There’s a simplified equation for telling a dogs age: 10½ Human years for the first 2 dog years of a dogs life, then 4 human years for every subsequent dog year. However, dogs don’t only age differently than humans, they also age differently than each other. A dogs size and breed are important factors when it comes to how old your dog really is.
For example: A 1 year-old small dog is the equivalent of 15 human years. By the time it turns 11, 56 human years, it is considered geriatric. A 1-year-old large dog is 12 human years, and by the time it turns 11 it reaches about 82 human years. Large dogs mature much more slowly than small dogs but are considered geriatric by the time they’re 8, equivalent to a human age of 61.
Before Columbus people thought the world was flat.