Socialism is a social darwinism.

(left image; Ikki Kita　Social philosopher １８８３－１９３７）
Japanese often misunderstand social Darwinism. That is to say,market economy is under the law of the jungle,or Meritocracy is natural selection. As if free economy system were social Darwinism.
Before WWⅡ, There was a famous National Socialist "Ikki Kita(北一輝）. He would imagine free competitive marriage system. He thought this would make social evolution. He was ultra right. He was known as one who was seriously influenced by Darwin in Japan.
Generally speaking, the socialists are influenced by Darwin on concern with not economy but family problem.
Of course, Darwinism itself is ,Whether his theory is right or not, biological science, not family system studies.