The arrival of the dingo in Australia greatly altered the continent's ecology and coincided with a significant break in the apparent isolation of indigenous Australians. Our best estimates of when this happened have now been shifted hundreds or even thousands of years, thanks to more accurate dating of the oldest identified dingo bones.

Dingo bones have been found at many sites around Australia, although Professor Sue O'Connor of the Australian National University told IFLScience that old examples are missing from northern Australia, where they must have first arrived.

In the better-studied south, the oldest known specimens come from Madura Cave, beneath the Nullarbor Plain. These bones have been estimated at 3,450 years old based on charcoal samples they seem to be associated with, but this figure had error margins of hundreds of years.

However, O'Connor and her team used advancements in the precision of radiocarbon dating to measure the bones directly. In Scientific Reports, the bones come from dingoes that died 3,348-3,081 years ago.

O'Connor's figures are only a few hundred years later than the previous estimates, but their precision could drastically change thinking about the dingoes' arrival dates.

DNA analysis suggests the dingo separated from Asian dogs as far back as 18,000 years ago. This has encouraged the use of the oldest dates for archaeological samples with wide error bars. Consequently, the most quoted figures for arrival dates has been 4,000-5,000 years ago.

However, O'Connor pointed out that dingoes brought by boat would have been domesticated. “Their spread would have been rapid because it would have been aided by people. As they were useful animals or pets, they were likely transferred between groups,” said O’Connor. 

Although not fully domesticated, dingoes helped indigenous women guard campsites and hunt goannas and smaller marsupials. Consequently, O'Connor proposes their introduction occurred around 3,500 years ago.

O'Connor admits that much earlier bones might be waiting to be found, but noted to IFLScience that with so many locations dated only a little younger than Madura Cave, it's unlikely far older samples have been overlooked.

As the first large placental mammal (humans aside) to inhabit the continent, dingos had a big impact. Many native animals went extinct entirely. Others, like the thylacine, were wiped out on the mainland, surviving in Tasmania, which the dingo never reached.

O'Connor also pointed out: “Dingoes constitute the only hard evidence of non-European people visiting Australia prior to European contact about 400 years ago.”

Trading possibly occurred centuries earlier between Australia and what is now Indonesia. Nevertheless, the dingo's arrival indicates a period of interaction organized enough for dogs to be brought across the Timor Sea. If so, identifying the timing, and ideally the reasons for this contact, becomes particularly important.