Blame your ancestors for your dental problems, says new research.
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DUBLIN: If you're living in an industrialised country and suffering with certain dental problems, blame your ancestors. The switch from a hunter-gatherer diet to a reliance on domestic plants or animals are responsible, say scientists.
A study of 11 globally distributed populations found that as humans shifted to an agricultural lifestyle, the size and shape of their lower jaw changed, potentially explaining the relatively high incidence of dental crowding and dental misalignment in modern populations.
"The hunter-gatherer groups had longer and narrower mandibles, indicating more room for the teeth to erupt correctly, while the agriculturalists had generally shorter and broader mandibles, increasing the likelihood of dental crowding," said Noreen von Cramon-Taubadel of the University of Kent in England, who reported her findings in Proceedings of the National Academy of Sciences today.
Hunter-gatherers
For years, there has been debate over whether the move from a largely hunter-gatherer to an agricultural subsistence strategy across much of the world impacted the growth and development of the human skull and jaw.
Von Cramon-Taubadel has found that lower jaw shape (mandible), and to a lesser extent the upper palate, was related to diet, whereas the skull (cranium) is strongly related to the genetic relationships of populations. Chewing behaviour causes the lower jaw to grow and develop differently depending on whether you hunt and gather or live off agricultural produce. The skull is not affected, however.
Von Cramon-Taubadel compared the shape of the cranium (skull) and mandible (lower jaw) of 11 populations from around the world - six agricultural and five hunter-gatherer fishers. Included were Italians, Han Chinese and Japanese, as well as African San, Greenland Inuit and Australian Aborigines.
A packed jaw
The results showed that those of us living on agricultural produce have packed the same number of teeth into a shorter jaw, with hunter-gatherers having consistently longer and narrow mandibles.
"That is the case irrespective which part of the world they come from," von Cramon-Taubadel said. Her findings support the idea that a softer diet means reduced chewing stress, which causes the jaws of people on agricultural diets to grow and develop differently.
The mismatch between the size of the lower face and the dentition leads to increased prevalence of dental crowding and malocclusions in modern post-industrial populations, von Cramon-Taubadel wrote in the study. She predicted that hunter-gatherer societies do not suffer so much from these dental problems.It is impossible to say when the change occurred, or how long it might have taken, she said. "All my samples are modern, so they can't speak to the nature of the transition. That would require a look at prehistoric samples."
Dental bills
Anthropologist Clark Larsen of Ohio State University in the U.S. commented that the transition likely began as soon as populations began the shift to farming and began to use technology that softened food consistency, texture, and hardness, such boiling and cooking in ceramic vessels.
Larsen has studied populations that adopted maize agriculture in the 12th century A.D. "Comparison of the pre- and post-maize farmers showed a reduction in craniofacial robusticity (smaller jaws and faces). I regard the reduction as largely developmental rather than rapid evolutionary (genetic) change."
He added that the foraging to farming transition was a process involving a wide variety of plants and animals, varying levels of commitment to farming once the transition was made, and considerable variation in how foods - plants, in particular - were processed for consumption. Moreover, the transition took place not "on several occasions" but rather in at least 10 independent centres.
diet causes painful dental bills ?
As if longer life expectancy does not affect dental health at all.
Further research on human plasticity
PhD Mary Doria Russell wrote a ground-breaking paper on how using the mouth as a tool influences skull shape, published in Current Anthropology, Vol. 26, No. 3, June 1985. 'The Supraorbital Torus: "A Most Remarkable Peculiarity" ' Recommended for further reading on the subject.