In Praise of Antiquity

There is no email I await with greater anticipation and, indeed, trepidation, than one captioned ‘Your radiocarbon results’.

I am a long-term admirer of the journal Antiquity. Every couple of months, a new copy appears in my department mailbox and I keenly look at the table of contents for my next reads. I never knew the founder and first editor, O G S Crawford, but count all six subsequent editors as colleagues and friends. I have been on the editorial advisory board for over 30 years, and it has been most rewarding. Glyn Daniel succeeded Crawford as editor in 1958, and remained at the helm for nearly 30 years. I remember well visiting his Cambridge home – the front door embellished with a stag’s head presented by another of his students, the Prince of Wales – to find him and Ruth working on the latest issue. Long before we had Photoshop or FreeHand to do our illustrations, she would draw the maps, and I would find Glyn at his desk in a sea of manuscripts and proofs.

Getting an article published then required jumping through far fewer hoops than today. In 1982, I submitted a paper on irregular earthworks in North-east Thailand, and Glyn’s editorial response could never happen today. He rang me and said, simply, ‘Charles, we don’t need referees for this, do we? Let’s just go ahead.’ I would like now to contrast this with my latest contribution, written with ten colleagues and published in August this year, which also incorporates one of those fascinating irregular earthworks.

The long or short of it

In 2012, I received funds from the Marsden Fund in New Zealand to radiocarbon date the later prehistory of south-east Asia and southern China. It made it possible, at last, to get the basic chronology sorted. For years I had contributed to a heated debate over the merits of either a long time span, which pushed for early dates that supported the notion that major innovations, such as the domestication of rice or copper-base metallurgy, were significantly early, or a short time span, which rejected these claims.

My research grant came just as a new paradigm emerged from the Oxford radiocarbon laboratory, one that required multiple samples from assured contexts in a cultural sequence, interpreted with Bayesian statistics. Most fortuitously, this coincided with advances in Accelerator Mass Spectrometry (AMS) 14C-dating that enabled the dating of samples as small as a millet grain and, by ultrafiltration, the reliable dating of human bone. We were thus able to cut through a thicket of Gordian knots. The first came with the chronology for 12 phases at Ban Non Wat, one of the irregular earthworks, which placed early Neolithic rice-farmers in the 18th century BC, and the first tin-bronzes c.11th century BC. We then dated human remains from the sequences at other north-east Thai sites, Non Nok Tha and Ban Chiang, with similar results. Compare this with the long chronology for those two sites, which dates tin-bronze casting to the early 2nd millennium BC.

There remained, however, a major gap in our knowledge. Ban Non Wat and the other two sites are located far from any copper deposits. Surely, the best way to pin down when copper-base technology arrived is to find copper deposits exploited in prehistory. In 1991, when I was excavating the site of Nong Nor in Central Thailand, the dig hosted a visit from a TAP team then working in the Khao Wong Prachan Valley as part of the Penn Museum–Thai Fine Arts Department sponsored Thailand Archaeometallurgy Project (TAP). Located about 90km north of Bangkok, on the edge of the Petchabun uplands, the inselbergs – the metamorphic island hills of this region – are rich in veins of copper ore. Andy Weiss, TAP field director, worked under the direction of TAP co-directors Surapol Natapintu and Vince Pigott. There seemed to be an interesting link between Nong Nor and the Valley sites, because at Nong Nor we found one man interred with thin, socketed, chisel-like tools that could have been cast in the moulds being unearthed by my visitors.

After my excavations ended, I arranged with Surapol Natapintu, then from Silpakorn University, to drive up to the Khao Wong Prachan to visit the sites. He took me to the adits into the ancient copper mines, and then to one of the open excavation squares at Non Pa Wai, and on to neighbouring Nil Kham Haeng. The former was a massive 5ha build-up of smelting debris, stratified over a shallow Neolithic deposit with contemporary burials. Bronze Age burials, also present, had been cut into the Neolithic deposit and contained pairs of ceramic bivalve casting moulds and a single, copper-base, socketed axe. Nil Kham Haeng, a similarly massive site, had a remarkable stratigraphy, where the tons of crushed ore, slag, and other smelting remains had been smoothed flat, presumably during monsoon downpours. Human burials were interspersed within the c.6m of site matrix. Dating these sites has proved very difficult, in part because prehistoric disturbances complicate securing well-defined contexts for radiocarbon dates.

Three years ago, I emailed Vince Pigott with a proposal. Why don’t we deploy my research funds to go for broke dating your Valley sites? Andy Weiss, who had been responsible as field director for overseeing much of the excavating, had long since left archaeology, but came back to play a key role in identifying what contexts could best be sampled for dating. Vince had ensured, through a flotation programme directed by the late Steve Weber of Washington State University Vancouver, (WSUV) that plant remains were recovered. These had been meticulously analysed, and Weber identified many seeds of domestic millet, the earliest yet known in South-east Asia, suggestive of contact with China. There were also many seeds from the weed Spilanthes and, naturally in a smelting site, ample amounts of charcoal. Weber’s archaeobotanical programme was completed by Jade d’Alpoim Guedes (now at the University of California San Diego) and her then WSUV graduate student Sydney Hanson.

ABOVE Map made using GeoMapApp that shows the location of copper and tin deposits. Site 1 is Non Pa Wai and Site 5 is Ban Non Wat.
Map made using GeoMapApp that shows the location of copper and tin deposits. Site 1 is Non Pa Wai and Site 5 is Ban Non Wat.

Archaeology is increasingly a cooperative, team effort. One of our objectives was to go beyond producing a solid chronology by integrating the mining sites with the consumer sites, like Ban Non Wat, that we had already dated. So we called on Oli Pryce and his South-east Asian Lead Isotope Project (SEALIP) to contribute vital information on the lead-isotope values to see if some of the copper mined in the Khao Wong Prachan Valley shared isotopic signatures with artefacts from Ban Non Wat. This site and the Valley sites, 180km apart, lie on either side of the Petchabun Range, but there is a convenient pass that links them. We then had to engage with a radiocarbon lab capable of AMS-dating seeds. Here there was no issue: my son Tom, who directs the 14C lab at Oxford, and his colleague Christopher Bronk Ramsey were called in. There was also the need to interpret and date Valley-site contexts and the mortuary offerings within the burials. For this, we called on the expertise of Fiorella Rispoli and Roberto Ciarla from the International Association of Mediterranean and Oriental Studies in Rome, senior excavators at the Valley sites.

The gestation of this paper has been the most intensively difficult that I have ever been involved in. Andy Weiss had to pore over multitudes of archived field records to sort the best contexts and select the best samples to date. They had to be found, some being stored in the Penn Museum Philadelphia, others in the collections analysed by Steve, Jade, and Sydney. They then had to join the queue at Oxford, nigh on 100 precious samples. There is no email I await with greater anticipation and, indeed, trepidation, than one captioned ‘Your radiocarbon results’. Might they throw a spanner in the works and reveal no clear pattern, or might they reignite the old debate between the long and the short chronologies? Would they harmonise with the dates proposed on the basis of the material from the graves? Was there any evidence that dated copper from the Valley actually found its way through exchange into any of the consumer sites to the north-east?

First and foremost, the dates were most encouraging. They placed the initial Neolithic settlement around 2000 BC plus or minus a century or so. Then we faced the prime problem of dating thick, disturbed deposits of smelting debris. We would have liked to apply an OxCal Bayesian analysis, but Tom decided that the samples were not suitable. So he came up with a brainwave, applying what is known as Kernel Density Estimate or KDE modelling. This teases out a dated span of activity on the reasonable assumption that a millet grain reflects human presence. This placed the first copper production in the late 2nd millennium BC, followed by the casting of a huge quantity of quite small ingots well into the 1st millennium BC and perhaps later. We then turned to the lead isotopes. Oli Pryce had found that copper-base axes from early Bronze Age burials at Ban Non Wat had signatures compatible with Khao Wong Prachan metal. And the dates for both formed an excellent match.

We decided that our paper should be sent to Antiquity. It went through multiple variations until its 11 co-authors agreed that it was ready. We submitted our paper in September 2019 and, after the usual tense wait for referees’ opinions, it was accepted and published this August, along with a related article on archaeobotanical investigations at the Valley and neighbouring sites by Jade and her colleagues. It has been an endeavour that brought us both great satisfaction and grief: as we were nearing completion both Andy Weiss and Steve Weber, valued friends and teammates, passed away – well before their time.

T F G Higham et al. (2020) ‘A prehistoric copper-production centre in central Thailand: its dating and wider implications’, Antiquity 94: 948-965.