Charles Darwin's life fundamentally challenged existing beliefs about evolution by introducing the concept of natural selection. His observations from the Galápagos Islands led him to propose that species evolve over time through gradual changes, contradicting the widely accepted idea of fixed species as outlined in religious texts. Darwin's work, particularly "On the Origin of Species," sparked intense debate and laid the groundwork for modern evolutionary biology. His theory prompted a reevaluation of humanity's place in the natural world, marking a significant shift in scientific thought and challenging the intellectual dominance of religious doctrines in explaining life's diversity.