Taste responsiveness of Western chimpanzees (Pan troglodytes verus) to five food-associated saccharides

Ellen Norlén,Madeleine Hjelm,Therese Hård,Matthias Laska,Desirée Sjöström

doi:10.1007/s10329-018-0697-0

Ellen Norlén, Madeleine Hjelm + Show 3 more

Open Access

https://doi.org/10.1007/s10329-018-0697-0

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Abstract

Using a two-bottle choice test of short duration, we determined taste preference thresholds for sucrose, fructose, glucose, lactose, and maltose in three Western chimpanzees (Pan troglodytes verus). Further, we assessed relative preferences for these five saccharides when presented at equimolar concentrations and determined taste preference difference thresholds for sucrose, that is, the smallest concentration difference at which the chimpanzees display a preference for one of the two options. We found that the chimpanzees significantly preferred concentrations as low as 20 mM sucrose, 40 mM fructose, and 80 mM glucose, lactose, and maltose over tap water. When given a choice between all binary combinations of these five saccharides presented at equimolar concentrations of 100, 200, and 400 mM, respectively, the animals displayed significant preferences for individual saccharides in the following order: sucrose > fructose > glucose = maltose = lactose. The taste difference threshold for sucrose, expressed as Weber ratio (ΔI/I), was 0.3 and 0.4, respectively, at reference concentrations of 100 and 200 mM. The taste sensitivity of the chimpanzees to the five saccharides falls into the same range found in other primate species. Remarkably, their taste preference thresholds are similar, and with two saccharides even identical, to human taste detection thresholds. The pattern of relative taste preferences displayed by the chimpanzees was similar to that found in platyrrhine primates and to the pattern of relative sweetness as reported by humans. Taken together, the results of the present study are in line with the notion that taste sensitivity for food-associated carbohydrates may correlate positively with phylogenetic relatedness. Further, they support the notion that relative preferences for food-associated carbohydrates, but not taste difference thresholds, may correlate with dietary specialization in primates.

Highlights

Comparative studies of taste perception allow us to gain insight into the mechanisms underlying the evolution of the sense of taste and the causes of between-species differences in taste performance
The results of the present study show that Western chimpanzees have a well-developed sensitivity for food-associated saccharides
They show that the five carbohydrates differ in their attractiveness and in their relative sweetness and that P. troglodytes verus has a well-developed ability to distinguish between different concentrations of sucrose

Summary

Introduction

Comparative studies of taste perception allow us to gain insight into the mechanisms underlying the evolution of the sense of taste and the causes of between-species differences in taste performance. 2011; McLennan 2013; Morgan and Sanz 2006; Watts et al 2012; Wrangham et al 1998). They are often referred to as primarily frugivorous and as ripe fruit specialists (Milton 1999; Pruetz 2006). Their food selection behavior suggests that chimpanzees may use the sweetness of fruits as a criterion for consumption (Dominy et al 2016; Hladik and Simmen 1996)

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