in the last few chapters, how has sinclair conveyed the idea of social darwinism

Social Darwinism is a theory from the social sciences that argues that one can understand society in evolutionary terms. Just as Charles Darwin proposed that, in nature, the strongest members of a species survive and then carry those survival traits to new generations, Social Darwinism argues that the strongest and most fit members of society survive while the weaker members naturally die from a lack of resources. Social Darwinism has been a controversial proposal because it ignores traits of human benevolence.

Sinclair proposes that the reader see Packingtown in terms of Social Darwinism. The title of the book, The Jungle, alludes to the idea that in an environment such as Packingtown, certain members of society will survive while other weaker members will not. Sinclair also uses metaphors of nature, such as how winter's cold kills those trees which cannot find light, to describe the process through which economic and societal forces push the weaker members of Packingtown into sickness and death. Throughout the novel, Sinclair describes this process pejoratively.