https://www.khanacademy.org/science/ap-biology/natural-selection/extinction/v/biodiversity-and-extinction-then-and-now 2023-06-22T09:47:49.118446933Z Biodiversity and extinction, then and now Extinctions may occur because of direct, natural phenomena or the inability of species to adapt quickly enough to changing environmental conditions or ecological interactions. Five major mass extinctions have happened on Earth. A sixth mass extinction is currently underway and is driven by human activity, which underscores the need to learn from the past to safeguard our future. video https://cdn.kastatic.org/googleusercontent/gXJgcpcD6uIuj2YNFQZl-XWJW0N46gwbOulhkBenXd75Wk9snjQuLyT-qz1NRqYgjyVRx_AUMWUKgBhGqsO4hHxAMQ Biodiversity and extinction, then and now Extinctions may occur because of direct, natural phenomena or the inability of species to adapt quickly enough to changing environmental conditions or ecological interactions. Five major mass extinctions have happened on Earth. A sixth mass extinction is currently underway and is driven by human activity, which underscores the need to learn from the past to safeguard our future. https://cdn.kastatic.org/ka-youtube-converted/v8PPsI0LqOY.mp4/v8PPsI0LqOY.mp4 742 Extinction Events https://www.khanacademy.org/science/ap-biology/natural-selection/extinction/a/a-brief-history-of-mass-extinctions 2025-07-21T19:27:31.703149266Z A brief history of mass extinctions Learn about mass extinction events on Earth. article https://www.khanacademy.org/science/ap-biology/natural-selection/extinction/e/extinction 2025-11-24T23:10:47.038405073Z Extinction Test your knowledge of extinction! exercise