Sociality, ecology, and relative brain size in lemurs

MacLean, Evan L.; Barrickman, Nancy L.; Johnson, E. M.; Wall, Christine E.

doi:10.1016/j.jhevol.2008.12.005

Cited by 62 publications

(59 citation statements)

References 76 publications

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“…Comparisons with foliovorous and cathemeral species might result in interesting differences in waiting times. Despite the overall lack of an influence of group size on brain size in MacLean et al (2009), studies of specific cognitive tasks do show differences in performance. For instance, the more highly social ring-tailed lemurs (Lemur catta) outperformed less social species such as mongoose lemurs (Eulemur mongoz), black lemurs, and ruffed lemurs in transitive inference and social cognition tasks (MacLean et al, 2008;Sandel et al, 2011).…”

Section: Discussionmentioning

confidence: 95%

“…For instance, in a comparative analysis of 19 species, MacLean et al (2009) explored how pairbonding, group size, diet, and activity pattern relate to brain size in lemurs. Though the social factors did not relate to brain size in their analysis, the ecological factors did: frugivores had larger brains that foliovores and cathemeral species (those active both during day and night) had larger brains than diurnal species.…”

Section: Discussionmentioning

confidence: 99%

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Intertemporal choice in lemurs

Stevens

Mühlhoff

2012

Behavioural Processes

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Different species vary in their ability to wait for delayed rewards in intertemporal choice tasks. Models of rate maximization account for part of this variation, but other factors such as social structure and feeding ecology seem to underly some species differences. Though studies have evaluated intertemporal choice in several primate species, including Old World monkeys, New World monkeys, and apes, prosimians have not been tested. This study investigated intertemporal choices in three species of lemur (black-and-white ruffed lemurs, Varecia variegata, red ruffed lemurs, Varecia rubra, and black lemurs, Eulemur macaco) to assess how they compare to other primate species and whether their choices are consistent with rate maximization. We offered lemurs a choice between two food items available immediately and six food items available after a delay. We found that by adjusting the delay to the larger reward, the lemurs were indifferent between the two options at a mean delay of 17 s, ranging from 9-25 s. These data are comparable to data collected from common marmosets (Callithrix jacchus). The lemur data were not consistent with models of rate maximization. The addition of lemurs to the list of species tested in these tasks will help uncover the role of life history and socio-ecological factors influencing intertemporal choices.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Intertemporal choice in lemurs

Stevens

Mühlhoff

2012

Behavioural Processes

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“…If these behaviors conferred fitness benefits, selection for these traits in particular lineages may have been an important factor in the evolution of species differences in self-control. A second possibility is that dietary breadth represents an ecological constraint on brain evolution, rather than a selective pressure per se (116,155,184,185). Accordingly, species with broad diets may be most capable of meeting the metabolic demands of growing and maintaining larger brains, with brain enlargement favored through a range of ecological selective pressures (86).…”

Section: Discussionmentioning

confidence: 99%

The evolution of self-control

MacLean¹,

Hare

Nunn³

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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652

708

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Cognition presents evolutionary research with one of its greatest challenges. Cognitive evolution has been explained at the proximate level by shifts in absolute and relative brain volume and at the ultimate level by differences in social and dietary complexity. However, no study has integrated the experimental and phylogenetic approach at the scale required to rigorously test these explanations. Instead, previous research has largely relied on various measures of brain size as proxies for cognitive abilities. We experimentally evaluated these major evolutionary explanations by quantitatively comparing the cognitive performance of 567 individuals representing 36 species on two problem-solving tasks measuring self-control. Phylogenetic analysis revealed that absolute brain volume best predicted performance across species and accounted for considerably more variance than brain volume controlling for body mass. This result corroborates recent advances in evolutionary neurobiology and illustrates the cognitive consequences of cortical reorganization through increases in brain volume. Within primates, dietary breadth but not social group size was a strong predictor of species differences in self-control. Our results implicate robust evolutionary relationships between dietary breadth, absolute brain volume, and self-control. These findings provide a significant first step toward quantifying the primate cognitive phenome and explaining the process of cognitive evolution.psychology | behavior | comparative methods | inhibitory control | executive function S ince Darwin, understanding the evolution of cognition has been widely regarded as one of the greatest challenges for evolutionary research (1). Although researchers have identified surprising cognitive flexibility in a range of species (2-40) and potentially derived features of human psychology (41-61), we know much less about the major forces shaping cognitive evolution (62-71). With the notable exception of Bitterman's landmark studies conducted several decades ago (63, 72-74), most research comparing cognition across species has been limited to small taxonomic samples (70, 75). With limited comparable experimental data on how cognition varies across species, previous research has largely relied on proxies for cognition (e.g., brain size) or metaanalyses when testing hypotheses about cognitive evolution (76-92). The lack of cognitive data collected with similar methods across large samples of species precludes meaningful species comparisons that can reveal the major forces shaping cognitive evolution across species, including humans (48,70,89,(93)(94)(95)(96)(97)(98). SignificanceAlthough scientists have identified surprising cognitive flexibility in animals and potentially unique features of human psychology, we know less about the selective forces that favor cognitive evolution, or the proximate biological mechanisms underlying this process. We tested 36 species in two problemsolving tasks measuring self-control and evaluated the leading hypotheses regarding how ...

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“…Both groups are of small to medium body size and more encephalized than the average mammal, and they thus devote a relatively large percentage of basal metabolism to brain maintenance (11%-12% as compared with 8%-9% in cercopithecoid primates, as calculated from Mink et al 1981;Isler et al 2008). Godfrey et al (2001) and Catlett et al (2010) showed that age at weaning is positively (or dental precocity is negatively) correlated to brain size in lemurs, but otherwise strepsirrhines do not exhibit the usual correlates of encephalization found in anthropoid primates, such as group size (Shultz and Dunbar 2007;MacLean et al 2009) or diet quality (Fish and Lockwood 2003).…”

Section: Introductionmentioning

confidence: 99%

Effects of Seasonality on Brain Size Evolution: Evidence from Strepsirrhine Primates

Woerden

Schaik

Isler

2010

The American Naturalist

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Seasonal changes in energy supply impose energetic constraints that affect many physiological and behavioral characteristics of organisms. As brains are costly, we predict brain size to be relatively small in species that experience a higher degree of seasonality (expensive brain framework). Alternatively, it has been argued that larger brains give animals the behavioral flexibility to buffer the effects of habitat seasonality (cognitive buffer hypothesis). Here, we test these two hypotheses in a comparative study on strepsirrhine primates (African lorises and Malagasy lemurs) that experience widely varying degrees of seasonality. We found that experienced seasonality is negatively correlated with relative brain size in both groups, controlling for the effect of phylogenetic relationships and possible confounding variables such as the extent of folivory. However, relatively larger-brained lemur species tend to experience less variation in their dietary intake than indicated by the seasonality of their habitat. In conclusion, we found clear support for the hypothesis that seasonality restricts brain size in strepsirrhines as predicted by the expensive brain framework and weak support for the cognitive buffer hypothesis in lemurs. Winterthurerstrasse 190, 8057 Zurich, Switzerland Submitted March 29, 2010; Accepted August 16, 2010; Electronically published October 20, 2010 Online enhancement: appendix.abstract: Seasonal changes in energy supply impose energetic constraints that affect many physiological and behavioral characteristics of organisms. As brains are costly, we predict brain size to be relatively small in species that experience a higher degree of seasonality (expensive brain framework). Alternatively, it has been argued that larger brains give animals the behavioral flexibility to buffer the effects of habitat seasonality (cognitive buffer hypothesis). Here, we test these two hypotheses in a comparative study on strepsirrhine primates (African lorises and Malagasy lemurs) that experience widely varying degrees of seasonality. We found that experienced seasonality is negatively correlated with relative brain size in both groups, controlling for the effect of phylogenetic relationships and possible confounding variables such as the extent of folivory. However, relatively largerbrained lemur species tend to experience less variation in their dietary intake than indicated by the seasonality of their habitat. In conclusion, we found clear support for the hypothesis that seasonality restricts brain size in strepsirrhines as predicted by the expensive brain framework and weak support for the cognitive buffer hypothesis in lemurs.

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Sociality, ecology, and relative brain size in lemurs

Cited by 62 publications

References 76 publications

Intertemporal choice in lemurs

Intertemporal choice in lemurs

The evolution of self-control

Effects of Seasonality on Brain Size Evolution: Evidence from Strepsirrhine Primates

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