A commonly held belief among dog owners is that if they want to know how old their pet is, they simply have to times its age by seven. Then, it can be decided whether man's best friend is acting up because it is a naughty teenager - or simply due to poor training. However, new research has found that this method is not based on science, and our pooches may be far 'older' than previously believed. As people, and animals, age, the number and placement of methyl groups in the genome change. By mapping these, scientists can tell the age of an organism. The researchers from the University of California San Diego School of Medicine used blood samples from 105 Labrador retrievers to accurately work out how quickly the breed ages. The study, published in Cell Systems, found the comparison is not a 1:7 ratio over time. Especially when dogs are young, they age rapidly compared to humans. A one-year-old dog is similar to a 30-year-old human. A four-year-old dog is similar to a 52-year-old human. Then by seven years old, dog aging slows, and a 12-year-old dog is 70 in human years. Click here to read full news..