Australian Aborigines spent 50,000 years isolated from the rest of us

Geneticists sequenced the Y chromosomes of Aboriginal Australians and found evidence that the population was isolated for tens of thousands of years.

Robert Harbison / The Christian Science Monitor / File
The flag of Aboriginal Australians flies over a Corroboree near Sydney where talented natives perform.

Australia, Papua New Guinea, and Tasmania made up one of the first regions modern humans reached after leaving Africa some 50,000 years ago. But, before Europeans arrived in the colonial era, did others follow?

Some scientists have said the archaeological record hints at an influx of new people around 4,000 to 5,000 years ago from India. At that time, languages and stone tools changed significantly, and Australian wild dogs, dingoes, arrived.

But geneticists found no evidence of such a migration in the Y chromosome of indigenous people living there today in a new study published Thursday in the journal Current Biology. Y chromosomes, passed from father to son, represent only paternal lineages. 

"We show conclusively that the Aboriginal Australian Y chromosome did not originate from India or South Asia a few thousand years ago, but rather have these deep roots going back 50,000 years in Australia," says Chris Tyler-Smith, one of the study's lead authors, in an interview with The Christian Science Monitor.

And this means Aboriginal Australians may have 50,000 years of history completely separate from the rest of humankind.

When they arrived, lower sea levels meant that what are now separate island nations were then one continental land mass. "Sahul, the name of that ancient continent, seems to have been isolated, as far as migrations of people were concerned, for 50,000 years," says Dr. Tyler-Smith.

The region was beyond a section of ocean, called Wallace's Line, that scientists say was for the most part uncrossable by many species for a long period of time, so the first outside influence on Sahul genetics came with seafaring European invaders in the 1700s.

As one of the earliest modern human populations outside of Africa, Sahul inhabitants represent a separate run of human evolution from the one that played out across Eurasia and the Americas, says Tyler-Smith, providing insight into how human evolution varies in isolated contexts.  

"Aboriginal Australians themselves have always seen themselves as having these very deep roots there," Tyler-Smith says. "The genetic analysis now confirms that."

The suggestion that other people arrived before the Europeans is not new, Darren Curnoe, an anthropologist at the University of New South Wales in Australia who was not part of the study, tells the Monitor in an email.

"The notion that Aboriginal Australians are closely related to South Asian people has been debated since the late 1800s," he says. Geneticists have sought to answer that question for over a decade.

"This new study marks a final nail in the coffin for this old idea, and it’s one that really should have been buried with its originator during the nineteenth century, Thomas Henry Huxley," Dr. Curnoe says.

Tyler-Smith says further analysis could strengthen his team's results. "We have studied this one particular region of the genome, the Y chromosome, but I think it's very important to study the rest of the genome," he says.

It's possible, he says, if unlikely, that people did come to Australia but left no trace of their Y chromosomes. 

If the new stone tools and new languages cannot be explained by the immigration of a distinct population, what actually happened?

Some scholars suggest a changing climate or resources available could have precipitated the need for new technology or ways of communicating. Previous studies have suggested a link between environmental changes and language

Or perhaps the population reached a critical mass and prompted the people to begin innovating.

But what about the dingoes?

They probably didn't swim across Wallace's line themselves, says Tyler-Smith. Nor could they have evolved from another animal already there.

He suggests that the dingoes could have been brought back from an expedition to South Asia by some of the people already living on Sahul, or that visitors to the region could have left the dogs, but not their DNA.

You've read  of  free articles. Subscribe to continue.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.