An ongoing international research study on the origins of dogs worldwide set out to examine if there's a genetic connection between dogs in Madagascar and the pets of ancient settlers from Indonesia. The international team, which included Stellenbosch University geneticist Dr Barbara van Asch, was taken by surprise. No trace of Indonesian ancestry was found among the island nation's dogs, as the scientists assumed would be the case. Instead, Madagascan dogs all appear to trace their heritage entirely from Africa.
"It's a mystery," the authors say of the study in the journal Royal Society Open Science. It sampled DNA of 145 dogs from Madagascar and 184 from the African mainland. "We were surprised when we saw the results. We expected 100 percent or 50 percent ancestry from Indonesia—but it was zero percent".
The international research project into Madagascar's dogs was led by Prof Peter Savolainen of the KTH Royal Institute of Technology in Sweden. The current study also included other colleagues from KTH, as well as Université d'Antananarivo in Madagascar and the National Institute of Genetic Engineering and Biotechnology in Iran.
Dr van Asch, who joined Stellenbosch University's Department of Genetics as senior lecturer earlier this year, has been part of the research team since 2010. Part of her PhD in Biology from the University of Porto in Portugal focused on the origin of domestic animals. In 2013 she was the lead author of a paper about the lineages and history of North American dogs, and their clear links with Asia.
"I'm fascinated by the history of dogs, as the first domesticated animals, and how their relationship with people sheds light on how humans migrated," she explains in her office in the SU Department of Genetics.
She is now finalising the results of the research team's study on the origins of African dogs. It seems that very exclusive and ancient dog lineages are to be found in Africa and nowhere else. "The presence of dogs in Africa might be older than previously thought," she hints. The final study is expected at the end of the year.
She is one of the co-authors on the Malagasy paper.
Man's best friend in Madagascar
Settlers from Indonesia sailed to Madagascar between 1500 and 2000 years ago.
In ancient times, the expeditions of Indonesians typically included domestic animals, such as pigs, chickens, and of course, man's best friend. Along with their Austronesian culture and DNA, the Indonesians introduced their dogs' genes into populations wherever they settled. This canine DNA can still be found in Hawaii, Southeast Asia, the Cook Islands and New Zealand, among other places.
"Dogs, together with pigs and chicken, were important domestic animals in the Austronesian culture," says Prof Peter Savolainen. "So it would be expected that dogs were brought in the colonization of major new areas, and a seemingly total absence in Madagascar of dogs with Austronesian heritage is surprising."
One possible explanation doesn't quite hold up, Savolainen says. If the migration from Indonesia to Madagascar was "a limited event" which brought only a small number of colonizers in a few voyages, then why does the human population of the island have such a high diversity of maternal and paternal lineages with Indonesian origin?
"This indicates that there was an introduction of large numbers of people, possibly in several successive waves rather, than a severe genetic bottleneck in the founder population," he says.
Savolainen offers a more likely, if unappealing scenario. "It is possible that if the dogs were brought along on these long journeys, they died from the hardship, or were used as a food source."
Indonesian dog DNA isn't the only missing trace of the Indonesian diaspora in Madagascar. As Savolainen points out, the Madagascan culture is mainly influenced by Africa and, except for the language, few clear contributions remain from the initial Indonesian culture."
- This article is based in part on a press release by the KTH Royal Institute of Technology in Sweden. For the original, visit https://www.kth.se/en/aktuellt/nyheter/who-left-the-dogs-out-1.567708
- For a link to the open access journal article, visit http://rsos.royalsocietypublishing.org/content/2/5/140552
Media enquiries:
Dr Barbara van Asch
Department of Genetics, Stellenbosch University
+27 21 808 5888
