Thanks to the help of WAL
First a simple look at aging
First let's talk about aging in laymen terms.
"I always hear that a deer is 2 and 1/2 years old, or 3 and
1/2 years old. Why is there always a
Don't forget that fawns are born in the spring. You hunt in the
fall which is 6 months later. Hence the 1/2 .
It is generally agreed by most sportsman and game managers that a
"good" buck is at or above the 3.5 year mark. Quality bucks that
most of us consider to be trophies are 4.5 and above.
See the aging chart below and it will give you a good perspective on
the antler development per year.
(Click on Photo for larger view.)
Below you will find some interesting information from W.A.L. on the
science of aging both bucks and does.
Next, let's talk some science with W.A.L.
"Wow, he's huge!",
"I wonder how old he is?", "She looks old, how old do you think she
is?", "I wonder how many years that old boy has been around here?" The
list goes on. One of the challenges hunters like I have had over the
years is knowing, for sure, how old the deer they harvested was. I had
bought all the books, wall charts, and aging wall plaques that promised
to teach and show an exact way of aging based on looking at the molars
in a deer?s jaw. Well, this seemed to work well for fawns and 1 ? year
olds, because the number and type of teeth seemed to accurately place
these age classes. But beyond that, my confidence that what the charts,
books, and ?experts? told me could be accurately applied to the jaw I
had in my hand was very low.
discovered three new pieces of knowledge. The first was that there had
been formal studies done by two different organizations/ researchers to
verify the accuracy (or lack thereof) of aging deer by looking at the
molars and their wear. The second was that there was a physiological
mechanism that occurred in almost all mammals that every year a layer of
cementum is deposited around the portion of the teeth located beneath
the gum. In addition to this there was and is a forensic laboratory
method the allowed histologists to prepare these teeth so that the rings
of cementum could be counted under a high powered microscope as easily
and accurately as counting the growth rings of a tree.
let?s look into these bits of new knowledge in more depth. First, the
studies revealed that the molar wear technique did not work, even for
trained experienced wildlife biologists that had looked at thousands of
deer. The first study ?Evaluating the Accuracy of Ages Obtained by Two
Methods for Montana Ungulates? by Hamlin, Pac, Sime, DeSimone, and Dusek,
all of Montana Fish, Wildlife and Parks was published in Journal of
Wildlife Management 64(2):441-449. The two methods studied were
eruption wear (looking at the molars) and forensic cementum annuli. A
quote from the abstract of this research says ?Ages assigned by
eruption-wear criteria were not reliable for comparing physical
measurements and population parameters by age among populations... The
accuracy provided by the cementum annuli method is necessary to
determine whether various physical and population parameters change
significantly with age of the animal.?
The other study we
discovered was done by Ken Gee and others at the 2,947 acre Noble
Wildlife Unit near Allan, Oklahoma. This study can be found at
http://www.noble.org/Ag/Wildlife/Deer/WILDDEER.HTM . A telling quote
from this study by Mr. Ken Gee is ?The results indicate that this widely
used technique (sic teeth wear and eruption patterns) is very inaccurate
for classifying deer into specific age-classes on the NFWU.?
Now, the second
bit of new knowledge was around the thing called cementum. The following
information comes from The University of Manitoba:
grows continuously during an organisms' lifetime without resorbing (as
bone and other dental tissues like dentine and enamel do). This means
that dental cementum offers a complete record of individual growth. For
this reason, dental cementum is particularly interesting to
Composition of dental cementum:
Dental cementum is a mineralized tissue closely related to bone. Both
are composed of approximately 65% inorganic components and about 35%
organic components, with relatively few cells per volume/mass of mature
tissue. Cells in cement, cementocytes, are secreted by cementoblasts
embedded in the tissue. The organic matrix which forms the basic
structural component of bone and cement is composed of collagen fibres.
Cementum growth pattern:
Cementum growth, or deposition, is most simply described as a two-phase
process: the first phase is the production of the organic matrix,
followed by the mineralization phase. Growth is appositional and results
in a banded structure, implying the existence of structural variations
in the deposited tissues.
The layering observable in dental cementum corresponds to the presence
of growth layers, composed of
growth zones, annuli and lines of arrested growth, or LAGs. A number
of possible explanations for the optical and physical expression of
growth layers in bone and cement have been offered: changes in mineral
density; cellular density; histochemical differences; and collagen fibre
orientation. Organisation of the collagen fibre matrix is currently
believed to be the source of the observed major structural variations
between growth layers.
Biologists have investigated
growth marks in a wide variety of vertebrate species from different
environments. They have empirically identified a yearly cycle of
cementum formation, consisting generally of a single paired
growth zone + annulus/LAG. These empirical observations, based on
control groups of animals of known age and season at death, are
supported by experimental studies involving the use of fluoromarkers as
"benchmarks" to record the position of cement growth at precise
intervals. The fact that several different types of bony tissue form
incremental lines in synchrony, i.e., dentine, cement and periosteal
bone, supports this identification.
I have left the hyperlinks in so you, the reader can research the
original literature if you choose. Another piece from this work says:
?Stained, Histological Thin Section:
Demineralised, stained sections, thin sectioned while frozen with the
use of a microtome saw, mounted in an aqueous medium, have also been
used to investigate banding in bone and cement. When stained with
Ehrlich's haematoxylin, for example, cement and primary cortical bone
show alternate bands of wide, poorly stained tissue and thin, darkly
stained tissue. The thin, chromophile bands correspond to annuli or,
more often, to LAGs. In stained, decalcified sections, the importance of
the orientation of the fibre matrix in determining the characteristics
of the increment is apparent. A number of different staining agents,
e.g., Mayer's haemalin and silver nitrate, have been used to produce
dichromism highlighting the histochemical differences between annuli and
growth zones in these tissues.?
So, we now know what cementum is and that there is a forensic laboratory
histological process that allows us to accurately determine the length
of time a tooth has been in a mammal?s mouth. We also know that most all
mammals (humans too!) deposit discrete layers of cementum around the
portion of the tooth located beneath the gum line. If you carefully
slice the tooth in thin sections, stain these sections, and place them
on a slide under a high power microscope, you can then count the rings
(annuli) of cementum and know the length of time that tooth was in that
deer?s jaw. It is just like counting the rings on a tree to determine
it?s age. The teeth we choose to use in a deer?s mouth for aging are the
two front center teeth (center incisors). The reason for this choice is
that these teeth are in place by the time the fawn is 4-6 months old and
remain in place through out the deer?s life. These teeth and the first
molar are the first permanent teeth a fawn gets. The center incisors are
much easier to remove than a jaw bone and especially a molar out of the
jaw bone. So, forensic cementum annuli aging is typically performed on
the two center incisors, but may also be performed on the M1 molar, the
fourth tooth from the front of the 3 premolar, 3 molar teeth in a mature
The next part of this story is what I did next, armed with these new
tidbits of knowledge. I went searching for a lab to age my trophies.
What I discovered was that there was only one private (not government or
University) lab that did this commercially. Also, none of the labs
seemed to be focused on quick reliable turn around. So I tried a lab
(actually a middleman that used a state government lab) and was
disappointed by the way the results were reported and the length of time
it took to get the results. I sent the four specimens in the first week
of February and received a call on July 18th in which I was told the
results over the telephone. No e-mail, fax, or letter confirming the
results, just a phone call and it took over 5 months.
Well, I decided that if someone was going to meet the needs of clients
like me, I was going to need to do it. So, I obtained every research
paper I could find on cementum annuli aging of any mammal, engaged an
experienced histologist, set up a well equipped laboratory, and created
Wildlife Analytical Laboratories?Home of www.DeerAge.com , to meet the
needs and desires of clients like myself. Those needs are- Accuracy
of Results and Great Customer Service. We also have developed a
service offering targeted to meet the needs of commercial clients and
resellers of our services.
So, What is a REAL Trophy Whitetail? Depends, but for me it is that
whitetail doe or buck who has successfully eluded predators and hunters
for many years, taken with the most challenging weapon I have
proficiency with. That is the buck or doe that goes up on my wall, with
a Certificate of Aging? right next to it.
Equally as important, I want to keep developing and fine tuning my
skills at aging my deer before I squeeze the trigger or loose the arrow.
That?s why I will be a lifelong student of aging. How I will do that is
to forensic cementum age every deer I harvest and compare their actual
age to what I estimated before the harvest. I am committed to mastery of
this important whitetail management skill.
Thanks to W.A.L. for their help on our site.