A review of nose picking in primates with new evidence of its occurrence in Daubentonia madagascariensis

Nose picking (rhinotillexis) is a common behaviour in humans which remains, however, poorly studied. Several species of primates are known to pick their nose and ingest the nasal mucus suggesting that this behaviour may actually be beneficial and showing it is not restricted to humans. Here, we review relevant literature and online sources, and document the species of primates observed to pick their nose. We also present the first occurrence of this behaviour in a species of strepsirrhine primate (lemurs and relatives) with a unique video showing an aye-aye picking its nose. While doing so this animal inserts the entire length of its extra-long, skinny and highly mobile middle finger into the nasal passages and then licks the nasal mucus collected. We further investigate the internal anatomy of the nasal cavity of the aye-aye in order to understand how it can introduce its entire finger in its nasal cavity and discover that the finger likely descends into the pharynx. We show that this behaviour is present in at least 12 species of primates, most of them also showing great manipulative/tool use skills and may have some associated benefits that need to be further investigated. Further comparative studies examining nose picking and mucophagy in other primate species and vertebrates in general may shed additional light on its evolution and possible functional role.

Duke Scholars

Author Christine Elizabeth Wall Evolutionary Anthropology