Arrival of the Tuvaluans

According to the evidence of linguists, who can work out how old a language is, and hence for how long people had been speaking it, the language of Tuvalu - and hence the settlement of the country - goes back about 2,000 years. The traditional stories and genealogies, however, mostly go back only about 300 years. It seems, therefore, that the story we have today came to us not from the earlier ancestors but from later arrivals in Tuvalu.
It is generally believed that the earlier ancestors came mostly from Samoa, possibly by way of Tokelau, while others came from Tonga and Uvea (Wallis Island). These settlers were all Polynesians with the exception of Nui where many people are descendants of Micronesians from Kiribati.
In 1986, off the northern shore of Nanumaga, scuba divers investigated a local legend of a "large house under the sea". They found and underwater cave more than 40 metres down the wall of the coral cliff. Inside the cave there was evidence of ancient human occupation more than 8,000 years ago, which is sharply at odds with the general view that the Pacific was settled just 4,000 years ago. Climatic evidence of a massive rise in the see level that began 18,000 years ago and stopped 4,000 years ago may have drowned most of the evidence of much earlier human migration to Tuvalu and other Pacific islands. Link: The Caves of Nanumaga
There are three distinct linguistic areas in Tuvalu. The first area contains the islands of Nanumea, Niutao and Nanumaga. The second is the island of Nui where the inhabitants speak a language that is fundamentally derived from I-Kiribati. The third linguistic group comprises the islands of Vaitupu, Nukufetau, Funafuti and Nukulaelae. Today, Tuvaluan and English are both spoken throughout the islands.
According to modern scholars the population of Tuvalu before 1900 was never more than 3000. These opinions are based on early missionary reports and on careful estimates of the population-supporting capacity of Tuvalu food resources. Although they may well be correct these views should not be accepted uncritically, for the written records come from people who were not intimately acquainted with life in Tuvalu. Moreover, there is always a danger that foreign commentators could impose a meaning of what they learned about Tuvalu which is quite different from those who live here.
There are suggestions from archeologists that the ancient population was possibly higher than the scholars will allow. For instance, at Niutao in the early 1930's one of the pastors organized the people to level the village malae. In doing so, they uncovered large numbers of human skulls buried about a metre below the surface. Similarly at Nukufetau numerous human graves can be counted, especially on the islet of Fale.
Further evidence comes from the huge holes that were dug in the ground to grow pulaka. These pits were dug to different depths. Most were from one-third of a metre to six metres deep, but some are deep as twenty metres from the base to the highest point of the soil thrown up. If the population was not above, say, 3000 why did the people build such numerous and deep pits which far exceeded their needs? How could our forefathers, if only a few hundred in number, have dug such pits? Looking at these huge pits it is difficult to avoid the suspicion that there were many thousands of people who needed to be fed from them and who were required to build them.
Moreover, Tuvaluan traditions do not contain any accounts of vast population losses. Certainly many people were killed in wars. Others probably died as a result of droughts or hurricanes. It is of course possible that their  ancestors, over centuries, thought it prudent to provide for the possible future needs of their descendants by digging more than they needed for themselves. Apart from that, if there was a massive decline in population, the reason for it is not readily apparent. In 1979 the population of Tuvalu was estimated to be 7349.
The present population of Tuvalu is estimated to be 10,500, and there are growing communities in other countries, mainly Australia, New Zealand and Kiribati.