In humans, mice, rats, primates and pigs, it has been observed that some genes contain a high number of mutations, while others contain no mutations at all. It has not been determined whether a relationship exists across species for the variability of mutation number (i.e. a gene with a large number of mutations in one species will also have a large number of mutations in a closely related species). Here, the number of mutations in regions of genes that code for proteins were compared across pig, human and mouse. For the comparison, the pig mutations were obtained using computational methods that sorted through gene sequences to find differences. The mutations in humans and mice were real mutations from studies of individuals/animals. A high human-pig correlation and a lesser human-mouse correlation were found after comparing mutation number in genes. This is the first evidence of similarity across species in the variability of mutation number in genes. It indicates that discovery of mutations in pigs could be increased by searching in pig genes that are similar to human genes previously shown to have a large number of mutations in their protein coding regions. Some of these newly discovered mutations will change the protein that is produced by the gene, which can affect the protein’s function, and result in changes in economically important traits such as growth, meat quality and reproduction. These mutations can then be used to select animals that are genetically superior.