The evolution of quantitative sensitivity

Area of Science:

• Comparative cognition
• Evolutionary neuroscience
• Animal behavior

Background:

• The ability to represent approximate quantities is widespread across species, but its evolutionary drivers and underlying mechanisms are not well understood.
• Understanding the factors influencing quantity representation can provide insights into cognitive evolution.

Purpose of the Study:

• To investigate the phylogenetic and proximate factors influencing quantity discrimination abilities in birds and mammals.
• To identify which cognitive, socioecological, and biological factors predict variations in the precision of quantity representation.

Main Methods:

• A novel Bayesian model was employed, integrating phylogenetic regression with number psychophysics and random effects.
• Data from 49 studies, encompassing 672 subjects across 33 bird and mammal species, were analyzed.
• The Weber fraction, a measure of quantity representation precision, was calculated for each species.

Main Results:

• Phylogeny significantly influenced quantity discrimination performance across taxa.
• Cortical neuron density and domain-general cognitive abilities were identified as the strongest predictors of the Weber fraction, even after controlling for phylogenetic effects.
• The study demonstrated a relationship between species-specific neuron density and a specific cognitive ability.

Conclusions:

• Evolutionary constraints play a role in shaping cognitive abilities like quantity representation.
• Cortical neuron density is a key biological factor associated with the precision of approximate number systems.
• This research offers a novel perspective on the interplay between neurobiology, cognition, and evolution.