Although the divergence of the aA-crystallin protein from other heat shock proteins has been examined, the extent to which the CRYAA gene controlling it has evolved across vertebrate species remains a scientific topic of inquiry. This gene could potentially be an accurate indicator of the evolutionary relationships between vertebrates, which could provide insight for future phylogenetic studies in this area. The purpose of this study was to determine how the CRYAA gene has evolved across vertebrate species. The aA-crystallin protein is crucial to the function of the vertebrate eye, as it maintains the transparency of the lens and prevents the denaturation of proteins. Because there have been no studies in this area, the null hypothesis that there is no sequence variation in the CRYAA gene encoding was assumed and tested with a phylogenetic analysis of the gene and the protein. The null hypothesis was unsupported by the results, as the CRYAA phylogeny did report evolutionary distances between each genus, although not between each species within those genera. Therefore, the CRYAA gene could be useful for hypothesizing evolutionary relationships between different vertebrate genera....