DNA from prehistoric sites telling

Some people might baulk at a career examining the secrets of the dead, but prehistoric burial grounds can tell us a massive amount about the society in which the people lived, University of Otago anthropologist and archaeologist Prof Charles Higham says.

Since the late 1960s, when he arrived fresh from completing a PhD at Cambridge University, Prof Higham has dedicated his time to researching sites across Southeast Asia, most recently in northeast Thailand, at Non Ban Jak.

Early DNA tests showed that the buried people that lived there between AD200 and AD600 were related to villages of Mon people, elsewhere in Thailand, who lived in the country before the Thais and had a distinct culture and language.

The village was the site of his Marsden Grant-funded project on the origins of social inequality in early societies - and he said his research traced it to changes in monsoon season.

There was a ''very significant fall in the strength of the monsoon, the rainfall'', Prof Higham said.

''Without rain the crops fail, it's the basis of life.''

There was a sharp downturn in the amount of rain falling in about AD200 or 300.

Prof Higham said reservoirs were constructed as a reaction to aridity, with trenches dug around the rice fields.

The people who owned the best riceland became leaders, with dependent serfs cultivating the land.

''A few hundred years later ... we find that these leaders had very fancy names,'' Prof Higham said.

''They were pretty powerful people; they were worshipped in their lifetimes and had further power when they died.''

The burials of the prehistoric people at Non Ban Jak were exceptionally well-preserved, he said.

''The amount of ritual ... that goes into a burial tells us a lot about the status of that dead individual in that society.''

Nowhere was that clearer than in the case of a woman his team once discovered dubbed ''The Princess'' by the archaeologists, interred at Khok Phanom Di about 3500 years ago with 120,000 shell beads.

The beads were made of nacreous shell, which reflected the sun.

When she was alive, she would have literally radiated sunlight, Prof Higham said. An infant buried nearby was interred with 15,000 shell beads.

Prof Higham said he did not really have favourite subject areas to work in, but he did have favourite discoveries.

One of them was 80 bronze-age pots at a site called Nong Jik, which it became apparent were part of a burial ground.

The first one he dug up was very large and elaborately decorated, and contained the crouched skeleton of a man.

The local Thai people who helped the archaeologists excavate the sites did not recognise the people as their ancestors, and had no qualms about digging them up.

''They are quite incredibly skilful [excavators].''

After the skeletons were excavated they were kept by the Thai Government, and were all archived and stored in the fine arts department.

''There must be at least 1000 to 1500 kept there.

The pots and jewellery were kept in Thailand's national museum.

''I've taken many of my students over to help excavate,'' he said.

Despite evidence of some wealth, life was hard.

Seventy percent of all burials were children. Working in and around rice fields, pregnant mothers could contract terrible pathogens.

''Women had a very, very tough time.''

While there was a lot known about Bronze and Iron Age rites and religious beliefs, little was known about prehistoric people's beliefs.

However, that they cared deeply for their dead and did think an afterlife existed was clear, and their burials were imbued with the notion of rebirth.

For instance infants, including babies born prematurely, were buried in pots with a ''womb-like'', blood-red interior.

How people died was of interest to Prof Higham - who worked in conjunction with his colleagues at the Dunedin School of Medicine to identify a cause.

Leprosy was a hazard, as was dying a violent death.

''Very few people survived beyond 30 or 40 years old.''

His new focus, for which he hoped to get a Marsden grant, was on DNA testing sites in Myanmar, Vietnam and China.

Unfortunately the hot climate meant DNA did not survive as well as it would, for example, in Siberia, where Prof Higham's son was working.

However DNA was about 100 times more likely to survive in the petrous bone, the hardest bone in the body, and using DNA from that bone had so far proved successful.

A DNA project on Non Ban Jak was completed in July, and would form the basis of the larger study.

elena.mcphee@odt.co.nz