Your interest in the gorillas at Prague Zoo does not cease in summer. Let's talk about gorillas' teeth today. We have not paid much attention to dentition in gorillas yet. However, you often ask Marek Zdansky about teeth and their development in gorillas - perhaps due to the fact that the Prague Zoo gorillas are happy and their smiles often reveal rows of seemingly healthy and strong teeth
Teeth are an interesting subject of research. Primitive placental mammals originally had a large number of teeth - their dentition comprised 44 teeth arranged in the 5.1.4.3 pattern (i.e. in this order: incisors, canines, bicuspids, and molars). At present, none of the existing primates has more than two pairs of incisors in each gnathic arch. Over the millennia of development, incisors and bicuspids were reduced while canines and molars proved very useful. They were not reduced but transformed. Depending on the sex, they differ substantially in size, shape, function, and position. Depending on the prevailing type of food, molars are equipped with various crests points, or ridges. Incisors lost their function to mince food. Instead, they find use in hunting and dissecting prey, or perform secondary functions, such as to express threat, as a weapon in fighting between males over a female, etc.
Gorillas, like humans and all ape species, have their dentition arranged in the 2.1.2.3 pattern with 32 teeth in adulthood. Evolutionary trend to reduce the number of teeth continues, as witnessed by the unfortunate wisdom teeth. It is noteworthy that the third set of molars is often absent in humans, while chimpanzees seldom lack them and gorillas have them virtually without exception. Dentition in gorillas changes completely during adolescence the same way as in humans. The first teeth erupt earlier in gorillas than in humans - the first two incisors are visible at the age of one month.
Gorilla teeth bear certain typical features. Incisors are relatively small. Canines are massive, with a significant difference in size between males and females. Canines in females are shorter and very robust, while the same teeth in males are also robust but much longer. Molars are large, flat, with pronounced ridges. Such configuration of teeth is rather unusual among existing apes. Originally, it was attributed to leaf-eating but modern studies suggest that foliage did not constitute such a big part of the diet of mountain gorillas in the past as it does today, and that this adaptation may stem from the necessity to mince large amounts of lower quality, tougher food - whether branches, tree bark, sprouts, and unripe fruit.
Let's take a closer look at the large canines in gorillas, especially in big males. There is no such sexually-conditioned duality in humans. In addition, human canines are not as protruding. Large canines are generally observed in carnivorous animals - predators need them to kill prey. Apes, like humans, are omnivorous and their teeth testify to that. Gorillas do not use their canines to acquire and dissect animal flesh yet these teeth have not lost their significance. They are useful for breaking hard materials, such as bamboo, and males use them as a weapon either to fight either each other (they usually only threaten a rival by showing the teeth), or against predators.
It is not easy to check the teeth of gorillas in captivity. If there is no visible manifestation of pain or other problems, there are no regular check-ups and the dentition is inspected only when an animal needs to be tranquillised for some reason. Unfortunately, this haphazard approach cannot reveal problems in early stages but usually when it develops. It is therefore necessary to provide appropriate diet, as natural as possible. Nevertheless, proper diet alone is not sufficient to prevent dental issues. Gorillas in the wild suffer from dental problems, too - inflamed gums and corrupt teeth have often been observed in dead gorillas, possibly as a consequence of daily consumption of woody food.
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