Evolution of the brain

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There is much to be discovered about the evolution of the brain and the principles that govern it. While much has been discovered, not everything currently known is well understood. The evolution of the brain has appeared to exhibit diverging adaptations within taxonomic classes such as Mammalia and more vastly diverse adaptations across other taxonomic classes. Brain to body size scales allometrically.^[1] This means as body size changes, so do other physiological, anatomical, and biochemical constructs connecting the brain to the body.^[2] Small bodied mammals have relatively large brains compared to their bodies whereas large mammals (such as whales) have smaller brain to body ratios. If brain weight is plotted against body weight for primates, the regression line of the sample points can indicate the brain power of a primate species. Lemurs for example fall below this line which means that for a primate of equivalent size, a larger brain would be expected. Humans lie well above the line indicating that humans are more encephalized than lemurs. In fact, humans are more encephalized compared to all other primates.^[3] This means that human brains have exhibited a larger evolutionary increase in complexity relative to size. Some of these evolutionary changes have been found to be linked to multiple genetic factors, such as proteins and other organelles.