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Multilingual Demographic Dictionary, second unified edition, English volume

Difference between revisions of "91"

Multilingual Demographic Dictionary, second unified edition, English vol.
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(Etienne van de Walle et al., second 1982 edition *** existing text overwritten ***)
(Eugen Grebenik et al., first edition 1958)
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=== 910 ===
 
=== 910 ===
  
In {{TextTerm|eugenics|1}}, a discipline which seeks to improve the quality of the population, attention is directed primarily to the role of {{TextTerm|heredity|2}}, the transmission of {{TextTerm|hereditary characteristics|3}}, such as the color of the eyes, from generation to generation. {{TextTerm|Acquired characteristics|4}} are not so transmitted. A {{TextTerm|lethal characteristic|5}} generally brings about the early death of the foetus.
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In {{TextTerm|eugenics|1|910}}, attention is directed primarily to the role of {{TextTerm|heredity|2|910}}, the transmission of human characteristics from generation to generation, operating through {{TextTerm|genes|3|910|IndexEntry=gene}}, which are transmitted to children by their parents. The development of eugenic theory is dependent on the progress of {{TextTerm|genetics|4|910}} (cf. {{RefNumber|10|3|.4}}*), the science concerned with the transmission and effects of hereditary factors. Eugenics as a social movement refers to policies aimed at improving the quality of human populations.
{{Note|1| {{NoteTerm|Eugenics}}, n. - {{NoteTerm|eugenic}}, adj. - {{NoteTerm|eugenist}}, n.: a specialist in eugenics.}}
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{{Note|1| {{NoteTerm|eugenics}} n. {{NoteTerm|eugenic}} adj. {{NoteTerm|eugenist}} n., a specialist in eugenics. 4. {{NoteTerm|genetics}} n. — {{NoteTerm|genetic}} adj. {{NoteTerm|geneticist}} n., a specialist in genetics.}}
{{Note|2| {{NoteTerm|Heredity}}, n. - {{NoteTerm|hereditary}}, adj. }}
 
  
 
=== 911 ===
 
=== 911 ===
  
The transmission of hereditary characteristics operates through {{TextTerm|genes|1}} which are transmitted to children by their parents. {{TextTerm|Genetics|2}} is the science concerned with the transmission and effects of hereditary factors. The genes are carried by {{TextTerm|chromosomes|3}} which are long filaments of DNA (deoxyribonucleic acid) located in the cell’s nucleus. The position of a gene on a chromosome is called its {{TextTerm|locus|4}}. Genes occupying the same locus affect the same characteristic, although they do so in various ways which correspond to various {{TextTerm|alleles|5}} of the gene in this locus. The new cell formed by the union of two sexual cells or {{TextTerm|gametes|6}} during the process of ''conception'' ({{RefNumber|60|2|1}}) is called a {{TextTerm|zygote|7}}.
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A distinction has sometimes been attempted between {{TextTerm|hereditary characteristics|1|911|IndexEntry=hereditary characteristic|OtherIndexEntry=characteristic hereditary}}, which are inherited, and {{TextTerm|acquired characteristics|2|911|IndexEntry=acquired characteristic|OtherIndexEntry=characteristic, acquired}} which are not so transmitted. This is now viewed as a distinction of degree only, because most {{TextTerm|phenotypic|3|911}} characteristics, i. e., observed characteristics, involve the interaction of both {{TextTerm|genotypic|4|911}}, i. e., inherited factors, and environmental factors. The characteristics determined by a {{TextTerm|dominant|5|911}} gene ({{RefNumber|90|1|.3}}) will appear in all who inherit it; this is not true of a {{TextTerm|recessive|6|911}} gene. The dominance of a gene, however, may be incomplete or its influence may be masked by other geaes in polygenic action. A {{TextTerm|lethal characteristic|7|911|OtherIndexEntry=characteristic, lethal}} generally brings about the early death of the foetus ({{RefNumber|60|2|.7}}). Changes in genes, called {{TextTerm|mutations|8|911|IndexEntry=mutation}}, are chance variations, and may be pathological in effect. {{TextTerm|Panmixia|9|911}} is the formation of unions ({{RefNumber|50|1|.3}}) at random, i. e., without regard to the affiliation of the parties to genetic groups.
{{Note|1| All of the genes carried by an individual are collectively called his or her {{NoteTerm|genetic endowment}}}}
 
{{Note|2| {{NoteTerm|Genetics}}, n. - {{NoteTerm|genetic}}, adj. - {{NoteTerm|geneticist}}, n.: a specialist in genetics.}}
 
  
 
=== 912 ===
 
=== 912 ===
  
The set of two genes of an individual at the same locus is called a {{TextTerm|genotype|1}}; the genotype is said to be {{TextTerm|homozygous|2}} if the alleles are identical at a given locus; it is said to be {{TextTerm|heterozygous|3}} in the opposite case. The {{TextTerm|phenotype|4}} consists in the observable characteristics as determined by the genotype and the environment. If an heterozygous individual (AA’) cannot be distinguished from an homozygous individual (AA), the allele A is said to be {{TextTerm|dominant|5}} over allele A’, and A’ is said to be {{TextTerm|recessive|6}}. Genes are subject to sudden and apparently random changes, called {{TextTerm|mutations|7}}. {{TextTerm|Panmixia|8}} or {{TextTerm|random mating|8}} insures uniform distribution of genes within populations.
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A distinction is often made in eugenic policy between {{TextTerm|positive eugenics|1|912|OtherIndexEntry=eugenics, positive}} aimed at increasing the number of persons believed to have desirable characteristics, and {{TextTerm|negative eugenics|2|912|OtherIndexEntry=eugenics, negative}} aimed at restricting the reproduction of persons expected to transmit undesirable characteristics or {{TextTerm|hereditary defects|3|912|IndexEntry=hereditary defect|OtherIndexEntry=defect, heredity}}. Much attention has been given to the discussion of {{TextTerm|eugenic sterilization|4|912|OtherIndexEntry=sterilization, eugenic}}, i. e., the sterilization of persons likely to transmit undesirable characteristics to their descendants. Objections to this measure have been raised on moral grounds and also because of its relatively low efficiency in reducing the frequency of recessive genes ({{RefNumber|91|1|.6}}). Among the measures proposed, {{TextTerm|pre-marital examination|5|912|OtherIndexEntry=examination, pre-marital}} may be mentioned; this is designed to give couples intending to marry information about the probable quality of their offspring, so that prospective partners to {{TextTerm|dysgenic marriages|6|912|IndexEntry=dysgenic marriage|OtherIndexEntry=marriage, dysgenic}}, i. e., those likely to produce defectives, may be warned.
{{Note|7| {{NoteTerm|Mutation}}, n. - {{NoteTerm|mutant}}, adj. or n.}}
 
 
 
=== 913 ===
 
 
 
A distinction is frequently made in eugenic policy between {{TextTerm|positive eugenics|1}}, aimed at increasing the number of persons believed to have desirable characteristics, and {{TextTerm|negative eugenics|2}} aimed at restricting the reproduction of persons expected to transmit undesirable characteristics or {{TextTerm|hereditary defects|3}}. Much attention has been given to the discussion of {{TextTerm|eugenic sterilization|4}}, i.e., the sterilization of persons likely to transmit undesirable characteristics to their descendants. Objections to this measure have been raised on moral grounds and also because of its relatively low efficiency in reducing the frequency of ''recessive genes'' ({{RefNumber|91|2|6}}). Among the measures proposed, {{TextTerm|pre-marital examination|5}} may be mentioned; this is designed to give couples intending to marry information about the probable quality of their offspring, so that prospective partners to {{TextTerm|dysgenic marriages|6}}, i.e., those likely to produce defectives, may be warned.
 
 
 
=== 914 ===
 
 
 
The probability that an individual of reproductive age will have a given number of offspring who also attain reproductive age may depend on his ''genotype'' ({{RefNumber|91|2|1}}). This differential reproduction is called {{TextTerm|selection|1}}. The {{TextTerm|selective value|2}} or {{TextTerm|fitness value|2}} of a genotype is the relative number of children of individuals with the genotype who survive to reproductive age. The {{TextTerm|mean selective value|3}} or {{TextTerm|fitness|3}} of a population is equal to the average of the selective values for the genotypes of its members. The {{TextTerm|genetic load|4}} of the population is the relative decline in the mean value of fitness resulting from the presence of different genotypes with varying fitness values. Random fluctuation of the frequency with which a specific gene is found in different generations of a population is called the {{TextTerm|genetic drift|5}}. The {{TextTerm|gene structure|6}} of a population refers to the distribution of the frequencies of different ''alleles'' ({{RefNumber|91|1|5}}) on a given ''locus'' ({{RefNumber|91|1|4}}) within the members of the population. The {{TextTerm|genotypic structure|7}} of a population refers to the distribution of different genotypes on the same locus.
 
 
 
=== 915 ===
 
 
 
In the case of an inbred individual, i.e., an individual whose parents have a common ancestor, two genes are said to be {{TextTerm|identical genes|1}} by descent, if both were carried by the same ancestor and are on the same locus. The probability that an individual chosen at random in a population carries two genes identical by descent is the {{TextTerm|coefficient of inbreeding|2}} of the population. The {{TextTerm|coefficient of kinship|3}} of a population is the probability that two individuals chosen at random in that population carry genes identical by descent on the same locus.
 
  
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{{SummaryShort}}
 
{{SummaryShort}}
  
 
{{OtherLanguages|91}}
 
{{OtherLanguages|91}}

Revision as of 20:40, 7 November 2009


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Go to: Introduction to Demopædia | Instructions on use | Downloads
Chapters: Preface | 1. General concepts | 2. The treatment and processing of population statistics | 3. Distribution and classification of the population | 4. Mortality and morbidity | 5. Nuptiality | 6. Fertility | 7. Population growth and replacement | 8. Spatial mobility | 9. Economic and social aspects of demography
Pages: 10 | 11 | 12 | 13 | 14 | 15 | 16 | 20 | 21 | 22 | 23 | 30 | 31 | 32 | 33 | 34 | 35 | 40 | 41 | 42 | 43 | 50 | 51 | 52 | 60 | 61 | 62 | 63 | 70 | 71 | 72 | 73 | 80 | 81 | 90 | 91 | 92 | 93
Index: Global Index | Index of chapter 1 | Index of chapter 2 | Index of chapter 3 | Index of chapter 4 | Index of chapter 5 | Index of chapter 6 | Index of chapter 7 | Index of chapter 8 | Index of chapter 9


910

In eugenics 1, attention is directed primarily to the role of heredity 2, the transmission of human characteristics from generation to generation, operating through genes 3, which are transmitted to children by their parents. The development of eugenic theory is dependent on the progress of genetics 4 (cf. 103-.4*), the science concerned with the transmission and effects of hereditary factors. Eugenics as a social movement refers to policies aimed at improving the quality of human populations.

  • 1. eugenics n. — eugenic adj. — eugenist n., a specialist in eugenics. 4. genetics n. — genetic adj. — geneticist n., a specialist in genetics.

911

A distinction has sometimes been attempted between hereditary characteristics 1, which are inherited, and acquired characteristics 2 which are not so transmitted. This is now viewed as a distinction of degree only, because most phenotypic 3 characteristics, i. e., observed characteristics, involve the interaction of both genotypic 4, i. e., inherited factors, and environmental factors. The characteristics determined by a dominant 5 gene (901-.3) will appear in all who inherit it; this is not true of a recessive 6 gene. The dominance of a gene, however, may be incomplete or its influence may be masked by other geaes in polygenic action. A lethal characteristic 7 generally brings about the early death of the foetus (602-.7). Changes in genes, called mutations 8, are chance variations, and may be pathological in effect. Panmixia 9 is the formation of unions (501-.3) at random, i. e., without regard to the affiliation of the parties to genetic groups.

912

A distinction is often made in eugenic policy between positive eugenics 1 aimed at increasing the number of persons believed to have desirable characteristics, and negative eugenics 2 aimed at restricting the reproduction of persons expected to transmit undesirable characteristics or hereditary defects 3. Much attention has been given to the discussion of eugenic sterilization 4, i. e., the sterilization of persons likely to transmit undesirable characteristics to their descendants. Objections to this measure have been raised on moral grounds and also because of its relatively low efficiency in reducing the frequency of recessive genes (911-.6). Among the measures proposed, pre-marital examination 5 may be mentioned; this is designed to give couples intending to marry information about the probable quality of their offspring, so that prospective partners to dysgenic marriages 6, i. e., those likely to produce defectives, may be warned.

* * *

Go to: Introduction to Demopædia | Instructions on use | Downloads
Chapters: Preface | 1. General concepts | 2. The treatment and processing of population statistics | 3. Distribution and classification of the population | 4. Mortality and morbidity | 5. Nuptiality | 6. Fertility | 7. Population growth and replacement | 8. Spatial mobility | 9. Economic and social aspects of demography
Pages: 10 | 11 | 12 | 13 | 14 | 15 | 16 | 20 | 21 | 22 | 23 | 30 | 31 | 32 | 33 | 34 | 35 | 40 | 41 | 42 | 43 | 50 | 51 | 52 | 60 | 61 | 62 | 63 | 70 | 71 | 72 | 73 | 80 | 81 | 90 | 91 | 92 | 93
Index: Global Index | Index of chapter 1 | Index of chapter 2 | Index of chapter 3 | Index of chapter 4 | Index of chapter 5 | Index of chapter 6 | Index of chapter 7 | Index of chapter 8 | Index of chapter 9