To answer these questions, Dr. Montenegro and his colleagues ran numerous voyage simulations and concluded that the Long Pause that delayed humans from reaching Hawaii, Tahiti and New Zealand occurred because the early explorers were unable to sail through the strong winds that surround Tonga and Samoa. They reported their results last week in the journal of the Proceedings of the National Academy of Sciences.

“Our paper supports the idea that what people needed was boating technology or navigation technology that would allow them to move efficiently against the wind,” Dr. Montenegro said.

The researchers studied climate data from the area to better understand the environmental conditions the explorers would have faced on their journeys. They also examined data on El Niño and La Niña conditions as well as wind and current directions and intensities.

Their computer simulations showed that the wind was an essential part of the early human expansion to these islands. While they sailed east from the Solomon Islands to Tonga and Samoa, the wind was at their backs, providing a smooth trip forward that let them populate islands like Fiji and Vanuatu. But after reaching this part of the Pacific, Samoa in particular, the environmental conditions changed significantly. At that point, instead of traveling with the wind they needed to travel against it to progress across the long distances.