California institute of technology neurobiologists suggest that this closeness in sensitivities is optimized toward detecting subtle changes in skin tone because of varying concentrations of oxygenated hemoglobin in the blood 美国加州理工学院的神经生物学家推测，人类与灵长类在此感应度上的雷同，应该是为了方便观察因血液中含氧血红素的浓度变化，而在皮肤上呈现的微妙起伏。
