Dental microwear, the pattern of tiny marks on worn tooth surfaces, is an important basis for understanding the diets of fossil mammals, including those of our own lineage. Now nanoscale research by an international multidisciplinary group that included members of the Max Planck Institute for Evolutionary Anthropology in Leipzig has unraveled some of its causes. It turns out that quartz dust is the major culprit in wearing away tooth enamel. Silica phytoliths, particles produced by plants, just rub enamel, and thus have a minor effect on its surface. The results suggest that scientists will have to revise what microwear can tell us about diets, and suggest that environmental factors like droughts and dust storms may have had a large effect on the longevity of teeth. In particular, East African hominins may have suffered during dust storms, particularly from particles carried in by seasonal winds from the Arabian peninsula.
New research published by the scientists in Leipzig suggests that the main cause of the physical wear of mammalian teeth is the extremely hard particles of in soils in many parts of the world. To show this, single particles were mounted on flat-tipped titanium rods and slid over flat tooth enamel surfaces at known forces. Quartz particles could remove pieces of tooth enamel at extremely low forces, meaning that even during a single bite, these particles could abrade much of the surface of the tooth if they are present in numbers.
In contrast, fossilized plant remains, so-called phytoliths, indented the enamel under the same conditions, but without tissue removal. The effect of the considerably softer phytoliths is similar to that of a fingernail pressed against a softwood desk. This kind of mark, called a rubbing mark, is visible but purely cosmetic.
The Max Planck Institute's Amanda Henry provided the phytoliths for the study, and assisted in the interpretation. "This study suggests that phytoliths do affect teeth, but in a different manner than we previously thought," she says. A new theory of wear, developed by collaborator Tony Atkins from Reading in the UK, suggests exactly what geometrical and material conditions are required for abrasive versus rubbing contacts. "People have not realized the vital importance of factoring fracture toughness into wear analyses" says Prof. Atkins. Study leader and Kuwait University researcher Peter Lucas says "we think that we've gone a lot further with the analysis of microwear than previous investigations because we realized that to uncover the mechanisms that cause it, you need to go one level smaller – to nanoscale. It is only then that the difference between relatively innocuous rubbing contacts and those that remove tooth tissues becomes clear." The team could distinguish between marks made by quartz dust, plant phytoliths, and also by enamel chips rubbing against larger pieces of enamel.
Lucas PW, Omar R, Al-Fadhalah K, Almusallam AS, Henry AG, Michael S, Arockia Thai L, Watzke J, Strait DS & Atkins AG. Mechanisms and causes of wear in tooth enamel: implications for hominin diets.
Journal of the Royal Society Interface. Published online, Journal of the Royal Society Interface, published online January 9, 2013
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Beyond military motives to copy animal hiding techniques, scientists foresee fabrics, cars and walls that change colour
The type of eruption that left an ashen landscape at the peak of Mount Ontake could occur at many apparently sleeping volcanoes
Experimental device uses an array of lenses to bend light, effectively rendering what is on the other side invisible to the eye
The Lady With an Ermine is believed to have been painted in 1489 or 1490
A new study argues that the theory biologists use to predict an ecosystem's biodiversity should be modified to account for the global economy. The post How Global Shipping Could Change Our Understanding of Biodiversity appeared first on WIRED.
The presenter and physicist Brian Cox says he supports the idea that many universes may exist.
Ripples in space touted as proof of the Big Bang theory might simply be cosmic interference, a new study finds
The eruption has been going for weeks. So far it hasn't been catastrophic, but it has been creating new ground.
The human eye has inspired physicists to create a processor that can analyse particle collisions 400 times faster than currently possible.
Adjusting the numbers of various types of molecule in the environment seem to improve the chances of self-replicating life generating spontaneously