Measurements of Salivary Alpha Amylase and Salivary Cortisol in Hominoid Primates Reveal Within-Species Consistency and Between-Species Differences

Abstract

Salivary alpha amylase (sAA) is the most abundant enzyme in saliva. Studies in humans found variation in enzymatic activity of sAA across populations that could be linked to the copy number of loci for salivary amylase (AMY1), which was seen as an adaptive response to the intake of dietary starch. In addition to diet dependent variation, differences in sAA activity have been related to social stress. In a previous study, we found evidence for stress-induced variation in sAA activity in the bonobos, a hominoid primate that is closely related to humans. In this study, we explored patterns of variation in sAA activity in bonobos and three other hominoid primates, chimpanzee, gorilla, and orangutan to (a) examine if within-species differences in sAA activity found in bonobos are characteristic for hominoids and (b) assess the extent of variation in sAA activity between different species. The results revealed species-differences in sAA activity with gorillas and orangutans having higher basal sAA activity when compared to Pan. To assess the impact of stress, sAA values were related to cortisol levels measured in the same saliva samples. Gorillas and orangutans had low salivary cortisol concentrations and the highest cortisol concentration was found in samples from male bonobos, the group that also showed the highest sAA activity. Considering published information, the differences in sAA activity correspond with differences in AMY1 copy numbers and match with general features of natural diet. Studies on sAA activity have the potential to complement molecular studies and may contribute to research on feeding ecology and nutrition.

Salivary amylase – The enzyme of unspecialized euryphagous animals

“…75 Similar enzyme activity has been detected in the closely related bonobos (Pan paniscus). 76 However, when compared with Western lowland gorilla In conclusion, focusing on the activity of salivary α-amylase in humans, interesting differences from other primates and other Hominidae can be found (Fig. 4).…”

“…Focusing on humans, salivary α-amylase is very active in comparison with that in many other animals as discussed above 73,76,107 (Fig. 4).…”

“…ruminants 72,73 and primates. [74][75][76] In general, in the animal kingdom three nutritional types occur; carnivores, herbivores and omnivores can be distinguished. This leads to the question of whether amylase can be found in saliva of these different nutritional types and if so, whether the amount is comparable to that of humans.…”

“…The variations in α-amylase activity occurring between different ape species could result from the different dietary patterns and the corresponding genetic disposition and selection. 76 Accordingy, it is still unclear which nutritional component is mainly responsible for these inter-species differences in enzyme activity.…”

Sex‐specific variation in the onset of reproduction and reproductive trade‐offs in a boreal small mammal

“…In order to avoid these problems, researchers have shown increasing interest in noninvasive methods for hormonal sampling. Saliva, hairs, urine and feces have been under research in order to obtain a reliable, but noninvasive method for studying hormonal status , Keckeis et al 2012, Behringer et al 2013, Zeugswetter et al 2013. With many species fecal samples are shown to be a practical method for this purpose Palme 2005, Sheriff et al 2011).…”