https://www.academia.edu/1276752/The_causes_of_brain_enlargement_in_human_evolution https://www.academia.edu/1276752/The_causes_of_brain_enlarge... didcusses th

https://www.academia.edu/1276752/The_causes_of_brain_enlargement_in_human_evolution https://www.academia.edu/1276752/The_causes_of_brain_enlarge... didcusses that bigger brain could have evolved as it was easier to keep brain functional under intense heat.