For the first time, archaeologists have used advanced science and technology on 4,000-year-old dental plaques to see traces of beta biting in ancient Thai communities.
Bellfish nuts are usually bitten as a “quiz.” This is a mixture of sliming lime and ground bellfish nuts, containing psychoactive compounds that increase energy, vigilance, euphoria and relaxation.
Stimulants that can leave red, brown or black stains on teeth are considered to be the most commonly used psychoactive substance in the world, with hundreds of millions of users worldwide after caffeine, alcohol and nicotine.
In the past, kinmatz has been identified at archaeological sites via plant fragments or stained teeth, providing circumstantial evidence that its use dates back at least 8,000 years ago.
However, using advanced technology, an international team of researchers has identified beard bites in individuals who have no dental discoloration.
The study, published Thursday in the Environmental Archaeology Frontier, provides the earliest direct biochemical proof in Southeast Asia, preceded at least 1,000 years of previous evidence, said Piyawit Moonkam, an archaeologist at Chiang Mai University in Thailand.
The discovery of “invisible” traces of beard nut chewing on molars is that, due to some prehistoric practices, “the visible evidence that we have may not tell us the entire story,” Mooncam said.
Very sensitive and minimally invasive, the method only requires small samples of plaque and offers a “attractive” way to find more clues about the past, said Thanik Lertcharnrit, an associate professor at Shilpakorn University in Bangkok, Thailand and an expert on Southeast Asian archaeology, who is not involved in the study.
“From a methodological perspective, few, if any, archaeologists use such scientific methods of residual analysis to infer the lives, traditions and cultures of people (prehistoric periods),” says Lertcharnrit.
“This paper represents a pioneer. It is cutting edge in terms of archaeological research in mainland South Asia, particularly Thailand.”
Researchers began collecting ancient dental plaques known as calculus from Nong Rachawat, a Neolithic burial site in central Thailand.
This method, called liquid chromatography mass spectroscopy (LC-MS), extracts, separates and identifies chemicals by measuring whether molecules are compared to charge.
However, before testing the ancient samples, the team needed control samples. The results can be compared to show how traces of the kinmatz liquid look.
“We tried to mimic the culture of chewing,” Moonkham said, adding to the core components of dried kinna nuts, red limestone paste and Piper’s bean leaves, as well as some of the control samples contained catetchu bark and tobacco, and the ingredients grounded together with human saliva.
The latest control samples were first tested to validate the methods before analyzing the dental samples.
They detected three samples from one individual known as “burial 11,” perhaps a 25-year-old woman’s trace plant alkaloids (including the major psychoactive compounds of Betel Nut, Arecoline and Arecaidine.
Researchers say the advantage of this technique is that it does not destroy the original sample and leaves the rest intact for future research.
“No one has done this before.”
LC-MS is currently used in a variety of fields, including pharmaceuticals, food safety and environmental testing.
However, its previous use in archaeology has been limited, said Dr. Meland Vrok, a biofactorologist and lecturer in anatomy and physiology at Charles Sturt University in Australia.
“Many of the work done using this (method) is looking for proteins in dental calculus for dietary reasons. So, using it to pick up these compounds that are trapped in dental plaques, it’s really innovative.
There’s a reason that’s not common. This method requires expensive machines such as orbits, one of the most advanced mass spectrometers on the market, identifying molecules by measuring the mass-to-charge ratio that many researchers cannot access.
“It’s starting to be used more routinely by several larger labs like Harvard and Max Planck, which makes this research even more surprising. “To see this research come from within the region is actually what excites me the most.”
The team in this paper included researchers from eight institutions on three continents and chemical residue analysis was conducted at Washington State University, where Mooncam received his PhD.
The control samples from the studies that created the “standard” to test are another novelty, and future studies can further improve this by considering how the compounds deteriorate over thousands of years, Vlok said.
“This is a way that you can definitely see it being used very frequently in the area from now on,” she added.
Beta nuts have long been linked to hospitality and religious rituals, but much of recent research has focused on classification as a carcinogen and the correlation between beta use and oral cancer.
“Bean nut chewing means a lot to people’s health,” says Vlok. “It affects millions of people in the tropical Asia-Pacific today, but I really don’t know how long people are doing this.”
A better understanding of where tradition comes from and how and why people use it will help address some of these concerns, she added.
In Thailand, Mooncam said that this practice has been strongly discouraged by the government since the 1940s and is still popular in rural areas, but is now rare in cities and younger generations.
He recognizes the potential health risks, but Mooncam believes this practice is overly “devilized” and hopes that such research will demonstrate the long history of beard nuts in Thailand and their importance in society. He also has a personal attachment to practice. He has memories of his grandparents’ childhood, but usually chews his grandparents’ quiz while smacking him with friends or relaxing after a family meal.
“I asked my grandmother once, ‘Why do you bite it?’ And she replied, as it helps me to clean my teeth and relax,” Mooncam recalled. “When she bit it, she tended to share with friends, family, or colleagues. I think that’s important in the way that creates social bonds.”
Researchers are still investigating possible reasons why the individuals they investigated have no tooth stains. This speculates that it could have been rotten for different chewing methods, cleaning habits, or thousands of years.
Further research may help narrow down your possibilities. The team will analyze more individuals on the non-rachawat site, where 150 individuals can test signs of Kinmatz’s use, as they seek to dig deeper into the social, religious and medical role of Kinmatz in ancient society in future projects.
This technique can also be applied to a wide range of plant and food residues, opening up a new pathway to understanding ancient practices.
“I think people tend to ignore the social and cultural aspects of plants,” Mooncam said. “It’s important to understand the overall perspective.”
