The method of aging a whitetail deer by examining its jawbone is a standard practice for wildlife management and a valuable tool for hunters seeking to understand their local herd structure. This technique relies on analyzing the pattern of tooth replacement in young deer and the degree of wear on permanent teeth in older deer. Determining a deer’s age provides necessary context for evaluating body weight, antler development, and overall herd health, which informs selective harvesting decisions. The aging process categorizes deer into half-year increments (e.g., 1.5 or 2.5 years) because most deer are born in late spring and are harvested during the fall hunting season, making them approximately six months older than their birthdate.
Essential Deer Dental Anatomy
A mature whitetail deer possesses 32 teeth. The lower jaw contains a full set of permanent cheek teeth on each side, separated from the incisors by a large, toothless gap known as the diastema. The chewing surfaces consist of six teeth—three premolars followed by three molars—all used for grinding vegetation.
The upper surface of these cheek teeth features raised points called cusps, which are aligned along ridges known as lingual crests on the side closest to the tongue. As a deer chews, the hard, white enamel wears away, exposing the softer, darker inner core called dentine. The degree to which the dark dentine becomes wider than the surrounding white enamel is the primary indicator of age in mature deer.
Aging Deer Up to 1.5 Years
Aging deer up to 1.5 years old relies on observing the presence and replacement of deciduous, or “milk,” teeth. A fawn harvested in the fall (around six months old) will generally have three or four cheek teeth, consisting of temporary premolars and the first permanent molar (M1) beginning to erupt.
The most reliable marker for this age class is the third premolar (P3), which temporarily has three distinct cusps. A yearling (1.5 years old) will have a full set of six cheek teeth, but the first three are still the temporary, three-cusped premolars.
Around 18 months of age, the temporary premolars are replaced by permanent ones. The permanent third premolar has only two cusps, making the transition from a three-cusped temporary tooth to a two-cusped permanent tooth the definitive sign of a deer transitioning out of the yearling age class. If the six fully erupted cheek teeth include a new, two-cusped third premolar, the deer is likely 1.5 years old; if that tooth shows wear, the deer is at least 2.5 years old.
Aging Mature Deer
For whitetail deer 2.5 years and older, aging relies on assessing the wear on the permanent molars, which is a more subjective process than tooth replacement. The key is comparing the width of the exposed dentine to the surrounding enamel, focusing on the lingual crests. At 2.5 years, all six permanent cheek teeth are fully erupted, but the cusps on the first molar (M1) are still sharp, and the dark dentine line is noticeably thinner than the white enamel.
The first significant wear milestone occurs at 3.5 years, where the dentine on the first molar (M1) is now as wide as, or wider than, the enamel. The cusps on this tooth become blunted, while the second molar (M2) typically still shows dentine that is narrower than the enamel. By 4.5 years, wear progresses to the second molar (M2), where the dentine is wider than the enamel, and the first molar may show signs of the cusps being worn away near the gum line.
Deer 5.5 years and older exhibit significant and heavy wear across all cheek teeth, making precise aging increasingly difficult. At this stage, the dentine is wider than the enamel on the first, second, and third molars (M1, M2, and M3), and the chewing surface appears flatter and “dished.” Aging past 5.5 years is highly subjective, as individual variation in diet and habitat can accelerate or slow the rate of tooth wear.