Homo erectus shipbuilders?
My answer to that is simple: when a modern human, i.e. Homo sapiens sapiens, with our considerably larger brains, is able to build a seagoing vessel using only Acheulian tools, then, and only then, will I entertain the possibility that Homo erectus sailed anywhere.
Alternative possibilities for how the Homo erectus fossils got there:
- The geologists are wrong and Homo erectus did walk there
- They co-existed with upper palaeolithic or later Homo sapiens, who built basic ships (perhaps like the Kon-tiki one) and took Homo erectus with them as slaves or captives or shipmates or concubines or food or companions or purely for decoration, and that’s how they got there
- The palaeoanthropologists got the dates wrong and H. erectus walked there, but not at the time they supposed