The 19th century philosopher Herbert Spencer promoted the idea of social Darwinism. Social Darwinism takes Darwin's theories about survival of the fittest and natural selection and applies it to social, political, and economic issues.
On paper, social Darwinism shouldn't include anything biological. The most perfect interpretation of social Darwinism doesn't take into account biological differences; however, its historical applications have proved otherwise.
I'll use the most horrific example I can think of to illustrate my point. During World War II, Nazi Germany used the concept of social Darwinism to help justify mass genocide. Hitler and the Nazi party saw the Jews (among many others) as an inferior race. Hitler used social Darwinism to help justify what he called cleansing the gene pool. Other dictators have used social Darwinism too in order to justify killing people with biological differences.