147. Evolution

See also 44. BIOLOGY ; 74. CHANGE ; 191. GROWTH ; 219. IMPROVEMENT .

Darwinism

the theory of evolution by natural selection of those species best adapted to survive the struggle for existence. — Darwinian , n., ad) .

evolutionism

a principle or theory of evolution. — evolutionist , n., adj .

Lamarckism

the theory of organic evolution advanced by the French naturalist Lamarck that characteristics acquired by habit, diseases, or adaptations to change in environment may be inherited. — Lamarckian , n., adj .

Neo-Darwinism

the theory that maintains natural selection to be the major factor in plant and animal evolution and denies the possibility of inheriting acquired characteristics. — Neo-Darwinist , n ., adj . — Neo-Darwinian , n ., adj .

Neo-Lamarckism

a modern theory based on Lamarckism that states that acquired characteristics are inherited. — Neo-Lamarckian , n., adj .

orthogenesis

progressive evolution, leading to the development of a new form, as can be seen through successive generations. See also 376. SOCIETY . — orthogenetic , adj .

pangenesis

the theory advanced by Darwin, now rejected, that each part of the body is represented in each cell by gemmules, which are the basic units of hereditary transmission. — pangenetic , adj .

phylogeny

the history of the development of a plant, animal, or racial type. — phylogenist , n . — phylogenetic , adj .

primordialism

a devotion to the conditions which existed at the beginning of creation.

transformism

the ability of one species to change into another. — transformist , n .

tychism

1 . the theory that chance is involved in evolution and that variation within a species is accidental.

2 . the belief that chance rather than mere determinism operates in the cosmos. Cf. uniformitarianism .

uniformitarianism

1 . Philosophy . a doctrine that the universe is governed only by rigid, unexceptionable law.

2 . Geology . the concept that current geological processes explain all past geological occurrences. — uniformitarian , n., adj .