Investigating the activity of genes in dog brain tissues revealed that a large portion of genes (16,000 out of 20,000) are active in all animals, and approximately 3,500 were differentially expressed between the age groups with fewer than 100 genes being active only in old dogs but not in young ones. This indicates that genetic changes associated with aging are more about quantity than quality. The genes with altered activity had functions in regulating other genes, neural development, activity, and the immune system. Some genes with important neural functions showed a pattern of changes similar to humans but distinct from rodents.
