What is Cementum Annuli aging?
The basis for cementum aging is the cyclic nature of cementum deposits on the roots of mammals’ teeth each year, which results in a pattern of “rings” in the tooth, like those formed in the wood of trees. A darkly staining ring, or “annulus”, is formed during winter on most all mammals. Abundant, lightly staining cementum is formed during the growth seasons of spring and summer. Some “experts” say these rings occur because of nutritional or seasonal stress, but since the same rings occur on human teeth, we doubt that is true. The purpose of these cementum layers on the roots of mammals’ teeth is to provide a new “rough” surface for the flesh in the jaw to adhere to the root of the teeth each year.
How to Age Harvested Game Mammals – by Henry Chidgey
Why do people care how old their harvested deer (or other mammal) is?
Mostly asked by our non hunter friends. We like to refer to three different reasons as:
1) Respect/Honor; 2) Harvest Criteria; and 3) Scientific Management Data
What we mean by Respect/Honor is that for many hunters/wildlife stewards knowing everything possible about the life and condition of the harvested animal is just one more way to have the taking of the animal’s life be respectful and appreciative. The accurate age is one element of this knowledge.
Harvest Criteria refers to learning how to accurately age the animal prior to harvest and then verifying that decision after the fact. One way we know to communicate this is by way of an analogy. If you were a master gardener and your passion was growing tomatoes you might have as an objective raising the largest, most beautiful tomatoes you could. In addition to genetics and nutrition (soil, fertilizer and water) you would want to learn the right time to pick or harvest these tomatoes. You wouldn’t want to pick them too early or too late. Experience of picking too early & too late, over time, would allow you to do a better job at maximizing your goal—having the largest, most beautiful tomatoes you could. Whitetail deer hunters and managers have goals for bucks that are very similar to these master gardeners. They want to have the bucks they harvest achieve their maximum potential. In a whitetail that usually occurs when they are 5-6 years old. They want feedback on the deer that they harvest about how good their judgment was this time, so that they can learn and improve their skills at judging age before they squeeze the trigger or let loose of the arrow.
Scientific Management Data refers to the need to know the age of harvested mammals so as to collect data that enables correlation between habitat and the health of the mammals in that habitat. Body weight vs. age is a critical indicator over time of changes in habitat conditions either good or bad.
How does cementum-annuli compare to that of eruption-wear?
The molar wear technique of aging ungulates compares the tooth wear of known age animals to the tooth wear of harvested animals. The theory is that you should be able to determine age by finding a match, wear wise, with a known age specimen. I think the cold hard facts show that this is just guesswork, especially for deer 2 ½ years or older. Simply spoken, molar wear does not work if you want an accurate age of the animal you harvested. It is a myth that is still taught to wildlife biologists in college today, even though only one study done in 1949 purported to have scientific evidence it actually worked. Ever study done since then has been unable to verify its accuracy.
The cementum-annuli (cross-sectioning teeth) method of aging deer, elk and other wild animals is much different. It first requires decalcifying the central lower incisors (sometimes the M1 molar or other tooth) and then cutting cross-sections of the root tips to a thinness measured in microns. The slice of tooth is then placed on a slide and a special dye is added to enhance viewing. It is placed under a microscope. Lines within the tooth’s diameter are readily visible and can be counted much like the rings of growth on a tree, indicating a deer’s age.
How effective are each of the methods for aging Deer? (Cementum Annuli and eruption-wear) Replacement/Eruption and Molar Wear Aging)
In a study done by Kenneth L. Hamlin et al. of the Montana Fish, Wildlife, and Parks ( Journal of Wildlife Management 64(2):441-449) accuracy rates of cementum annuli were 97.3% for elk through age 14, 92.6% for mule deer through age 14, and 85.1% for white-tailed deer through 9 years old.
Tooth eruption or tooth replacement is a highly reliable way to age mammals until they have all their permanent teeth. In whitetails you can accurately place deer as 6 months old, 18 months old, or 2 ½ or older using this easily learned technique.
This is probably a good time to bring up one of the most popular and prevalent myths of how to age game mammals, molar wear aging. This technique suggests that we should be able to determine the age of a mammal by looking at the wear on the molars. Sort of like determining the age of your tires by tread wear. In the same study by Hamlin referred to above; the accuracy of molar wear aging was 62.3% for mule deer, 42.9% for whitetails, and 50% for elk in the 3-4 year classes, 16% for elk 5 years old. They ultimately concluded that “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.” So what is the source of this popular myth of molar wear aging? In 1949 Wildlife Biologist C.W. Severinghaus published a study “Tooth Development and Wear as a Criteria of Age in White-tailed Deer” Journal of Wildlife Management 13:195-215. In this study he suggested two methods of aging; Eruption or tooth replacement aging and Molar wear aging. Subsequent studies since 1949 have supported his eruption aging results, but no study has been able to validate his hypothesis concerning molar wear aging. In fact in addition to the Hamlin study cited above here are some more comments by wildlife biologists in recent years:
….this widely used technique (molar wear) is very inaccurate for classifying adult deer…. (Ken Gee, Wildlife Biologist, Noble Foundation Wildlife Unit 1996 study)
We believe age-specific information and conclusions drawn….using the tooth-wear aging technique to “determine” ages of adult white-tail deer are unfounded…Review of all other published data sets using known-age deer supports this conclusion.(Wildlife Society Bulletin 2002, 30(2):387-393 Ken Gee et al.)
Ages assigned by … wear criteria were not reliable….. (Kenneth Hamlin et al. 2000 Journal of Wildlife Management 64(2):441-449)
….we conclude that tooth replacement and wear should be used for deer <2-1/2 years old, while cementum annuli should be used for deer >3-1/2 years old. (Mickey W. Hellickson, Ph.D. King Ranch Chief Wildlife Biologist 2007)
Curiously this molar wear aging is still part of the course curriculum taught to current wildlife biology students. That is probably a key reason that the myth continues.
In conclusion, if someone wants to really know the age of mature trophy game mammals, the only choice is cementum annu
Why do you ask me to provide the estimated age of the trophy? I thought I was sending those teeth to you for you to tell me that!
We are committed to giving you the most accurate information regarding the age of your trophy that we can. We long ago decided that the best way to do that was to use all the data we receive about each specimen to help us in that determination. We intend to be and believe we are the “CSI” of the game mammal aging world. One piece of that information is your estimate-which comes from your observation of the live mammal, trail cameras, etc. If there is a significant difference between what we see under the microscope and the other data you have provided (including estimated age), we process the second incisor, this time taking 4 slices for analysis. We then give you the results based on what we see on these slides.
Can you tell me the age if I have only one of the incisors?
Yes. We ask for the second incisor as backup, in case something happens to the first incisor during processing. Also, If there is a significant difference between what we see under the microscope and the other data you have provided (including estimated age), we process the second incisor, this time taking 4 slices for analysis. We then give you the results based on what we see on these slides. So, if you only have one incisor, send it to us and we should be able to the age for you.
How do I package the teeth?
Place your order online and we will send you an envelope with instructions on how to package the teeth. In the mean time if you have already extracted them place them in a PAPER envelope and no plastic with a bit of salt to remove the moisture.
Where do I send the teeth?
Wildlife Analytical Laboratories
2814 Brooks St. #114
Missoula, MT 59801
Is there a discount for multiple sets of teeth?
We offer commercial accounts for large volume clients such as taxidermists, Ranchers, Outfitters and Researchers. Please contact us at email@example.com to see if you qualify for a commercial account”