Final answer:
To reach Flores Island, hominins like Homo erectus or their descendants had to cross water barriers perhaps using simple rafts, since Flores was never connected by land to the main Asian landmass due to deep ocean trenches like the Wallace and Weber lines.
Step-by-step explanation:
To migrate to the island where Homo floresiensis is found, hominins would have had to cross a significant geographical barrier, which during the ice ages when sea levels were lower, still required some form of water crossing. Flores Island, part of Indonesia, was never connected to the main Asian landmass by a land bridge due to the deep ocean trenches in the region. The Wallace Line runs between Bali and Lombok, and another deeper trench, Weber's Line, is further to the east. When Homo erectus settled on Java, it is believed that they might have traveled via a land route during lower sea levels, but for Homo floresiensis to reach Flores, hominins would have had to make a deliberate water crossing.
It is speculated that these hominins could have arrived on simple watercraft like bamboo rafts. This ability to cross water indicates that early hominins such as Homo erectus or their descendants were capable of planning, building, and using rafts to traverse waterways, venturing into island environments with unique evolutionary pressures.