Herbert Spencer :
April 27, 1820 - December 8, 1902 (Lived 83 years)
The first clear articulation of evolutionary perspective was in an essay he wrote which was published in the Westminster Review in 1857. Spencer is known for the concept "survival of the fittest", which was put into the book, Principles of Biology (1864). The concept of survival of the fittest is something that is in the theory today. Spencer was very important in the Victoria era and was popular among many people. During Herbert's lifetime he had sold over a million copies of his work. He had built upon Darwin's thoughts on the theory of evolution and used Darwin's work to help him get more in depth of what might happen and how organisms were only getting better and better.
Ronald Fisher :
February 17, 1890 - July 29, 1962 (Lived 72 years)
Sewall Green Wright:
December 21, 1889 - March 3, 1988 (Lived 98 years)
Mr. Wright was born in the United States of America in Massachusetts. He was a geneticist know for his work on evolutionary theory. Sewall Wright, Ronald Fisher and J. B. S. Haldane worked and used each others work to create the theoretical population genetics, which was the a very important step for the development of the modern evolutionary synthesis. Wright discovered inbreeding coefficient and methods of computing in pedigrees. As he extended his work to populations inbreeding, it led to results of genetic drift, distribution of gene frequencies among populations, that had a result of interaction of natural selection, mutation, and migration. Sewall's theory on evolution was that in order to evolve to higher peak, the species would first have to pass through a valley of maladaptive intermediate stages that would happen through genetic drift if the population was small enough. This was Sewall Wright's shifting balance theory of evolution. Wright did some work on the genetics of guinea pigs with help develop the mammalian genetics. In Wrights life time he was awarded the Daniel Giraud Elliot Medal in1945, the National Metal of Science in 1966, Darwin Medal in 1980 and a few more awards. Mr. Sewall Green Wright was the connection of genetics and evolution together.Theodosius Dobzhansky
January 24, 1900 - December 18, 1975 (Lived 75 years)
Theodosius Grygorovych Dobzhansky was born in Russia and when he was 27 years old he had emigrated to the United States on a scholarship so he could study in the States. Before moving to the United States Theodosius had published 35 scientific works. In the states, he began with working on genetic experiments using fruit flies. He published a major work of the modern evolutionary synthesis in 1937 and defined evolution as "a change in the frequency of an allele within a gene pool". In 1941, he was awarded with the Daniel Giraud Elliot Medal and the Franklin Medal in 1973.