| spontaneous evolution | The unaided delivery of the foetus from a transverse lie. (05 Mar 2000) |
|---|---|
| Darwinian evolution | The proposition that the phylogeny of all species is wholly ascribable to the combined effects of random variation (mutation) in genotypes of the members of a stock as a result of the operation of undirected accidents with consequences to their phenotypes and the operation of preferential (but by no means certain) survival of those resulting phenotypes most suited to survive in the contemporary environment. The proposed system survives largely because of genetic factors that avidly conserve the ontogeny of the stock. (05 Mar 2000) |
| Denman's spontaneous evolution | A mechanism of spontaneous molding of the foetus and impaction of the shoulder with prolapse of the arm noted in some cases of transverse lie; vaginal delivery is achieved with the breech appearing at the vulva immediately after the prolapsed shoulder. (05 Mar 2000) |
| divergent evolution | The process by which a species or gene product gives rise to two or more different products. (05 Mar 2000) |
| Douglas' spontaneous evolution | A mechanism whereby molding of the foetus and impaction of the shoulder and prolapsed arm occurs in transverse lie, allowing vaginal delivery with the lateral aspect of the thorax following the prolapsed shoulder. (05 Mar 2000) |
| quantum evolution | An extremely rapid evolutionarychange in a single genetic lineage, thought to result from a sudden and radical change in the species'environment. (09 Oct 1997) |
| organic evolution | Biologic evolution was contrasted with cultural evolution in 1968 by A.G. Motulsky who pointed out that biologic evolution is mediated by genes, shows a slow rate of change, employs random variation (mutations) and selection as agents of change, new variants are often harmful, these new variants are transmitted from parents to offspring, the mode of transmission is simple, complexity is achieved by the rare formation of new genes by chromosome duplication, biologic evolution occurs with all forms of life, and the biology of humans requires cultural evolution. See Cultural evolution. (12 Dec 1998) |
| emergent evolution | Appearance of a property in a complex system e.g., organism that could have been predicted only with difficulty, or perhaps not at all, from a knowledge and understanding of the individual genotype changes taken separately. (05 Mar 2000) |
| evolution | 1. An unrolling. 2. A process of development in which an organ or organism becomes more and more complex by the differentiation of its parts, a continuous and progressive change according to certain laws and by means of resident forces. Origin: L. Evolutio (18 Nov 1997) |
| evolution, biologic | A.G. Motulsky in 1968 contrasted biologic evolution with cultural evolution, pointing out that biologic evolution is mediated by genes, shows a slow rate of change, employs random variation (mutations) and selection as agents of change, new variants are often harmful, these new variants are transmitted from parents to offspring, the mode of transmission is simple, complexity is achieved by the rare formation of new genes by chromosome duplication, biologic evolution occurs with all forms of life, and the biology of humans requires cultural evolution. See Evolution, cultural. (12 Dec 1998) |
| evolution, chemical | Chemical and physical transformation of the biogenic elements from their nucleosynthesis in stars to their incorporation and subsequent modification in planetary bodies and terrestrial biochemistry. It includes the mechanism of incorporation of biogenic elements into complex molecules and molecular systems, leading up to the origin of life. (12 Dec 1998) |
| evolution, cultural | By contrast with biologic evolution, A.G. Motulsky in 1968 pointed out that social evolution is mediated by ideas, shows a rapid (exponential) rate of change, is usually purposeful, often beneficial, is widely disseminated by diverse means, is frequently transmitted in complex ways, further complexity comes from the frequent formation of new ideas and new technologies. Cultural evolution is unique to humans among all forms of life. Human culture required biologic evolution to achieve the human brain. See Evolution, social. (12 Dec 1998) |
| evolution, planetary | Creation and development of bodies within solar systems, includes study of early planetary geology. (12 Dec 1998) |
| relative molecular mass | The sum of the atomic weight's of all the atoms constituting a molecule; the mass of a molecule relative to the mass of a standard atom, now 12C (taken as 12.000). Relative molecular mass (Mr) is the mass relative to the dalton and has no units. See: atomic weight. Synonym: molecular mass, molecular weight ratio, relative molecular mass. (05 Mar 2000) |
| gram-molecular weight | Molecular weight expressed in grams. Compare: mole. (05 Mar 2000) |