How did Mark Twain’s late writing differ from the humor in his earlier work?

Mark Twain’s late writing did not necessarily represent a change in his moral stance, as he had always been a critic of greed, corruption, and cruelty. Instead, the primary difference in his later work—often associated with his so-called "bad mood" period—was the frequent absence of the "palliative humor" that had seasoned his earlier social critiques.1

While Twain continued to express powerful moral indignation in his later polemical essays and fiction, these works often lacked the lighthearted, humorous touch that characterized his earlier career as the "Wild Humorist of the Pacific Slope". Despite this shift, his late period was not devoid of humor; he maintained a capacity for ironic detachment and antically comic writing in works such as Extracts from Captain Stormfield’s Visit to Heaven and Eve’s Diary. Ultimately, his late writings reflected a more candid, often sardonic exploration of philosophical determinism and the "damn’d human race," written with a vitality that prevented them from being merely the expressions of an angry man.12