Ancient Aboriginal DNA and repatriations
When people first reached Australia 50,000 years ago, they rapidly colonised the new land. But once people settled in a region, they tended to stay there, suggests the biggest genetics study yet on Aboriginal DNA.
The research, published this week in the British journal Nature, will fuel the push for the repatriation of Aboriginal bones and other biological material. It challenges, but does not refute, the argument posed by some that modern communities are not necessarily closely related to the human remains in their area, and cannot claim ownership of them.
The study was led by Alan Cooper, director of the Australian Centre for Ancient DNA at the University of Adelaide. DNA is defined as “ancient” if it is highly degraded.
The research follows sensitive negotiations between Cooper’s team and Aboriginal groups.
Scientists seeking to study Indigenous remains want answers to questions on evolutionary origins, and the diet, health and behaviour of the people of the past. But they are tainted by the practices of some early collectors.
Collecting began in the 19th century and persisted into the 20th century. Some material was obtained ethically, with the consent of Aboriginal people. Some was not, and stories abound of the looting of burial sites. Skeletons were sold on a bullish world market hungry for what were considered curiosities from the colonies. Some material wound up in Australian museums and universities, while some was sent overseas.
The repatriation campaign gained momentum in the late 1980s. It has been played out in courts, parliaments, universities, museums and the media, and even in the United Nations. The issue remains hot.
The federal government has funded the repatriation of Indigenous ancestral remains for more than 20 years, a spokeswoman for the Department of Communications and the Arts told The Saturday Paper.
“To date, the Indigenous Repatriation Program has supported the return of over 1400 ancestral remains and over 1400 secret sacred objects from the eight major Australian museums, and brought home more than 1300 ancestral remains from overseas,” she said.
It is unknown how many Aboriginal and Torres Strait Islander individuals are represented by remains held overseas, and how old they are, but most are thought to be in Britain, Germany, France, Poland, Austria and the United States. It is understood that the government is negotiating with these and other countries for the return of the remains.
In late 2015, skeletal remains from the World Heritage-listed Willandra Lakes Region on the New South Wales–Victorian border were returned to traditional owners of the vast expanse of dry lakebeds. They included the famous 40,000-year-old Mungo Man skeleton.
The remains were being stored at the Australian National University, in Canberra, under an agreement between scientists and tribal elders. They were transferred to the repatriation unit of the National Museum of Australia, also in Canberra, in anticipation of their journey back to country.
This latest research was conducted on hair samples stored at the South Australian Museum. The museum’s Aboriginal Family History Unit used archival records of the samples as part of outreach to the donors or their families. The University of Adelaide had obtained the samples during expeditions between the 1920s and ’70s.
Cooper’s team confirmed earlier research suggesting there were four major genetic groups common among Aboriginal people. It used the “molecular clock” – the known rate of DNA mutation in the genome – to pin down the timing of the peopling of Australia.
The team used dates obtained by other scientists through radiocarbon and other methods to check the results. The scientists sequenced DNA from the mitochondria – the tiny metabolic powerhouses in cells. They sequenced the complete genomes of the donors, a feat made possible only by recent advances in DNA sequencing.
Mitochondrial DNA carries the instructions for the conversion of food into energy. The mitochondria are outside the cell nuclei. We all have this specialised DNA critical to life but it is passed down exclusively through the maternal line.
In contrast, the bigger nuclear genome mostly comprises DNA inherited from both parents that is shuffled in a process called recombination. Nuclear DNA carries the blueprint for other physical traits, such as body structure and hair colour, as well as some behavioural characteristics. However, only males have a Y chromosome among their 46, and they inherit it exclusively from their fathers.
The team worked on about 110 hair samples from Point Pearce and Koonibba, in South Australia, and from Cherbourg in Queensland. The samples form a subset of about 5000 held in the museum’s Aboriginal collection.
“We placed the lineages on the map as far back along the maternal line as possible,” Cooper tells The Saturday Paper. “That allowed us to go back beyond European disruption and forced relocation.”
The group reconstructed the routes of the first immigrants, who made landfall on Sahul, the ancient continent comprising what is now Australia and New Guinea, which were joined before rising sea levels separated them about 9000 years ago.
The team found that people colonised Australia in a single wave followed by a clockwise and counter-clockwise migration along the east and west coasts, reaching southern Australia by about 50,000 years ago.
Strong regional DNA patterns developed and survived, despite big environmental changes amid ice age aridification, and, later, cultural changes.
“Remarkably, we find evidence for the continuous presence of populations in the same geographical areas dating back to around 50,000 years,” Cooper says. “This is in agreement with Aboriginal traditional knowledge, which in turn underpins their strong metaphysical attachment to their country.”
The ANU’s Colin Groves, a world-renowned biological anthropologist outside the research team, tells The Saturday Paper that the correlations of these mitochondrial genes with latitude and longitude are “good but not perfect”.
“They did this just by mitochondrial DNA,” he says. “And total DNA, especially Y chromosome DNA, might reveal there has been more wandering among males.”
The team has conducted research on the Y chromosome but cannot reveal the results until they are published in a learned journal, due to the protocol requiring research to undergo peer review.
Groves says the work suggests a deep relationship between Aboriginal people and people from New Guinea, but little gene exchange after the initial colonisation
This article was first published in the print edition of The Saturday Paper on Mar 11, 2017 as "Bones of contention". Subscribe here.