is finally moving away from protein. Although the slips in the literature are interesting, as I say, right up till 2010 anyways, of talking about hunting evolving to provide protein for the brain. There's a new interest in omega-3 fatty acids, and one of them in particular has this lovely name of docosahexaenoic acid — DHA is a lot simpler. It's an essential fatty acid. The human is capable of biosynthesizing its own DHA, but very inefficiently. And the DHA is an essential component of the nervous system, the brain and the rest of the nervous system. So, in other words, when somebody has a fat head, a major part of that fat is DHA. Where this has come to play in the nutritional world is the major source, or one of the major sources, of DHA is aquatic foods, particularly fish, and Western women don't eat enough fish. So if you're gonna — also we bottle feed, very commonly, rather than breastfeed, but even if we breastfeed, these studies have indicated that Western mothers don't produce, they don't biosynthesize enough DHA. And they don't get enough in their diet. So the infants are deprived of adequate intakes of DHA, which presumably has negative consequences for the development of the nervous system. So if you're bottle feeding, the question is how much DHA should you put in it. So the medical profession has done all sorts of studies — there's 1000s of articles on the role of DHA, biosynthesizing DHA, and so forth. And so now, in paleoanthro, you'll see studies, you'll see a shift in discussions of of hunting, to targeting — there's no DHA, by the way, in marrow, there's fat. And that's the primary reason for targeting marrow, but there's no DHA — DHA is in the brain. So now people are talking about — well, one of the major things they're targeting in going after big game is the brain. And I'll try to indicate shortly that this is an incredibly expensive way of getting DHA. And I'm not convinced that you need it. This nutritionist that I indicate at the bottom, Graham Bird, starting in 2000 published a series of studies that kind of blew me away.
He pointed out that almost all of the studies of DHA that relate to breastfeeding and bottle feeding were done on men. God knows why. All right. Sometimes they were mixed study groups, males and females. But there were almost no studies of women. So he began conducting studies of biosynthesis of DHA in women. And lo and behold, no surprise, women have a much higher rate of biosynthesis of DHA than men do. And also women store body fat differently — more of it's stored here, whereas men store it here. And that women actually differentially accumulate DHA in these fat deposits, which is mobilized when they begin to nurse. And it's also mobilized late in pregnancy and during nursing. So Graham Bird basically comes out and said, you know, women probably did just fine without all these supplements, that they have the capacity to biosynthesize and that it increases during pregnancy and nursing. So I'm not sure it's an issue. All right, I'm going to try to show you that it doesn't make sense to go and kill a giraffe to try to get a DHA supply. And that there's no archaeological, no decent archaeological, evidence for reliance early on, on aquatic resources. It's a very late development in the human record, maybe 300,000 years ago, maybe 200,000, certainly not with early hominids. There are some arguments to the contrary, but we just don't have the evidence at this point. Now fish bones don't preserve very well, but mollusks do. And that would be another major source. So let's turn to the to the last part of this. And this is to look at modern hunter-gatherers. They add another dimension to this. The two best study groups — and you're all familiar with them, I'm sure: the Hadza in East Africa and the Bushmen, or San, in southern Africa, Namibia, Botswana, and so forth. Now, let me emphasize right off the bat, these groups, and all hunter-gatherers, highly value meat. So it's something that is very desirable to them. So my question is, is it desirable? Obviously nutrition and prestige and other factors enter in political variables, but so I'm not making this a dichotomy — it's one or the other — but is the the major push towards big game hunting driven by a nutritional need, or is it driven more by political factors. And I'm going to basically argue that it's more by political factors, and the nutritional aspect of it is sort of an afterthought. It's an — it's useful, but given the costs of acquiring this stuff, it's not justified by that. Okay. Very briefly, Bushmen, when they hunt — they are the world's best hunters. When I was an undergraduate undergraduate, especially with the publication of Man the Hunter, these be the whole world became seen through Bushman eyes. All right, they are the world's greatest trackers: they can follow animals when, you know, and tell you that it was a female, it was three and a half years old, and that it walked by here on Wednesday at 9am and we know exactly where it's going, etc. Amazing. Then you look at the data: they fail 77% of the time. The Hadza fail 29 out of every 30, hundred days. In other words, both of them had a really lousy record. Now you could say, well, maybe you know, in the Bushman case, you could argue, well, maybe the modern world has so over-hunted everything out there that there's not much out there. No wonder they fail. That's not true with the Hadza. And yet, their failure rate is worse than the Bushmen. In both groups, they lose weight when they hunt. And since a lot of this hunting is done sitting behind a blind, it's not that they're out there running after these things. A lot of it is done through ambush hunting at waterholes. And I think they're on an Atkins diet basically.
The study after study of modern hunter-gatherers who — by behavioral ecologists — is showing that men would do better in terms of reliability of returns, and in fact, in terms of total return rates, if they did what the women did. Some of these studies have actually gone far enough to show that if men did what women did, they would nonetheless not be competing for the same resources with a woman. For instance, the Aché in Paraguay, in South America, one of the major resources is starch palm, and Kim Hill has done, I don't know, 30 years or more, now, studies of the Aché has pointed out that they walk past palm after palm after palm that they don't bother using and when asked they're they're perfectly usable. So it's very unlikely that they're competing with each other. Now the thing that really blew me away was the Bushman bow. I had been bothered by this for years, but I never put two and two together until my son and — I was a late starter with kids — turned 10 and wanted to start shooting a bow and arrow. And so I went to a local sporting goods chain and asked them, you know, for a 10 year old, what's the maximum draw weight I should get? They said 20 pounds. Guess what a Bushman bow is? Twenty pounds. And it's a toy. It's really a toy; it's not a shock weapon at all. And in fact, it's good enough to — if you're lucky enough — to hit an animal, to barely penetrate the skin. Alright, and you have to be pretty damn close to do it. And the literature, the 19th 18th and 19th century literature, is filled with pejorative statements about Bushman bows. And even Charles Dickens got in the act and describes it, basically describe it, a shot from a Bushman arrow is kind of like an animal accidentally bumping up against a thorn, and it kind of rubs its butter its leg against something to rub this thorn and off and walks away. So what's deadly about it is the poison. Okay? If you compare this to Native American bows that are described in the literature, the minimum typically for for Native American bows is 40 pounds, double the draw weight of a Bushman bow. And of course, there are recurve bows, and so forth, which get up to 60, 70, 80 pounds. The Hadza bow is 100 pounds — so strong, in fact, that many hundreds of males apparently can't pull it. And their failure rate is worse than a Bushman, so it's not the power of the bow either. All right, non-lethal shots, they miss — the Bushmen miss almost 80% of the time. They don't hit anything. When they get it, the poison typically takes six to 24 hours to act. The bigger the animal, the slower its effect. So the average tracking time is a day and a half. And of those that they hit and then track for a day and a half, they lose half of those. They either never find them, or they're already consumed by carnivores. And the thing that blew me away, we have lots of studies now how long it takes to reach peak hunting capacity, and it's 30 to 40 years or more. It's way past your physical prime. So why do you spend 30 or 40 years to do this? It seems to me just sort of mind-boggling. As some of the new studies of hunter gatherers have shown that, that pooling of risks through sharing doesn't work either, that people bring this meat back — this very unreliable, very spotty resource — and then they share it mostly with non-kin. And you know, if you're provisioning family, this is not the way to do it. And it's not balanced over time. Study after study shows that once a klutz, always a klutz, and there are good hunters and there are bad hunters. The dichotomy is a little misleading, but what it is is there are some superstars. Those are the ones that do all the hunting. And the non-superstars do some; they're not very effective at it, and they don't work very long at it. The good hunters basically spend tremendous number of hours doing it.
And you look at the alternative resources that are out there for protein and fat. And it's mind-boggling what's available. Now, I'm not saying it's always available, they never fail. But they're a hell of a lot more reliable than than going after these big animals. And they include, you know, some groups have mongongo nuts — you've all heard about mongongo nuts, [non-English], marula nuts, baobab seeds. Many of these are described by nutritionists as, in terms of protein quality, being better than any of our cereal grains. Alright, so they're there, and, having high fat contents, they are, in general, very, very good foods. Here's a mongongo nut grove. There are other things like mopane worms. And there's such an industry in Botswana, that — these are caterpillars, and I have read one lovely description about a professor, I should be doing it here, as he's lecturing is popping dried mopane worms in his mouth — the exploitation is so heavy that that they're becoming an endangered species in Botswana. But they are a huge source of fat, and dry they last a long time, if you can keep them dry. And then I started playing around with the seasonality of this stuff. And what I found — this really was a surprise for me — that peak hunting coincides with the peak of all these other resources. In other words, they're doing most of the hunting at precisely the time of year when all this other stuff is available. And that leads me to my first really step out on the limb. And that is, I think the hunting is underwritten by what women are doing; that is, rather than rather than these males provisioning the women, I think the fact that they can devote all this time and energy to big game hunting is basically made possible by the reliability of what the women are producing. When you look at the Hadza, it actually — they're doing the peak hunting during the worst possible time of year, if they're not going after fat, I mean, if they're going trying to get fat. The peak hunting for the Hadza is in the dry season. This is the worst possible time for animals, which are already very, very lean on average. But that's when the baobab peaks. And so it's the same pattern is there, they're indulging — and they're losing, the men are losing weight. They're out there, as far as I'm concerned on this Atkins diet; the Aché, a South American group, expend as much energy as an Eskimo staying alive. And what they do, according to Kim Hill, is they go out in one hour, without using any tools or weapons, they fulfill both their protein and their fat needs. And then they spend the next six hours hunting.
There's your baobabs; I love these trees. I wish I could grow one in Ann Arbor. There's data to suggest that maybe chimps are doing the same thing, that a lot of the hunting that they do seems to be during peak fruiting times when you have large groups of males together. And it's pointing in my view, at least — and I'm not an expert on this at all — but just looking at at what's coming out on chimps, it's it doesn't look to me like it's nutritionally motivated, that it's more likely socially, politically motivated, rather than driven by nutrition. All right, so let's bring this to a close here. And as I said, this is very speculative. Okay, and I, you know, I put it in a book, so I guess I'm stuck with it. But it's it's intriguing, but it's, as I say, it's rather unorthodox. Meat is clearly highly valued. And there's no self respecting hunter-gatherer, I think, that would think otherwise, men and women. They like the taste of it. And it's something that is highly valued. Obviously, it produces fat, it produces protein, so I mean, it's nutrition — and calories — so it's nutritionally valuable, but it has a lot of negatives. You don't need much: You need, for a typical hunter-gatherer body size, you need about 50 grams a day. Chimps, apparently the termites do this, get this amount in about half an hour, something like that. And you certainly don't need to get it from a giraffe or a wildebeest; you can get it from a mopane worm, you can get it from termites — you don't need to go chasing these big animals around the landscape. Fat is very limited in these animals. It's a huge expenditure of time and energy and training for 35 years or 40 years, in order to go after the brain or the marrow to get DHA. If this were a primary source of DHA, which is being seriously argued in the literature, it's an incredibly inefficient and expensive way of doing it. And I'm not sure it's necessary. It's unreliable. And in many cases and areas, it's dangerous. So now let's look at the political side of this and then we'll call it quits.
Some of the most interesting work has been done by a woman named Polly Wiessner, who's been working off and on — on not every year, but off and on — with the Bushmen for more than 30 years. And her data are really, really interesting. What she finds — first of all, she divides good hunters and poor hunters, again, on the basis of those that are clearly, and respected by everyone as, good hunters. They're, they're the superstars in hunting. The poor hunters, they aren't necessarily complete flops, but they don't do it as well. They have reputations of not being as successful. And what you find is, these guys work really hard and they work overtime. And these guys basically sort of work "under" time. What she found is when you look at the groups, in some of these dimensions, the completed fertility, that means the number of kids, is significantly higher in local groups that have a good hunter. Children surviving to the age of 15 are significantly greater in groups that have a good hunter. The number — if you're not familiar with xaro, I have no idea how you're supposed to really pronounce this, but the Bushmen have this set of social relations that extend out in many cases hundreds of kilometers, where there'll be a a relationship, an exchange relationship. It gives you access to resources, it gives you access to mates, it gives you access to information. You establish these networks; you can pass them on to your kids. And what she found, what Polly found, was that groups that have good hunters have much more extensive — first, more xaro connections, as with other people and groups elsewhere, as well as greater distances, so they have access to information and resources and so forth over a much greater area. Really interestingly, she found that the duration of camps of stable — I don't mean sedentary now, but I may describe the way the Bushmen work: They have what they call n!ore or n!oresi. These are resource areas surrounding waterholes, and they belong to groups. Now you've all heard the debates about whether hunter-gatherers and Bushmen and others are territorial or not; in a sense, they are.
What they do, basically, the longer you've had residence at a waterhole — I don't mean year round, I don't mean sedentary over the year, but over generations, that that waterhole and the associated resources, it may be more than one waterhole and the resource area that goes with it, belongs to certain individuals, and that's inherited through both sides of the family. Kids inherit it from both parents. And the longer you can trace your your presence and your ancestors' presence in that n!ore, the greater your rights to those resources. And it was argued in the literature that well, but you know, others can come in and use these resources. All they have to do is ask. Yes, that's true. But then you find others who say, "But they would never ask." Or rarely ask. It's clear that people who do not have rights to that n!ore can't stay there very long. All right, they're they're unstable. So what what Polly Wiessner found was the groups that have a good hunter, and have had good hunters in the past, have had rights to that particular n!ore for generations. So there's a stability to access to to resources that's linked in some way to the presence of good hunters. The percentage — I mentioned this, I think — the percentage of children surviving to age 15, the percentage of children that marry and bring their spouse to that n!ore is much greater. So basically what you have is a series of related individuals. Now what Polly does I think is a very valuable thing. Behavioral ecololgists tend to think of kinship in terms of blood relationship. Polly says that's a mistake, that you have to consider relatives through marriage because they have a vested interest in the kids. And so when — it's true that these hunters are provisioning non-kin, if you think in terms of blood kin, but they're actually provisioning people who have a vested interest in the success of those kids, a vested interest in finding them xaro partnerships, of finding them mates, and so forth. So in fact, in this broader sense, they are provisioning kin. And what Polly found was that groups with good hunters have a hell of a lot more kin that are long term stable residents of that n!ore. So here's sort of the way I would pull it together: meat tastes good. I'm not totally satisfied with this yet — Polly has speculated about what it is about good hunting, successful hunters, that ultimately leads to these consequences. But it's interesting and something, I think, well worth thinking about. Meat is a highly valued resource. It tastes good, they like it, they want it. That does not mean that it's protein that they want, alright. And that's, I think, a mistake we've made in the field; we've sort of put that, equated that, in a way with a nutritional need. Meat is hard to get. Meat, therefore, is a valued resource. It's something these groups want; these people want. And one of the things that Polly did was to interview a lot of these good hunters and to see what the how they would express themselves, on their own, why they were doing this. And — whoops, I guess I didn't put the quote in here. Well, okay. Basically what she found was that what they would tell her was, "We do this so we keep our kin together." In other words, they actually are conscious of this being politically motivated. Now, they may also be conscious of, you know, showing off their macho and whatever. But basically, what she's finding with a Bushman, at least, is they are very conscious of this as a means of providing a valued resource that makes them attractive and holds a core of kin, and kin defined in this broader sense of blood- and marriage-related individuals. So let me stop there.
Sure, more than happy to — tomatoes, whatever.
Audience Member 1:08:15
Well if it's not really nutritionally important, then how can it function in a way that you're saying it functions?
Dr. John Speth 1:08:25
This is why I said I'm not sure that Polly has found the answer yet. One answer that's also not satisfied: You could ask, in a way, why they don't emphasize collecting big mushrooms or big tree stumps or something? Why did they zero in on meat? So far, I've stayed away from it, recognizing this is a really critical question, why — and it's the same issue with chimpanzees. Why is this targeted? And again, I have to say there is a nutritional value to it. But the the time and energy that goes into this is not, to me, is not justified by the nutrition. What scares me about this — I'm thinking a lot about it, but I be totally honest, I don't have an answer yet. I don't have anything that I find really convincing. The danger of this is if you remember back to the day, the 50s with Robert Ardrey and African Genesis, the killer ape hypothesis and so forth — I don't want to go there again. So I'm not sure what what what really is driving — what makes it a valued resource. Maybe it's just the taste and the novelty. They will tell you, many hunter gatherers will say, "Well, we're craving meat," and we've generally translated that to mean there's a nutritional craving going on. And it may not be some strictly nutritional shortage. It may be that it just tastes good. But I don't know if I want to go into print with that. I'm not I'm not convinced, and I'm not sure what's driving — to me this is now a really interesting question. Another one that is sort of like this is: What happens when you get into more northerly latitudes? You know, what happens to the nutritional component of this? So I'm not there are a lot of loose ends yet that I, you know, I'm not not satisfied with. I like, I guess, let me put it this way. At this point, what I like about it is not that it's necessarily right. But it's nice for change after 150 years, to look at something other than nutrition, to look at a social-political dimension. And this brings in another whole class of issues. And anthropology is, in so many ways, beautifully divided. I put beautiful in quotes here. You know, this is like the argument of why women don't hunt, and there are a lot of us searching for biological reasons: you know, they, they're handicapped by having to carry children and so forth. Although with all these kinsmen around through marriage, as well as through blood, and what now everybody talks about as alloparenting, maybe that's a nonissue. But on the other side, there's the gender politics that say, well, the reason women don't hunt is because men don't allow them to develop the skills and won't let them touch the weapons. And right now, these two arguments are sitting, you know, polar opposites. And I find both intriguing: What I'm trying to find a way is to somehow pull these two together. I don't think we can ignore one for the for the other. There are undoubtedly biological factors involved, but there probably are very important social and political variables as well. And right now they're studied in two different sub-departments, if you like that don't seem to talk to each other all that much.
So you look at the literature, for instance, on the Hadza: You have the behavioral ecologists, who are talking about all the calories and protein that these hunters are bringing in and distributing among the group, but there's no ethnography in there. In fact, when I got the book, when I did the book, the editor said, "You better put some pictures in it." So I wrote to Jim McConnell and said, "Hey, can you send me some pictures of the of the Hadza?" And he sent me a, an image of a Hadza camp, and it suddenly dawned on me: I'd never seen a picture of a Hadza camp. I didn't know what they look like. And then it turns out, if you read some of the ethnographers of the Hadza, they talk about a ritual practice in which only men, only initiated men, are allowed to eat the fattest parts on the on the game that they kill. And then women were under threat of death if they got involved with this. I have never seen that discussed by the behavioral ecologists. So they provide all this quantitative data on the calories and nutrients and time expended, but they don't talk about the gender politics, and that must have a hell of an impact on the nutritional value. So somehow, we have to put these together, and I can't — you know, the question you've asked is a really important one, and I'm sort of starting from ground zero now and trying to come up with a reason why meat is valued. And I'm scared of dabbling in psychology. I don't have the training for it.
Audience Member 1:13:35
I'm just curious to know: what would be the fatty acid sources, non-animal fatty acid sources, for these hunter-gatherers?
Dr. John Speth 1:13:44
You mean for these essential for the essential fatty acids?
Audience Member 1:13:48
Dr. John Speth 1:13:52
Well, I mean, you know, you could argue that, you know, frog brains — Bushmen ate a lot of frogs in certain seasons, rodents, birds. Nobody really talks about that. They're looking at the big game. But as I said, from Graham Burdge's studies and so forth, you know, if you look at the brains of vegans, I'm not sure anybody has shown that they're DHA deficient — obviously, depends on the specific nature of the diet, but if they're not eating seafood, they're not eating eggs, they're not eating a bunch of these other things, the question is, where are they getting it from? Well, you know, these are things we need to look at. And it's it's not been looked at seriously enough. And I've looked at studies of reptiles that that have no DHA in their diet, supposedly, and they seem to — I mean, I can't evaluate the brain of a reptile — I don't know whether they're normal or not, but they, you know, presumably they're normal brains. And what Graham Burdge is suggesting is it may be a nonissue: That is, women may be capable of biosynthesizing and storing adequate DHA to fulfill those needs without having to go to these external sources. But, again, Burdge has just started this in 2000, so it's fairly new. And he's doing a lot of studies now of pregnant nursing women on different types of diets to see what, you know, what the consequences of that are for brain development. It's hard to do in humans, obviously, because of all the ethical issues.
Audience Member 1:15:37
Can I ask a very closely related question? So the list of deleterious effects of excess protein consumption, is that unchanged? That the protein sources are non-animal, or?
Dr. John Speth 1:15:51
You know, that's an interesting question, too. And I've been helped a lot by a nutritionist named Loren Cordain. And he basically says that the key seems to be the animal protein; originally I included the plant protein component because that would elevate it significantly in certain times and certain areas. And he said a lot of that seems to be metabolized for for energy. And I'm not sure why because it still must be producing nitrogen. And so I need to — I've never actually met him; this is all by email. And I need to actually go and sit down with him and say, "Okay, explain to me why the these high plant protein intakes don't figure into these totals," because he does not include them. And it's not clear to me why. I don't know what happens to the nitrogen because to me, it's there. And I, if you include the plant protein, then these hunter-gatherer nitrogen intakes or protein intakes are much, much higher. And that would bring them to the threshold much sooner, and would mean that the amount of meat they could safely consume is even lower. So it's a really good question. And again, it's another one of these areas that I don't know the answer to. And you know, I'm handicapped by not being trained in nutrition. This is dangerous, dangerous turf, but Cordain has been a huge help to me because without that — you know, he's not guilty for anything I say, but, but he's been a tremendous help. And and that's a really important question. As I say, when I started writing about this, I combined the two. And he told me, "Don't do that, take it out," that the the metabolic pathways for the plant proteins are different. But I don't understand why at this point, so.
Event Facilitator 1:17:38
We have one last question.
Audience Member 1:17:40
Thanks for your interesting talk. I believe Farley Mowat, I think, wrote a book called People of the Deer in which he talks about, I think the Athabaskans, whose diets are almost entirely reindeer. And so it seems that to some degree, human diets are just very, very adaptable, because I would assume that if they're eating almost nothing but reindeer meat that they're not getting sick by any [inaudible].
Dr. John Speth 1:18:06
Well, there's a very famous set of studies by a guy named Stefansson, who was an Arctic explorer — spent years in the early part of the 20th century living among Eskimo and wrote — he wrote a lot of stuff, but one of my favorite books by him, and you can find this in probably almost any library, is called Arctic Manual. I think it was, I don't remember the exact date, but in the 1940s. And what he shows is that all of these groups, that roughly 75% of their calories came from fat, even these people dependent on reindeer. And in fact, you can see this in descriptions of the way the Athabaskans and others assessed whether there was enough fat in the animal: What they would do is, there's a fat depletion sequence in animals, that — I mean, it varies to some extent among different species, but basically, the first thing to go is the fat under the skin. And then if you deplete that, it doesn't wait till it's totally depleted; you start depleting the fat around the internal organs. And then when that progresses to a certain point, you begin to deplete the fat in the marrow. And that actually goes in a linear sequence, starting close to the body and moving towards the feet. And it's interesting: When you read these ethnographies of these reindeer hunters, when they kill an animal, if they have — a reindeer, caribou — when if they have any worry about whether it has enough fat, they'll break open the lower front left — the front limb goes faster than the rear limb — but they'll break open that lower front limb, and if the marrow is watery, it means it's fat depleted. They'll throw the animal away. So they're very conscious of this. And what what Stefansson did, he was trying to convince the US military to use pemmican, which is, you know, dried meat mixed with fat — by the way, typically 75% fat, 25% protein. And there's a huge literature on this from the fur trappers and explorers and so; they were really conscious of exactly how it had to be made, what kinds of fats so it doesn't go rancid, and so forth. Stefansson was trying to get the the military away from chocolate bars as emergency rations and to use pemmican. And in order to convince them that it was safe to eat nothing but pemmican, he went on a, he and an associate of his, went under medical supervision in New York City for an entire year eating nothing but meat. And he was monitored every every possible way, at least — this was done in the in the late 30s. He was monitored very — blood levels, all sorts of stuff. And they experimented a little bit, changing the ratios of fat to protein, and, you know, he developed diarrhea, then they changed the ratios again and the diarrhea would go away, and he subsisted, or the two of them subsisted, for an entire year on this.
And as I say, if you start looking at the explorer, traveler accounts, trapper accounts — it's not just in the Arctic; you look in Australia, Africa, and so forth — you'll find recognition of the same phenomenon. They had a good gut sense, if you like, of exactly what they needed in order to maintain the right ratio. And a lot of these groups, if there are problems with available fat — and you look at the literature — most of these interior Athabaskan and other groups, again it depends where they are, sometimes fish to acquire fat, or go for waterfowl, or interestingly enough beaver tails because beaver maintain a very high fat level in their tail in the spring when everything else is fat depleted. So I think beaver were under pressure before the fur trade because of this, but at any rate, many of the groups, the interior Alaskan groups and Canadian groups, had trade relations with coastal groups. And if things failed in the interior, they became coastal groups; they would actually live on the coast and exploit marine resources. And they had all kinds of rituals that would purify the these marine resources, pouring freshwater in the mouth of the animal before they butchered it, and so forth. But these relationships were apparently really critical. Many of them traded for fish oils. And so those were, I don't know if you want to call them commodities, but containers of fish oil were being traded to the interior. So Stefansson does a beautiful job of documenting what those ratios have to be. And his is quantified whereas, you know, a lot of these earlier accounts they're, they're only sort of semi-quantitative, which was why a lot of the nutritionists when I first got into this would reject them. You know, nobody does this. It didn't make any sense. But there's so much of it, and then you find Stefansson who actually put numbers to it.
Event Facilitator 1:23:16
I think we should continue our questioning of our speaker at the reception which will be in the Hall of North American Indian. Thank you very much.
Dr. John Speth 1:23:24