Polynesians migrating between island groups are commonly believed to have carried on their voyaging canoes a standard colonization package, which included certain useful items, among them a cluster of plants, and chickens, dogs, rats and pigs. But a new study suggests it may not be as simple as that.

The report, published in the Proceedings of the National Academy of Sciences of the U.S., studies the genetic makeup of pigs across the Pacific and suggests that the people who ended up colonizing Polynesia may have picked up their pigs along the way rather than starting out with them.

And if they picked up something as important to the Pacific culture as the pig, what other parts of the culture were also adopted as they moved through the Pacific?

Most Polynesian migration theories, based on language, artifacts and even human genetics clues, conclude that the people who ultimately populated most of the Pacific came from the island now known as Taiwan, swinging through the Philippines, south to the region around what's now Indonesia, where they left pottery fragments and were named the Lapita people, and then moved eastward to eventually reach Hawai'i and the rest of Polynesia.

An extensive international team of scientists studied genetic material of pigs from ancient archaeological sites — most collected in museums — as well as genetic material from modern pigs. They found that the pigs of Polynesia, including Hawai'i, the Cooks and the Marquesas, are related to the pigs of Vanuatu, of the Reef Islands of the Solomons, of New Guinea — and Vietnam.

"The types of pigs that eventually found their way into the Eastern Pacific are distinct in origin from Taiwanese pigs," said University of Hawai'i anthropology lecturer Robert Bollt, one of the paper's 32 authors.

There is evidence that a second wave of migration out of Taiwan did carry pigs from that island. That migratory movement went from southeast China to Taiwan, the Philippines and Micronesia, Bollt said.

But Polynesian pigs — a genetically distinct grouping referred to in the paper as the Pacific Clade — are genetically different, as identified in mitochondrial DNA studies.

It is clear that where pigs went in the Pacific, they were carried by humans, the authors say.

"Pigs are good swimmers but not good enough to reach Hawai'i," Swedish archaeologist Greger Larson, the lead author of the study, said in a press release.

The study is titled "Phylogeny and Ancient DNA of Sus Provides Insights into Neolithic Expansion in Island Southeast Asia and Oceania." Sus is the genus of pigs. Neolithic refers to Stone Age people who have developed agriculture.

Bollt says this does not mean the authors believe Polynesians originated or even visited Southeast Asia, or even that they necessarily sailed from Taiwan without pigs. They may have lost their pigs. They could have stopped at some point along what is now Vietnam and traded for or captured pigs, and then moved on, leaving no trace. Or perhaps the pigs were carried into the Lapita islands by other people, and the folks who would populate Polynesia picked them up there.

"It does support a more complex theory of migration that is not as linear as we've thought," Bollt said.

The paper suggests that there are other explanations than the popular "Speedboat out of Taiwan" theory, which argues that a single culture moved through Oceania, evolving as it went but without much outside influence. An alternative view is that there may be "multiple origins of the various cultural components," the paper said.

"The complete absence of Pacific Clade haplotypes from modern and ancient specimens from mainland China, Taiwan, the Philippines, Borneo and Sulawesi suggests that any human dispersal from Taiwan out (to) the New Guinea region via the Philippines, as purported by the 'Out of Taiwan' model, did not include the movement of domestic pigs," the paper says.

And it may not be just pigs. The paper says recent studies suggest modern chickens may have first been domesticated in the area of Vietnam, Burma and Thailand.

"This finding raises the possibility that the earliest domestic chickens and pigs to arrive in Island Southeast Asia and Oceania derive from the same geographic source and may have formed part of the same Neolithic dispersal complex," the paper says.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.