15 September 2011

Dingo origin predates Neolithic expansion

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Genetic evidence has revealed that dingoes may have arrived in Australia earlier than previously believed, and likely took a very different route that began in South China.
Dingo predates Neolithic expansion to Australia

A dingo (Canis lupus dingo) in a wildlife park in South Australia. New genetic evidence show the Dingo originated in China and likely came to Australia earlier than previously indicated. Credit: wikimedia

LONDON: Genetic evidence has revealed that dingoes may have arrived in Australia earlier than previously believed, and likely took a very different route that began in South China.

Australian dingoes (Canis lupus dingo) and domesticated dogs from Polynesia originated in China and travelled via Thailand and Indonesia to reach their final destination, rather than coming from Taiwan – a journey that would have entailed more sea crossings.

The findings, published in the journal Proceedings of the Royal Society B, could have implications for human history in the region as well, revealing clues about the geographic origin of the Polynesian population and its Neolithic culture.

It also reveals information about the extent of contact, or isolation rather, between pre-Neolithic cultures of Australia and their surrounding world.

Dingo arrival before Neolithic?

In Australia there is little evidence of any interaction with Neolithic cultures: apart from the feral dingo, which is viewed as a Neolithic introduction, and has led many researchers to conclude that Australia was not completely isolated.

Dingoes appear in the Australian archaeological record roughly 3,500 years before present, but the study, which analysed the genetic code of around 900 dogs, indicates an earlier introduction to Australia sometime between 4,600 and 10,000 years ago.

The arrival of dogs in Australia predates any Taiwanese Neolithic expansion, according to the study, and therefore underscores the notion that Australia was indeed quite isolated prior to this period.

An ancient mystery

The key problem in the history of Polynesia is explaining the existence of Neolithic domesticated animals — including the dog, chicken and pig — which indicate an expansion from Taiwan, possibly during the Neolithic farming expansion.

However, the data presented here indicates that the Polynesian domestic dogs trace their ancestry from mainland Southeast Asia, and that dogs could have appeared before the arrival of the Neolithic.

“Dogs, chicken and pigs were the only household animals that accompanied the people who colonised Polynesia,” said co-author Peter Savolainen, a geneticist at KTH Institute of Technology in Sweden.

“However, because the dog came through Thailand and man through Taiwan, we now believe that human populations and cultures must have mixed on the way to Polynesia,” he added.

While it does not definitively clarify the origin of Polynesian culture, it seems to overrule the simpler theory that a single rush of Taiwanese farmers where responsible for Polynesian culture, and suggests there was likely a greater mix of influences along the way.

Origin mystery solved?

The researchers compared a total of 674 samples of dog mitochondrial DNA, together with 232 samples from dingoes.

The team identified the three ‘haplotypes’ specific to Polynesia and Australia (two in the former, one in the latter) and traced a path backwards by comparing the proportion of correct mtDNA present amongst samples taken from throughout Oceania and South Asia.

None of the matching ‘haplotypes’ appeared in Taiwan at all. Instead the dingoes’ mtDNA, named ‘A29′, was found in South China, South East Asia, the western Islands of Kalimantan and Bali, and Papua New Guinea.

When plotted on the map, it seems to indicate a clear route towards Australia. The two Polynesian types, Arc1 and Arc2, seem to have followed a similair route.

“This research illustrates beautifully how the power of DNA sequence analysis can throw light on the origins and history of life on this planet,” commented Chris Thomas, a geneticist from the University of Birmingham in the U.K. who was not involved in the study.

“However, it is important to note that while the new information rules out some previous ideas, it does not yet provide a simple history – sometimes the more information we have the more complicated the picture seems to be,” Thomas added.

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