the scientific and most accurate way to age a Deer is the teeth and NO you do NOT need to cut the cheek open or anything to age it.
Some stores are now selling plastic Deer jaws as guages for comparison.
A Deers color, nose, ears, antler's, belly, girth, length, height & weight, muscle mass and hoof size can help a person guess at a Deers age but
it's only a guess and sometimes isn't even close to the actual age of the deer.
It's All in the Teeth
The science of aging deer is based on tooth development and wear. Like humans, deer replace their "baby teeth" with permanent teeth at a relatively set rate.
As surely as a 6-year-old child will soon lose their two front teeth, an 18-month-old buck will be in the process of losing its third premolar.
By the time a deer is 2-1/2; years old, all permanent teeth are in. At this stage, estimating age is based largely on the rate of tooth wear.
I hope this info helps.
Democracy is two wolves and a lamb voting on what to have for lunch.
Liberty is a well-armed lamb contesting the outcome of the vote.