Human exceptionalism, our ordinary cortex and our research futures

Area of Science:

• Neuroscience
• Evolutionary Biology
• Comparative Anatomy

Background:

• The prevailing view posits an exceptionally large human cortex relative to overall brain size.
• This belief influences genomic studies, treating the cortex as novel rather than a product of scaling.
• It has led to misattribution of functions and neglect of subcortical brain evolution.

Purpose of the Study:

• To challenge the notion of exceptional human cortex size.
• To identify and correct methodological errors in comparative brain analysis.
• To re-evaluate the evolutionary trajectory of the human brain.

Main Methods:

• Comparative analysis of brain size scaling across diverse species, including rodents and primates.
• Critique of linear extrapolation methods for predicting brain size changes.
• Re-examination of assumptions in comparing brains of different sizes.

Main Results:

• The widely held belief in an exceptionally large human cortex is based on flawed comparative methods.
• Errors include limited species comparison, ignoring rodent vs. primate scaling differences, and invalid linear extrapolation.
• The human cortex is a product of predictable scaling, not exceptional innovation.

Conclusions:

• The exceptionalism of the human cortex is a misconception due to methodological errors.
• Future research should focus on accurate brain scaling and subcortical contributions to brain evolution.
• Understanding human brain development requires acknowledging predictable scaling patterns.