It’s a grass! It’s a weed! It’s a crop plant! It’s something in a box! It’s an evil grain! Yes, wheat is one of the most wondrous of crops, wonderful at all levels. Its domestication from wild ancestors is a puzzle still being worked out. Its genetics are complicated enough to cause introductory genetics students to groan, and such courses overall separate the “wheat from the chaff.” In any debate on evolution it represents perhaps the best model of speciation—better than even the Drosophila fruit fly story—though generally unknown. Its place in the development of western civilization is as central as the printing press. It is central to the Green Revolution, which has saved the lives of perhaps a billion people. And as such, it is central to debates regarding monoculture, biodiversity loss, genetic engineering, population growth, and deforestation. And it is even central to dietary arguments regarding the pros and cons of carbohydrates. Wheat is simply an amazing plant.
And from such humble beginnings in the highlands of Ethiopia, the Nile River Valley, and the Mideast. Like all cereal crops, its wild ancestor was a grass that shed its nutritious seeds very easily—in technical terms, it “shattered.” Then maybe 10,000 years ago, in the process of collecting seeds for eating, early humans selected those plants that naturally had reduced “shatter” because after all, that would be the most efficient way to go about it. And in this way humans started the evolution of wheat down the path to becoming what it is today. But unknown to early domesticators, those plants had within them the genetic potential to resist diseases and temperature extremes such that wheat now covers more acreage than any crop on the planet—it is cultivated from South Africa to Norway, with centers of production in the Great Plains of the U.S. and Canada, southern Brazil, throughout Europe and the Near East, India, and eastern China.
Fundamental to this genetic “flexibility” is wheat’s ability to withstand hybridization with other related species. What we call wheat is actually not just one species. Yes, “wheat” is actually not one species. After many many years of study, the world seems to have settled on wheat consisting of five or six species (Triticum monococcum, T. urartu, T. turgidum,T. dicoccoides, T. dicoccum T. aestivum). This alone should signal that wheat is highly variable in terms of its appearance, distribution, tolerance to environmental conditions and disease, as well as its number of chromosomes. Yes, many species differ from one another by their total number of chromosomes, which varies between 14 and 42. Consequently, you’d never look at some species of wheat and say “that is wheat,” because it does not look like the wheat you are used to. And, as further proof of their “coolness,” and complicating their species classification, wheat plants can hybridize with each other—both in the laboratory and in the field. In fact many of the wheat “types” (different species) can be created in the laboratory. In less than five generations! (Beat that, you Drosophila geneticists!).
Further, an entirely NEW species has been created, which itself has been domesticated for many years. It represents a cross between wheat (genus Triticum) and rye (genus Secale), and it’s called Triticale. Get it? Let me say that again—this is a new species. It does not occur in nature, and it’s only about 100 years old (created in 1888). The goal was to take the best qualities of wheat and combine them with the disease resistance and environmental tolerance of rye. Triticale (pronounced tritiKAYlee) is now grown in 29 countries around the world, but even so, it is only a very small percentage of total wheat acreage. I can only assume that if triticale were developed today using genetic engineering techniques, there would be a hue and cry about us not having the “right” to combine two different species. Good thing it took place more than 100 years ago, or it might be outlawed in some countries today! And I guess we would not have the Star Trek episode called “Trouble with Tribbles” wherein a mythical “quadrotriticale” cereal is consumed by humans, but nearly destroyed by Tribbles.
Now, wheat taxonomy/classification, genetics, and evolution is very complicated—in many ways as much or more than that of other grass crops such as rice, oats, barley, and corn. But I just can’t say anything about wheat without going in to it a LITTLE, since it is not only quite fascinating but also it is a great example of plant evolution, and an excellent model for evolution in general. That’s right—plants evolve! From the absence of examples of plant evolution in popular literature, such as books by Richard Dawkins, Sean Carroll, Matt Ridley, or even Stephen Gould, that if not exclusively focus on animals, you’d think that there is nothing to say about plants! But in many ways, plants show the BEST examples of evolution. Sigh. Plants just get no respect. I guess that’s because they are so simple. Yea, right.
For our purposes, the first domesticated wheats were the einkorn wheats (Triticum monococcum), which have one “set” (called AA) of paired chromosomes, 14 in total. These einkorn wheats date back to about 7,500 B.C. in southeastern Turkey and Syria. Einkorn wheat is still grown as a forage crop in France, Morocco, former Yugoslavia, and Turkey where the soil is so poor that “normal” wheat can’t grow. You can purchase einkorn wheat flour on the internet, or maybe at your local health food store. There is some evidence that it may not cause the “wheat” intolerance known to sufferers of celiac disease. I’ve never eaten it, but it would be fun to sample a loaf of bread made from this cute little plant, just like Paleolithic man.
Another AA type wheat is Triticum uratu, which was never domesticated. It is important because chromosomal and DNA analysis shows that it hybridized with another closely related species with BB chromosomes called goat grass (Aegilops speltoides) and produced ANOTHER new species (T. dicoccoides) with two “sets” of chromosomes, totaling 28 (called AABB). These are the “emmer” wheats, found originally in Syria, and dated at 9,600 B.C. By 2000 B.C. the emmer wheats had spread from the Fertile Crescent to China, Germany, Greece, Cyprus, and England and Scandinavia.
Modern forms of these emmer wheats gave rise to what we now call Durum wheat (Triticum turgidum durum, closely related to T. dicoccum, if not the same species), which is grown all around the world, with about 7300 acres under cultivation in North America. We love it as pasta, and they are used for everything from couscous to spaghetti and flat round bread. In general, it is very high in protein, but low in gluten, which is a gelatinous type of wheat protein. For food purposes, the function of gluten is to trap the carbon dioxide produced by yeast, which causes the bread to swell up, or “rise”. Since durum wheat doesn’t have much gluten, it does not rise.
And then one day, in some farmer’s field at least 8000 years ago in southeastern Turkey, there arose yet ANOTHER species, this one with three sets (AABBDD) of chromosomes, totaling 42. The hybridization probably involved T. dicoccum (a domesticated form of T. dicoccoides) and yet another wild goat weed (Aegilops tauschii) with a DD chromosome set. Actually, this probably took place at least twice—once making what today is called “spelt” wheat, and the other making what is called “bread wheat.” Bread wheat, of course, is the one that is most widely grown, and is the one we use for making, uh, bread. It is very high in gluten, which causes bread made from wheat to rise very satisfactorily. Spelt wheat is still grown in central Europe and Spain, and can be found in health food stores. It appears to have no benefit to those that have gluten intolerance.
So today, as a food or feed crop, we have an AA type of wheat (einkorn), an AABB type (Durum), and two AABBDD types, either bread wheat or spelt wheat.
But the main wheat is “bread wheat.” It occupies more acreage than any other crop plant, and its overall tonnage is exceed only by corn and rice. It is considered to be the most important staple food in the world. It has more world trade than all other crops combined. It can be grown from within the Arctic Circle to equatorial highlands, and in any month of the year, it is being harvested somewhere in the world.
The importance of wheat to civilization cannot be overstated; it was probably early man’s cultivation of wheat 8,000 years ago that led to the development of agriculture and the consequent rise of civilizations in Europe , the Nile River Valley, and the Middle East. Extolling all of wheat’s benefits, however, is beyond my scope, though there is one story that just HAS to be mentioned. And that is its central role in the Green Revolution of the 1960s.
Those of you who can remember back that far, may recall that by the mid 1960s India was facing starvation. Its population was growing, but wheat yields had stagnated.. This train wreck was averted largely by the efforts of ONE man—a wheat breeder by the name of Norman Borlaug. He had saved Mexico from starvation in the early 1960s by developing high yielding, disease resistant, and, critically, dwarf wheat varieties. Why dwarf? Because wheats in those days responded to fertilizer by growing longer stems, which then fell over (“lodged”) as a result of the heavy grains of the high yielding wheat strains. What Borlaug did is introduce dwarfing genes discovered by Japanese researchers into these otherwise high yielding, lodging wheats. These new varieties had shorter and stronger stems, and so they “stood up” to harvesting.
So he introduced dwarf wheat into India and Pakistan (a fascinating story in itself—would be a great novel, in fact!), and within five years India was self sufficient and exporting wheat. Problem solved. For this he won the Noble Peace Prize in 1970, the only biologist to have done so, then or since.
And so now our story could morph into the pros and cons of the Green Revolution, which is a subject for another blog (or book!). But it is indisputable that increased wheat production eliminated famine and hunger around the world. Another benefit is that as wheat yields have increased, there has been consequent reduction in pressure to bring additional land into production, since farmers get a higher yield per acre. It has been estimated that in Asia the yields of cereals in general doubled between 1970 and 1975, but land usage only increased 4%.
However, there is another trend going on: the “anti-carb” movement. Like so many other things, it is beyond the scope of this blog to go into detail about that issue, but the data speak for themselves. In 1972 the low-carb Atkins Diet book was published, and by 2002, 1 in 11 adults in North America were on a low-carb diet. In recent years the “paleo diet” has become more popular, which also stresses low-carbs. Further, there has been growing awareness of gluten intolerance. Gluten intolerance seems to be a catch-bag of conditions including celiac disease and allergies to gluten, and there may also be a generalized immunological response to gluten and related proteins that occurs in 5-7% of the population. The research is still in its early stages, so who knows what will emerge one way or the other, but there seems to be something going on.
Given the prevalence of low carb diets plus increasing reports of gluten intolerance, you’d think this would express itself in terms of sales of bread. And this is indeed the case. Bread sales appear to be going down slightly, at least in those populations that are rich enough to afford alternative sources of carbs and calories. However, the decreased demand for bread has not resulted in decreased demand for wheat in general. The world consumes all the wheat it can produce, in part due to the fact that wheat is fed to livestock and the world’s consumption of meat is going up.
Oklahoma State University has been producing new wheat varieties since the 1950s. Due to a multi-disciplinary team consisting of pathologists, entomologists, geneticists, and plant breeders, OSU is creating new varieties at the rate of 1-2 per year. Wheat varieties developed at OSU are planted on at least 47% of the wheat acreage in Oklahoma, and they are attracting the attention of growers in Kansas, Colorado, and Texas. Novel combined cropping and livestock production systems are being developed, with special wheat varieties being planted in the fall, grazed by cattle in the winter, and then allowed to flower and produce grain in the spring.
I just love the smell of fresh bread. Spare time, a fresh loaf of heavy bread, butter, coffee, a book, and free Wi-Fi—what could be better than that? But whatever your personal reaction to grains in general and bread in particular, remember to give wheat the respect it deserves. You might not be sitting here reading this right now if it had never evolved and many brilliant scientists had not adapted it for agriculture around the world.
And from such humble beginnings in the highlands of Ethiopia, the Nile River Valley, and the Mideast. Like all cereal crops, its wild ancestor was a grass that shed its nutritious seeds very easily—in technical terms, it “shattered.” Then maybe 10,000 years ago, in the process of collecting seeds for eating, early humans selected those plants that naturally had reduced “shatter” because after all, that would be the most efficient way to go about it. And in this way humans started the evolution of wheat down the path to becoming what it is today. But unknown to early domesticators, those plants had within them the genetic potential to resist diseases and temperature extremes such that wheat now covers more acreage than any crop on the planet—it is cultivated from South Africa to Norway, with centers of production in the Great Plains of the U.S. and Canada, southern Brazil, throughout Europe and the Near East, India, and eastern China.
Fundamental to this genetic “flexibility” is wheat’s ability to withstand hybridization with other related species. What we call wheat is actually not just one species. Yes, “wheat” is actually not one species. After many many years of study, the world seems to have settled on wheat consisting of five or six species (Triticum monococcum, T. urartu, T. turgidum,T. dicoccoides, T. dicoccum T. aestivum). This alone should signal that wheat is highly variable in terms of its appearance, distribution, tolerance to environmental conditions and disease, as well as its number of chromosomes. Yes, many species differ from one another by their total number of chromosomes, which varies between 14 and 42. Consequently, you’d never look at some species of wheat and say “that is wheat,” because it does not look like the wheat you are used to. And, as further proof of their “coolness,” and complicating their species classification, wheat plants can hybridize with each other—both in the laboratory and in the field. In fact many of the wheat “types” (different species) can be created in the laboratory. In less than five generations! (Beat that, you Drosophila geneticists!).
Further, an entirely NEW species has been created, which itself has been domesticated for many years. It represents a cross between wheat (genus Triticum) and rye (genus Secale), and it’s called Triticale. Get it? Let me say that again—this is a new species. It does not occur in nature, and it’s only about 100 years old (created in 1888). The goal was to take the best qualities of wheat and combine them with the disease resistance and environmental tolerance of rye. Triticale (pronounced tritiKAYlee) is now grown in 29 countries around the world, but even so, it is only a very small percentage of total wheat acreage. I can only assume that if triticale were developed today using genetic engineering techniques, there would be a hue and cry about us not having the “right” to combine two different species. Good thing it took place more than 100 years ago, or it might be outlawed in some countries today! And I guess we would not have the Star Trek episode called “Trouble with Tribbles” wherein a mythical “quadrotriticale” cereal is consumed by humans, but nearly destroyed by Tribbles.
Now, wheat taxonomy/classification, genetics, and evolution is very complicated—in many ways as much or more than that of other grass crops such as rice, oats, barley, and corn. But I just can’t say anything about wheat without going in to it a LITTLE, since it is not only quite fascinating but also it is a great example of plant evolution, and an excellent model for evolution in general. That’s right—plants evolve! From the absence of examples of plant evolution in popular literature, such as books by Richard Dawkins, Sean Carroll, Matt Ridley, or even Stephen Gould, that if not exclusively focus on animals, you’d think that there is nothing to say about plants! But in many ways, plants show the BEST examples of evolution. Sigh. Plants just get no respect. I guess that’s because they are so simple. Yea, right.
For our purposes, the first domesticated wheats were the einkorn wheats (Triticum monococcum), which have one “set” (called AA) of paired chromosomes, 14 in total. These einkorn wheats date back to about 7,500 B.C. in southeastern Turkey and Syria. Einkorn wheat is still grown as a forage crop in France, Morocco, former Yugoslavia, and Turkey where the soil is so poor that “normal” wheat can’t grow. You can purchase einkorn wheat flour on the internet, or maybe at your local health food store. There is some evidence that it may not cause the “wheat” intolerance known to sufferers of celiac disease. I’ve never eaten it, but it would be fun to sample a loaf of bread made from this cute little plant, just like Paleolithic man.
Another AA type wheat is Triticum uratu, which was never domesticated. It is important because chromosomal and DNA analysis shows that it hybridized with another closely related species with BB chromosomes called goat grass (Aegilops speltoides) and produced ANOTHER new species (T. dicoccoides) with two “sets” of chromosomes, totaling 28 (called AABB). These are the “emmer” wheats, found originally in Syria, and dated at 9,600 B.C. By 2000 B.C. the emmer wheats had spread from the Fertile Crescent to China, Germany, Greece, Cyprus, and England and Scandinavia.
Modern forms of these emmer wheats gave rise to what we now call Durum wheat (Triticum turgidum durum, closely related to T. dicoccum, if not the same species), which is grown all around the world, with about 7300 acres under cultivation in North America. We love it as pasta, and they are used for everything from couscous to spaghetti and flat round bread. In general, it is very high in protein, but low in gluten, which is a gelatinous type of wheat protein. For food purposes, the function of gluten is to trap the carbon dioxide produced by yeast, which causes the bread to swell up, or “rise”. Since durum wheat doesn’t have much gluten, it does not rise.
And then one day, in some farmer’s field at least 8000 years ago in southeastern Turkey, there arose yet ANOTHER species, this one with three sets (AABBDD) of chromosomes, totaling 42. The hybridization probably involved T. dicoccum (a domesticated form of T. dicoccoides) and yet another wild goat weed (Aegilops tauschii) with a DD chromosome set. Actually, this probably took place at least twice—once making what today is called “spelt” wheat, and the other making what is called “bread wheat.” Bread wheat, of course, is the one that is most widely grown, and is the one we use for making, uh, bread. It is very high in gluten, which causes bread made from wheat to rise very satisfactorily. Spelt wheat is still grown in central Europe and Spain, and can be found in health food stores. It appears to have no benefit to those that have gluten intolerance.
So today, as a food or feed crop, we have an AA type of wheat (einkorn), an AABB type (Durum), and two AABBDD types, either bread wheat or spelt wheat.
But the main wheat is “bread wheat.” It occupies more acreage than any other crop plant, and its overall tonnage is exceed only by corn and rice. It is considered to be the most important staple food in the world. It has more world trade than all other crops combined. It can be grown from within the Arctic Circle to equatorial highlands, and in any month of the year, it is being harvested somewhere in the world.
The importance of wheat to civilization cannot be overstated; it was probably early man’s cultivation of wheat 8,000 years ago that led to the development of agriculture and the consequent rise of civilizations in Europe , the Nile River Valley, and the Middle East. Extolling all of wheat’s benefits, however, is beyond my scope, though there is one story that just HAS to be mentioned. And that is its central role in the Green Revolution of the 1960s.
Those of you who can remember back that far, may recall that by the mid 1960s India was facing starvation. Its population was growing, but wheat yields had stagnated.. This train wreck was averted largely by the efforts of ONE man—a wheat breeder by the name of Norman Borlaug. He had saved Mexico from starvation in the early 1960s by developing high yielding, disease resistant, and, critically, dwarf wheat varieties. Why dwarf? Because wheats in those days responded to fertilizer by growing longer stems, which then fell over (“lodged”) as a result of the heavy grains of the high yielding wheat strains. What Borlaug did is introduce dwarfing genes discovered by Japanese researchers into these otherwise high yielding, lodging wheats. These new varieties had shorter and stronger stems, and so they “stood up” to harvesting.
So he introduced dwarf wheat into India and Pakistan (a fascinating story in itself—would be a great novel, in fact!), and within five years India was self sufficient and exporting wheat. Problem solved. For this he won the Noble Peace Prize in 1970, the only biologist to have done so, then or since.
And so now our story could morph into the pros and cons of the Green Revolution, which is a subject for another blog (or book!). But it is indisputable that increased wheat production eliminated famine and hunger around the world. Another benefit is that as wheat yields have increased, there has been consequent reduction in pressure to bring additional land into production, since farmers get a higher yield per acre. It has been estimated that in Asia the yields of cereals in general doubled between 1970 and 1975, but land usage only increased 4%.
However, there is another trend going on: the “anti-carb” movement. Like so many other things, it is beyond the scope of this blog to go into detail about that issue, but the data speak for themselves. In 1972 the low-carb Atkins Diet book was published, and by 2002, 1 in 11 adults in North America were on a low-carb diet. In recent years the “paleo diet” has become more popular, which also stresses low-carbs. Further, there has been growing awareness of gluten intolerance. Gluten intolerance seems to be a catch-bag of conditions including celiac disease and allergies to gluten, and there may also be a generalized immunological response to gluten and related proteins that occurs in 5-7% of the population. The research is still in its early stages, so who knows what will emerge one way or the other, but there seems to be something going on.
Given the prevalence of low carb diets plus increasing reports of gluten intolerance, you’d think this would express itself in terms of sales of bread. And this is indeed the case. Bread sales appear to be going down slightly, at least in those populations that are rich enough to afford alternative sources of carbs and calories. However, the decreased demand for bread has not resulted in decreased demand for wheat in general. The world consumes all the wheat it can produce, in part due to the fact that wheat is fed to livestock and the world’s consumption of meat is going up.
Oklahoma State University has been producing new wheat varieties since the 1950s. Due to a multi-disciplinary team consisting of pathologists, entomologists, geneticists, and plant breeders, OSU is creating new varieties at the rate of 1-2 per year. Wheat varieties developed at OSU are planted on at least 47% of the wheat acreage in Oklahoma, and they are attracting the attention of growers in Kansas, Colorado, and Texas. Novel combined cropping and livestock production systems are being developed, with special wheat varieties being planted in the fall, grazed by cattle in the winter, and then allowed to flower and produce grain in the spring.
I just love the smell of fresh bread. Spare time, a fresh loaf of heavy bread, butter, coffee, a book, and free Wi-Fi—what could be better than that? But whatever your personal reaction to grains in general and bread in particular, remember to give wheat the respect it deserves. You might not be sitting here reading this right now if it had never evolved and many brilliant scientists had not adapted it for agriculture around the world.
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