Historical Influences on Darwin

There were many influences upon Darwin's lifetime that encouraged him to publish his book, i feel that the person who had most influence on him was Thomas Malthus. Malthus was a political economist who was concerned with life at the time in England while Darwin was interested in how evolution happens. Although he unlike Darwin was not interested in species change, he was interested in the limits of human population growth. His essay "The Principle of Evolution" brought to Darwin's attention that in nature, populations increase in numbers when there is a lot of resources and little or no predators. Also, that population to increase in sizes held by availability of resources, as long as food and supplies remain stable. As an example, when Malthus was doing his studies on humans; producing more offspring that can survive establishes competitive environment among siblings, then produces variation among them which then creates some siblings to have greater chances of survival. I would argue that he had the most influence to Darwin's theory of Natural Selection because with the help of Malthus's ideas Darwin saw how selection in nature could be explained. Malthus observation in nature plants and animals produce far more offspring than can survive "struck" Darwin and made him see how selection in nature could be explained. Darwin saw that in struggle for existence those individuals who have favorable variations would survive and reproduce while unfavorable ones are destroyed. Darwin extended Malthus's discovery to all organisms, that population size is limited by resource availability, constant competition for food and water, making competition the key to Natural Selection.After reading from Malthus, Darwin himself stated that "Here then, i had at last got a theory by which to work". 

The points that most directly are affected by Malthus's work would start with all organisms have the potential of reproducing exponentially, this was influenced by Malthus because he believed that people and organisms could produce as much as they desired to, offspring would always be the result of mating which was his main worry overpopulation. Resources are limited is another as well as organisms with better access to resources will be more successful in their reproductive efforts because as long as the organisms are willing to do what is necessary for the resources, they will be successful in reproductive efforts, as for resources, they are limited and our planet can only hold certain amount of resources which then makes competition among the populations. Who gets access to these limited resources? is another one as well that Malthus could have influenced, by having more offspring establishes competitive environment, which then creates greater chances for surviving. 

Darwin could not have developed his theory of natural selection without the influence of Malthus and his ideas. Because even Darwin himself, saw that the ideas Malthus had enlightened him to discover what natural selection could start off as. Darwin went off of Malthus's ideas and further explored and researched how his essay and ideas could be applied to all organisms which helped Darwin realize just how natural selection could be explained. 

The church affected Darwin's publication of his book On the Origin of Species because questioning the church was a risky move in that time frame. People believed the church over anything else at the time and the theories that Darwin had went against everything taught in the church to people. The church was the strongest sense of power and once people had read Darwin's book, they would start to question the church themselves.

source : http://www.ucmp.berkeley.edu/history/malthus.html