Polynesia

I don’t think you should dismiss resource
scarcity as motivation for the Polynesian people for
pushing off into the Pacific in search of living
space. Some recent archaeology throughout the Pacific
suggests that the struck out from Taiwan, down to
Mindanao and then out into the Pacific. If you go
down to Ken Ding, in the southernmost tip of Taiwan
and look south, you can just “feel” that there is
something just over the horizon. Climb to the top of
Mount Tagpochau on Saipan, and you can see Tinian and
Rota and Farallon de Medinilla. Even in the middle
of the ocean, you can look to the horizon and see
clouds and birds even if you can't see land. The
explorers who set off from Taiwan would have had the
benefit of more than the feelings of some modern guy
who has seen a map and actually knows there IS
something there. Those explorers would have been
attuned to the shape of clouds that would suggest they
were over land beyond the horizon. They would have
known that birds that flew in over the ocean from the
south had stomach contents different from local birds.
The explorers would have known there was something
over the horizon along a particular vector, they just
could not have known exactly how far.

But even knowing that there is something there, why
would anyone risk it? I think the simple answer is
that ambitious young men who did not have prospects
locally went out to better their lives.
Alternatively, overfarming or drought probably
compelled people to look for fertile lands. The Asian
continent was not hospitable since it was already
settled, and population pressure was pushing
mainlanders toward Taiwan. So, the only alternative
was to push east.

The Pacific is vast, but people who have lived their
entire lives on an island in the ocean would have been
more comfortable and less intimidated by a long ocean
voyage in a wood or reed boat than you or I would be.
Then again, I think it is reasonable to assume that
many attempted the ocean crossings but only a small
percentage made it successfully. But that small
cohort’s success, repeated many times over thousands
of years eventually populated Oceania. The fact that
they did it seems to me evidence that they needed to
do it, and that they were successful.