The pulse-pause model is an “innovationist” one – it suggests that the big expansions were driven by big advances in technology, or social organisation. In this case, Gray suggests that the first big expansion from Taiwan was made possible by the invention of the outrigger canoe and effective sailing. These innovations turned a land-locked society into a sea-faring one capable of crossing into the Philippines and beyond. The second pulse into Eastern Polynesia involved longer journeys – perhaps it needed a better knowledge of astronomy for navigation, the creation of more stable double-hulled canoes, or the skills needed to sail across prevailing winds.
Source : https://www.nationalgeographic.com/science/phenomena/2009/01/22/bacteria-and-languages-reveal-how-people-spread-through-the-pacific/