What Are Shovel Teeth? A Look at This Genetic Dental Trait

Shovel-shaped incisors, commonly called shovel teeth, are front teeth whose tongue-side surface is scooped out like a shallow spoon, bordered by raised ridges along both edges. The trait is one of the most studied features in dental anthropology because it varies dramatically across human populations and traces back to a single well-characterized gene variant. What makes shovel teeth especially interesting is that the same genetic change responsible for the dental shape also affects hair thickness, sweat gland density, and breast tissue, linking a quirky tooth shape to a much broader story about human adaptation.

How to Recognize a Shovel-Shaped Incisor

If you run your tongue along the back of your upper front teeth, you might feel a mostly flat surface, or you might notice that the edges feel raised while the center dips inward. That dip is the hallmark of shoveling. Technically, shovel-shaped incisors have thickened marginal ridges surrounding a concave depression on the tongue-facing surface of the tooth, known as the lingual fossa.¹ The trait exists on a spectrum. Some people have barely perceptible ridges, while others have deep, pronounced scooping that gives the back of the tooth a genuinely spoon-like contour. Researchers have long scored these grades using standardized reference plaques, and the depth of that lingual concavity is the feature that most influences how strongly an observer rates the shoveling.²

The upper central incisors show shoveling most obviously, but upper lateral incisors and even canines can display it. A related feature called “double shoveling” refers to ridging on the lip-facing (labial) side of the tooth, and the two traits don’t always travel together. In fact, genetic studies of tooth development have found that shoveling and double shoveling tend to be negatively correlated, meaning the developmental program that builds up the tongue-side ridges actually constrains the lip-side surface.³ The labial convexity of the tooth, the outward bulge you see from the front, also tends to decrease as double shoveling increases.⁴

The EDAR Gene and Why It Matters

The genetics of shovel teeth zeroed in on one gene faster than many dental traits: EDAR, which stands for ectodysplasin A receptor. A specific variant in this gene, known as V370A (where one amino acid in the protein is swapped for another), is strongly correlated with higher shoveling grades. In a study of Japanese individuals, the number of copies of the relevant allele a person carried predicted their shoveling grade with high statistical confidence, and the effect was additive, meaning two copies produced more shoveling than one.⁵ That single variant accounted for about a fifth of the total variation in shoveling grade, which corresponds to roughly a quarter of the trait’s estimated heritability. A combined analysis of Korean and Japanese populations confirmed the same allele increases both shoveling and double shoveling grades.⁶

That said, a fifth of total variance means the EDAR variant is far from the whole story. Other genes contribute to the final shape of the tooth, and environmental factors during development play a role too. Still, for a single variant to explain that large a fraction of a morphological trait is remarkable. Most complex traits are influenced by hundreds of variants with tiny individual effects. EDAR V370A is something of an outlier in that regard.

One Gene, Many Effects

The EDAR gene doesn’t just shape teeth. It sits in a signaling pathway that influences how several tissues develop during embryonic life, and the V370A variant nudges all of them. Researchers confirmed this by engineering mice that carry the human version of the variant and comparing them with mice carrying the ancestral version. The mice with the 370A allele had thicker hair fibers, recapitulating the association already seen in human populations between the variant and coarser, straighter hair.⁷ The same mice also developed more eccrine sweat glands per footpad, with animals carrying two copies of the allele showing the highest density.⁷

Beyond hair and sweat glands, the variant affected mammary tissue in the mice: animals carrying the 370A allele had smaller mammary fat pads but denser ductal branching inside the glands.⁸ This cluster of effects, thick hair, more sweat glands, altered breast tissue, and shovel-shaped incisors, all flow from the same amino acid change. The technical term for one gene affecting multiple seemingly unrelated traits is pleiotropy, and EDAR V370A is one of the best-documented examples in human genetics. It means that if you have strongly shoveled incisors, the same genetic variant may also be contributing to your hair texture and how many sweat glands you have, even though you’d never connect those features to your teeth.

Who Has Shovel Teeth

Shovel-shaped incisors appear at some level in virtually all human populations, but the most pronounced expressions cluster in East Asian, Southeast Asian, and Indigenous American populations. The EDAR 370A allele reaches its highest frequencies in these groups, and its geographic signature closely tracks patterns identified in dental anthropology decades before the gene was found. The classic framework in the field divides the “Mongoloid dental complex” into two patterns: Sinodonty, found in Northeast Asian populations and characterized by strong shoveling among other features, and Sundadonty, a somewhat simpler version seen in Southeast Asian populations.⁹ Large dental-trait studies of prehistoric populations in the region have confirmed this division, showing a clear separation between early Southeast Asian samples (which cluster with modern Australian and Melanesian populations) and a distinct Northeast Asian grouping, with later Southeast Asian samples showing gradual genetic mixing from the north.¹⁰

European and African populations carry the ancestral version of the EDAR gene and generally have flat or trace shoveling, though mild ridging isn’t unheard of. Populations in Turkey’s Black Sea region, for example, have been studied for the trait and show varying low-level expression.¹ The trait reaches its most extreme expression in Indigenous American populations, consistent with their descent from Northeast Asian groups who carried the variant at high frequency before crossing into the Americas.¹¹

When Did This Variant Appear

Ancient DNA has started to pin down the timeline. In a study of prehistoric genomes from northern East Asia, the EDAR V370A allele showed up in all ancient East Asian individuals in the sample except the two who predated the Last Glacial Maximum, roughly 20,000 years ago. The oldest carrier in the dataset lived about 19,000 years ago, pushing the allele’s confirmed emergence further back than previous statistical estimates from modern genomes had suggested.¹² This timing matters because it argues against the hypothesis that the allele was selected for in a warm, humid environment where sweat gland density would have been a clear advantage. Instead, it seems to have risen to high frequency during or shortly after one of the coldest periods of the last ice age.

The idea that shoveled incisors themselves are ancient isn’t limited to modern humans. Shovel-shaped front teeth have been observed in Homo erectus and Neanderthal fossils, though in those cases the trait arose independently, not from the same EDAR variant found in living people. The EDAR 370A allele is absent from Denisovan and Neanderthal genomes, confirming that the modern version of the trait is a separate evolutionary event.¹³

Why Natural Selection Favored It

The EDAR V370A allele shows clear genetic signatures of positive selection, meaning it didn’t drift to high frequency by chance. But figuring out which of its many effects was actually useful to ancient populations has been a long-running debate. The sweaty-climate hypothesis, which proposed that more sweat glands gave a thermoregulatory advantage, doesn’t fit well with the timing from ancient DNA, since the allele rose during the ice age, not during a warm period.

A different hypothesis ties the allele’s spread to infant nutrition. The same variant that produces shovel teeth also increases mammary ductal branching, which could plausibly improve the transfer of fat-soluble nutrients through breast milk. Researchers have proposed that in the Beringian refugium, where ice-age populations survived in vitamin D-deficient, high-latitude conditions, mothers who carried the 370A allele may have delivered more vitamin D and fatty acids to their nursing infants, giving those children a survival edge.¹⁴ Under this model, shovel-shaped teeth are essentially a side effect of selection that was really acting on the breast tissue. The tooth shape hitched a ride because both traits are controlled by the same genetic switch.

This remains a hypothesis, not a settled conclusion. Selection could have acted on any of EDAR’s many downstream effects, or on a combination of them simultaneously. Hair thickness and sweat gland number each have their own plausible adaptive stories in different climates. The breast-milk hypothesis is appealing because it directly ties to infant survival and fits the geographic and temporal evidence, but proving which trait was the actual target of selection in a 20,000-year-old scenario is extremely difficult.

Were Shovel-Shaped Teeth Ever Mechanically Useful

The independent appearance of shovel-shaped incisors in Neanderthals and Homo erectus has led researchers to ask whether the shape itself, regardless of genetics, is biomechanically advantageous. Neanderthals used their front teeth heavily, not just for eating but for gripping and processing materials like animal hides, a behavior sometimes called the “third hand” hypothesis. Finite element analysis of Neanderthal incisors, essentially a computer-simulated stress test, found that the combination of shovel shape, labial convexity, and a well-developed lingual tubercle helped distribute mechanical stress more evenly across the tooth.¹⁵ The ridged, scooped shape concentrated tensile stress along grooves on the biting surface, giving the tooth higher resistance to the kinds of forces generated by clamping down on tough materials.¹⁶

This doesn’t necessarily mean that modern human shovel teeth are selected for mechanical strength. The EDAR-driven version in living populations arose through a different genetic mechanism and in a different selective context from the Neanderthal version. But the convergence is interesting: evolution arrived at a similar tooth shape in multiple lineages, and in at least one of them, the shape appears to have provided genuine structural benefits under heavy use.

Shovel Teeth in Forensic and Archaeological Identification

Because shoveling frequency and intensity vary so consistently across populations, the trait has become a standard tool in forensic anthropology. When skeletal remains are found without any identifying documents, dental morphology is one of the methods used to estimate the individual’s likely ancestry. Shovel-shaped incisors are considered a key feature in this process, with the strongest expressions pointing toward Indigenous American or East Asian ancestry.¹¹

Modern software has formalized this approach. One web-based application, rASUDAS, uses a statistical algorithm to assign an individual to an ancestry group based on a set of dental trait scores. In one published case, the system was applied to a roughly 1,500-year-old skeleton found in Slovenia. The teeth showed moderate shoveling of the upper incisors along with other crown features more common in East Asian populations. The software calculated a probability close to 1.0 for Eastern Asian ancestry, consistent with archaeological evidence suggesting the individual was a Hun warrior from the Migration Period.¹⁷ That case neatly illustrates how a dental trait like shoveling can speak across millennia.

It’s worth noting that these ancestry estimates deal in probabilities, not certainties. No single dental trait is diagnostic on its own. Forensic dentists score a battery of features, including cusp number on molars, root shape, and the presence or absence of other traits like Carabelli’s cusp, and the statistical model weighs them all together. Shoveling is one of the stronger signals, but it’s part of a package.

Practical Dental Considerations

For most people, shovel-shaped incisors are just an anatomical curiosity with no health consequences. But the deep grooves and ridges that define the trait can occasionally create clinical concerns. The lingual fossa can trap plaque in ways that a flatter tooth surface wouldn’t, potentially raising caries risk in the fissures. Deep invaginations, where the enamel folds inward, are sometimes associated with shoveled incisors and may require preventive filling to avoid decay. In more pronounced cases, the ridges can contribute to bite issues or irritate the tongue. Attrition over time can sometimes wear down to a central pulp horn, requiring conservative dental treatment or, rarely, root canal therapy.

Dentists who work with populations where the trait is common tend to be familiar with these patterns, but a practitioner who mostly sees patients with flatter incisors might not immediately recognize the anatomy. If you know you have strongly shoveled front teeth, it’s worth mentioning the grooves to your dentist during checkups so they can keep an eye on plaque accumulation in those harder-to-reach spots. Most of the time, good oral hygiene handles the issue without any special intervention.

How the Trait Is Classified and Scored

Dental anthropologists don’t just eyeball shoveling and call it present or absent. The field uses standardized reference plaques, originally developed by Albert Dahlberg in the mid-twentieth century, that represent a graded series from no shoveling through trace, semi-shovel, and full shovel. A researcher holds the actual tooth (or a cast of it) against the plaque series and assigns a grade. This approach treats shoveling as a continuous trait rather than a simple yes-or-no, which is important because the genetic influences are themselves continuous and additive.

More recently, geometric morphometric methods, which capture the three-dimensional shape of the tooth surface mathematically, have been applied to shoveling. These approaches tend to confirm that the depth of the lingual concavity is the dominant feature driving how observers assign grades.² The width of the marginal ridges matters too, but less so. This matters because it means traditional grading scales, despite being subjective, have been capturing the right biological signal all along. The trait is real, measurable, and genetically grounded, not just an impression in the eye of the scorer.

Shovel Teeth and the Broader Landscape of Dental Variation

Shoveling is just one entry in a catalog of tooth-shape variants that dental anthropologists track. Others include Carabelli’s cusp, a small extra bump on the tongue side of upper molars that is more common in European populations; protostylid, an extra ridge on lower molars; and hypocone reduction, where the fourth cusp on an upper molar shrinks or disappears. Each of these traits has its own frequency pattern across populations, its own heritability estimate, and in most cases still-murky genetics. Shoveling stands out because it has a much clearer genetic story than most of the others, thanks to the outsized effect of the EDAR variant.

The relationship between shoveling and other dental traits is not straightforward. As noted earlier, shoveling and double shoveling (ridging on the front surface of the tooth) tend to be negatively correlated, suggesting that the developmental programs for the lingual and labial surfaces of a single tooth are somewhat in tension.³ This kind of constraint is important because it means you can’t simply stack dental features without limit. Building up one surface tends to come at the expense of another, which shapes what combinations of traits are possible in a given individual or population. It also means that the striking variety in human tooth shapes isn’t random; it’s channeled by underlying developmental architecture that evolution can only push so far in any one direction.