1. Whatever you want: Inconsistent results are the rule, not the exception, in the study of primate brain evolution
- Author
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Wartel, Andreas, Lindenfors, Patrik, and Lind, Johan
- Subjects
Primates ,Male ,Computer and Information Sciences ,Physiology ,Science ,Neocortex ,Animal Phylogenetics ,Research and Analysis Methods ,Mathematical and Statistical Techniques ,Medicine and Health Sciences ,Animals ,Body Size ,Humans ,Evolutionary Systematics ,Statistical Methods ,Nutrition ,Taxonomy ,Data Management ,Statistical Data ,Mammals ,Cerebral Cortex ,Evolutionary Biology ,Statistics ,Organisms ,Biology and Life Sciences ,Eukaryota ,Brain ,Biological Evolution ,Diet ,Phylogenetics ,Physiological Parameters ,Vertebrates ,Amniotes ,Physical Sciences ,Medicine ,Female ,Anatomy ,Zoology ,Mathematics ,Research Article ,Forecasting - Abstract
Primate brains differ in size and architecture. Hypotheses to explain this variation are numerous and many tests have been carried out. However, after body size has been accounted for there is little left to explain. The proposed explanatory variables for the residual variation are many and covary, both with each other and with body size. Further, the data sets used in analyses have been small, especially in light of the many proposed predictors. Here we report the complete list of models that results from exhaustively combining six commonly used predictors of brain and neocortex size. This provides an overview of how the output from standard statistical analyses changes when the inclusion of different predictors is altered. By using both the most commonly tested brain data set and the inclusion of new data we show that the choice of included variables fundamentally changes the conclusions as to what drives primate brain evolution. Our analyses thus reveal why studies have had troubles replicating earlier results and instead have come to such different conclusions. Although our results are somewhat disheartening, they highlight the importance of scientific rigor when trying to answer difficult questions. It is our position that there is currently no empirical justification to highlight any particular hypotheses, of those adaptive hypotheses we have examined here, as the main determinant of primate brain evolution.
- Published
- 2019