I recently encountered an interesting article on Medical News Today about research conducted by Kent State University scholars about children’s food preferences, “Strawberries, Watermelon, Grapes, Oh My! Study Finds Students Will Opt For Healthy Foods In The Lunch Line.” Despite the upbeat title, I find the news reported hopeful but mixed from the standpoint of healthy nutrition choices.
The fact that children rank fruits among their favorite foods is encouraging. This is balanced, though by the inclusion of preference for pizza and fast-food-style choices as also among their favorites. I’m also more ambivalent than the article’s author in seeing something like “string cheese” as a healthy food. At the same time, it is encouraging to hear that even as they offer lunch options of pizza and fast food style choices, more school districts are offering healthier versions of these items than in the past.
On a last note, while the researchers attribute preferences such as pizza, French fries, or chicken nuggets to cultural influence, I would tend to argue that preferences for things like fruits or for such fast food fare are all mediated by a combination of evolutionarily selected biological factors and cultural influences. A taste for certain food qualities, such as sweetness, the taste and texture of fats or proteins, saltiness, etc., seem to be a part of our evolutionary heritage, with this part of the reason that children (or adults) find fruits or chicken nuggets tasty. Patterns of consuming and acquiring a preference for specific food items are clearly also shaped by cultural context, though the precise influences shaping children’s desires for grapes or pizza differ.
The following is a selection from the article:
“Strawberries, grapes, and yogurt are just some of the healthier food items children prefer, researchers argue in a new study released this week. Kent State University researchers surveyed 1,818 students in grades 3 through 12, asking them what their favorite foods were. The study, included in the Winter 2007 issue of the Journal of Child Nutrition & Management, found that items such as strawberries, watermelon, white milk, and string cheese ranked among the "Top 20" foods, demonstrating that children will eat fruits, vegetables, and dairy products. “The researchers also found differences in taste between grade levels. Elementary school students were more likely to rank fruits much higher than older children, while "fast and familiar" foods such as chicken nuggets and hamburgers were less preferred by middle school and high school students.
“Although healthy items made the "Top 20" list, children still consider pizza, French fries, and chicken nuggets among their favorite foods. The researchers attribute this to the influence of culture on students. On average, approximately 30% of students consume fast food on any given day, making it more likely that students will eat these foods at school. To accommodate their tastes, school nutrition professionals offer these items, but use healthier ingredients such as whole grains, low-fat cheese, and lean meats and prepare the foods with healthier cooking techniques such as baking.
"School foodservice professionals and dietitians have been promoting the consumption of a wide variety of foods for a healthy diet," concluded researchers Natalie Caine-Bish, PhD, RD, LD and Barbara Scheule, PhD, RD. "Menu planners should consider the inclusion of these selections (favorite foods) in their menus as means to improve nutritional quality as well as satisfaction."
Showing posts with label human evolution. Show all posts
Showing posts with label human evolution. Show all posts
Wednesday, December 12, 2007
Thursday, October 25, 2007
Economics, Human Evolution, Genetics, and the Obesity Epidemic
At a recent research symposium on Addictive and Health Behaviors Research, I heard an informative talk by Kelly Brownell, co-founder and director of the Rudd Center for Food Policy and Obesity at Yale University.
Brownell’s talk was titled “A New and Important Frontier: Food and Addiction.” A key topic of his talk was whether “food addiction” is a real phenomenon for some individuals or a bad analogy drawn with addiction to a variety of mind-altering substances. He concluded that, at least for some, food addiction probably is a real clinical phenomenon, drawing on several bodies of evidence: foods high in sugar or fat have been shown to cause dopamine production in a way similar to that of many drugs (i.e. the experience of pleasure from such foods is not just in the taste buds); there’s evidence of addictive behavior around such foods in some lab animals; the narratives and descriptions of favorite foods by “food addicts” mirrors that of drug addicts.
In the process of laying out his arguments about food addiction, Brownell gave an overview of the obesity epidemic in the U.S. over the past few decades. Much of what he covered was generally available knowledge, though his comprehensive synthesis of a vast amount of material was impressive.
These were by no means the only factors he addressed (see the Rudd Center’s website that I linked above for a fairly comprehensive overview of obesity research), but I was particularly struck by his comments on economics and human evolution.
Economics and Obesity
Brownell addressed economics and obesity in several ways.
Agricultural Economics and Obesity
As many are aware, industrial agriculture is heavily subsidized in the U.S. and many other developed countries. In the U.S., corn (maize) agricultural interests are particularly well set up with regard to subsidization of the industry. In its current form, such heavy subsidization dates back to the Nixon era, intended as a way to combat food price inflation.
An effect of this was the tremendous growth of corn and other agribusiness, and the development of a number of at the time unanticipated corn products (greater availability of corn oil and development of high fructose corn syrup), all kept artificially cheap by agricultural subsidies. A result of this is that processed foods high in fats and sugars are often quite cheap, especially when compared to prices of healthier foods, in particular the relatively high cost of fresh produce. So, for example, even while some fast food chains commendably offer healthy salad options, the healthy options tend to be quite expensive compared to the price of a meal of corn-fed-beef patties, potatoes fried in corn oil, and high-fructose-corn-syrup-laden beverages in giant portions.
Junk Food as a Caloric Bargain
High fat and/or high sugar foods tend to nowadays be available cheaply, at least in the U.S. and other developed countries – and increasingly this seems to be true elsewhere as well. Brownell made another interesting point here, though. If we look at food economics not just in terms of monetary cost but calories, junk food is a tremendous bargain. By weight, junk food is typically already cheaper than healthier food, but calorie for calorie, junk food is tremendously cheaper.
Poverty and Obesity
On top of the basic economics of food in the U.S. today, in impoverished communities, high fat and/or high sugar foods tend to be easily available relatively cheaply (even if not as cheaply as the same foods in other areas because of the lower incidence of full service grocery stores), while things like fresh produce are often hardly available at all and at higher prices, contributing to the problem of obesity in poor communities.
Human Evolution and Obesity
I was happy to see Brownell address a topic often left out of debates about obesity: human evolution. There’s strong evidence that humans generally take great pleasure in fatty or sweet foods (those dopamines mentioned above). This is something we share in common with other mammals, and is almost certainly something selected for in our evolutionary history.
This makes perfect sense – foods high in fats and sugars are caloric bargains, but are not particularly common in many natural environments. Animals who take pleasure in eating these foods would tend to seek them out more often and would tend to have an evolutionary advantage over those who didn’t.
But take this evolutionary heritage and add it to an economic environment unlike any our hominid or earlier primate ancestors ever adapted to, with an over-abundance of sugars and fats, and you get the obesity epidemic.
Genetics and Obesity
Both during his talk and during the question session, Brownell spoke of genetics as a factor in order to dismiss it as significant. I had been similarly dismissive of genetics as a significant factor in producing patterns of obesity before hearing this talk, and generally agree with his perspective here, particularly at the level of populations and gene pools: gene pools haven’t changed in the past 20-30 years in any significant way; the food environment has changed in multiple significant and obvious ways; therefore, genetics is not a serious consideration.
Interestingly, as I listened to Brownell present a position similar to that I have tended to take, I began to see the possibility for a change in genetic predispositions as a factor in obesity at the individual level. With increases in rates of obesity, we’re talking about a change to phenotype. Phenotype is always the product of genotype in interaction with environment. In this case, genotypes haven’t changed; it’s a variety of environmental factors that have changed; but that doesn’t mean that changing phenotype is solely the product of the changing environment necessarily, for phenotype is, again, always the product of that relationship between genotype and environment. A genotype that didn’t contribute to increased predisposition to obesity in one context might in another.
Still, I agree with a point that Brownell made during the Q and A session. Regardless of any potential genetic predisposition to obesity that some individuals may have, from a prevention or intervention stand point, it’s essentially irrelevant. At the population level, environmental factors are clearly the directly relevant ones and genetic predispositions aren’t something that can be particularly addressed at that level anyway. But even for individuals, for a person attempting to lose weight, the trick is to expend more calories than are taken in, irrespective of genotype.
Brownell’s talk was titled “A New and Important Frontier: Food and Addiction.” A key topic of his talk was whether “food addiction” is a real phenomenon for some individuals or a bad analogy drawn with addiction to a variety of mind-altering substances. He concluded that, at least for some, food addiction probably is a real clinical phenomenon, drawing on several bodies of evidence: foods high in sugar or fat have been shown to cause dopamine production in a way similar to that of many drugs (i.e. the experience of pleasure from such foods is not just in the taste buds); there’s evidence of addictive behavior around such foods in some lab animals; the narratives and descriptions of favorite foods by “food addicts” mirrors that of drug addicts.
In the process of laying out his arguments about food addiction, Brownell gave an overview of the obesity epidemic in the U.S. over the past few decades. Much of what he covered was generally available knowledge, though his comprehensive synthesis of a vast amount of material was impressive.
These were by no means the only factors he addressed (see the Rudd Center’s website that I linked above for a fairly comprehensive overview of obesity research), but I was particularly struck by his comments on economics and human evolution.
Economics and Obesity
Brownell addressed economics and obesity in several ways.
Agricultural Economics and Obesity
As many are aware, industrial agriculture is heavily subsidized in the U.S. and many other developed countries. In the U.S., corn (maize) agricultural interests are particularly well set up with regard to subsidization of the industry. In its current form, such heavy subsidization dates back to the Nixon era, intended as a way to combat food price inflation.
An effect of this was the tremendous growth of corn and other agribusiness, and the development of a number of at the time unanticipated corn products (greater availability of corn oil and development of high fructose corn syrup), all kept artificially cheap by agricultural subsidies. A result of this is that processed foods high in fats and sugars are often quite cheap, especially when compared to prices of healthier foods, in particular the relatively high cost of fresh produce. So, for example, even while some fast food chains commendably offer healthy salad options, the healthy options tend to be quite expensive compared to the price of a meal of corn-fed-beef patties, potatoes fried in corn oil, and high-fructose-corn-syrup-laden beverages in giant portions.
Junk Food as a Caloric Bargain
High fat and/or high sugar foods tend to nowadays be available cheaply, at least in the U.S. and other developed countries – and increasingly this seems to be true elsewhere as well. Brownell made another interesting point here, though. If we look at food economics not just in terms of monetary cost but calories, junk food is a tremendous bargain. By weight, junk food is typically already cheaper than healthier food, but calorie for calorie, junk food is tremendously cheaper.
Poverty and Obesity
On top of the basic economics of food in the U.S. today, in impoverished communities, high fat and/or high sugar foods tend to be easily available relatively cheaply (even if not as cheaply as the same foods in other areas because of the lower incidence of full service grocery stores), while things like fresh produce are often hardly available at all and at higher prices, contributing to the problem of obesity in poor communities.
Human Evolution and Obesity
I was happy to see Brownell address a topic often left out of debates about obesity: human evolution. There’s strong evidence that humans generally take great pleasure in fatty or sweet foods (those dopamines mentioned above). This is something we share in common with other mammals, and is almost certainly something selected for in our evolutionary history.
This makes perfect sense – foods high in fats and sugars are caloric bargains, but are not particularly common in many natural environments. Animals who take pleasure in eating these foods would tend to seek them out more often and would tend to have an evolutionary advantage over those who didn’t.
But take this evolutionary heritage and add it to an economic environment unlike any our hominid or earlier primate ancestors ever adapted to, with an over-abundance of sugars and fats, and you get the obesity epidemic.
Genetics and Obesity
Both during his talk and during the question session, Brownell spoke of genetics as a factor in order to dismiss it as significant. I had been similarly dismissive of genetics as a significant factor in producing patterns of obesity before hearing this talk, and generally agree with his perspective here, particularly at the level of populations and gene pools: gene pools haven’t changed in the past 20-30 years in any significant way; the food environment has changed in multiple significant and obvious ways; therefore, genetics is not a serious consideration.
Interestingly, as I listened to Brownell present a position similar to that I have tended to take, I began to see the possibility for a change in genetic predispositions as a factor in obesity at the individual level. With increases in rates of obesity, we’re talking about a change to phenotype. Phenotype is always the product of genotype in interaction with environment. In this case, genotypes haven’t changed; it’s a variety of environmental factors that have changed; but that doesn’t mean that changing phenotype is solely the product of the changing environment necessarily, for phenotype is, again, always the product of that relationship between genotype and environment. A genotype that didn’t contribute to increased predisposition to obesity in one context might in another.
Still, I agree with a point that Brownell made during the Q and A session. Regardless of any potential genetic predisposition to obesity that some individuals may have, from a prevention or intervention stand point, it’s essentially irrelevant. At the population level, environmental factors are clearly the directly relevant ones and genetic predispositions aren’t something that can be particularly addressed at that level anyway. But even for individuals, for a person attempting to lose weight, the trick is to expend more calories than are taken in, irrespective of genotype.
Monday, May 21, 2007
An Evolutionary Argument for Barbecue
In my post, “Technology and Freedom,” while discussing the relationship between technology and environment in shaping human action, I wrote:
“Human and hominid relations to the environment have always been mediated by technology, i.e. we use tools to provide for our basic needs from the physical environment, whether in the form of using a digging stick to uproot a wild tuber or plowing fields with massive tractors. Innovations in technology have also always had a transformative effect on what it is possible to do within a particular environment. The use of fire by Homo erectus was one of several technologies allowing that hominid species to expand into cooler areas previously unoccupied by hominids. Presuming Homo erectus groups used fire to cook plant and animal foods, this same technology would have made for a safer food supply (especially for groups that might have subsisted partly by scavenging carcasses) and enabled their bodies to extract more nutritional value from some plant foods.”
This was meant simply as an example of how technology can shape the range of possible uses of an environment, and hence the range of possible action within it for humans, or in this case hominids. After writing that paragraph, I began thinking more about the use of fire for cooking, and in particular about barbecue (the fact that it was approaching lunch time as I wrote that passage probably influenced my own train of thought). To my mind, there are few things more delicious than good barbecue. I don’t have in mind so much barbecue sauce, though a good sauce is nice, but well cooked smoky meat cooked over a fire with a thorough char around the edges (by charred I don’t mean burnt).
Barbecue seems to have near universal appeal. Nearly every culture I’m familiar with, whether directly or through reading ethnographies, seems to have a tradition of grilled, smoky meat, and of other grilled foods. (There are exceptions – so far as I’m aware, the Inuit don’t barbecue, probably related to simple lack of firewood – but the exceptions are few in number.) The details of grilling or barbecuing vary, of course, and there are wonderful arguments to be had about the relative merits of different styles of barbecue, but the basic appeal is there in each case.
Part of the basic appeal of barbecue is no doubt related to its simplicity – light a fire and cook meat in or over it. But beyond this I’d like to argue here that there’s good evolutionary reason to find barbecue appealing.
There are a number of basic tastes and/or food textures that have near universal appeal for humans, and probably other mammals as well, such as salty, fatty, or sweet tastes. This makes sense. Sugars and fats have high concentrations of calories. In a world of often scarce resources, natural selection would favor creatures who find these tastes appealing and even crave them. Fats are also essential to the body, as is salt, and so natural selection would again favor animals preferring these tastes. It’s only in the modern, developed world, where food is hyperabundant, that this is at all a problem for human health. For most of human history, a desire for salty, sweet, and fatty tastes would have helped drive humans to seek out sufficient quantities of these foods and to favor them whenever they were present.
What about the delectable smoky taste of good grilled meat and other food though? Depending on whether a sauce is used, and what kind, barbecue can be appealing in part because of the combination of fatty, salty, and sweet flavors involved, but there’s also a tremendous appeal to the smokiness of it, to the taste of having been cooked over fire. I argue that this appeal is also the result of natural selection. Here I’m engaging in speculation, but it’s reasoned speculation. Among the distinct advantages of using fire would have been to expand the range of foods that could be eaten and the nutritional value that could be gained from them, but also a general increase in the safety of food. Given this suite of advantages, individuals preferring the taste of fire-cooked food would have been favored by natural selection and would have left behind more of their barbecue-loving descendants.
“Human and hominid relations to the environment have always been mediated by technology, i.e. we use tools to provide for our basic needs from the physical environment, whether in the form of using a digging stick to uproot a wild tuber or plowing fields with massive tractors. Innovations in technology have also always had a transformative effect on what it is possible to do within a particular environment. The use of fire by Homo erectus was one of several technologies allowing that hominid species to expand into cooler areas previously unoccupied by hominids. Presuming Homo erectus groups used fire to cook plant and animal foods, this same technology would have made for a safer food supply (especially for groups that might have subsisted partly by scavenging carcasses) and enabled their bodies to extract more nutritional value from some plant foods.”
This was meant simply as an example of how technology can shape the range of possible uses of an environment, and hence the range of possible action within it for humans, or in this case hominids. After writing that paragraph, I began thinking more about the use of fire for cooking, and in particular about barbecue (the fact that it was approaching lunch time as I wrote that passage probably influenced my own train of thought). To my mind, there are few things more delicious than good barbecue. I don’t have in mind so much barbecue sauce, though a good sauce is nice, but well cooked smoky meat cooked over a fire with a thorough char around the edges (by charred I don’t mean burnt).
Barbecue seems to have near universal appeal. Nearly every culture I’m familiar with, whether directly or through reading ethnographies, seems to have a tradition of grilled, smoky meat, and of other grilled foods. (There are exceptions – so far as I’m aware, the Inuit don’t barbecue, probably related to simple lack of firewood – but the exceptions are few in number.) The details of grilling or barbecuing vary, of course, and there are wonderful arguments to be had about the relative merits of different styles of barbecue, but the basic appeal is there in each case.
Part of the basic appeal of barbecue is no doubt related to its simplicity – light a fire and cook meat in or over it. But beyond this I’d like to argue here that there’s good evolutionary reason to find barbecue appealing.
There are a number of basic tastes and/or food textures that have near universal appeal for humans, and probably other mammals as well, such as salty, fatty, or sweet tastes. This makes sense. Sugars and fats have high concentrations of calories. In a world of often scarce resources, natural selection would favor creatures who find these tastes appealing and even crave them. Fats are also essential to the body, as is salt, and so natural selection would again favor animals preferring these tastes. It’s only in the modern, developed world, where food is hyperabundant, that this is at all a problem for human health. For most of human history, a desire for salty, sweet, and fatty tastes would have helped drive humans to seek out sufficient quantities of these foods and to favor them whenever they were present.
What about the delectable smoky taste of good grilled meat and other food though? Depending on whether a sauce is used, and what kind, barbecue can be appealing in part because of the combination of fatty, salty, and sweet flavors involved, but there’s also a tremendous appeal to the smokiness of it, to the taste of having been cooked over fire. I argue that this appeal is also the result of natural selection. Here I’m engaging in speculation, but it’s reasoned speculation. Among the distinct advantages of using fire would have been to expand the range of foods that could be eaten and the nutritional value that could be gained from them, but also a general increase in the safety of food. Given this suite of advantages, individuals preferring the taste of fire-cooked food would have been favored by natural selection and would have left behind more of their barbecue-loving descendants.
Subscribe to:
Posts (Atom)