Elephants have a nose for quantity

Abstract

Animals often face situations that require making decisions based on quantity. Many species, including humans, rely on an ability to differentiate between more and less to make judgments about social relationships, territories, and food. Habitat-related choices require animals to decide between areas with greater and lesser quantities of food while also weighing relative risk of danger based on group size and predation risk. Such decisions can have a significant impact on survival for an animal and its social group. Many species have demonstrated a capacity for differentiating between two quantities of food and choosing the greater of the two, but they have done so based on information provided primarily in the visual domain. Using an object-choice task, we demonstrate that elephants are able to discriminate between two distinct quantities using their olfactory sense alone. We presented the elephants with choices between two containers of sunflower seeds. The relationship between the amount of seeds within the two containers was represented by 11 different ratios. Overall, the elephants chose the larger quantity of food by smelling for it. The elephants’ performance was better when the relative difference between the quantities increased and worse when the ratio between the quantities of food increased, but was not affected by the overall quantity of food presented. These results are consistent with the performance of animals tested in the visual domain. This work has implications for the design of future, cross-phylogenetic cognitive comparisons that ought to account for differences in how animals sense their world.

Elephant Genomes Reveal Accelerated Evolution in Mechanisms Underlying Disease Defenses

“…4 and 5 , supplementary data , Supplementary Material online). This is perhaps related to uniquely acute elephant olfaction abilities compared with other mammals ( Plotnik et al 2019 ). Many of the significantly enriched GO terms were also related to the immune system in both elephant species ( fig.…”

Investigating Indirect and Direct Reputation Formation in Asian Elephants (Elephas maximus)

“…Another limitation is that our experiments were mainly visual tasks and elephants rely on more non-visual sensory information, such as auditory and olfactory cues (Plotnik et al, 2013 , 2014 , 2019 ; Schmitt et al, 2018 , 2020 ; McArthur et al, 2019 ; Jacobson and Plotnik, in press ). The elephants did have access to complementary visual, acoustic, and olfactory cues in our study; apart from the individuals' smell, the partners wore contrasting clothes and said different sentences when they interacted with the demonstrator.…”

“…An alternative explanation is that elephants may require different types of information to eavesdrop than chimpanzees. This could be because chimpanzees are more visual, while Asian elephants may be more reliant on acoustic and olfactory information in their environments (e.g., Plotnik et al, 2013 , 2019 ; Ketchaisri et al, 2019 ); thus, they may need more non-visual sensory information to understand the partner's different roles.…”

Long‐term monitoring of seed dispersal by Asian elephants in a Sundaland rainforest

“…Asian elephants have dichromatic vision during the day and are therefore unable to distinguish red from green and orange from yellow (Yokoyama et al., 2005). This suggests that Asian elephants do not rely on color cues but on their sensitive olfactory sense (Plotnik et al., 2019; Rizvanovic et al., 2012) to find fruits on the forest floor. Fruits consumed by Asian elephants in Thailand emit a sweet aroma (Kitamura et al., 2007) and fruits like Durio spp., Artocarpus spp., Mangifera spp., and Dillenia indica emit a distinct pungent scent that is perceivable from a considerable distance.…”