I think you guys are bickering oversemantics - the age of "maturity" is a fuzzy line, one which even the mostreasonable, competentbiologists could disagree or dispute.

Approach this from another angle: At what age does a human reach "maturity." Is "maturity" the age of reproductive capability? Is it a mental status? Is it the age of top physical condition? Can it vary between people?

The answer is: There is no right answer. We can flesh out those areas where almost everyone is in agreement, but once you go down the timeline, things become increasingly muddled.

Is a button buck mature? No.
What about a yearling? If we're basing it on reproductive capacity, then yes, but I'd surmise that most of youwould say no.
2.5? Things start to get muddy...
3.5? Maybe.
4.5? More than likely.
5.5+? Almost everyone would agree that by this time, the animal has matured.

Look at our own medical profession. Two highly-esteemed, competent MD's can look at an MRI film and arrive at two conflicting opinions regarding the same set of data. One guy sees an asymptomatic bulge. The other guy sees an operable herniation.

I think that's where we're at with this "maturity" discussion.