93. Evidence for Evolution – Evolution Observed Selection against small guppies results in an increase in average size
94. Evolutionary Time Scales Macroevolution: Long time scale events that create and destroy species.
95. Microevolution: Short time scale events (generation-to-generation) that change the genotypes and phenotypes of populations Evolutionary Time Scales
From 1830 to 1833 his multi-volume Principles of Geology was published. The work's subtitle was "An attempt to explain the former changes of the Earth's surface by reference to causes now in operation", and this explains Lyell's impact on science. He drew his explanations from field studies conducted directly before he went to work on the founding geology text. [3] He was, along with the earlier John Playfair , the major advocate of James Hutton 's idea of uniformitarianism , that the earth was shaped entirely by slow-moving forces still in operation today, acting over a very long period of time. This was in contrast to catastrophism , a geologic idea of abrupt changes, which had been adapted in England to support belief in Noah's flood Cuvier was a major figure in natural sciences research in the early 19th century, and was instrumental in establishing the fields of comparative anatomy and paleontology through his work in comparing living animals with fossils. He is well known for establishing extinction as a fact, being the most influential proponent of catastrophism in geology in the early 19th century, and opposing the evolutionary theories of Lamarck Between 1798 and 1826 Malthus published six editions of his famous treatise, An Essay on the Principle of Population , updating each edition to incorporate new material, to address criticism, and to convey changes in his own perspectives on the subject. He wrote the original text in reaction to the optimism of his father and his father's associates (notably Rousseau) regarding the future improvement of society. Malthus also constructed his case as a specific response to writings of William Godwin (1756–1836) and of the Marquis de Condorcet (1743–1794). Malthus regarded ideals of future improvement in the lot of humanity with skepticism, considering that throughout history a segment of every human population seemed relegated to poverty. He explained this phenomenon by arguing that population growth generally expanded in times and in regions of plenty until the size of the population relative to the primary resources caused distress
Hutton also advocated uniformitarianism for living creatures too – evolution , in a sense – and even suggested natural selection as a possible mechanism affecting them: "...if an organised body is not in the situation and circumstances best adapted to its sustenance and propagation, then, in conceiving an indefinite variety among the individuals of that species, we must be assured, that, on the one hand, those which depart most from the best adapted constitution, will be the most liable to perish, while, on the other hand, those organised bodies, which most approach to the best constitution for the present circumstances, will be best adapted to continue, in preserving themselves and multiplying the individuals of their race." – Investigation of the Principles of Knowledge , volume 2. [38] Hutton gave the example that where dogs survived through "swiftness of foot and quickness of sight... the most defective in respect of those necessary qualities, would be the most subject to perish, and that those who employed them in greatest perfection... would be those who would remain, to preserve themselves, and to continue the race". Equally, if an acute sense of smell were "more necessary to the sustenance of the animal... the same principle [would] change the qualities of the animal, and.. produce a race of well scented hounds, instead of those who catch their prey by swiftness". The same "principle of variation" would influence "every species of plant, whether growing in a forest or a meadow". He came to his ideas as the result of experiments in plant and animal breeding , Lamarck stressed two main themes in his biological work. The first was that the environment gives rise to changes in animals. He cited examples of blindness in moles, the presence of teeth in mammals and the absence of teeth in birds as evidence of this principle. The second principle was that life was structured in an orderly manner and that many different parts of all bodies make it possible for the organic movements of animals. [14] Although he was not the first thinker to advocate organic evolution, he was the first to develop a truly coherent evolutionary theory Alfred Russel Wallace , OM , FRS (8 January 1823 – 7 November 1913) was a British naturalist , explorer, geographer, anthropologist and biologist. He is best known for independently proposing a theory of evolution due to natural selection that prompted Charles Darwin to publish his own theory. Wallace did extensive fieldwork, first in the Amazon River basin and then in the Malay Archipelago , where he identified the Wallace Line that divides the Indonesian archipelago into two distinct parts, one in which animals closely related to those of Australia are common, and one in which the species are largely of Asian origin. He was considered the 19th century's leading expert on the geographical distribution of animal species and is sometimes called the "father of biogeography ". [1] Wallace was one of the leading evolutionary thinkers of the 19th century and made a number of other contributions to the development of evolutionary theory besides being co-discoverer of natural selection. These included the concept of warning colouration in animals, and the Wallace effect , a hypothesis on how natural selection could contribute to speciation by encouraging the development of barriers against hybridization .