Tarsiers represent an odd line of evolution in the primate radiation. Their overall small size and strange body confused early investigators, and tarsiers were grouped with lorises, galagos, and lemurs as prosimian primates, that is, below the monkey (simian) level. That classification has now been changed, and the molecular evidence places them as an early surviving branch of the anthropoid radiation (Ross and Kay, 2004). What is unusual about the evolution of tarsiers is that early anthropoids were diurnal and specialized for daytime vision, and the tarsier line started off as diurnal, having lost its specializations for nocturnal vision, but then returned to nocturnal life by re-specializing for dim light. This largely consisted of evolving huge eyes relative to the head. Consistent with their reclassification, the dorsal lateral geniculate lamination pattern of tarsiers is clearly of the anthropoid type, rather than of the strepsirrhine type (Wong et al., 2010). Interestingly, the primary visual cortex, V1 of tarsiers is proportionately greater than almost any other primate at 20% or more of all visual cortex. As an extreme visual predator of insects and other small prey, tarsiers depend on a large V1 for the detailed representation that is needed for this function. As tarsiers are small, and have small brains, this dependence on a large V1 may have cost them in number of cortical areas.