How did social Darwinism fuel expansionism?

Social Darwinism is the combination of Charles Darwin's theory of natural selection and survival of the fittest of Herbert Spencer its purpose is to justify imperialism, racism, and laissez-faire. Herbert Spencer is one of the influenced people in America. Americans used Darwinism to make an expansion, western imperialism was above all a quest markets and raw materials. Business leaders, manufacturers, and the bitter rivalries of European powers. It is resulting in a widespread process of imperial expansion into Africa and Asia.