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Evolutionary Models Of Human Drug Use
Evolutionary models of drug use seek to explain human drug usage from the perspective of evolutionary fitness. Plants for instance, may provide fitness benefits by relieving pain. Proponents of this model of drug use suggest that the consumption of pharmacological substances for medicinal purposes evolved in the backdrop of human-plant coevolution as a means of self-medication. Humans thus learned to ignore the cues of plant toxicity (e.g. bitter taste) because ingesting the bioactive compounds of plants in small amounts was therapeutic. The hijack model of substance addiction suggests that Psychoactive drugs act on ancient and evolutionarily conserved neural mechanisms associated with positive emotions that evolved to mediate incentive behavior. They induce emotions that in human evolutionary history signaled a benefit for the group. Modern drugs tap into these emotions without passing on any evolutionary advantage. This may explain the modern problems of overuse and addiction. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fitness (biology)
Fitness (often denoted w or ω in population genetics models) is a quantitative representation of individual reproductive success. It is also equal to the average contribution to the gene pool of the next generation, made by the same individuals of the specified genotype or phenotype. Fitness can be defined either with respect to a genotype or to a phenotype in a given environment or time. The fitness of a genotype is manifested through its phenotype, which is also affected by the developmental environment. The fitness of a given phenotype can also be different in different selective environments. With asexual reproduction, it is sufficient to assign fitnesses to genotypes. With sexual reproduction, recombination scrambles alleles into different genotypes every generation; in this case, fitness values can be assigned to alleles by averaging over possible genetic backgrounds. Natural selection tends to make alleles with higher fitness more common over time, resulting in Darwini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recreational Drug Use
Recreational drug use is the use of one or more psychoactive drugs to induce an altered state of consciousness, either for pleasure or for some other casual purpose or pastime. When a psychoactive drug enters the user's body, it induces an Substance intoxication, intoxicating effect. Recreational drugs are commonly divided into three categories: depressants (drugs that induce a feeling of relaxation and calmness), stimulants (drugs that induce a sense of energy and alertness), and hallucinogens (drugs that induce perceptual distortions such as hallucination). In popular practice, recreational drug use is generally tolerated as a social behaviour, rather than perceived as the medical condition of self-medication. However, drug use and drug addiction are Social stigma, severely stigmatized everywhere in the world. Many people also use prescribed and controlled depressants such as opioids, opiates, and benzodiazepines. What controlled substances are considered generally unlawful t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleogenetics
Paleogenetics is the study of the past through the examination of preserved genetic material from the remains of ancient organisms. Emile Zuckerkandl and Linus Pauling introduced the term in 1963, long before the sequencing of DNA, in reference to the possible reconstruction of the corresponding polypeptide sequences of past organisms. The first sequence of ancient DNA, isolated from a museum specimen of the extinct quagga, was published in 1984 by a team led by Allan Wilson. Paleogeneticists do not recreate actual organisms, but piece together ancient DNA sequences using various analytical methods. Fossils are "the only direct witnesses of extinct species and of evolutionary events" and finding DNA within those fossils exposes tremendously more information about these species, potentially their entire physiology and anatomy. The most ancient DNA sequence to date was reported in February 2021, from the tooth of a Siberian mammoth frozen for over a million years. Applications ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coevolution
In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection. The term sometimes is used for two traits in the same species affecting each other's evolution, as well as gene-culture coevolution. Charles Darwin mentioned evolutionary interactions between flowering plants and insects in ''On the Origin of Species'' (1859). Although he did not use the word coevolution, he suggested how plants and insects could evolve through reciprocal evolutionary changes. Naturalists in the late 1800s studied other examples of how interactions among species could result in reciprocal evolutionary change. Beginning in the 1940s, plant pathologists developed breeding programs that were examples of human-induced coevolution. Development of new crop plant varieties that were resistant to some diseases favored rapid evolution in pathogen populations to overcome those plant defenses. That, in turn, required the development of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macronutrients
A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excreted by cells to create non-cellular structures such as hair, scales, feathers, or exoskeletons. Some nutrients can be metabolically converted into smaller molecules in the process of releasing energy such as for carbohydrates, lipids, proteins and fermentation products (ethanol or vinegar) leading to end-products of water and carbon dioxide. All organisms require water. Essential nutrients for animals are the energy sources, some of the amino acids that are combined to create proteins, a subset of fatty acids, vitamins and certain minerals. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves. Fungi live on dead or living organic matter and meet nutrient needs from their host. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotoxin
Neurotoxins are toxins that are destructive to nervous tissue, nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insult (medical), insultsSpencer 2000 that can adversely affect function in both developing and mature nervous tissue.Olney 2002 The term can also be used to classify endogenous compounds, which, when abnormally contacted, can prove neurologically toxic. Though neurotoxins are often neurologically destructive, their ability to specifically target neural components is important in the study of nervous systems. Common examples of neurotoxins include lead, ethanol (drinking alcohol), glutamate,Choi 1987 nitric oxide, botulinum toxin (e.g. Botox), tetanus toxin,Simpson 1986 and tetrodotoxin. Some substances such as nitric oxide and glutamate are in fact essential for proper function of the body and only exert neurotoxic effects at excessive concentrations. Neurotoxins inhibit neuron control over ion concentrations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drug Metabolism
Drug metabolism is the metabolic breakdown of drugs by living organisms, usually through specialized enzymatic systems. More generally, xenobiotic metabolism (from the Greek xenos "stranger" and biotic "related to living beings") is the set of metabolic pathways that modify the chemical structure of xenobiotics, which are compounds foreign to an organism's normal biochemistry, such as any drug or poison. These pathways are a form of biotransformation present in all major groups of organisms and are considered to be of ancient origin. These reactions often act to detoxify poisonous compounds (although in some cases the intermediates in xenobiotic metabolism can themselves cause toxic effects). The study of drug metabolism is the object of pharmacokinetics. Metabolism is one of the stages (see ADME) of the drug's transit through the body that involves the breakdown of the drug so that it can be excreted by the body. The metabolism of pharmaceutical drugs is an important as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicotine Poisoning
Nicotine poisoning describes the symptoms of the toxic effects of nicotine following ingestion, inhalation, or skin contact. Nicotine poisoning can potentially be deadly, though serious or fatal overdoses are rare. Historically, most cases of nicotine poisoning have been the result of use of nicotine as an insecticide. More recent cases of poisoning typically appear to be in the form of Green Tobacco Sickness, or due to unintended ingestion of tobacco or tobacco products or consumption of nicotine-containing plants. Standard textbooks, databases, and safety sheets consistently state that the lethal dose of nicotine for adults is 60 mg or less (30–60 mg), but there is overwhelming data indicating that more than 500 mg of oral nicotine is required to kill an adult. Children may become ill following ingestion of one cigarette; ingestion of more than this may cause a child to become severely ill. The nicotine in the e-liquid of an electronic cigarette can be hazardou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bitter Taste Evolution
The evolution of bitter taste receptors has been one of the most dynamic evolutionary adaptations to arise in multiple species. This phenomenon has been widely studied in the field of evolutionary biology because of its role in the identification of toxins often found on the leaves of inedible plants. A palate more sensitive to these bitter tastes would, theoretically, have an advantage over members of the population less sensitive to these poisonous substances because they would be much less likely to ingest toxic plants. Bitter-taste genes have been found in a host of vertebrates, including sharks and rays, and the same genes have been well characterized in several common laboratory animals such as primates and mice, as well as in humans. The primary gene responsible for encoding this ability in humans is the ''TAS2R'' gene family which contains 25 functional loci as well as 11 pseudogenes. The development of this gene has been well characterized, with proof that the ability evolv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenobiotic
A xenobiotic is a chemical substance found within an organism that is not naturally produced or expected to be present within the organism. It can also cover substances that are present in much higher concentrations than are usual. Natural compounds can also become xenobiotics if they are taken up by another organism, such as the uptake of natural human hormones by fish found downstream of sewage treatment plant outfalls, or the chemical defenses produced by some organisms as protection against predators. The term "xenobiotic" is also used to refer to organs transplanted from one species to another. The term "xenobiotics", however, is very often used in the context of pollutants such as dioxins and polychlorinated biphenyls and their effect on the biota, because xenobiotics are understood as substances foreign to an entire biological system, i.e. artificial substances, which did not exist in nature before their synthesis by humans. The term xenobiotic is derived from the Gree ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herbivore Adaptations To Plant Defense
Herbivores are dependent on plants for food, and have coevolution, coevolved mechanisms to obtain this food despite the evolution of a diverse arsenal of Plant defense against herbivory, plant defenses against herbivory. Herbivore adaptations to plant defense have been likened to "offensive traits" and consist of those traits that allow for increased feeding and use of a host.Karban, R., and A. A. Agrawal. 2002. Herbivore offense. ''Annual Review of Ecology and Systematics'' 33:641 – 664. Plants, on the other hand, protect their resources for use in growth and reproduction, by limiting the ability of herbivores to eat them. Relationships between herbivores and their host plants often results in reciprocal evolutionary change. When a herbivore eats a plant it Natural selection, selects for plants that can mount a defensive response, whether the response is incorporated biochemically or physically, or induced as a counterattack. In cases where this relationship demonstrates "speci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herbivore
A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat non-vascular autotrophs such as mosses, algae and lichens, but do not include those feeding on decomposed plant matters (i.e. detritivores) or macrofungi (i.e. fungivores). As a result of their plant-based diet, herbivorous animals typically have mouth structures ( jaws or mouthparts) well adapted to mechanically break down plant materials, and their digestive systems have special enzymes (e.g. amylase and cellulase) to digest polysaccharides. Grazing herbivores such as horses and cattles have wide flat- crowned teeth that are better adapted for grinding grass, tree bark and other tougher lignin-containing materials, and many of them evolved rumination or cecotropic behaviors to better extract nutrients from plants. A larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
