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Biology

Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth,evolution, distribution, and taxonomy.^[1] Modern biology is a vast and eclectic field, composed of many branches and subdisciplines. However, despite the broad scope of biology, there are certain general and unifying concepts within it that govern all study and research, consolidating it into single, coherent fields. In general, biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the synthesis and creation of new species. It is also understood today that all organisms survive by consuming and transforming energy and by regulating their internal environment to maintain a stable and vital condition.

Subdisciplines of biology are defined by the scale at which organisms are studied, the kinds of organisms studied, and the methods used to study them: biochemistry examines the rudimentary chemistry of life; molecular biology studies the complex interactions among biological molecules; botany studies the biology of plants; cellular biology examines the basic building-block of all life, thecell; physiology examines the physical and chemical functions of tissues, organs, and organ systems of an organism; evolutionary biology examines the processes that produced the diversity of life; and ecology examines how organisms interact in theirenvironment.^[2]

History

Main article: History of biology

Ernst Haeckel's Tree of Life (1879)

The term biology is derived from the Greek word βίος, bios, "life" and the suffix -λογία, -logia, "study of."^[3][4] The Latin form of the term first appeared in 1736 when Swedish scientist Carl Linnaeus (Carl von Linné) used biologi in his Bibliotheca botanica. It was used again in 1766 in a work entitled Philosophiae naturalis sive physicae: tomus III, continens geologian, biologian, phytologian generalis, by Michael Christoph Hanov, a disciple of Christian Wolff. The first German use, Biologie, was used in a 1771 translation of Linnaeus' work. In 1797, Theodor Georg August Roose used the term in a book, Grundzüge der Lehre van der Lebenskraft, in the preface. Karl Friedrich Burdachused the term in 1800 in a more restricted sense of the study of human beings from a morphological, physiological and psychological perspective (Propädeutik zum Studien der gesammten Heilkunst). The term came into its modern usage with the six-volume treatiseBiologie, oder Philosophie der lebenden Natur (1802–22) by Gottfried Reinhold Treviranus, who announced:^[5]

The objects of our research will be the different forms and manifestations of life, the conditions and laws under which these phenomena occur, and the causes through which they have been effected. The science that concerns itself with these objects we will indicate by the name biology [Biologie] or the doctrine of life [Lebenslehre].

Although modern biology is a relatively recent development, sciences related to and included within it have been studied since ancient times. Natural philosophy was studied as early as the ancient civilizations of Mesopotamia, Egypt, the Indian subcontinent, and China. However, the origins of modern biology and its approach to the study of nature are most often traced back to ancient Greece.^[6] While the formal study of medicine dates back to Hippocrates (ca. 460 BC – ca. 370 BC), it was Aristotle (384 BC – 322 BC) who contributed most extensively to the development of biology. Especially important are his History of Animals and other works where he showed naturalist leanings, and later more empirical works that focused on biological causation and the diversity of life. Aristotle's successor at the Lyceum,Theophrastus, wrote a series of books on botany that survived as the most important contribution of antiquity to the plant sciences, even into the Middle Ages.^[7]

Scholars of the medieval Islamic world who wrote on biology included al-Jahiz (781–869), Al-Dinawari (828–896), who wrote on botany,^[8] and Rhazes (865–925) who wrote onanatomy and physiology. Medicine was especially well studied by Islamic scholars working in Greek philosopher traditions, while natural history drew heavily on Aristotelian thought, especially in upholding a fixed hierarchy of life.

Biology began to quickly develop and grow with Anton van Leeuwenhoek's dramatic improvement of the microscope. It was then that scholars discovered spermatozoa, bacteria,infusoria and the diversity of microscopic life. Investigations by Jan Swammerdam led to new interest in entomology and helped to develop the basic techniques of microscopicdissection and staining.^[9]

Advances in microscopy also had a profound impact on biological thinking. In the early 19th century, a number of biologists pointed to the central importance of the cell. Then, in 1838, Schleiden and Schwann began promoting the now universal ideas that (1) the basic unit of organisms is the cell and (2) that individual cells have all the characteristics oflife, although they opposed the idea that (3) all cells come from the division of other cells. Thanks to the work of Robert Remak and Rudolf Virchow, however, by the 1860s most biologists accepted all three tenets of what came to be known as cell theory.^[10][11]

Meanwhile, taxonomy and classification became the focus of natural historians. Carl Linnaeus published a basic taxonomy for the natural world in 1735 (variations of which have been in use ever since), and in the 1750s introduced scientific names for all his species.^[12] Georges-Louis Leclerc, Comte de Buffon, treated species as artificial categories and living forms as malleable—even suggesting the possibility of common descent. Though he was opposed to evolution, Buffon is a key figure in the history of evolutionary thought; his work influenced the evolutionary theories of both Lamarck and Darwin.^[13]

Serious evolutionary thinking originated with the works of Jean-Baptiste Lamarck, who was the first to present a coherent theory of evolution.^[14] He posited that evolution was the result of environmental stress on properties of animals, meaning that the more frequently and rigorously an organ was used, the more complex and efficient it would become, thus adapting the animal to its environment. Lamarck believed that these acquired traits could then be passed on to the animal's offspring, who would further develop and perfect them.^[15] However, it was the British naturalist Charles Darwin, combining the biogeographical approach of Humboldt, the uniformitarian geology of Lyell, Malthus's writings on population growth, and his own morphological expertise and extensive natural observations, who forged a more successful evolutionary theory based on natural selection; similar reasoning and evidence led Alfred Russel Wallace to independently reach the same conclusions.^[16][17] Although it was the subject of controversy (which continues to this day), Darwin's theory quickly spread through the scientific community and soon became a central axiom of the rapidly developing science of biology.

The discovery of the physical representation of heredity came along with evolutionary principles and population genetics. In the 1940s and early 1950s, experiments pointed toDNA as the component of chromosomes that held the trait-carrying units that had become known as genes. A focus on new kinds of model organisms such as viruses andbacteria, along with the discovery of the double helical structure of DNA in 1953, marked the transition to the era of molecular genetics. From the 1950s to present times, biology has been vastly extended in the molecular domain. The genetic code was cracked by Har Gobind Khorana, Robert W. Holley and Marshall Warren Nirenberg after DNA was understood to contain codons. Finally, the Human Genome Project was launched in 1990 with the goal of mapping the general human genome. This project was essentially completed in 2003,^[18] with further analysis still being published. The Human Genome Project was the first step in a globalized effort to incorporate accumulated knowledge of biology into a functional, molecular definition of the human body and the bodies of other organisms.

Foundations of modern biology

Cell theory

Cell theory states that the cell is the fundamental unit of life, and that all living things are composed of one or more cells or thesecreted products of those cells (e.g. shells, hairs and nails etc.). All cells arise from other cells through cell division. In multicellular organisms, every cell in the organism's body derives ultimately from a single cell in a fertilized egg. The cell is also considered to be the basic unit in many pathological processes.^[19] In addition, the phenomenon of energy flow occurs in cells in processes that are part of the function known as metabolism. Finally, cells contain hereditary information (DNA), which is passed from cell to cell during cell division.

Emmer

For other uses, see Emmer (disambiguation).

Emmer wheat
Spikes (ears) of cultivated emmer wheat
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
(unranked):	Commelinids
Order:	Poales
Family:	Poaceae
Genus:	Triticum
Species:	T. dicoccum
Binomial name
Triticum dicoccum Schrank ex Schübl.[1]
Synonyms[2]
Spelta amylea (Ser.) Ser. Triticum amyleum Ser. Triticum armeniacum (Stolet.) Nevski Triticum arras Hochst. Triticum atratum Host Triticum cienfuegos Lag. Triticum dicoccum Schrank.[3] Triticum farrum Bayle-Bar. Triticum gaertnerianum Lag. Triticum immaturatum Flaksb. nom. inval. Triticum ispahanicum Heslot Triticum karamyschevii Nevski Triticum maturatum Flaksb. nom. inval. Triticum palaecocolchicum(Menabde) L.B. Cai Triticum palaeocolchicum Menabde Triticum subspontaneum (Tzvelev) Czerep. Triticum tricoccum Schübl. Triticum volgense (Flaksb.) Nevski

Emmer wheat, also known as farroespecially in Italy, or hulled wheat,^[3] is a type of awnedwheat. Emmer is a tetraploid (2n=4x=28 chromosomes). The domesticated species areTriticum turgidum subsp. dicoccum andTriticum turgidum conv. durum. The wild species is called Triticum turgidum subsp. dicoccoides. The principal difference between the wild and the domestic species is that the ripened seed head of the wild species shatters and spreads the seed onto the ground while in the domesticated emmer the seed head remains intact, thus making it easier for humans to harvest the grain.^[4]

Along with Einkorn wheat, Emmer was one of the first crops domesticated in theNear East. It was widely cultivated in the ancient world, but is now a relict crop in mountainous regions of Europe and Asia.

Contents

  [hide] 

• 1 Taxonomy
  • 1.1 Wild emmer
• 2 Morphology
• 3 History
• 4 Cultivation
• 5 Food uses
• 6 Etymology
• 7 Notes
• 8 References

Taxonomy[edit]

Strong similarities in morphology and genetics show that wild emmer (Triticum dicoccoides Koern.) is the wild ancestor and acrop wild relative of domesticated emmer. Because wild and domesticated emmer are interfertile with other tetraploid wheats, some taxonomists consider all tetraploid wheats to belong to one species, T. turgidum. Under this scheme, the two forms are recognized atsubspecies level, thus T. turgidum subsp. dicoccoidesand T. turgidum subsp.dicoccum. Either naming system is equally valid; the latter lays more emphasis on genetic similarities.

For a wider discussion, seeWheat#Genetics & Breedingand Wheat taxonomy

Wild emmer[edit]

Wild emmer (Triticum dicoccoides) grows wild in the fertile crescent of the Near East. It is a tetraploid wheat formed by the hybridization of two diploid wild grasses, Triticum urartu(closely related to wild einkorn (T. boeoticum), and an as yet unidentifiedAegilops species related toA. searsii or A. speltoides.

Morphology[edit]

Cultivated emmer wheat

Like einkorn and speltwheats, emmer is a hulled wheat. In other words, it has strong glumes (husks) that enclose the grains, and a semi-brittle rachis. On threshing, a hulled wheat spike breaks up into spikelets. These require milling or pounding to release the grains from the glumes.

Wild emmer wheat spikelets effectively self-cultivate by propelling themselves mechanically into soils with their awns. During a period of increased humidity during the night, the awns of the spikelet become erect and draw together, and in the process push the grain into the soil. During the daytime the humidity drops and the awns slacken back again; however, fine silica hairs on the awns act as hooks in the soil and prevent the spikelets from reversing back out again. During the course of alternating stages of daytime and nighttime humidity, the awns' pumping movements, which resemble a swimmingfrog kick, will drill the spikelet as much as an inch or more into the soil.^[5]

History[edit]

Wild emmer is native to theFertile Crescent of the Middle East, growing in the grass and woodland of hill country from modern-day Israel toIran. The origin of wild emmer has been suggested, without universal agreement among scholars, to be theKaraca Dag mountain region of southeastern Turkey. In 1906, Aaron Aaronsohn's discovery of wild emmer wheat growing in Rosh Pinna(now in Israel) created a stir in the botanical world.^[6]Emmer wheat has been found in archaeological excavations and ancient tombs. Emmer was collected from the wild and eaten by hunter gatherers for thousands of years before its domestication. Grains of wild emmer discovered at Ohalo IIhad a radiocarbon dating of 17,000 BC and at the Pre Pottery Neolithic A (PPNA) site of Netiv Hagdud are 10,000-9,400 years old. ^[7]and at the Pre Pottery Neolithic A (PPNA) site ofNetiv Hagdud are 10,000-9,400 years old.

The oldest evidence of domesticated emmer wheat has found near Damascus, Syria dating from 7,650 to 8,200 years BC. The dryness of the site, requiring irrigation for agriculture, suggests that the emmer was introduced as an already domesticated plant from elsewhere outside the Damascus Basin. Emmer is found in a large number of Neolithic sites scattered around the fertile crescent. From its earliest days of cultivation, emmer was a more prominent crop that its cereal contemporaries and competitors, einkorn wheat and barley. ^[8] Small quantities of emmer are present during Period 1 at Mehrgharh on the Indian subcontinent, showing that emmer was already cultivated there by 7000-5000 BC.^[9]

In the Near East, in southernMesopotamia in particular, cultivation of emmer wheat began to decline in the Early Bronze Age, from about 3000 BC, and barley became the standard cereal crop. This has been related to increased salinization of irrigated alluvial soils, of which barley is more tolerant,^[10] although this study has been challenged.^[11] Emmer had a special place in ancient Egypt, where it was the main wheat cultivated in Pharaonic times, although cultivated einkorn wheat was grown in great abundance during the Third Dynasty, and large quantities of it were found preserved, along with cultivated emmer wheat and barleys, in the subterranean chambers beneath the Step Pyramid atSaqqara.^[12] Neighbouring countries also cultivated einkorn, durum and common wheat.^[13] In the absence of any obvious functional explanation, the greater prevalence of emmer wheat in the diet of ancient Egypt may simply reflect a marked culinary or cultural preference, or may reflect growing conditions having changed after the Third Dynasty. Emmer and barley were the primary ingredients in ancient Egyptian bread and beer. Emmer recovered from the Phoeniciansettlement at Volubilis^[14] (in present day Morocco) has been dated to the middle of the first millennium BC.

Emmer wheat is mentioned in ancient rabbinic literatureas one of the five grains to be used by Jews duringPassover as matzah (that is, without leavening agents of any kind).^{[citation needed]} It is often incorrectly translated as spelt in English translations of the rabbinic literature but spelt did not grow in ancient Israel, and emmer was a significant crop until the end of the Iron Age. Likewise, references to emmer in Greek and Latin texts are traditionally translated as "spelt," even though spelt was not common in the Classical world until very late in its history.

In northeastern Europe, emmer (in addition to einkorn and barley) was one of the most important cereal species and this importance can be seen to increase from 3400 BC onwards. Pliny the Elder, notes that although emmer was called far in his time formerly it was calledadoreum (or "glory"), providing an etymology explaining that emmer had been held in glory (N.H.18.3), and later in the same book he describes its role in sacrifices.

Cultivation[edit]

Today emmer is primarily a relict crop in mountainous areas. Its value lies in its ability to give good yields on poor soils, and its resistance to fungal diseases such asstem rust that are prevalent in wet areas. Emmer is grown in Armenia, Morocco, Spain (Asturias), the Carpathian mountains on the border of the Czech and Slovak republics, Albania, Turkey, Switzerland, Germany, Greece and Italy. It is also grown in the U.S. as a specialty product. A traditional food plant in Ethiopia, this relatively little-known grain has potential to improve nutrition, boost food security, foster rural development and support sustainable landcare.^[15]

In Italy, uniquely, emmer cultivation is well established and even expanding. In the mountainous Garfagnana area of Tuscany emmer (known as farro) is grown by farmers as an IGP (Indicazione Geografica Protetta) product, with its geographic identity protected by law. Production is certified by a co-operative body, the Consorzio Produttori Farro della Garfagnana. IGP-certified farro is widely available inhealth food shops across Europe, and even in some British supermarkets. The demand for Italian farro has led to competition from non-certified farro, grown in lowland areas and often consisting of a different wheat species, spelt (Triticum spelta).

Food uses[edit]

Emmer's main use is as a human food, though it is also used for animal feed. Ethnographic evidence from Turkey and other emmer-growing areas suggests that emmer makes good bread (judged by the taste and texture standards of traditional bread), and this is supported by evidence of its widespread consumption as bread in ancient Egypt.^[16]Emmer bread is available in Switzerland.^[17] In Italy, whole emmer grains can be easily found in most supermarkets and groceries, emmer bread (pane di farro) can be found in bakeries in some areas, and emmer has traditionally been consumed in Tuscany as whole grain in soup. Higher in fiber than common wheat, emmer's use for making pasta is a recent response to the health food market; some consumers^[who?], however, judge that emmer pasta has an unattractive texture. Emmer has also been used in beer production.^[18] As with most varieties of wheat, however, emmer is probably unsuitable for sufferers fromwheat allergies or coeliac disease.^[19]

Etymology[edit]

First use: 1908 Origin: species of wheat, from German Emmer, variant of Amelkorn, from amel "starch", from Latin amylum.^[20]

Notes[edit]

1. Jump up^ "Tropicos.org". Retrieved30 June 2014.
2. Jump up^ "The Plant List: A Working List of All Plant Species". RetrievedJune 30, 2014.
3. ^ Jump up to:^a b "USDA GRIN Taxonomy".
4. Jump up^ Weiss, Ehud and Zohary, Daniel (October 2011), "The Neolithic Southwest Asian Founder Crops,Current Anthropology, Vo 52, Supplement 4, p. S240
5. Jump up^ Elbaum, Rivka; Zaltzman, Liron; Burgert, Ingo; Fratzl, Peter (2007). "The Role of Wheat Awns in the Seed Dispersal Unit". Science 316 (5826): 884–886.Bibcode:2007Sci...316..884E.doi:10.1126/science.1140097.PMID 17495170.
6. Jump up^http://www.jafi.org.il/education/100/PEOPLE/BIOS/aron.html
7. Jump up^ Zohary & Hopf 2000, p. 46
8. Jump up^ Weiss and Zohary, pp. S240-S242
9. Jump up^ Possehl, Gregory. "The Indus Civilization: An Introduction to Environmental, Subsistence, and Cultural History: (2003)
10. Jump up^ Jacobsen & Adams 1958
11. Jump up^ Powell, M. A. (1985) Salt, seed, and yields in Sumerian agriculture. A critique of the theory of progressive salinization. Zeitschrift für Assyriologie und Vorderasiatische Archäologie 75, 7-38.
12. Jump up^ Jean-Phillipe Lauer, Laurent Taeckholm and E. Aberg, 'Les Plantes Decouvertes dans les Souterrains de l'Enceinte du Roi Zoser a Saqqarah' in Bulletin de l'Institut d'Egypte, Vol. XXXII, 1949-50, pp. 121–157, and see Plate IV for photo of ears of both wheats recovered from beneath the pyramid.
13. Jump up^ Zohary & Hopf 2000, pp. 50f
14. Jump up^ C. Michael Hogan. 2008. Volubilis: Ancient settlement in Morocco, The Megalithic Portal, ed. Andy Burnham
15. Jump up^ National Research Council (1996-02-14). "Other Cultivated Grains".Lost Crops of Africa: Volume I: Grains. Lost Crops of Africa 1. National Academies Press.ISBN 978-0-309-04990-0. Retrieved2008-07-18.
16. Jump up^ Hulled wheats. Proceedings of the First International Workshop on Hulled Wheats. Promoting the conservation and use of underutilized and neglected crops 4. Edited by S. Padulosi, K. Hammer, and J. Heller, 1996. Rome: International Plant Genetic Resources Institute.
17. Jump up^ "Renaissance alter Brotgetreidesorten - swissinfo" (in German). Swissinfo.ch. Retrieved2010-11-13.
18. Jump up^ Samuel, Delwen. 1996. Archeology of Ancient Egyptian Beer. Journal of the American Society of Brewing Chemists 54(1): 3-12
19. Jump up^ "Grains in Relation to Celiac (Coeliac) Disease". Wheat.pw.usda.gov. Retrieved2010-11-13.
20. Jump up^ "Online Etymology Dictionary". Retrieved 2011-08-10.

References[edit]

• Daniel Zohary, Maria Hopf (2000). Domestication of plants in the Old World. Oxford: Oxford University Press. ISBN 0-19-850356-3.
• Hulled Wheats. Promoting the conservation and use of underutilized and neglected crops. 4. Proceedings of the First International Workshop on Hulled Wheats 21-22 July 1995, Castelvecchio Pascoli, Tuscany, Italy[invalid link]
• Zohary, Michael (1982).Plants of the Bible. Cambridge: Cambridge University Press. ISBN 0-521-24926-0. Up-to-date reference to cereals in the Biblical world.
• Wheat evolution: integrating archaeological and biological evidence
• Alternative Wheat Cereals as Food Grains: Einkorn, Emmer, Spelt, Kamut, and Triticale
• Luo, M.-C.; Yang, Z.-L.; You, F. M.; Kawahara, T.; Waines, J. G.; Dvorak, J. (2007). "The structure of wild and domesticated emmer wheat populations, gene flow between them, and the site of emmer domestication".Theoretical and Applied Genetics 114 (6): 947–59.doi:10.1007/s00122-006-0474-0. PMID 17318496.
• Jacobsen, Thorkild; Adams, Robert M. (1958). "Salt and Silt in Ancient Mesopotamian Agriculture".Science 128 (3334): 1251–8.Bibcode:1958Sci...128.1251J.doi:10.1126/science.128.3334.1251. PMID 17793690.
• [1] Oldest domesticated wheat found at Abu Hureyra.
• Jacomet, Stefanie (2006). "Plant economy of the northern Alpine lake dwellings — 3500–2400 cal. BC". Environmental Archaeology 11 (1): 65–85.doi:10.1179/174963106x97061.

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