Brains, brawn and sociality: a hyaena's tale.

Area of Science:

• Evolutionary biology
• Cognitive science
• Neuroscience

Background:

• Theories suggest intelligence evolves to solve environmental problems.
• The social complexity hypothesis posits intelligence evolved for social interactions.
• Primate and spotted hyena social systems show remarkable convergence.

Purpose of the Study:

• Investigate if social complexity drives cognitive evolution in carnivores.
• Test predictions of the social complexity hypothesis regarding cognition and brain size.
• Determine if social complexity explains domain-general intelligence.

Main Methods:

• Reviewed social complexity and cognitive abilities in primates and hyenas.
• Examined brain size and frontal cortex volume in Hyaenidae family.
• Assessed problem-solving innovation in 39 carnivore species using puzzle boxes.

Main Results:

• Spotted hyenas and primates show convergent social cognition.
• Social complexity may correlate with frontal cortex enlargement in Hyaenidae.
• Larger relative brain size predicted innovation in puzzle box tasks, not social complexity.
• Social complexity did not predict brain volume or problem-solving success outside the social domain.

Conclusions:

• Social complexity appears to enhance social cognition.
• No clear causal link found between social complexity and brain size or non-social problem-solving in carnivores.
• Evolution of domain-general intelligence may not be solely driven by social complexity.