Masticatory and nonmasticatory functions: craniofacial adaptation

Gradients of occlusal wear in hunter‐gatherers and agriculturalists

“…Nondietary wear can be caused by using the teeth as a third hand or as a tool, from bruxism (grinding and/or clenching the teeth together), holding objects between the teeth (such as a pipe), objects rubbing against the lingual surface of a tooth (e.g., a lip disk) (Larsen, 1983(Larsen, , 1997aMilner and Larsen, 1991), or through erosion from chemical dissolution of the tooth surface by intrinsic (gastrooesophageal reflux) factors (Kaidonis et al, 1998;Kieser et al, 2001). These causes have been related to dental wear in archeological samples of modern humans (e.g., Molnar, 1972;Larsen, 1995Larsen, , 1997b.Variations in diet and daily task activities can produce different dental wear patterns. This was most clearly seen in comparisons between hunter-gatherers and agricultural groups where diet and food preparation, and daily task activities (not diet related) differ (Molnar, 1971a;P Smith, 1972;BH Smith, 1981, 1984a, BD Smith, 1995Turner, 1979;Hinton et al, 1980;Behrend, 1981;Hinton, 1981;Larsen, 1983;Turner and Cheuiche Machado, 1983;Richards, 1985;Walker and Erlandson, 1986;Walimbe and Lukacs, 1992;Lalueza et al, 1996;Lukacs, 1996;Kaifu, 2000).…”

Oral health in prehistoric San Pedro de Atacama oases, Northern Chile

“…The classic studies (for an example see Larsen, 1997b) propose a decrease in dental wear in the transition between hunting-gathering and cultivation. This decrement is related to two complementary factors: the ingestion of less diversified vegetable items and pre-oral food processing (Deter, 2009;Larsen, 1997b). It is very unlikely that the methods of food processing varied significantly during the different periods of the local pre-history.…”

“…The fibers that we suggested as part of the "new" diet during the Tiwanaku period could be responsible for the increase of dental wear and act as a protector against dental decay in two different ways. First, these fibers could have had a mechanical action (abrasion), removing the cariogenic biofilm from the dental surface (Larsen, 1997b). At the same time, these fibers could have increased the masticatory action, increasing the saliva flow providing a higher buffer capacity against bacterial cariogenic acids (Coogan et al, 2008;Dawes, 2008;Johansson et al, 2010).…”

Secular trends in Cherokee cranial morphology: Eastern vs Western bands

“…Relethford (2004) notes the presence of cranial plasticity being represented in craniometric dimensions, as Boas (1912) had originally proposed, but he supports Sparks & Jantz's (2002) findings that craniometric variation primarily reflects genetic variation. Buretic-Tomljanovic et al (2006) reference the influence of epigenetic factors on facial growth, with mastication (Larsen, 1997;Varella, 1992), dietary and technological changes (Larsen, 1997) or respiration (Mattar et al, 2004;Yang et al, 2002) also impacting craniofacial morphological changes.…”