Yes, the popular phrase, "Another year older, another year wiser" paints an accurate picture of aging. Of course at the end of someone's life their mind is someone degrading, but for most of the years people are alive, with each year comes additional wisdom, knowledge, and also greater understanding of the world and society in general.
Yes, as we get older in age we are constantly going through more and more things that help us to lear a lot and help us to know more about what to expect on an event in the future. Every day that you are alive you learn something worth your while.
I believe the phrase, "another year older, another year wiser," is very correct. I believe a person continues learning throughout their life and with each year you get a little bit smarter or wiser. I believe the older generations are far more experienced than their younger counterparts and often this is obvious in the advice that they give.
Let's face it, there are no wise babies in the world. There are however, plenty of wise grandparents, wise medicine men, wise pastors, and wise politicians. All very old. The more you age, the more wise you become because of the power of experience, and how much doing and seeing things shapes your view on life and the world. As long as you don't forget it, aging does increase wisdom.
While some people may grow out of stupidity, others make stupidity a life-long endeavor. It is possible to make progressively worse and poorer decisions as one ages. My mother used to live in a nice property and have a decent life. Her choices each year have brought her to live in a cramped apartment with broken plumbing and no wiser for the experience.
Wisdom comes with reflection, to state that older means wiser, is to assume that people grow without actively pondering their actions and experiences. If I were to trip and fall while dancing, I am now given a chance to grow, I could chose to ignore the mistake and continue the wreckless dance, or I might chose to improve my ability. And so to say that because I fell, I must now be wiser, proves to be an illogical statement. I may not grow at all, and ignore my mistake, carrying out the careless dance and falling again. If I intend to grow, than I must practice and ponder.
You only gain wisdom with reflection. You must have age to obtain wisdom, but because you have age you are not automatically wise. An adult who never questions is far less wise than a child that contemplates their beliefs and actions daily.
To sum it up, wisdom is age of the mind, not age of the body.