Video | Business Headlines | Internet | Science | Scientific Ethics | Technology | Search

 

DNA offers clues to ancient Samoan settlement

DNA offers clues to ancient Samoan settlement and unique ancestry


Dr Ethan Cochrane and Pena of Falevao Village taking a break from identifying ancient structures in the Samoan bush

Samoa experienced an exponential jump in its population around 1000 years ago and the ancestry of contemporary Samoans is relatively unique when compared to other Pacific island groups, a new study has found.
Published today in Proceedings of the National Academy of Sciences (PNAS) of the United States of America, the study, which included Associate Professor Ethan Cochrane from the University of Auckland, analysed modern DNA collected from more than 1,100 Samoans from an earlier study involving several US universities and the Samoan Ministry of Health.

While the earlier study uncovered links between particular genetic profiles and increased risk of heart disease, the latest study analysed the same data to estimate the degree of shared ancestry of present-day Samoans with other human groups, the degree of shared genetic similarity within Samoan people and then estimated changing population size over time.

The data consisted of whole genomes (entire genetic blueprints) of individuals, but was broken down for more specific analyses, says Dr Cochrane.

“Although our study was not focused on health issues, we analysed the data from the earlier study to answer some key questions about the settlement history of Samoa: how big was the founding population of Samoa 3,000 years ago, were there multiple ancient migrations to Samoa and how did the Samoan population grow over time?"

And they made some unexpected discoveries.

“Despite the prevailing archaeological opinon that the initial population size of Samoa would have been relatively similar to nearby Tonga and Fiji, our genetic results indicate that the founding population of Samoa was actually quite small, between 800 and 3300 people and stayed quite low until about 1000 years ago.”

He says estimates of population size changes over time involved complicated analyses referred to as Identity by Descent (IBD).

“Put simply, populations share genetic code via sexual reproduction and as a result of mating, the chunks of this code from the parents get cut up into smaller chunks in their children. The distribution of DNA-chunk sizes (IBD segments) is therefore influenced by population size; that is, a larger population equals more sexual reproduction, leading to smaller chunk sizes. Also as reproduction happens in a population over time, the longer time frame over which the population exists means more reproduction, and smaller chunk sizes.”

The IBD analyses also suggested a marked jump in the Samoan population size about 1000 years ago, up to as many as 10,000 people, which coincides with a number of other cultural changes in Samoa, as well as the initial settlment of distant archipelagos like Tahiti, Hawaii and the Cook Islands.

“It’s possible that the populating of these other islands is related to demographic changes in Samoa,” says Dr Cochrane. “The jump in Samoan population size might also be related to archaeologically documented changes in agriculture, as well as an increasing number of monumental mound structures, both of which might signify hierarchical society. We could be seeing the origins of the Samoan chiefly system 1000 years ago.”

He says the study also found that modern Samoans come largely from the Austronesian lineage (people in Taiwan, Island Southeast Asia, Micronesia, coastal New Guinea, Island Melanesia, Polynesia, and Madagascar) and share only 24 percent of their ancestry with Papuans, the descendants of the people who settled Papua/New Guinea.

This is markedly lower than neighbouring Polynesian groups which on average, share about 35 percent Papuan ancestry. The unique mixture of Austronesian and Papuan ancestry in Samoans is possibly related to the initial settlement of the islands and suggests that groups with somewhat different ancestry settled Samoa, compared to nearby Tonga, Dr Cochrane says.

“For the last several decades, the origins of the Polynesians has been understood as story of a singular migration and common cultural and demographic changes throughout the islands. But what we are learning now from this study, and others like it, is that there may have been different migrations with different mixes of people and unique demographic histories that have contributed to modern cultural, biological and linguistic diversity in the Pacific.”

Read the full PNAS article here


Editor’s notes

• This genetic data were obtained by Stephen McGarvey, a professor of epidemiology and anthropology at Brown University, United States.

• Professor McGarvey collaborated with Dr Daniel Harris and Assistant Professor Timothy O’Connor from the University of Maryland and others, including Associate Professor Ethan Cochrane from the University of Auckland.

• The study was supported by the TransOmics for Precision Medicine (TOPMed) program of the National Heart, Lung and Blood Institute (NHLBI) of the US National Institutes of Health (NIH).

• Ethan Cochranes work was partly funded by the Royal Society Te Apārangi.


© Scoop Media

 
 
 
Business Headlines | Sci-Tech Headlines

 

Science Media Centre: Funding For R&D In New Zealand – Expert Reaction

Research, Science and Innovation Minister Dr Megan Woods has today announced $401.3 million funding for research and development through Budget 2020 and the COVID Response and Recovery Fund. The fund includes $150 million for an R&D loan scheme, ... More>>

ALSO:

Maritime NZ: NZ Joins Global Initiative Keeping Ports Open And Freight Moving

New Zealand has joined an international port authorities’ global initiative for safe and efficient movement of goods and shipping during the COVID-19 crisis. World-wide, 56 port authorities have agreed how they will work together facilitating maritime ... More>>

ALSO:

National: National Backs Businesses With $10k JobStart

National will provide a $10,000 cash payment to businesses that hire additional staff as part of our commitment to keeping New Zealanders in jobs, National Party Leader Todd Muller and Finance spokesperson Paul Goldsmith have announced. Our JobStart ... More>>

ALSO:

DIY Law: Government Exempts Some Home Improvements From Costly Consents

Homeowners, builders and DIYers will soon have an easier time making basic home improvements as the Government scraps the need for consents for low-risk building work such as sleep-outs, sheds and carports – allowing the construction sector ... More>>

ALSO:

Media Awards: The New Zealand Herald Named Newspaper Of The Year, Website Of The Year At Voyager Media Awards

The New Zealand Herald has been labelled a “powerhouse news operation” as it claims the two biggest prizes – Newspaper of the Year and Website of the Year – along with many individual awards at the 2020 Voyager Media Awards Website of the ... More>>

ALSO:

ASB Bank: ASB Takes The Lead Again With New Low Home Loan Interest Rate

ASB has moved again to support its customers, cutting a number of home loan rates, including the two-year special rate to a new low of 2.69% p.a. Craig Sims, ASB executive general manager Retail Banking says the reduced rate will be welcome news for many ... More>>

ALSO:

Nathan Hoturoa Gray: The Problems With Testing And Case Statistics For Covid-19

To begin to understand disease transmission in a country requires adequate testing of your population with properly vetted, accurate tests. As the world struggles to find what 'adequate percentage' of the population is necessary, (estimates predict ... More>>

ALSO:

RNZ: Fletcher Building To Lay Off 1000 Staff In New Zealand

The construction company will cut around 10 percent of its workforce as it struggles with the fallout from Covid-19. More>>

ALSO:

Can Pay, Won't Pay: Cashflow Moves Urged

Government Ministers are asking significant private enterprises to adopt prompt payment practices in line with the state sector, as a way to improve cashflow for small businesses. More>>

ALSO:

Gordon Campbell: On Why We Should Legally Protect The Right To Work From Home

For understandable reasons, the media messaging around Level Two has been all about “freedom” and “celebration”, but this is not necessarily going to be a universal experience. When it comes to workplace relations, Level Two is just as likely to ... More>>

ALSO:



New Zealand Government: Supporting Kiwi Businesses To Resolve Rent Disputes

The Government will legislate to ensure businesses that suffered as a result of the COVID-19 response will get help to resolve disputes over commercial rent issues, Justice Minister Andrew Little announced today. More>>

ALSO:


Science Media Centre: Understanding 5G Concerns – Expert Q&A


Recent attacks on cell phone towers have brought concerns over the rollout of 5G technology into sharp relief.
While scientific research has consistently shown that the technology does not adversely affect human health, public concerns about its impact have spread around the world, fueled in part by growing misinformation online. The SMC asked experts to comment... More>>

ALSO:


Trade: Record Monthly Surplus As Imports Dive

Imports in April 2020 had their biggest fall since October 2009, resulting in a monthly trade surplus of $1.3 billion, Stats NZ said today. “This is the largest monthly trade surplus on record and the annual goods trade deficit is the lowest ... More>>

ALSO:


Media Blues: Stuff Chief Executive Buys Company For $1

Stuff chief executive Sinead Boucher has purchased Stuff from its Australian owners Nine Entertainment for $1.
The chief executive was returning the company to New Zealand ownership, with the sale is expected to be completed by 31 May.
"Our plan is to transition the ownership of Stuff to give staff a direct stake in the business as shareholders," Boucher said in a statement.... More>>

ALSO:

RNZ: Bar Reopening Night 'much, Much Quieter'

Pubs and bars are reporting a sluggish first day back after the lockdown, with the fear of going out, or perhaps the joy of staying home, thought to be a reason for the low numbers. More>>

ALSO:

Stats NZ: New Zealand’s Population Passes 5 Million

New Zealand's resident population provisionally reached 5 million in March 2020, Stats NZ said today. More>>

NIWA: Seven Weeks Of Clearing The Air Provides Huge Benefits: Scientist

Seven weeks of lockdown has provided evidence of how pollution can vanish overnight with benefits for the environment and individuals, says NIWA air quality scientist Dr Ian Longley. Dr Longley has been monitoring air quality in Auckland, Wellington ... More>>

ALSO:

Government: Milestone In Cash Flow Support To SMEs

A significant package of tax reforms will be pushed through all stages in Parliament today to throw a cash flow lifeline to small businesses. More>>

ALSO: