^ We don't really know the life expectancy of the average Eorzean, though. In the real world, most people up until the 20th century could only expect to live to about 35 or so, before war, famine or disease claimed them. Life was harsh, and people were forced to "grow up" a lot sooner, shouldering "adult" responsibilities by their mid-teens. Heck, Alexander the Great was only 20 when he became the King of Macedonia, and by the time he was 30, he had conquered the known world. So, yes, there is good reason why a 30-year-old would be considered an antediluvian in a mediaeval setting.