why is the appendix vestigial

The human appendix was traditionally considered a vestigial organ because it is a small, worm-shaped pouch attached to the large intestine and its removal does not cause any apparent harm. It was believed to be a remnant from ancestors who had a larger cecum used for digesting cellulose-rich plant material, which humans no longer do with the same reliance. This reduced use over evolutionary time led to the appendix becoming smaller and regarded as functionally redundant. However, recent research challenges this view. The appendix may have a role in immune function and gut health. It contains lymphoid tissue that supports gut immunity, and it may serve as a safe-house or reservoir for beneficial gut bacteria, helping to repopulate the gut flora after infections or illnesses. This suggests the appendix retains some physiological function rather than being truly useless or vestigial. In summary, the appendix was labeled vestigial due to its reduced size and seemingly minor role compared to ancestral species, but modern evidence indicates it likely has important immune and microbiome-related functions.