Intentional gestural communication in Hanuman langur
Data files
Sep 05, 2023 version files 6.47 KB
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Data_file_IGC.csv
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README.md
Abstract
Contrary to previous beliefs, intentional gestural communication (IGC) is not exclusive to the hominoid lineage but is also present in other non-human primates. Here, we report the presence of IGC among free-ranging Hanuman langur troop in Dakshineswar, West Bengal, India. These langurs exhibit a food-requesting behaviour wherein they use several gestures to communicate with the humans nearby. Moreover, they can also assess the recipient's mental state and persistently check if the signal (food request) has been received, waiting until they receive the desired food item. We have identified eight begging gestures used by langurs of all ages, except infants. The most common gesture is by holding cloth (BGc), but provocation-initiated begging (BGpi) and begging by embracing legs (BGe) efficiently direct these events to its success. The frequency of successful begging events is higher in the evening due to increased human interactions. Our findings suggest that ontogenetic ritualization might be at play here among these troop members as this gestural communication has been learned through imitation and reinforced by the reward of receiving food. Moreover, these successful begging events serve as an effective foraging strategy for urban-adapted langurs, allowing them to acquire high-calorie processed food items within a human-modified urban ecosystem.
README: Intentional gestural communication in Hanuman langur
We found that these langurs exhibit first-order intentional gestural communication wherein the langurs acknowledge the mental state of the human recipient, exhibit means-end dissociation and show signs of waiting for the human to respond to it's gestural call. The given dataset contains details of begging (intentional gestural communication) events observed in the langur troop of Dakshineswar. We observed langurs during different time slots of the day following Altman(1976) with a combination of AOS (10 minutes) and Scan(1 minute). These langurs use around eight different postures to communicate with nearby human and ask for food. From our observations we have noted down the different postures, the total number of successful begging, total number of begging shown by the different age groups - Adult, sub-adult, Juvenile and Infant. Given that this study troop has high adult females, this age group has been found to have a high impact on the outcome of begging event alongwith the begging posture that involves pulling of human's clothes.
Description of the data and file structure
The following data structure contains around 20 columns having different data points.
Column A has slot details S1 (Session 1: Morning), S2 (Session 2: Afternoon) and S3(Session 3: Evening)
Column B to Column I contain details of begging events executed by the free-ranging langurs in the eight
postures described in the manuscript. PA: Bipedal begging, PB: Quadrapedal begging, PC: begging by embracing human legs, PD: posture involving langur pulling human hand, PE: begging with aggression, PF: posture involving langur pulling human's cloth, PG: passive begging, PH: provocation inititated begging
Column J (PS: Successful begging events) has details of successful begging events that occurred during
the observation period.
Column K to Column N has details of begging events shown by different age groupd of langurs - Column K: (BA) Adult, Column L: (BS) Subadult, Column M: (BJ) Juvenile and Column N: (BI) Infant
Column O to Column T has details about the food offering sequence number from humans where B1 stands for food offered after one round of begging, B2 stands for food offered after second round of begging, B3 for food offered after the third round of begging, b4 for food offered after fourth round of begging, B5 and B6 for food offered after the fifth and sixth round of begging respectively.
There are 84 rows out of which 83 rows contain details of begging events recorded for different sessions(see Column A description about session) during the observation period.
Sharing/Access information
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Code/Software
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Methods
This dataset was collected through field-based observation in a field site spanning three years. We carried out field observation across three sessions of three hours each - Morning , Afternnon and Evening. Observations consisted of 10 minutes of All Occurence Sampling (AOS) and 1 minute Scan done randomly across three sessions of the day.