Titi monkey neophobia and visual abilities allow for fast responses to novel stimuli

Allison R Lau,Mark N Grote,Tristan J Franzetti,Karen L Bales,Madison E Dufek,Lynne A Isbell

doi:10.1038/s41598-021-82116-4

Allison R Lau, Mark N Grote + Show 4 more

Open Access

https://doi.org/10.1038/s41598-021-82116-4

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Abstract

The Snake Detection Theory implicates constricting snakes in the origin of primates, and venomous snakes for differences between catarrhine and platyrrhine primate visual systems. Although many studies using different methods have found very rapid snake detection in catarrhines, including humans, to date no studies have examined how quickly platyrrhine primates can detect snakes. We therefore tested in captive coppery titi monkeys (Plecturocebus cupreus) the latency to detect a small portion of visible snake skin. Because titi monkeys are neophobic, we designed a crossover experiment to compare their latency to look and their duration of looking at a snake skin and synthetic feather of two lengths (2.5 cm and uncovered). To test our predictions that the latency to look would be shorter and the duration of looking would be longer for the snake skin, we used survival/event time models for latency to look and negative binomial mixed models for duration of looking. While titi monkeys looked more quickly and for longer at both the snake skin and feather compared to a control, they also looked more quickly and for longer at larger compared to smaller stimuli. This suggests titi monkeys’ neophobia may augment their visual abilities to help them avoid dangerous stimuli.

Highlights

The Snake Detection Theory implicates constricting snakes in the origin of primates, and venomous snakes for differences between catarrhine and platyrrhine primate visual systems
We investigate the ability of coppery titi monkeys (Plecturocebus cupreus) to detect quickly a small portion (2.5 cm) of a snake skin, which provides only the visual cue of scale pattern, and the entire body of a snake, which, in addition to scale pattern, provides the visual cue of a curvilinear shape
Titi monkeys were relatively unresponsive in the presence of the partial snake skin

Summary

Introduction

The Snake Detection Theory implicates constricting snakes in the origin of primates, and venomous snakes for differences between catarrhine and platyrrhine primate visual systems. While titi monkeys looked more quickly and for longer at both the snake skin and feather compared to a control, they looked more quickly and for longer at larger compared to smaller stimuli This suggests titi monkeys’ neophobia may augment their visual abilities to help them avoid dangerous stimuli. Laboratory studies using different methods have consistently shown that both human and non-human primates visually detect snakes more quickly or attend to them longer than other stimuli, including animate stimuli such as spiders, frogs, caterpillars, and birds [ 16–22; earlier studies reviewed in23]. We investigate the ability of coppery titi monkeys (Plecturocebus cupreus) to detect quickly a small portion (2.5 cm) of a snake skin, which provides only the visual cue of scale pattern, and the entire body of a snake, which, in addition to scale pattern, provides the visual cue of a curvilinear shape. Titi monkeys are small-bodied, pair-bonded, platyrrhine p rimates[35,36] that are vulnerable to snakes[33,34] and, like many other primate species, give alarm calls and mob snakes when they are detected[34]

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