Mendelian Genetics Quotes

Dartmouth College employs computer learning techniques in a very broad array of courses. For example, a student can gain a deep insight into the statistics of Mendelian genetics in an hour with the computer rather than spend a year crossing fruit flies in the laboratory.

hemophilia is an inherited blood-clotting deficiency, transmitted by women according to the sex-linked recessive Mendelian pattern. Thus, while women carry the defective genes, they almost never suffer from the disease. With rare exceptions, it strikes only males. Yet it does not necessarily strike all the males in a family. Genetically as well as clinically, hemophilia is capricious.

I may finally call attention to the probability that the association of paternal and maternal chromosomes in pairs and their subsequent separation during the reducing division as indicated above may constitute the physical basis of the Mendelian law of heredity.

In Darwin's time no serious attempt had been made to examine the manifestations of variability. A vast assemblage of miscellaneous facts could formerly be adduced as seemingly comparable illustrations of the phenomenon "Variation." Time has shown this mass of evidence to be capable of analysis. When first promulgated it produced the impression that variability was a phenomenon generally distributed amongst living things in such a way that the specific divisions must be arbitrary. When this variability is sorted out, and is seen to be in part a result of hybridisation, in part a consequence of the persistence of hybrids by parthenogenetic reproduction, a polymorphism due to the continued presence of individuals representing various combinations of Mendelian allelomorphs, partly also the transient effect of alteration in external circumstances, we see how cautious we must be in drawing inferences as to the indefiniteness of specific limits from a bare knowledge that intermediates exist.

Using a Mendelian randomization approach, a genetic variant involved in metabolizing alcohol was shown to be associated with heart attack risk, and only in those consuming alcohol.10

Social Darwinism had continued to flourish in German. Together with Mendelian genetics, it was widely thought to provide a scientific basis for the eugenic ‘Racial Hygiene’ movement.

Natural scientists denied that the races observed in social life were natural biological groupings, and social scientists proposed that the human units of moral and political significance were those based on shared culture rather than shared biology. It helped that Darwin’s point had been strengthened by the development of Mendelian population genetics, which showed that the differences found between the geographic populations of the human species were statistical differences in gene frequencies rather than differences in some putative racial essence.

This opened up the possibility that physical and mental traits that had allowed man to adapt to a savage environment, whether in the remote past (of the Neanderthal hunter) or in the present (of the Watusi warrior), could inadvertently be passed on to his modern civilized descendants. The Darwinian zoologist Henry Maudsley explained this with the chilling observation that there is “truly a brute brain within the man’s,” making it possible to “trace savagery in civilization, as we can trace animalism in savagery.”10 Nineteenth-century biologists called this brutish survival “atavism,” after the Latin word atavus , or remote ancestor. Atavism taught that every organism had certain “lost” characteristics that were ready to reappear under certain conditions and would then be passed on to offspring. Atavistic theory had existed before Darwin, but his theory of evolution only seemed to confirm it, as did Mendelian genetics later on.

Daedalus Winter 2002. Vol. 131, pg. 89 The Biology of Race and the Concept of Equality. Ernst Mayr There is a widespread feeling that the word "race" indicates something undesirable and that it should be left out of all discussions. This leads to such statements as "there are no human races." Those who subscribe to this opinion are obviously ignorant of modern biology. Races are not something specifically human; races occur in a large percentage of species of animals. You can read in every textbook on evolution that geographic races of animals, when isolated from other races of their species, may in due time become new species. The terms "subspecies" and "geographic race" are used interchangeably in this taxonomic literature. … In a recent textbook of taxonomy, I defined a "geographic race" or subspecies as "an aggregate of phenotypically similar populations of a species inhabiting a geographic subdivision of the range of that species and differing taxonomically from other populations of that species." A subspecies is a geographic race that is sufficiently different taxonomically to be worthy of a separate name. What is characteristic of a geographic race is, first, that it is restricted to a geographic subdivision of the range of a species, and second, that in spite of certain diagnostic differences, it is part of a larger species. No matter what the cause of the racial difference might be, the fact that species of organisms may have geographic races has been demonstrated so frequently that it can no longer be denied. And the geographic races of the human races established before the voyages of European discovery and subsequent rise of a global economy - agree in most characteristics with the geographic races of animals. Recognizing races is only recognizing a biological fact. from Wikipedia: Ernst Mayr Ernst Walter Mayr was one of the 20th century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, philosopher of biology, and historian of science. His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept.