Albert Wegner proposed the theory of continental drift, which suggested that the continents were once joined together and have since drifted apart. Evidence for this includes how the coastlines of South America and Africa fit together, and that South America, Africa, and Asia were once a single landmass. Additionally, Australia was once attached to Antarctica, and North America was once connected to Europe, while India broke off from Africa and collided with Asia. The strongest evidence is how the continents appear to fit together like puzzle pieces on a world map.