Atele (Tonga) :Ancient Baby Teeth Reveal Secrets Of A Polynesian Empire
Kristina Killgrove
Prehistoric child from the site of ‘Atele, Kingdom of Tonga. (Image used with kind permission of Siân Halcrow.)
In the middle of the South Pacific, near Fiji and American Samoa, lies the island of Tonga. Until the 19th century, this now sovereign archipelago was ruled by a line of kings called the Tu’i Tonga. The peak of power of the Tu’i Tonga Empire came in the early 16th century. But then civil wars rocked Tonga, and European explorers arrived, causing chaos. A team of archaeologists has been investigating skeletal remains from the Tu’i Tonga Empire to find out what the human toll was from this time of political instability.
With the permission of the contemporary Royal Kingdom of Tonga, archaeologists from the University of Otago in New Zealand analyzed baby teeth from two burial mounds at the prehistoric site of ‘Atele on the island of Tongatapu, the center of the ancient Empire. The skeletons date to about 1500-1800 AD, a time when there was increased trade and also increased differences among the social classes.
During this period, the paramount chief of the Tu’i Tonga Empire funded massive buildings by commandeering the surplus production of the lower classes. Within a couple of centuries, these social classes – and the Empire itself – fractured as a result of internal political struggles and war.
The archaeological site of ‘Atele, with its large sample of infant and child skeletons, is allowing archaeologists to address questions about health, disease, and physiological stress during infancy. The spread of infectious disease and periodic episodes of famine during this time, the archaeologists suspected, likely affected the vulnerable sectors of the population most severely.
In order to test their hypothesis, the team, led by dentist Rami Farah and bioarchaeologist Siân Halcrow, used X-ray microtomography (XMT) to closely study the ancient children’s teeth for evidence of discoloration caused by physical stress. XMT essentially creates multiple X-rays of a small object that can be sliced in two different dimensions: almost like a CT scan for baby teeth.
Using XMT, Farah and colleagues write in the open-access science journal Matters Select that they found a significant difference between the discolored and non-discolored baby teeth from the ‘Atele burial sites. That is, the discolored teeth are the result of physical stress early in life, not a result of staining from the burial environment.
Halcrow explained to me that “our findings of early life stress from the teeth are echoed in the pathological evidence for infectious and metabolic disease in many of the infants and children from this site;” information that has previously been published by study co-author Hallie Buckley.
The defects in enamel that the team found may have been related to infection from a disease like yaws, to other common tropical infections like hookworm, or to periodic under-nutrition, all of which can affect a growing child’s metabolism and result in poor development of the teeth and bones.
“This paper,” the researchers write, “is the first step for providing a fuller understanding of the life histories of these infants and children in Chiefdom Period in Tonga, a period of increasing hierarchy and interactions through trade networks.”
Woodcut by Isaack Gilsemans based on the travel diary of Abel Tasman (1642-1643), portraying the clothing, boats, and settlements of the population of Tongatapu. (Image via wikimedia commons, in the public domain.)
More importantly, though, this new study represents a novel way of examining health of very young children in the past. Archaeologists routinely examine adult teeth for evidence of defects in enamel. Because the permanent teeth grow during childhood, defects in them are related to stress that the person went through during childhood. But what about the people who didn’t live through infancy?
“With previous methods,” Halcrow tells me, “we can only look at the people who survived early childhood.” She further explains that this new technique, which identifies defects in early-forming teeth, “has allowed us to identify early life stress of the children who succumbed to illness during this politically and socially turbulent time.”
The team has so far applied their new method to look at the stress experience of the most vulnerable people living in a powerful ancient empire in the Pacific Islands. They plan, however, to undertake more of this type of research in the future.