There's an idea currently circulating that sugar is the main reason why healthy traditional cultures end up obese and sick. It’s easy to find non-industrial cultures that are lean and don’t eat much sugar, and it’s easy to find industrial cultures that are obese and eat a lot of it. But many factors are changing simultaneously there. We could use the same examples to demonstrate that blue jeans and hair gel cause obesity. If sugar is truly the important factor, then cultures with a high sugar intake, but an otherwise ancestral diet and lifestyle, should also be overweight and sick. Let’s see if that's true.
Showing posts with label native diet. Show all posts
Showing posts with label native diet. Show all posts
Saturday, June 9, 2012
Sugar Intake and Body Fatness in Non-industrial Cultures
Around the world, non-industrial cultures following an ancestral diet and lifestyle tend to be lean. When they transition a modern diet and lifestyle, they typically put on body fat and develop the classic "diseases of civilization" such as diabetes and cardiovascular disease. If we can understand the reasons why this health transition occurs, we will understand why these problems afflict us today. Research has already identified a number of important factors, but today I'm going to discuss one in particular that has received a lot of attention lately: sugar.
There's an idea currently circulating that sugar is the main reason why healthy traditional cultures end up obese and sick. It’s easy to find non-industrial cultures that are lean and don’t eat much sugar, and it’s easy to find industrial cultures that are obese and eat a lot of it. But many factors are changing simultaneously there. We could use the same examples to demonstrate that blue jeans and hair gel cause obesity. If sugar is truly the important factor, then cultures with a high sugar intake, but an otherwise ancestral diet and lifestyle, should also be overweight and sick. Let’s see if that's true.
Read more »
There's an idea currently circulating that sugar is the main reason why healthy traditional cultures end up obese and sick. It’s easy to find non-industrial cultures that are lean and don’t eat much sugar, and it’s easy to find industrial cultures that are obese and eat a lot of it. But many factors are changing simultaneously there. We could use the same examples to demonstrate that blue jeans and hair gel cause obesity. If sugar is truly the important factor, then cultures with a high sugar intake, but an otherwise ancestral diet and lifestyle, should also be overweight and sick. Let’s see if that's true.
Thursday, May 17, 2012
Beyond Ötzi: European Evolutionary History and its Relevance to Diet. Part III
In previous posts, I reviewed some of the evidence suggesting that human evolution has accelerated rapidly since the development of agriculture (and to some degree, before it). Europeans (and other lineages with a long history of agriculture) carry known genetic adaptations to the Neolithic diet, and there are probably many adaptations that have not yet been identified. In my final post in this series, I'll argue that although we've adapted, the adaptation is probably not complete, and we're left in a sort of genetic limbo between the Paleolithic and Neolithic state.
Recent Genetic Adaptations are Often Crude
It may at first seem strange, but many genes responsible for common genetic disorders show evidence of positive selection. In other words, the genes that cause these disorders were favored by evolution at some point because they presumably provided a survival advantage. For example, the sickle cell anemia gene protects against malaria, but if you inherit two copies of it, you end up with a serious and life-threatening disorder (1). The cystic fibrosis gene may have been selected to protect against one or more infectious diseases, but again if you get two copies of it, quality of life and lifespan are greatly curtailed (2, 3). Familial Mediterranean fever is a very common disorder in Mediterranean populations, involving painful inflammatory attacks of the digestive tract, and sometimes a deadly condition called amyloidosis. It shows evidence of positive selection and probably protected against intestinal disease due to the heightened inflammatory state it confers to the digestive tract (4, 5). Celiac disease, a severe autoimmune reaction to gluten found in some grains, may be a by-product of selection for protection against bacterial infection (6). Phenylketonuria also shows evidence of positive selection (7), and the list goes on. It's clear that a lot of our recent evolution was in response to new disease pressures, likely from increased population density, sendentism, and contact with domestic animals.
Read more »
Recent Genetic Adaptations are Often Crude
It may at first seem strange, but many genes responsible for common genetic disorders show evidence of positive selection. In other words, the genes that cause these disorders were favored by evolution at some point because they presumably provided a survival advantage. For example, the sickle cell anemia gene protects against malaria, but if you inherit two copies of it, you end up with a serious and life-threatening disorder (1). The cystic fibrosis gene may have been selected to protect against one or more infectious diseases, but again if you get two copies of it, quality of life and lifespan are greatly curtailed (2, 3). Familial Mediterranean fever is a very common disorder in Mediterranean populations, involving painful inflammatory attacks of the digestive tract, and sometimes a deadly condition called amyloidosis. It shows evidence of positive selection and probably protected against intestinal disease due to the heightened inflammatory state it confers to the digestive tract (4, 5). Celiac disease, a severe autoimmune reaction to gluten found in some grains, may be a by-product of selection for protection against bacterial infection (6). Phenylketonuria also shows evidence of positive selection (7), and the list goes on. It's clear that a lot of our recent evolution was in response to new disease pressures, likely from increased population density, sendentism, and contact with domestic animals.
Read more »
Monday, May 7, 2012
Beyond Ötzi: European Evolutionary History and its Relevance to Diet. Part II
In previous posts, I described how Otzi was (at least in large part) a genetic descendant of Middle Eastern agriculturalists, rather than being purely descended from local hunter-gatherers who adopted agriculture in situ. I also reviewed evidence showing that modern Europeans are a genetic mixture of local European hunter-gatherers, incoming agricultural populations from the Middle East, neanderthals, and perhaps other groups. In this post, I'll describe the evidence for rapid human evolution since the end of the Paleolithic period, and research indicating that some of these changes are adaptations to the Neolithic (agricultural/horticultural/pastoral) diet.
Humans have Evolved Significantly Since the End of the Paleolithic
Evolution by natural selection leaves a distinct signature in the genome, and geneticists can detect this signature tens of thousands of years after the fact by comparing many genomes to one another. A landmark paper published in 2007 by Dr. John Hawks and colleagues showed that humans have been undergoing "extraordinarily rapid recent genetic evolution" over the last 40,000 years (1). Furthermore:
Read more »
Humans have Evolved Significantly Since the End of the Paleolithic
Evolution by natural selection leaves a distinct signature in the genome, and geneticists can detect this signature tens of thousands of years after the fact by comparing many genomes to one another. A landmark paper published in 2007 by Dr. John Hawks and colleagues showed that humans have been undergoing "extraordinarily rapid recent genetic evolution" over the last 40,000 years (1). Furthermore:
Read more »
Saturday, May 5, 2012
Media Appearances
Last October, I participated in a panel discussion organized by the Harvard Food Law Society in Boston. The panel included Drs. Walter Willett, David Ludwig, Robert Lustig, and myself, with Corby Kummer as moderator. Dr. Willett is the chair of the Harvard Department of Nutrition; Dr. Ludwig is a professor of nutrition and pediatrics at Harvard; Dr. Lustig is a professor of clinical pediatrics at UCSF; and Kummer is a food writer and senior editor for The Atlantic.
Read more »
Read more »
Saturday, April 28, 2012
Beyond Ötzi: European Evolutionary History and its Relevance to Diet. Part I
In the previous post, I explained that Otzi descended in large part from early adopters of agriculture in the Middle East or nearby. What I'll explain in further posts is that Otzi was not a genetic anomaly: he was part of a wave of agricultural migrants that washed over Europe thousands of years ago, spreading their genes throughout. Not only that, Otzi represents a halfway point in the evolutionary process that transformed Paleolithic humans into modern humans.
Did Agriculture in Europe Spread by Cultural Transmission or by Population Replacement?
There's a long-standing debate in the anthropology community over how agriculture spread throughout Europe. One camp proposes that agriculture spread by a cultural route, and that European hunter-gatherers simply settled down and began planting grains. The other camp suggests that European hunter-gatherers were replaced (totally or partially) by waves of agriculturalist immigrants from the Middle East that were culturally and genetically better adapted to the agricultural diet and lifestyle. These are two extreme positions, and I think almost everyone would agree at this point that the truth lies somewhere in between: modern Europeans are a mix of genetic lineages, some of which originate from the earliest Middle Eastern agriculturalists who expanded into Europe, and some of which originate from indigenous hunter-gatherer groups including a small contribution from neanderthals. We know that modern-day Europeans are not simply Paleolithic mammoth eaters who reluctantly settled down and began farming.
Read more »
Did Agriculture in Europe Spread by Cultural Transmission or by Population Replacement?
There's a long-standing debate in the anthropology community over how agriculture spread throughout Europe. One camp proposes that agriculture spread by a cultural route, and that European hunter-gatherers simply settled down and began planting grains. The other camp suggests that European hunter-gatherers were replaced (totally or partially) by waves of agriculturalist immigrants from the Middle East that were culturally and genetically better adapted to the agricultural diet and lifestyle. These are two extreme positions, and I think almost everyone would agree at this point that the truth lies somewhere in between: modern Europeans are a mix of genetic lineages, some of which originate from the earliest Middle Eastern agriculturalists who expanded into Europe, and some of which originate from indigenous hunter-gatherer groups including a small contribution from neanderthals. We know that modern-day Europeans are not simply Paleolithic mammoth eaters who reluctantly settled down and began farming.
Read more »
Tuesday, April 24, 2012
Lessons From Ötzi, the Tyrolean Ice Man. Part III
There are two reasons why I chose this time to write about Otzi. The first is that I've been looking for a good excuse to revisit human evolutionary history, particularly that of Europeans, and what it does and doesn't tell us about the "optimal" human diet. The second is that Otzi's full genome was sequenced and described in a recent issue of Nature Communications (1). A "genome" is the full complement of genes an organism carries. So what that means is that researchers have sequenced almost all of his genes.
Read more »
Read more »
Tuesday, April 17, 2012
Lessons From Ötzi, the Tyrolean Ice Man. Part II
Otzi's Diet
Otzi's digestive tract contains the remains of three meals. They were composed of cooked grains (wheat bread and wheat grains), meat, roots, fruit and seeds (1, 2). The meat came from three different animals-- chamois, red deer and ibex. The "wheat" was actually not what we would think of as modern wheat, but an ancestral variety called einkorn.
Isotope analysis indicates that Otzi's habitual diet was primarily centered around plant foods, likely heavily dependent on grains but also incorporating a variety of other plants (3). He died in the spring with a belly full of einkorn wheat. Since wheat is harvested in the fall, this suggests that his culture stored grain and was dependent on it for most if not all of the year. However, he also clearly ate meat and used leather made from his prey. Researchers are still debating the quantity of meat in his diet, but it was probably secondary to grains and other plant foods. It isn't known whether or not he consumed dairy.
Read more »
Otzi's digestive tract contains the remains of three meals. They were composed of cooked grains (wheat bread and wheat grains), meat, roots, fruit and seeds (1, 2). The meat came from three different animals-- chamois, red deer and ibex. The "wheat" was actually not what we would think of as modern wheat, but an ancestral variety called einkorn.
Isotope analysis indicates that Otzi's habitual diet was primarily centered around plant foods, likely heavily dependent on grains but also incorporating a variety of other plants (3). He died in the spring with a belly full of einkorn wheat. Since wheat is harvested in the fall, this suggests that his culture stored grain and was dependent on it for most if not all of the year. However, he also clearly ate meat and used leather made from his prey. Researchers are still debating the quantity of meat in his diet, but it was probably secondary to grains and other plant foods. It isn't known whether or not he consumed dairy.
Read more »
Tuesday, April 10, 2012
Lessons From Ötzi, the Tyrolean Ice Man. Part I
Otzi is Europe's oldest natural human mummy, and as such, he's an important window into the history of the human species in Europe. His genome has been sequenced, and it offers us clues about the genetic history of modern Europeans.
Otzi's Story
Read more »
Subscribe to:
Comments (Atom)