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top 10 words in brain distribution (in article): species human wolf male time type state cell wild common |
top 10 words in brain distribution (in article): design type wood plant size key form fruit allow common |
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times more probable under bee 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under corn (words not in the model) | |
| Bees'" are flying insects closely related to wasps and ants. Bees are a monophyletic lineage within the superfamily "'Apoidea'", presently classified by the unranked taxon name "'Anthophila'". There are nearly 20,000 known species of bee, in nine recognized families, though many are undescribed and the actual number is probably higher. They are found on every continent except Antarctica, in every habitat on the planet that contains insect-pollinated flowering plants. Introduction. Bees are adapted for feeding on nectar and pollen, the former primarily as an energy source, and the latter primarily for protein and other nutrients. Most pollen is used as food for larvae. Bees have a long proboscis (a complex "tongue") that enables them to obtain the nectar from flowers. They have antennae almost universally made up of 13 segments in males and 12 in females, as is typical for the superfamily. Bees all have two pairs of wings, the hind pair being the smaller of the two; in a very few species, one sex or caste has relatively short wings that make flight difficult or impossible, but none is wingless. The smallest bee is "Trigona minima", a stingless bee whose workers are about 2.1 mm (5 64") long. The largest bee in the world is "Megachile pluto", a leafcutter bee whose females can attain a length of 39 mm (1.5"). Members of the family Halictidae, or sweat bees, are the most common type of bee in the Northern Hemisphere, though they are small and often mistaken for wasps or flies. The best-known bee species is the European honey bee, which, as its name suggests, produces honey, as do a few other types of bee. Human management of this species is known as beekeeping or apiculture. Bees are the favorite meal of "Merops apiaster", the bee-eater bird. Other common predators are kingbirds, mockingbirds, bee wolves, and dragonflies. Pollination. Bees play an important role in pollinating flowering plants, and are the major type of pollinator in ecosystems that contain flowering plants. Bees either focus on gathering nectar or on gathering pollen depending on demand, especially in social species. Bees gathering nectar may accomplish pollination, but bees that are deliberately gathering pollen are more efficient pollinators. It is estimated that one third of the human food supply depends on insect pollination, most of which is accomplished by bees, especially the domesticated European honey bee. Contract pollination has overtaken the role of honey production for beekeepers in many countries. Monoculture and the massive decline of many bee species (both wild and domesticated) have increasingly caused honey bee keepers to become migratory so that bees can be concentrated in seasonally-varying high-demand areas of pollination. Most bees are fuzzy and carry an electrostatic charge, which aids in the adherence of pollen. Female bees periodically stop foraging and groom themselves to pack the pollen into the scopa, which is on the legs in most bees, and on the ventral abdomen on others, and modified into specialized pollen baskets on the legs of honey bees and their relatives. Many bees are opportunistic foragers, and will gather pollen from a variety of plants, while others are oligolectic, gathering pollen from only one or a few types of plant. A small number of plants produce nutritious floral oils rather than pollen, which are gathered and used by oligolectic bees. One small subgroup of stingless bees, called "vulture bees," is specialized to feed on carrion, and these are the only bees that do not use plant products as food. Pollen and nectar are usually combined together to form a "provision mass", which is often soupy, but can be firm. It is formed into various shapes (typically spheroid), and stored in a small chamber (a "cell"), with the egg deposited on the mass. The cell is typically sealed after the egg is laid, and the adult and larva never interact directly (a system called "mass provisioning"). Visiting flowers can be a dangerous occupation. Many assassin bugs and crab spiders hide in flowers to capture unwary bees. Other bees are lost to birds in flight. Insecticides used on blooming plants kill many bees, both by direct poisoning and by contamination of their food supply. A honey bee queen may lay 2000 eggs per day during spring buildup, but she also must lay 1000 to 1500 eggs per day during the foraging season, mostly to replace daily casualties, most of which are workers dying of old age. Among solitary and primitively social bees, however, lifetime reproduction is among the lowest of all insects, as it is common for females of such species to produce fewer than 25 offspring. The population value of bees depends partly on the individual efficiency of the bees, but also on the population itself. Thus, while bumblebees have been found to be about ten times more efficient pollinators on cucurbits, the total efficiency of a colony of honey bees is much greater, due to greater numbers. Likewise, during early spring orchard blossoms, bumblebee populations are limited to only a few queens, and thus are not significant pollinators of early fruit. Depopulation. Recently, managed populations of European honey bees have experienced substantial declines. This has prompted investigations into the phenomenon amidst great concern over the nature and extent of the losses. One aspect of the problem is believed to be "Colony Collapse Disorder" but many of the losses outside the US are attributed to other causes. Pesticides used to treat seeds, such as Clothianidin and Imidacloprid, may also negatively impact honey bee populations. Other species of bees such as mason bees are increasingly cultured and used to meet the agricultural pollination need. Most native pollinators are solitary bees, which often survive in refuge in wild areas away from agricultural spraying, but may still be poisoned in massive spray programs for mosquitoes, gypsy moths, or other insect pests. Evolution. Bees, like ants, are a specialized form of wasp. The ancestors of bees were wasps in the family Crabronidae, and therefore predators of other insects. The switch from insect prey to pollen may have resulted from the consumption of prey insects that were flower visitors and were partially covered with pollen when they were fed to the wasp larvae. This same evolutionary scenario has also occurred within the vespoid wasps, where the group known as "pollen wasps" also evolved from predatory ancestors. Up until recently the oldest non-compression bee fossil had been "Cretotrigona prisca" in New Jersey amber and of Cretaceous age, a meliponine. A recently reported bee fossil, of the genus "Melittosphex", is considered "an extinct lineage of pollen-collecting Apoidea sister to the modern bees", and dates from the early Cretaceous (~100 mya). Derived features of its morphology ("apomorphies") place it clearly within the bees, but it retains two unmodified ancestral traits ("plesiomorphies") of the legs (two mid-tibial spurs, and a slender hind basitarsus), indicative of its transitional status. The earliest animal-pollinated flowers were pollinated by insects such as beetles, so the syndrome of insect pollination was well established before bees first appeared. The novelty is that bees are "specialized" as pollination agents, with behavioral and physical modifications that specifically enhance pollination, and are generally more efficient at the task than beetles, flies, butterflies, pollen wasps, or any other pollinating insect. The appearance of such floral specialists is believed to have driven the adaptive radiation of the angiosperms, and, in turn, the bees themselves. Among living bee groups, the Dasypodaidae are now considered to be the most "primitive", and sister taxon to the remainder of the bees, contrary to earlier hypotheses that the "short-tongued" bee family Colletidae was the basal group of bees; the short, wasp-like mouthparts of colletids are the result of convergent evolution, rather than indicative of a plesiomorphic condition. Eusocial and semisocial bees. Bees may be solitary or may live in various types of communities. The most advanced of these are eusocial colonies found among the honey bees, bumblebees, and stingless bees. Sociality, of several different types, is believed to have evolved separately many times within the bees. In some species, groups of cohabiting females may be sisters, and if there is a division of labor within the group, then they are considered semisocial. If, in addition to a division of labor, the group consists of a mother and her daughters, then the group is called eusocial. The mother is considered the "queen" and the daughters are "workers". These castes may be purely behavioral alternatives, in which case the system is considered "primitively eusocial" (similar to many paper wasps), and if the castes are morphologically discrete, then the system is "highly eusocial". There are many more species of primitively eusocial bees than highly eusocial bees, but they have rarely been studied. The biology of most such species is almost completely unknown. The vast majority are in the family Halictidae, or "sweat bees". Colonies are typically small, with a dozen or fewer workers, on average. The only physical difference between queens and workers is average size, if they differ at all. Most species have a single season colony cycle, even in the tropics, and only mated females (future queens, or "gynes") hibernate (called diapause). A few species have long active seasons and attain colony sizes in the hundreds. The orchid bees include a number of primitively eusocial species with similar biology. Certain species of allodapine bees (relatives of carpenter bees) also have primitively eusocial colonies, with unusual levels of interaction between the adult bees and the developing brood. This is "progressive provisioning"; a larva's food is supplied gradually as it develops. This system is also seen in honey bees and some bumblebees. Highly eusocial bees live in colonies. Each colony has a single queen, many workers and, at certain stages in the colony cycle, drones. When humans provide the nest, it is called a hive. A honey bee hive can contain up to 40,000 bees at their annual peak, which occurs in the spring, but usually have fewer. Bumblebees. Bumblebees ("Bombus terrestris", "B. pratorum", et al.) are eusocial in a manner quite similar to the eusocial Vespidae such as hornets. The queen initiates a nest on her own (unlike queens of honey bees and stingless bees which start nests via swarms in the company of a large worker force). Bumblebee colonies typically have from 50 to 200 bees at peak population, which occurs in mid to late summer. Nest architecture is simple, limited by the size of the nest cavity (pre-existing), and colonies are rarely perennial. Bumblebee queens sometimes seek winter safety in honey bee hives, where they are sometimes found dead in the spring by beekeepers, presumably stung to death by the honey bees. It is unknown whether any survive winter in such an environment. Stingless bees. Stingless bees are very diverse in behavior, but all are highly eusocial. They practice mass provisioning, complex nest architecture, and perennial colonies. Honey bees. The true honey bees (genus "Apis") have arguably the most complex social behavior among the bees. The European (or Western) honey bee, "Apis mellifera", is the best known bee species and one of the best known of all insects. Africanized honey bee. Africanized bees, also called killer bees, are a hybrid strain of "Apis mellifera" derived from experiments to cross European and African honey bees by Warwick Estevam Kerr. Several queen bees escaped his laboratory in South America and have spread throughout the Americas. Africanized honey bees are more defensive than European honey bees. Solitary and communal bees. Most other bees, including familiar species of bee such as the Eastern carpenter bee ("Xylocopa virginica"), alfalfa leafcutter bee ("Megachile rotundata"), orchard mason bee ("Osmia lignaria") and the hornfaced bee ("Osmia cornifrons") are solitary in the sense that every female is fertile, and typically inhabits a nest she constructs herself. There are no "worker" bees for these species. Solitary bees typically produce neither honey nor beeswax. They are immune from acarine and "Varroa" mites (see diseases of the honey bee), but have their own unique parasites, pests and diseases. Solitary bees are important pollinators, and pollen is gathered for provisioning the nest with food for their brood. Often it is mixed with nectar to form a paste-like consistency. Some solitary bees have very advanced types of pollen carrying structures on their bodies. A very few species of solitary bees are being increasingly cultured for commercial pollination. Solitary bees are often oligoleges, in that they only gather pollen from one or a few species genera of plants (unlike honey bees and bumblebees which are generalists). No known bees are nectar specialists; many oligolectic bees will visit multiple plants for nectar, but there are no bees which visit only one plant for nectar while also gathering pollen from many different sources. Specialist pollinators also include bee species that gather floral oils instead of pollen, and male orchid bees, which gather aromatic compounds from orchids (one of the only cases where male bees are effective pollinators). In a very few cases only one species of bee can effectively pollinate a plant species, and some plants are endangered at least in part because their pollinator is dying off. There is, however, a pronounced tendency for oligolectic bees to be associated with common, widespread plants which are visited by multiple pollinators (e.g., there are some 40 oligoleges associated with creosotebush in the US desert southwest, and a similar pattern is seen in sunflowers, asters, mesquite, etc.) Solitary bees create nests in hollow reeds or twigs, holes in wood, or, most commonly, in tunnels in the ground. The female typically creates a compartment (a "cell") with an egg and some provisions for the resulting larva, then seals it off. A nest may consist of numerous cells. When the nest is in wood, usually the last (those closer to the entrance) contain eggs that will become males. The adult does not provide care for the brood once the egg is laid, and usually dies after making one or more nests. The males typically emerge first and are ready for mating when the females emerge. Providing nest boxes for solitary bees is increasingly popular for gardeners. Solitary bees are either stingless or very unlikely to sting (only in self defense, if ever). While solitary females each make individual nests, some species are gregarious, preferring to make nests near others of the same species, giving the appearance to the casual observer that they are social. Large groups of solitary bee nests are called "aggregations", to distinguish them from colonies. In some species, multiple females share a common nest, but each makes and provisions her own cells independently. This type of group is called "communal" and is not uncommon. The primary advantage appears to be that a nest entrance is easier to defend from predators and parasites when there are multiple females using that same entrance on a regular basis. Cleptoparasitic bees. Cleptoparasitic bees, commonly called "cuckoo bees" because their behavior is similar to cuckoo birds, occur in several bee families, though the name is technically best applied to the apid subfamily Nomadinae. Females of these bees lack pollen collecting structures (the scopa) and do not construct their own nests. They typically enter the nests of pollen collecting species, and lay their eggs in cells provisioned by the host bee. When the cuckoo bee larva hatches it consumes the host larva's pollen ball, and if the female cleptoparasite has not already done so, kills and eats the host larva. In a few cases where the hosts are social species, the cleptoparasite remains in the host nest and lays many eggs, sometimes even killing the host queen and replacing her. Many cleptoparasitic bees are closely related to, and resemble, their hosts in looks and size, (i.e., the "Bombus" subgenus "Psithyrus", which are parasitic bumblebees that infiltrate nests of species in other subgenera of "Bombus"). This common pattern gave rise to the ecological principle known as "Emery's Rule". Others parasitize bees in different families, like "Townsendiella", a nomadine apid, one species of which is a cleptoparasite of the dasypodaid genus "Hesperapis", while the other species in the same genus attack halictid bees. Nocturnal bees. Four bee families (Andrenidae, Colletidae, Halictidae, and Apidae) contain some species that are crepuscular (these may be either the vespertine or matinal type). These bees have greatly enlarged ocelli, which are extremely sensitive to light and dark, though incapable of forming images. Many are pollinators of flowers that themselves are crepuscular, such as evening primroses, and some live in desert habitats where daytime temperatures are extremely high. Bee flight. In his 1934 French book "Le vol des insectes", M. Magnan wrote that he and a Mr. Saint-Lague had applied the equations of air resistance to bumblebees and found that their flight could not be explained by fixed-wing calculations, but that "One shouldn't be surprised that the results of the calculations don't square with reality". This has led to a common misconception that bees "violate aerodynamic theory", but in fact it merely confirms that bees do not engage in fixed-wing flight, and that their flight is explained by other mechanics. In 1996 Charlie Ellington at Cambridge University showed that vortices created by many insects’ wings and non-linear effects were a vital source of lift; vortices and non-linear phenomena are notoriously difficult areas of hydrodynamics, which has made for slow progress in theoretical understanding of insect flight. In 2005 Michael Dickinson and his Caltech colleagues studied honey bee flight with the assistance of high-speed cinematography and a giant robotic mock-up of a bee wing. Their analysis revealed sufficient lift was generated by "the unconventional combination of short, choppy wing strokes, a rapid rotation of the wing as it flops over and reverses direction, and a very fast wing-beat frequency". Wing beat frequency normally increases as size decreases, but as the bee's wing beat covers such a small arc, it flaps approximately 230 times per second, faster than a fruitfly (200 times per second) which is 80 times smaller. In 2008 Barbara Shipman discovered a mathematical connection between the dance of bees and the Flag manifold. Bees and humans. Bees figure prominently in mythology (See Bee (mythology)) and have been used by political theorists as a model for human society. Journalist Bee Wilson states that the image of a community of honey bees "occurs from ancient to modern times, in Aristotle and Plato; in Virgil and Seneca; in Erasmus and Shakespeare; Tolstoy, as well as by social theorists Bernard Mandeville and Karl Marx." Despite the honey bee's painful sting and the stereotype of insects as pests, bees are generally held in high regard. This is most likely due to their usefulness as pollinators and as producers of honey, their social nature, and their reputation for diligence. Bees are one of the few insects regularly used on advertisements, being used to illustrate honey and foods made with honey (such as Honey Nut Cheerios). In North America, yellowjackets and hornets, especially when encountered as flying pests, are often misidentified as bees, despite numerous differences between them; see Characteristics of common wasps and bees. Although a bee sting can be deadly to those with allergies, virtually all bee species are non-aggressive if undisturbed and many cannot sting at all. Humans are often a greater danger to bees, as bees can be affected or even harmed by encounters with toxic chemicals in the environment; see Bees and toxic chemicals. | Maize'" ("Zea mays" L. ssp. "mays"), known as corn'" in some countries, is a cereal grain domesticated in Mesoamerica and subsequently spread throughout the American continents. After European contact with the Americas in the late 15th and early 16th century, maize spread to the rest of the world. Maize is the most widely grown crop in the Americas (332 million tonnes annually in the United States alone). Hybrid maize, due to its high grain yield as a result of heterosis ("hybrid vigor"), is preferred by farmers over conventional varieties. While some maize varieties grow up to 7 metres (23 ft) tall, most commercially grown maize has been bred for a standardized height of 2.5 metres (8 ft). Sweet corn is usually shorter than field-corn varieties. Naming conventions. The term "maize" derives from the Spanish form ("maíz") of the indigenous Taino term for the plant, and was the form most commonly heard in the United Kingdom. In the United States, Canada (maïs in French speaking Canadian regions) and Australia, the usual term is "corn", which originally referred to any grain, but which now refers exclusively to maize, having been shortened from the form "Indian corn" (which currently, at least in the U.S. & Canada, is often used to refer specifically to multi-colored "field corn" cultivars). Physiology. Maize stems superficially resemble bamboo canes and the internodes can reach 20–30 centimetres (8–12 in). Maize has a very distinct growth form; the lower leaves being like broad flags, 50–100 centimetres long and 5–10 centimetres wide (2–4 ft by 2–4 in); the stems are erect, conventionally 2–3 metres (7–10 ft) in height, with many nodes, casting off flag-leaves at every node. Under these leaves and close to the stem grow the ears. They grow about 3 milimetres a day. The ears are female inflorescences, tightly covered over by several layers of leaves, and so closed-in by them to the stem that they do not show themselves easily until the emergence of the pale yellow silks from the leaf whorl at the end of the ear. The silks are elongated stigmas that look like tufts of hair, at first green, and later red or yellow. Plantings for silage are even denser, and achieve an even lower percentage of ears and more plant matter. Certain varieties of maize have been bred to produce many additional developed ears, and these are the source of the "baby corn" that is used as a vegetable in Asian cuisine. Maize is a facultative long-night plant and flowers in a certain number of growing degree days >50 °F (10 °C) in the environment to which it is adapted. The magnitude of the influence that long nights have on the number of days that must pass before maize flowers is genetically prescribed and regulated by the phytochrome system. Photoperiodicity can be eccentric in tropical cultivars, while the long days characteristic of higher latitudes allow the plants to grow so tall that they do not have enough time to produce seed before being killed by frost. These attributes, however, may prove useful in using tropical maize for biofuels. The apex of the stem ends in the tassel, an inflorescence of male flowers. Each silk may become pollinated to produce one kernel of corn. Young ears can be consumed raw, with the cob and silk, but as the plant matures (usually during the summer months) the cob becomes tougher and the silk dries to inedibility. By the end of the growing season, the kernels dry out and become difficult to chew without cooking them tender first in boiling water. Modern farming techniques in developed countries usually rely on dense planting, which produces on average only about 0.9 ears per stalk because it stresses the plants. The kernel of corn has a pericarp of the fruit fused with the seed coat, typical of the grasses. It is close to a multiple fruit in structure, except that the individual fruits (the kernels) never fuse into a single mass. The grains are about the size of peas, and adhere in regular rows round a white pithy substance, which forms the ear. An ear contains from 200 to 400 kernels, and is from 10–25 centimetres (4–10 inches) in length. They are of various colors: blackish, bluish-gray, red, white and yellow. When ground into flour, maize yields more flour, with much less bran, than wheat does. However, it lacks the protein gluten of wheat and, therefore, makes baked goods with poor rising capability and coherence. A genetic variation that accumulates more sugar and less starch in the ear is consumed as a vegetable and is called sweet corn. Immature maize shoots accumulate a powerful antibiotic substance, DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one). DIMBOA is a member of a group of hydroxamic acids (also known as benzoxazinoids) that serve as a natural defense against a wide range of pests including insects, pathogenic fungi and bacteria. DIMBOA is also found in related grasses, particularly wheat. A maize mutant (bx) lacking DIMBOA is highly susceptible to be attacked by aphids and fungi. DIMBOA is also responsible for the relative resistance of immature maize to the European corn borer (family Crambidae). As maize matures, DIMBOA levels and resistance to the corn borer decline. Due to its shallow roots of only one to two inches deep, maize is susceptible to droughts, intolerant of nutrient-deficient soils, and prone to be uprooted by severe winds. Allergy. Maize contains lipid transfer protein, an undigestable protein which survives cooking. This protein has been linked to a rare and understudied allergy to maize in humans. The allergic reaction can cause skin rash, swelling or itching of mucus membranes, diarrhoea, vomiting, asthma and, in severe cases, anaphylactic shock. It has been noted that those with corn allergy almost always have peach allergy as well. It is unclear how common this allergy is in the general populace. Genetics. Many forms of maize are used for food, sometimes classified as various subspecies: This system has been replaced (though not entirely displaced) over the last 60 years by multi-variable classifications based on ever more data. Agronomic data were supplemented by botanical traits for a robust initial classification, then genetic, cytological, protein and DNA evidence was added. Now the categories are forms (little used), races, racial complexes, and recently branches. Maize has 10 chromosomes (n=10). The combined length of the chromosomes is 1500 cM. Some of the maize chromosomes have what are known as "chromosomal knobs": highly repetitive heterochromatic domains that stain darkly. Individual knobs are polymorphic among strains of both maize and teosinte. Barbara McClintock used these knob markers to prove her transposon theory of "jumping genes", for which she won the 1983 Nobel Prize in Physiology or Medicine. Maize is still an important model organism for genetics and developmental biology today. There is a stock center of maize mutants, "The Maize Genetics Cooperation Stock Center", funded by the USDA Agricultural Research Service and located in the Department of Crop Sciences at the University of Illinois at Urbana-Champaign. The total collection has nearly 80,000 samples. The bulk of the collection consists of several hundred named genes, plus additional gene combinations and other heritable variants. There are about 1000 chromosomal aberrations (e.g., translocations and inversions) and stocks with abnormal chromosome numbers (e.g., tetraploids). Genetic data describing the maize mutant stocks as well as myriad other data about maize genetics can be accessed at MaizeGDB, the Maize Genetics and Genomics Database. In 2005, the U.S. National Science Foundation (NSF), Department of Agriculture (USDA) and the Department of Energy (DOE) formed a consortium to sequence the maize genome. The resulting DNA sequence data will be deposited immediately into GenBank, a public repository for genome-sequence data. Sequencing the corn genome has been considered difficult because of its large size and complex genetic arrangements. The genome has 50,000–60,000 genes scattered among the 2.5 billion bases—molecules that form DNA—that make up its 10 chromosomes. (By comparison, the human genome contains about 2.9 billion bases and 26,000 genes.) On February 26, 2008, researchers announced that they had sequenced the entire genome of maize. Origin. There are several theories about the specific origin of maize in Mesoamerica: The first model was proposed by Nobel Prize winner George Beadle in 1939. Though it has experimental support, it has not explained a number of problems, among them: The domestication of maize is of particular interest to researchers — archaeologists, geneticists, ethnobotanists, geographers, etc. The process is thought by some to have started 7,500 to 12,000 years ago (corrected for solar variations). Recent genetic evidence suggests that maize domestication occurred 9,000 years ago in central Mexico, perhaps in the highlands between Oaxaca and Jalisco. The crop wild relative teosinte most similar to modern maize grows in the area of the Balsas River. Archaeological remains of early maize ears, found at Guila Naquitz Cave in the Oaxaca Valley, date back roughly 6,250 years (corrected; 3450 BC, uncorrected); the oldest ears from caves near Tehuacan, Puebla, date ca. 2750 BC. Little change occurred in ear form until ca. 1100 BC when great changes appeared in ears from Mexican caves: maize diversity rapidly increased and archaeological teosinte was first deposited. Perhaps as early as 1500 BC, maize began to spread widely and rapidly. As it was introduced to new cultures, new uses were developed and new varieties selected to better serve in those preparations. Maize was the staple food, or a major staple, of most the pre-Columbian North American, Mesoamerican, South American, and Caribbean cultures. The Mesoamerican civilization was strengthened upon the field crop of maize; through harvesting it, its religious and spiritual importance and how it impacted their diet. Maize formed the Mesoamerican people’s identity. During the 1st millennium AD, maize cultivation spread from Mexico into the U.S. Southwest and a millennium later into U.S. Northeast and southeastern Canada, transforming the landscape as Native Americans cleared large forest and grassland areas for the new crop. It is unknown what precipitated its domestication, because the edible portion of the wild variety is too small and hard to obtain to be eaten directly, as each kernel is enclosed in a very hard bi-valve shell. However, George Beadle demonstrated that the kernels of teosinte are readily "popped" for human consumption, like modern popcorn. Some have argued that it would have taken too many generations of selective breeding in order to produce large compressed ears for efficient cultivation. However, studies of the hybrids readily made by intercrossing teosinte and modern maize suggest that this objection is not well founded. In 2005, research by the USDA Forest Service indicated that the rise in maize cultivation 500 to 1,000 years ago in what is now the southeastern United States contributed to the decline of freshwater mussels, which are very sensitive to environmental changes. Production quantities and methods. Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain. While the United States produces almost half of the world's harvest(~42.5%), other top producing countries include China, Brazil, Mexico, Argentina, India and France. Worldwide production was around 800 million tonnes in 2007—just slightly more than rice (~650 million tonnes) or wheat (~600 million tonnes). In 2007, over 150 million hectares of maize were planted worldwide, with a yield of 4970.9 kilogram hectare. Because it is cold-intolerant, in the temperate zones maize must be planted in the spring. Its root system is generally shallow, so the plant is dependent on soil moisture. As a C4 plant (a plant that uses C4 carbon fixation), maize is a considerably more water-efficient crop than C3 plants (plants that use C3 carbon fixation) like the small grains, alfalfa and soybeans. Maize is most sensitive to drought at the time of silk emergence, when the flowers are ready for pollination. In the United States, a good harvest was traditionally predicted if the corn was "knee-high by the Fourth of July," although modern hybrids generally exceed this growth rate. Maize used for silage is harvested while the plant is green and the fruit immature. Sweet corn is harvested in the "milk stage," after pollination but before starch has formed, between late summer and early to mid-autumn. Field corn is left in the field very late in the autumn in order to thoroughly dry the grain, and may, in fact, sometimes not be harvested until winter or even early spring. The importance of sufficient soil moisture is shown in many parts of Africa, where periodic drought regularly causes famine by causing maize crop failure. Maize was planted by the Native Americans in hills, in a complex system known to some as the Three Sisters: beans used the corn plant for support and in turn provided nitrogen from nitrogen-fixing bacteria which live on the roots of beans and other legumes; and squashes provided ground cover to stop weeds and inhibit evaporation by providing shade over the soil. This method was replaced by single species hill planting where each hill 60–120 cm (2–4 ft) apart was planted with 3 or 4 seeds, a method still used by home gardeners. A later technique was "checked corn" where hills were placed 40 inches apart in each direction, allowing cultivators to run through the field in two directions. In more arid lands this was altered and seeds were planted in the bottom of 10–12 cm (4–5 in) deep furrows to collect water. Modern technique plants maize in rows which allows for cultivation while the plant is young, although the hill technique is still used in the cornfields of some Native American reservations. In North America, fields are often planted in a two-crop rotation with a nitrogen-fixing crop, often alfalfa in cooler climates and soybeans in regions with longer summers. Sometimes a third crop, winter wheat, is added to the rotation. Fields are usually ploughed each year, although no-till farming is increasing in use. Many of the maize varieties grown in the United States and Canada are hybrids. Over half of the corn area planted in the United States has been genetically modified using biotechnology to express agronomic traits such as pest resistance or herbicide resistance. Before about World War II, most maize in North America was harvested by hand (as it still is in most of the other countries where it is grown). This often involved large numbers of workers and associated social events. Some one- and two-row mechanical pickers were in use but the corn combine was not adopted until after the War. By hand or mechanical picker, the entire ear is harvested which then requires a separate operation of a corn sheller to remove the kernels from the ear. Whole ears of corn were often stored in "corn cribs" and these whole ears are a sufficient form for some livestock feeding use. Few modern farms store maize in this manner. Most harvest the grain from the field and store it in bins. The combine with a corn head (with points and snap rolls instead of a reel) does not cut the stalk; it simply pulls the stalk down. The stalk continues downward and is crumpled in to a mangled pile on the ground. The ear of corn is too large to pass through a slit in a plate and the snap rolls pull the ear of corn from the stalk so that only the ear and husk enter the machinery. The combine separates out the husk and the cob, keeping only the kernels. Pellagra. When maize was first introduced into other farming systems than those used by traditional native-American peoples, it was generally welcomed with enthusiasm for its productivity. However, a widespread problem of malnutrition soon arose wherever maize was introduced as a staple. This was a mystery since these types of malnutrition were not normally seen among the indigenous Americans, to whom Maize was the principal staple food. It was eventually discovered that the indigenous Americans learned long ago to add alkali—in the form of ashes among North Americans and lime (calcium carbonate) among Mesoamericans—to corn meal, which liberates the B-vitamin niacin, the lack of which was the underlying cause of the condition known as pellagra. This alkali process is known by its Nahuatl (Aztec)-derived name: nixtamalization. Besides the lack of niacin, pellagra was also characterized by protein deficiency, a result of the inherent lack of two key amino acids in pre-modern maize, lysine and tryptophan. Nixtamalisation was also found to increase the lysine and tryptophan content of maize to some extent, but more importantly, the indigenous Americans had learned long ago to balance their consumption of maize with beans and other protein sources such as amaranth and chia, as well as meat and fish, in order to acquire the complete range of amino acids for normal protein synthesis. Since maize had been introduced into the diet of non-indigenous Americans without the necessary cultural knowledge acquired over thousands of years in the Americas, the reliance on maize in other cultures was often tragic. In the late 19th century pellagra reached endemic proportions in parts of the deep southern U.S., as medical researchers debated two theories for its origin: the deficiency theory (eventually shown to be true) posited that pellagra was due to a deficiency of some nutrient, and the germ theory posited that pellagra was caused by a germ transmitted by stable flies. In 1914 the U.S. government officially endorsed the germ theory of pellagra, but rescinded this endorsement several years later as evidence grew against it. By the mid-1920s the deficiency theory of pellagra was becoming scientific consensus, and the theory was proved in 1932 when niacin deficiency was determined to be the cause of the illness. Once alkali processing and dietary variety was understood and applied, pellagra disappeared. The development of high lysine maize and the promotion of a more balanced diet has also contributed to its demise. Insect pests. The susceptibility of maize to the European corn borer, and the resulting large crop losses, led to the development of transgenic expressing the "Bacillus thuringiensis" toxin. "Bt corn" is widely grown in the United States and has been approved for release in Europe. Food. Corn and cornmeal (corn flour) constitutes a staple food in many regions of the world. Corn meal is made into a thick porridge in many cultures: from the polenta of Italy, the angu of Brazil, the mămăligă of Romania, to mush in the U.S. or the food called sadza, nshima, ugali, tuwan-masara and mealie pap in Africa. Corn meal is also used as a replacement for wheat flour, to make cornbread and other baked products. Masa (cornmeal treated with lime water) is the main ingredient for tortillas, atole and many other dishes of Mexican food. Popcorn is kernels of certain varieties that explode when heated, forming fluffy pieces that are eaten as a snack. Chicha and "chicha morada"(purple chicha) are drinks made usually from particular types of maize. The first one is fermented and alcoholic, the second one is a soft drink commonly drunk in Peru Corn flakes are a common breakfast staple in the United States, and are increasingly popular all over the world. Maize can also be prepared as hominy, in which the kernels are soaked with lye; or grits, which are coarsely ground hominy. These are commonly eaten in the Southeastern United States, foods handed down from Native Americans. The Brazilian dessert canjica is made by boiling maize kernels in sweetened milk. Roasted dried corn cobs with semi-hardened kernels, coated with a seasoning mixture of fried chopped spring onions with salt added to the oil, is a popular snack food in Vietnam. Maize can also be harvested and consumed in the unripe state, when the kernels are fully grown but still soft. Unripe corn must usually be cooked to become palatable; this may be done by simply boiling or roasting the whole ears and eating the kernels right off the cob. Such corn on the cob is a common dish in the United States, United Kingdom and some parts of South America, but virtually unheard of in some European countries. The cooked unripe kernels may also be shaved off the cob and served as a vegetable in side dishes, salads, garnishes, etc. Alternatively, the raw unripe kernels may also be grated off the cobs and processed into a variety of cooked dishes, such as corn purée, tamales, pamonhas, curau, cakes, ice creams, etc. Sweetcorn, a genetic variety that is high in sugars and low in starch, is usually consumed in the unripe state. Maize is a major source of starch, a major ingredient in home cooking and in many industrialized food products. It is also a major source of cooking oil (corn oil) and of corn gluten. Maize starch can be hydrolyzed and enzymatically treated to produce syrups, particularly high fructose corn syrup, a sweetener; and also fermented and distilled to produce grain alcohol. Grain alcohol from maize is traditionally the source of bourbon whiskey. Maize is used to make chicha, a fermented beverage of Central and South America; and sometimes as the starch source for beer. In the United States and Canada maize is also widely grown to feed for livestock, as forage, silage (made by fermentation of chopped green cornstalks), or grain. Corn meal is also a significant ingredient of some commercial animal food products, such as dog food. Maize is also used as a fish bait, called "dough balls". It is particularly popular in Europe for coarse fishing. Chemicals and medicines. Starch from maize can also be made into plastics, fabrics, adhesives, and many other chemical products. Stigmas from female corn flowers, known popularly as corn silk, are sold as herbal supplements. The corn steep liquor, a plentiful watery byproduct of maize wet milling process, is widely used in the biochemical industry and research as a culture medium to grow many kinds of microorganisms. Biofuel. "Feed corn" is being used increasingly for heating; specialized corn stoves (similar to wood stoves) are available and use either feed corn or wood pellets to generate heat. Corncobs are also used as a biomass fuel source. Maize is relatively cheap and home-heating furnaces have been developed which use maize kernels as a fuel. They feature a large hopper that feeds the uniformly sized corn kernels (or wood pellets or cherry pits) into the fire. Maize is increasingly used as a biomass fuel, such as ethanol, which as researchers search for innovative ways to reduce fuel costs, has unintentionally caused a rapid rise in food costs. This has led to the 2007 harvest being one of the most profitable corn crops in modern history for farmers. Maize is widely used in Germany as a feedstock for biogas plants. Here the maize is harvested, shredded then placed in silage clamps from which it is fed into the biogas plants. A biomass gasification power plant in Strem near Güssing, Burgenland, Austria was begun in 2005. Research is being done to make diesel out of the biogas by the Fischer Tropsch method. Increasingly ethanol is being used at low concentrations (10% or less) as an additive in gasoline (gasohol) for motor fuels to increase the octane rating, lower pollutants, and reduce petroleum use (what is nowadays also known as "biofuels" and has been generating an intense debate regarding the human beings' necessity of new sources of energy, on the one hand, and the need to maintain, in regions such as Latin America, the food habits and culture which has been the essence of civilizations such as the one originated in Mesoamerica; the entry, January 2008, of maize among the commercial agreements of NAFTA has increased this debate, considering the bad labor conditions of workers in the fields, and mainly the fact that NAFTA "opened the doors to the import of corn from the United States, where the farmers who grow it receive multi-million dollar subsidies and other government supports. According to OXFAM UK, after NAFTA went into effect, the price of maize in Mexico fell 70% between 1994 and 2001. The number of farm jobs dropped as well: from 8.1 million in 1993 to 6.8 million in 2002. Many of those who found themselves without work were small-scale maize growers."). However, introduction in the northern latitudes of the U.S. of, and not for human or animal consumption, may potentially alleviate this. As a result of the U.S. federal government announcing its production target of 35 billion gallons of biofuels by 2017, ethanol production will grow to 7 billion gallons by 2010, up from 4.5 billion in 2006, boosting ethanol's share of corn demand in the U.S. from 22.6 percent to 36.1 percent. Ornamental and other uses. Some forms of the plant are occasionally grown for ornamental use in the garden. For this purpose, variegated and colored leaf forms as well as those with colorful ears are used. Additionally, size-superlative varieties, having reached 31 ft (9.4m) tall, or with ears 24 inches (60 cm) long, have been popular for at least a century. Corncobs can be hollowed out and treated to make inexpensive smoking pipes, first manufactured in the United States in 1869. An unusual use for maize is to create a "maize maze" as a tourist attraction. This is a maze cut into a field of maize. The idea of a maize maze was introduced by Adrian Fisher, one of the most prolific designers of modern mazes, with The American Maze Company who created a maze in Pennsylvania in 1993. Traditional mazes are most commonly grown using yew hedges, but these take several years to mature. The rapid growth of a field of maize allows a maze to be laid out using GPS at the start of a growing season and for the maize to grow tall enough to obstruct a visitor's line of sight by the start of the summer. In Canada and the U.S., these are called "corn mazes" and are popular in many farming communities. Corn kernels can be used in place of sand in a sandbox-like enclosure for children's play. Fodder. Maize makes a greater quantity of epigeous mass than other cereal plants, so can be used for fodder. Digestibility and palatability are higher when ensiled and fermented, rather than dried. In art. Maize has been an essential crop in the Andes since the pre-Columbian Era. The Moche culture from Northern Peru made ceramics from earth, water, and fire. This pottery was a sacred substance, formed in significant shapes and used to represent important themes. Maize represented anthropomorphically as well as naturally. In the United States, maize itself is sometimes used for temporary architectural detailing when the intent is to celebrate local agricultural productivity and culture. A well-known example of this use is the Corn Palace in Mitchell, South Dakota, which utilizes cobs of colored maize to implement a design that is recycled annually. External links. 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