In the realm of wildlife conservation and ecological studies, accurate aging of animals is of paramount importance. Determining the age of animals provides crucial insights into population dynamics, reproductive success, and overall health. One commonly used method for aging animals is based on the examination of cementum annuli in teeth. Cementum annuli aging is particularly prevalent in studies involving mammals like rodents, ungulates, and carnivores. However, while this method has been widely utilized, its accuracy has been a subject of debate and scrutiny.

What Are Cementum Annuli?

Cementum is a hard tissue that covers the roots of teeth in mammals, including humans. Similar to the growth rings in a tree, cementum annuli are incremental lines that form in the cementum of an animal’s teeth. These lines are believed to represent periods of reduced metabolic activity, often corresponding to the winter season when food is scarcer and metabolic rates decrease.

The Process of Cementum Annuli Aging

Cementum annuli aging involves extracting teeth from a deceased or captured animal and sectioning them. Researchers then examine the cross-sections of the teeth under a microscope to count the number of cementum annuli present. The number of annuli corresponds to the age of the animal. This is an extensive histological process and the teeth undergo treatment with numerous chemicals in order to be able to be placed onto a slide for reading.

The Controversy Surrounding Cementum Annuli Aging

While cementum annuli aging is a relatively straightforward method in theory, its accuracy can vary significantly depending on several factors:

  1. Species Variability: Different species may exhibit different patterns of cementum deposition. This means that the rate at which annuli form can vary widely among animals, making it challenging to apply a universal standard for aging.
  2. Environmental Factors: Environmental factors, such as food availability, stress and climate can influence cementum deposition rates. It is a common misconception that warmer climates dont see distinct CA deposits however we see very distinct lines from southern states regularly.
  3. Individual Variation: Individual variation in cementum deposition can occur due to differences in genetics, health, and diet. Some individuals may deposit annuli at different rates than their peers, further complicating accurate aging.
  4. Sample Size and Quality: The accuracy of cementum annuli aging is greatly influenced by the quality of the tooth samples and the size of the sample population. Small sample sizes and damaged teeth can lead to less accurate age estimates.
  5. Observer Bias: Human error and observer bias can also impact the accuracy of cementum annuli aging. Counting annuli is a manual process that relies on the observer’s judgment, which can introduce subjectivity and inconsistencies.

Improving the Accuracy of Cementum Annuli Aging

To enhance the reliability of cementum annuli aging, researchers have developed calibration studies that compare age estimates from cementum analysis with known-age animals. This allows for the development of species-specific growth models and can help account for individual and environmental variations.

Additionally, technological advancements such as high-resolution imaging and computer-aided image analysis have improved the accuracy and objectivity of cementum annuli counting. These tools can assist in reducing observer bias and increasing the precision of age estimates.

How does DeerAge specifically ensure accuracy?

At DeerAge.com we take accuracy very seriously. The first thing we have done to increase the accuracy of our results is reduce the possibility for human errors by utilizing barcodes. In a laboratory setting 70% of errors can be traced back to human mistakes which is why we do our best to confront that. We are the only company that offers a “second look” for our customers such that if the customer feels the age is off we look again and often run a second sample to be sure the lines are of the top quality. Most importantly we only hire top trained scientists in our specialty. Dr. Vipin Sharma has a PhD in Zoology and specializes in cementum annuli techniques; he is an excellent resource for ensuring our techniques are top notch. In addition all of our histology staff are ASCP certified and able to cut human diagnostic samples. Lastly, we understand that while the industry acceptable standard is +/-  one year, we work hard to ensure that we take all of the information into account such as environment, genetics and the hunters observations to ensure we are nailing it spot on with the age.


Cementum annuli aging has been a valuable tool in wildlife research for decades, offering insights into the age structure of populations and aiding conservation efforts. However, its accuracy can be influenced by a range of factors, including species variability, environmental conditions, individual variation, and human error. To maximize the accuracy of this aging method, DeerAge takes these factors into account, employ calibration studies, and utilize modern technology to improve their age estimates. Cementum annuli aging is a valuable tool and it is best when used in conjunction with other aging methods to ensure the most reliable results in wildlife research and conservation efforts

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