Kalmar "Lamarckism" tana nufin ka'idar nazarin halittu da ɗan ƙasar Faransa Jean-Baptiste Lamarck ya gabatar a ƙarshen karni na 18 da farkon 19th. Lamarckism kuma ana kiransa Lamarckian inheritance, Lamarckian evolution, ko kuma kawai Lamarckianism.A cewar ka'idar Lamarck, kwayoyin halitta na iya ba da halayen da suka samu a lokacin rayuwarsu ga zuriyarsu. Misali, idan rakumi ya mike wuyansa har ya kai ga ganyaye masu tsayi, ka’idar ta nuna cewa wuyansa zai yi tsayi a kan lokaci, kuma wannan dabi’ar wuyan za ta koma ga ‘ya’yansa. Lamarck ya kuma ba da shawarar cewa yanayin yana taka muhimmiyar rawa wajen tsara halayen halitta kuma ana iya canza waɗannan halayen ta hanyar amfani da su da kuma yin amfani da su. Ka'idar zaɓin yanayi ta Charles Darwin ta maye gurbin daga baya, wacce ta bayyana tsarin juyin halitta ta hanyar bambance-bambancen rayuwa da haifuwar mutane masu fa'ida. A yau, ana ɗaukar Lamarckism gabaɗaya a matsayin tsohuwar ka'idar.