How did thomas malthus influence Charles Darwin's theory of evolution?

Answer 1

He did not have one himself, he simply stated that all populations eventually crash because population growth tends to follow exponential functions and resource growth tends to follow polynomial functions. Eventually the population will exceed its resources and mass starvation and population crash will occur.

Darwin used this as one of his assumptions in developing natural selection.

Answer 2

By writing a book that proposed human suffering and death from starvation because the population of humans went up exponentially but the supply of food goes up arithmetically. Darwin took this idea as an insight. He figured that populations of organisms produced far more progeny then the environment could supply with resources. So a selective process would be put in place. The fitter organisms would survive and reproduce while this much less fit would lose the struggle for existence.

Answer 3

Robert Malthus (he never called himself Thomas and only used his middle name) wrote that population growth could never be more than food supply could sustain, and that if population growth was bigger at any point, famine and disease would reduce it to a level that the food supply could sustain. Basically he wrote that this would lead to a 'survival of the fittest'.

Charles Darwin held that evolution was a process of adaption to changing circumstances in order to survive; and that only those species would survive that were most successful at adapting. So although he described a different process, he said - just as Robert Malthus did - that it was 'a survival of the fittest'.