Age‐related changes in molar topography and shearing crest length in a wild population of mountain Gorillas from Volcanoes National Park, Rwanda

Abstract

Our findings indicate that shearing function is maintained throughout the long lifetimes of mountain gorillas. Unlike the dental senescence experienced by other folivorous primates, mountain gorillas do not appear to possess senesced molars despite their long lifetimes, mechanically challenging diets, and decreases in occlusal topography with age.

Wear and its effects on dental topography measures in howling monkeys (Alouatta palliata)

“…Our finding that DNE increases with DER is generally consistent with previous work using similar topographic measures (e.g., Bunn & Ungar, ; Glowacka et al, ; M'Kirera & Ungar, ; Ungar & M'Kirera, ). Dennis et al () measured surface angularity (referring to it a measure of “ruggedness”) on teeth from the same population of howling monkeys examined here, and noted that angularity remained remarkably consistent despite wear stage and clear reduction of crown height.…”

“…To avoid inter‐observer error and reliance on occlusal features that are morphologically fluid with wear, some studies of brachydont teeth (particularly those concerning primates) have turned to topography‐based metrics when analyzing variably worn teeth or dental wear series (e.g., Bunn & Ungar, ; Glowacka et al, ; Ungar, ; Ungar & M'Kirera, ; Ungar & Williamson, ; Zuccotti, Williamson, Limp, & Ungar, ). Thus far, dental wear and topography studies on primates have focused on surface slope, angularity, and Ungar's formulation of RFI (Ungar & M'Kirera, ).…”

Applying wet sieving fecal particle size measurement to frugivores: A case study of the eastern chimpanzee (Pan troglodytes schweinfurthii)

“…Folivores such as geladas consume foods that are both tough and hard, which necessitates more average daily chewing cycles and larger average bite forces compared to frugivorous primates (Taylor, ). To cope with this, geladas have a highly specialized hypsodont dentition with shearing crests that are formed from repeated use, similar to a mechanism described for Edward's sifakas (King et al, ) and mountain gorillas (Glowacka, et al, ), but that wear down substantially in old age. This wear pattern is apparently responsible for prime adults having greater chewing, and thus digestive, efficiency than infants and past‐prime adults (Venkataraman et al, ).…”

“…This suggests that chewing efficiency was reduced in old geladas, presumably due to molar wear. In contrast, Edward's sifakas ( Propithecus edwardsi ) (King et al, ) and mountain gorillas ( Gorilla beringei beringei ) (Glowacka et al, ) maintain their molar morphology related to shearing function despite increased age‐related occlusal wear. However whether FPS increases in old individuals of these species is unknown.…”

Age-Related Tooth Wear Differs between Forest and Savanna Primates

“…The shearing capacity in sifakas and mountain gorillas appears, however, to be independent of age [18], except in very old sifakas [10]. The fact that age seems not to greatly impact shearing capacity in these two species suggests that natural selection may shape tooth anatomy to maintain a certain degree of occlusal relief and functionality, especially in those folivorous primates that may need higher cusps for a lifelong mastication of tough fibrous foods [10], [18]. Other studies show that folivorous colobines present more sloping surfaces and more relief in tooth crowns than frugivorous cercopithecines at every tooth wear stage and age [4].…”