Researchers can figure out the evolutionary relations of opsins in the various classes of cones and from different species by examining the sequences of nucleotide bases ( or dna “ letters ” ) in the genes that code for these proteins 透过比对视蛋白基因的核苷酸硷基（或称dna字母）序列，研究人员就能找出不同锥细胞视蛋白以及不同物种间视蛋白的演化关系。
