Prehistoric pooches: Where did Pacific's first dogs come from?

Kiwi researchers have drawn on DNA to work out how the first dogs came to arrive in the Pacific, thousands of years ago. Photo / 123RF

Kiwi researchers have drawn on DNA to work out how the first dogs came to the Pacific, thousands of years ago.

The study, just published in major journal Scientific Reports, has shed more light on the complex picture of how Oceania was settled by ancient migrants and the animals they took with them.

The settlement of the Pacific was part of the last great human migration, and was especially challenging as it took place across a vast expanse of ocean.

One of the strategies people used was to take their domesticated plants and animals on voyages with them, to help them establish communities on new islands.

It was known dogs were part of these migrations - archaeological evidence suggests dogs were introduced to Australasia and the Pacific via Southeast Asia around 3500 years ago - but that evidence had been patchy in places, and the origins and dispersal routes for dogs still weren't clear.

The new study, led by the University of Otago's Dr Karen Greig, aimed to investigate how dogs ultimately fitted into the picture of human settlement - and how their genetic traces linked with current human migration models.

They drew on molecular genetic analysis of DNA extracted from dog bones and teeth that had been excavated from archaeological sites across Southeast Asia and the Pacific islands.

The team specifically targeted the mitochondrial genome, because its high copy number in each cell meant there was a better chance of it surviving in archaeological samples.

They also sequenced the mitogenomes of dingoes from Wellington Zoo.

"Dingoes are descended from dogs introduced to Australia several thousand years ago, and are one of the earliest known dog introductions to the region," Greig explained.

"We used Next Generation Sequencing technology to generate the ancient and modern genetic sequences, and this technology enabled us to obtain far more data for each archaeological dog specimen than had been possible previously."

That meant they could pick out particular similarities and differences between the genetic lineages of the archaeological samples, the dingoes, and also some mitogenomes from modern village dogs published from a previous study.

The data revealed at least three dog introductions into the Pacific region - and in addition to the dingo introduction, each had a different time frame and dispersal pattern.

"This suggests perhaps that people faced challenges moving, establishing and sustaining viable dog populations on newly colonised islands."

They also found evidence for dogs being associated with the Lapita peoples, who were the first to colonise islands beyond the Solomons.

"But we also found evidence for a later and much more successful introduction, with dogs sharing the same genetic lineage being found in archaeological sites across the Pacific, including New Zealand," Greig said.

"We're not sure yet exactly how that dispersal relates to human movements and interactions at that time."

Dogs have a special place in human history as the first domesticated animal, she said, but when and how the domestication process occurred is still the subject of intense debate.

"Dogs are an exceptionally successful species, spreading with people to all corners of the globe, and their arrival in the Pacific is an important part of this story."

The relationships between dogs and people in the Pacific past were also incredibly diverse, and a part of the rich history of the region.

"As modern European dog breeds have replaced many indigenous dog populations, archaeological evidence is now one of the main sources of information about these Pacific dogs."