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Both social and ecological factors predict ungulate brain size
1School of Biological Sciences, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK. susanne.shultz@liv.ac.uk
Proceedings. Biological Sciences
|March 25, 2006
Summary
Ungulate brain size is linked to social complexity, not just group size. Sociality, a measure of social relationships, better predicts brain size than the number of individuals in a group.
Area of Science:
- Zoology
- Neuroscience
- Evolutionary Biology
Background:
- Mammalian brain size varies, with social and ecological factors proposed as drivers.
- Previous studies often analyzed primates, carnivores, and birds, exhibiting complex social and ecological traits.
Purpose of the Study:
- To investigate the relationship between social complexity and brain size specifically in ungulates.
- To differentiate the roles of social versus ecological pressures on ungulate brain evolution.
Main Methods:
- Phylogenetic generalized least squares (PGLS) statistical analysis.
- Examined relative brain size and relative neocortex size in ungulates.
- Utilized a sociality index and group size as predictors.
Main Results:
- Relative brain size independently correlated with sociality, social complexity, and habitat use.
- Relative neocortex size was associated with social factors but not ecological ones.
- A simple sociality index was a stronger predictor of brain size than group size.
Conclusions:
- Social complexity, rather than just group size, is a significant driver of ungulate brain evolution.
- The cognitive demands of social living, dependent on relationship intricacies, appear to shape brain size.
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