Here are four scientists which were involved in the theory of evolution.
Herbert Spencer :
April 27, 1820 - December 8, 1902 (Lived 83 years)
English man who was a philosopher, biologist, sociologist, and classical liberal political theorist. Herbert Spencer had writings of the theory of evolution before Darwin did. He had contributed a wide range of information to help support the ideas of evolution since his background of education.
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)
Sir Ronald Aylmer Fisher was an English man who lived in England as well as Australia. He was a statistician, geneticist, eugenicist, and evolutionary biologist. Ronald Fisher contributed to creating ANOVA (analysis of variance), which he is well known for. He attended Cambridge and was going to enter the army but failed due to poor eyesight. He married and during the war he had begun to write book reviews which increased his interest in genetic and statistical work around 1917. In 1916 he wrote an paper, "The Correlation Between Relatives on the Supposition of Mendelian Inheritance", which laid the foundation of biometrical genetics. In 1919, he started working at Rothamsted Experimental Station, where he later in 1925 he was working on publishing his first book, Statistical Methods for Research Workers. After a long field in ecological genetics, his work was important to the thought of natural selection and he was the original author of heterozygote advantage. Fisher promoted the method of maximum likelihood estimation as well as a few others. Mr. Fisher worked on the theory of population genetics and made himself one of the top people in that field. Another book he wrote, "The Genetical Theory of Natural Selection" that was published in 1930, stated ideas on sexual selection, mimicry, and evolution of dominance. He showed that the probability of a mutation increasing fitness of an organism decreases the proportionately with the magnitude of the mutation. He is who set the foundations of what is now population genetics.
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.
The Harlem Renaissance was a cultural movement which included the new African-American cultural expressions all over the northeast and midwest. Harlem was the largest center of the Great Migration of Africa Americans from the south to the north. African American writers, poets, artists, actors and musicians became a popular during this time.
In the 1920s, one of the largest social changes was the change in women's roles. Women went to college to work in workforce fields like social work, nursing, and teaching. Women not only changed with more education and work but also visual changes. Young women cut their hair short, wore more reviling clothing, wore makeup, went out and partied, and drank illegally. 
There were many new changes during the 1920s and some large cultural changes also. Dancing was a popular thing as well as jazz music. Building architecture was in the style of art deco. Going to the movies was also another popular thing that people in the 1920s would go do. Last but not least, Americans became largely involved with sports; like football and baseball. 
