Source Paper
Evan L. MacLean, Brian Hare, Charles L. Nunn, Elsa Addessi, Federica Amici et al.
Proceedings of the National Academy of Sciences • 2014
Significance Although 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 problem-solving tasks measuring self-control and evaluated the leading hypotheses regarding how and why cognition evolves. Across species, differences in absolute (not relative) brain volume best predicted performance on these tasks. Within primates, dietary breadth also predicted cognitive performance, whereas social group size did not. These results suggest that increases in absolute brain size provided the biological foundation for evolutionary increases in self-control, and implicate species differences in feeding ecology as a potential selective pressure favoring these skills.
Objective: Quantitatively compare cognitive performance of multiple species on two problem-solving tasks measuring self-control and inhibitory control to test evolutionary hypotheses about cognitive evolution
Experimentally evaluated major evolutionary explanations by quantitatively comparing cognitive performance across multiple species on two problem-solving tasks measuring self-control
Note: This was a large-scale comparative study integrating experimental and phylogenetic approaches
“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”
Subjects were tested on two problem-solving tasks designed to measure self-control and inhibitory control abilities
Note: Specific task details not provided in the methods section excerpt
“tested 36 species in two problem-solving tasks measuring self-control”
Quantitative performance data was collected from all 567 individuals across the 36 species on the two problem-solving tasks
Note: Performance metrics were recorded for subsequent analysis
“quantitatively comparing the cognitive performance of 567 individuals representing 36 species on two problem-solving tasks”
Phylogenetic analysis was conducted to evaluate relationships between brain volume measures and cognitive performance across species
Note: Analysis examined both absolute brain volume and brain volume controlling for body mass
“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”
Within primates, dietary breadth and social group size were evaluated as predictors of species differences in self-control performance
Note: Dietary breadth was found to be a strong predictor while social group size was not
“Within primates, dietary breadth but not social group size was a strong predictor of species differences in self-control”
567 individuals representing 36 species tested across two problem-solving tasks