Why did changing sea levels help Homo sapiens migrate to Australia and Pacific islands?

Lowered sea levels during the Pleistocene Epoch were instrumental in the migration of Homo sapiens to Australia and New Guinea because they created land bridges and exposed vast areas of the continental shelf that are currently submerged.12

During periods of maximum glaciation, such as 18,000 years ago, global sea levels dropped by more than 100 metres (330 feet). This recession connected Australia, Tasmania, and New Guinea into a single, massive paleocontinent known as Sahul. By reducing the expanse of open water, these lower sea levels facilitated human movement from Southeast Asia into the Sahul landmass.2314

While these land bridges significantly shortened travel distances, the migration still required early seafaring capabilities to cross deep-water gaps between islands in Wallacea, such as the passages between Bali and Lombok or Timor and Sahul. Once sea levels rose following the melting of continental ice sheets, these land connections were severed, isolating populations—such as those in Tasmania—and shaping the distinct geography of the region today.412