In 1881 he published a collection of polemics titled "Al-Radd 'ala al-Dahriyyi" (Refutation of the Materialists), agitating for pan-Islamic unity against Western imperialism. It included one of the earliest pieces of Islamic thought arguing against Darwin's then-recent "On the Origin of Species"; however, his arguments allegedly incorrectly caricatured evolution, provoking criticism that he had not read Darwin's writings. In his later work "Khatirat Jamal ad-Din al-Afghani" ("The memoir of Al-Afghani"), he accepted the validity of evolution, asserting that the Islamic world had already known and used it. Although he accepted abiogenesis and the evolution of animals, he rejected the theory that the human species is the product of evolution, arguing that humans have souls.