Why does the human retina possess a fovea?
D000818:Animals; D001181:Arthropods; D001717:Birds; D002829:Choroid; D003445:Crustacea; D000882:Haplorhini; D006801:Humans; D010786:Photoreceptor Cells / Q000502:physiology*; D012168:Retinal Pigments; D014794:Visual Fields
D012168:Retinal Pigments