The Sediq and Truku Indigenous peoples on the mountainous island of Formosa today called Taiwan say that their ancestors emerged in the beginning of time from Pusu Qhuni, a tree-covered boulder in the highlands. Living in the mountain forests, they observed the sacred law of Gaya, seeking equilibrium with other humans, the spirits, animals, and plants. They developed a politics in which each community preserved its autonomy and sharing was valued more highly than personal accumulation of goods or power. These lifeworlds were shattered by colonialism, capitalist development, and cultural imperialism in the twentieth century. Based on two decades of ethnographic field research, Truly Human portrays these peoples lifeworlds, teachings, political struggles for recognition, and relations with non-human animals. Taking seriously their ontological claims that Gaya offers moral guidance to all humans, Scott E. Simon reflects on what this particular form of Indigenous resurgence reveals about human rights, sovereignty, and the good of all kind. Truly Human contributes to a decolonizing anthropology at a time when all humans need Indigenous land-based teachings more than ever.