The lemur baseline: how lemurs compare to monkeys and apes in the Primate Cognition Test Battery

Abstract

Primates have relatively larger brains than other mammals even though brain tissue is energetically costly. Comparative studies of variation in cognitive skills allow testing of evolutionary hypotheses addressing socioecological factors driving the evolution of primate brain size. However, data on cognitive abilities for meaningful interspecific comparisons are only available for haplorhine primates (great apes, Old- and New World monkeys) although strepsirrhine primates (lemurs and lorises) serve as the best living models of ancestral primate cognitive skills, linking primates to other mammals. To begin filling this gap, we tested members of three lemur species (Microcebus murinus, Varecia variegata, Lemur catta) with the Primate Cognition Test Battery, a comprehensive set of experiments addressing physical and social cognitive skills that has previously been used in studies of haplorhines. We found no significant differences in cognitive performance among lemur species and, surprisingly, their average performance was not different from that of haplorhines in many aspects. Specifically, lemurs’ overall performance was inferior in the physical domain but matched that of haplorhines in the social domain. These results question a clear-cut link between brain size and cognitive skills, suggesting a more domain-specific distribution of cognitive abilities in primates, and indicate more continuity in cognitive abilities across primate lineages than previously thought.

Linking ecology and cognition: does ecological specialisation predict cognitive test performance?

“…Finally, most of the cognitive tests were not explicitly designed to have any functional relevance in terms of sociality or variation in social traits, so that a correlation with performance scores is unlikely. Hence, to address the relative importance of either ecological or social factors driving the evolution of brain size, comprehensive cognitive test batteries addressing both sets of factors are required (Shaw and Schmelz 2017;Völter et al 2018;Fichtel et al 2020).…”

Electrome & Cognition Modes in Plants: A Transdisciplinary Approach to the Eco-Sensitiveness of the World

“…For the first time reported about plants by Debono (2016Debono ( , 2018 [12,17] who adapted the concept of plasticity (Table 1) he developed [29,30] to their behavior (i.e. developing a mesological plasticity), that highlights the plant body anchored in the soil (Table 1).…”

“…If this hypothesis was adopted, added to the sensible vs sensitive nature recently admitted by the scientific community about the sensory system of plants, it would constitute a big step in our classification of the living kingdoms and in the modeling of sensory perception modes [34]. This could help solve the apparent conundrum of cognitive scales disproportionate to the size of the brain of animals like birds (recent works show that the delta observed between the small size of the brains of birds and their high cognitive abilities are probably due to a high density of neurons: see Olkowicz et al 2019) [28] or lemurs having relatively small brains for primates (Fichtel et al, 2020) [29], without mentioning one of the great puzzles of contemporary science, i.e. the unicellular unclassifiable organisms such as the Polycephalum physarum that are able to execute high cognitive tasks without brain.…”

Motion cues increase focused attention towards purely visual stimuli in a nocturnal primate and drive stimulus interaction and approach/avoidance in a context‐dependent manner

“…Therefore, it is suggested that their vision plays a minor or no role in some social tasks, such as species or mate recognition (e.g., Braune et al, 2008;Gomez et al, 2012;Kollikowski et al, 2019). Nevertheless, there is evidence from laboratory studies that visual stimuli consisting of two horizontally paired circles, resembling a pair of eyes, can trigger submissive gaze aversion in the gray mouse lemur (Coss, 1978) and that mouse lemurs can use visuosocial cues from a human experimenter to spontaneously solve tasks in a lemur version of the primate cognitive test battery (Fichtel et al, 2020). Finally, there is some evidence that vision supports predator detection and recognition in mouse lemurs (e.g., Rahlfs & Fichtel, 2010;Zimmermann et al, 2000).…”