Why Do We Get Wisdom Teeth? Purpose, Function, and When They Cause Problems
✓ Medically Reviewed. Last Updated on 09/16/2026.
Wisdom teeth are the third and final set of molars that usually develop in the late teens or early twenties. So, why do we get wisdom teeth if many people eventually have problems with them? A widely cited explanation points to evolution: our ancestors had larger jaws and diets that required more chewing, so an extra set of molars was useful, and as human diets changed and jaws became smaller, there was often less room for these teeth to erupt properly. Today, wisdom teeth may grow normally, remain hidden beneath the gums, or become impacted and cause pain, swelling, or infection.
Key Takeaways
Wisdom teeth are the third molars at the very back of the mouth.
An extra set of molars was likely useful to our ancestors, who had larger jaws and tougher diets.
Modern humans often have less space for wisdom teeth to erupt properly.
Not everyone develops or erupts all four wisdom teeth.
Healthy wisdom teeth do not automatically need to be removed.
Pain, swelling, infection, decay, or damage to nearby teeth may indicate the need for dental assessment.
Wisdom teeth are the third molars that typically emerge between ages 17 and 21. They develop because of an evolutionary mismatch: ancestral humans had larger jaws suited to tougher diets, while modern jaws are often smaller with less room for these extra molars to erupt. Not everyone develops or needs to remove their wisdom teeth. Removal is generally recommended only when a tooth is impacted, infected, decayed, damaging nearby teeth, or otherwise causing problems, not simply because it is present.
What Are Wisdom Teeth?
TL;DR: Wisdom teeth, or third molars, sit behind the second molars at the back of the upper and lower jaws. Most people who develop them have up to four, but not everyone does, and some remain unerupted beneath the gums.
Wisdom teeth are also called third molars. They are located behind the second molars, at the very back of the upper and lower jaws. Most people who develop them have up to four: one in each corner of the mouth.
They usually appear during the late teenage years or early adulthood. According to the American Dental Association, wisdom teeth commonly emerge around ages 17 to 21.
However, not everyone develops four wisdom teeth. Some people have fewer, while others may have wisdom teeth that remain beneath the gums and never erupt into the mouth.
Why Do We Get Wisdom Teeth?
TL;DR: The most commonly cited explanation is evolutionary: our ancestors had larger jaws and tougher, more fibrous diets, so extra molars provided useful chewing surfaces. As jaws became smaller and diets softer, many people were left with third molars but not enough room for them.
Our early ancestors generally had larger jaws and relied on foods that were harder and more fibrous, including tough plants, nuts, and uncooked foods. Extra molars provided additional chewing surfaces that could help process this type of diet.
Over time, human diets changed. Cooking, food preparation, and other changes made food easier to chew. At the same time, human jaw structure gradually became smaller. However, the development of wisdom teeth did not disappear at the same pace.
The result is a mismatch: many people still develop third molars, but their jaws may not have enough space for these teeth to erupt comfortably.
The Smithsonian Institution's Human Origins Program explains that wisdom teeth were useful to early ancestors who consumed tougher foods, while modern jaw size often leaves insufficient room for these molars. It's worth noting this jaw-size explanation is a simplified summary of a more complex picture. Some researchers argue that jaw growth is shaped as much by how much chewing a person's jaw does during childhood, rather than by evolutionary jaw shrinkage across generations, meaning diet during an individual's own development, not only diet across human history, may influence how much room is available for wisdom teeth to erupt.
Why Do Wisdom Teeth Sometimes Cause Problems?
TL;DR: The main issue is usually lack of space. When a wisdom tooth cannot fully erupt, it becomes impacted, which can lead to pain, infection, decay, or damage to nearby teeth.
The main issue is often lack of space.
When there is enough room and a wisdom tooth grows into a healthy position, it may function like another molar and cause no significant problems. However, when space is limited, the tooth may become impacted.
An impacted wisdom tooth is one that cannot fully erupt through the gum. It may remain trapped beneath the gum or jawbone, or it may grow at an unusual angle.
Potential problems include:
Pain or pressure at the back of the mouth
Swollen or inflamed gums
Difficulty cleaning around the tooth
Tooth decay
Gum infection
Damage to a neighbouring tooth
Repeated inflammation around a partially erupted tooth
Clinical perspective: According to the NCBI’s Overview of Wisdom Teeth, dental assessment tends to focus less on whether a wisdom tooth is present and more on its position and the angle at which it sits. A wisdom tooth growing straight up with full eruption and easy access for cleaning carries a very different risk profile from one lying sideways against the neighbouring molar. This is why an X-ray, rather than a visual check alone, is generally needed before any decision is made.
These problems can also explain why wisdom tooth pain may sometimes seem to spread toward the jaw, cheek, or surrounding areas.
Does Everyone Need Their Wisdom Teeth Removed?
TL;DR: No. Extraction is generally considered when a wisdom tooth is causing or is likely to cause problems, not simply because it is present.
No. Having wisdom teeth does not automatically mean you need wisdom tooth extraction.
If a wisdom tooth is healthy, positioned properly, fully erupted, and easy to clean, a dentist may recommend monitoring it rather than removing it.
Removal may be considered when there is evidence of problems such as:
Repeated infection or inflammation
Significant pain
Tooth decay that cannot be reasonably restored
Damage to nearby teeth
Cysts or other abnormalities
An impacted tooth causing or likely to cause dental problems
A dental examination and X-ray can help determine the tooth's position and whether treatment is appropriate.
The decision should therefore be based on the individual's dental condition rather than simply the fact that wisdom teeth are present. Learn more about when you should consider wisdom tooth extraction to understand when removal may be recommended.
What Is the Difference Between Wisdom Tooth Extraction and Surgery?
The treatment depends largely on how the tooth has erupted.
A fully erupted wisdom tooth that is accessible and positioned normally may sometimes be removed through a straightforward extraction. An impacted or partially erupted tooth may require wisdom tooth surgery, which can involve opening the gum and, depending on the tooth's position, removing or dividing part of the tooth.
Find out how wisdom tooth extraction differs from surgery to better understand the treatment options and when surgical removal may be needed.
Situation | Possible approach |
Fully erupted and accessible | Standard extraction |
Partially erupted | May require surgical removal |
Impacted beneath gum or bone | Surgical extraction may be considered |
Healthy and problem-free | Monitoring may be appropriate |
EZ Dental Care provides wisdom tooth extraction services at its clinics in Bedok North and Geylang Bahru, with assessment and X-ray imaging used to evaluate wisdom tooth position.
When Should You See a Dentist About Wisdom Teeth?
Not every sensation around a wisdom tooth requires immediate treatment, but persistent or worsening symptoms should be assessed.
See a dentist if you experience:
Persistent wisdom tooth pain
Swelling around the back of your mouth
Difficulty opening your mouth
Repeated gum inflammation
Pain when chewing
A bad taste or unpleasant smell around a partially erupted tooth
Symptoms that interfere with eating or daily activities
Seek prompt dental attention if pain or swelling becomes severe, particularly if you develop difficulty swallowing, difficulty breathing, significant facial swelling, or other concerning symptoms.
If you are unsure whether your symptoms are related to a wisdom tooth, a dentist can examine the area and determine whether an X-ray is needed.
Frequently Asked Questions
Do wisdom teeth have a purpose?
Wisdom teeth were likely useful to human ancestors because they provided additional chewing surfaces for tougher foods. Today, they are generally less important because modern diets are easier to chew. However, a healthy wisdom tooth can still function as a molar if it erupts properly.
Why do some people not have wisdom teeth?
Not everyone develops wisdom teeth, and some people develop fewer than four. Variation in the development of third molars is normal. Some wisdom teeth may also remain beneath the gums instead of erupting visibly.
Do wisdom teeth always need to be removed?
No. Healthy wisdom teeth that are properly positioned and easy to clean may not require extraction. A dentist can assess their position, condition, and potential risks before recommending treatment.
What causes wisdom tooth pain?
Wisdom tooth pain can occur when a tooth is erupting, impacted, partially covered by gum tissue, infected, or affected by decay. Pain at the back of the mouth can have other causes too, so a dental examination is useful when symptoms persist.
Conclusion
So, why do we get wisdom teeth? They are largely explained by our evolutionary history, though the details of that story are more nuanced than a single sentence can capture. Our ancestors likely benefited from an extra set of molars when their jaws were larger and their diets required more chewing, while modern humans often have smaller jaws and softer, more processed diets, leaving less room for these teeth.
Wisdom teeth are not automatically a problem, and not everyone needs wisdom tooth extraction. However, impacted or poorly positioned teeth can contribute to pain, infection, decay, and other dental concerns. If you are experiencing wisdom tooth symptoms, EZ Dental Care offers dental assessment and wisdom tooth treatment at its Bedok North and Geylang Bahru clinics.
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