natural selection

noun 0.729

survival

noun 0.679

survivability

noun 0.592

survivalism

noun 0.586

survivalist

noun 0.577

survivor

noun 0.564

law of the jungle

noun 0.549

evolution

noun 0.545

survivorship

noun 0.544

self-preservation

noun 0.544

evolutionary theory

noun 0.539

adaptationism

noun 0.537

fight to the death

noun 0.526

keep fit

noun 0.520

master race

noun 0.520

survival kit

noun 0.513

evolutionism

noun 0.511

eugenics

noun 0.505