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Evolution is the change in the heritable characteristics of biological populations over successive generations. [1] [2] It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. [3]
Alternatives to Darwinian evolution have been proposed by scholars investigating biology to explain signs of evolution and the relatedness of different groups of living things. The alternatives in question do not deny that evolutionary changes over time are the origin of the diversity of life, nor that the organisms alive today share a common ...
The key to life history theory is that there are limited resources available, and focusing on only a few life history characteristics is necessary. Examples of some major life history characteristics include: Age at first reproductive event; Reproductive lifespan and ageing; Number and size of offspring
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization , from kingdoms to species , and individual organisms and molecules , such as DNA and proteins .
The theory held that "lower" animals are generated by decaying organic substances. Aristotle stated that, for example, aphids arise from dew on plants, flies from putrid matter, mice from dirty hay, and crocodiles from rotting sunken logs. [16] The basic idea was that life was continuously created as a result of chance events. [17]
Darwinism subsequently referred to the specific concepts of natural selection, the Weismann barrier, or the central dogma of molecular biology. [2] Though the term usually refers strictly to biological evolution, creationists have appropriated it to refer to the origin of life or to cosmic evolution, that are distinct to biological evolution, [3] and therefore consider it to be the belief and ...
Henry Fairfield Osborn's 1918 book Origin and Evolution of Life claimed the evolution of Titanothere horns was an example of an orthogenetic trend in evolution. Main article: Orthogenesis Orthogenesis was the theory that life has an innate tendency to change, in a unilinear fashion in a particular direction.