As we age, our bodies go through many changes. One of the more noticeable shifts is in the appearance of our faces. Features like the nose, ears, and chin may seem to lengthen or droop over time. This leads many to wonder: does the skull itself actually change shape as we get older? In short – yes, the skull does undergo subtle changes with age. However, the amount and nature of shifting depends on a variety of factors.
What is the skull?
The skull is composed of 22 bones that surround and protect the brain and sensory organs like the eyes and ears. The skull bones are connected by immobile fibrous joints called sutures. The only bone-to-bone joints (synovial joints) are located in the mandible (jaw). The 8 cranial bones that form the neurocranium (housing the brain) fuse together during infancy and childhood. However, the 14 facial bones remain unfused, allowing for some movement.
Key age-related skull changes
While the overall size and shape of the skull remains largely unchanged from adulthood into old age, there are a few key shifts:
Bone resorption
Over time, osteoclast cells break down small amounts of bone more rapidly than osteoblasts can rebuild it. This leads to a gradual loss of bone mass and density. Resorption typically occurs in areas where muscle attachments are weak or absent. The frontal, occipital, and temporal bones thin noticeably, whereas the thick petrous ridges maintain their bulk.
Tooth loss
With advanced age, tooth loss is common and can impact facial bone structure. The maxilla (upper jaw) and mandible rely on stimulation from chewing forces to maintain bone mass. Without teeth, the jaws will atrophy, reducing the vertical dimension of the lower face. Dentures can’t fully restore natural nutrition or bone loading.
Tissue changes
Other tissue changes affect skull shape as well. For example, the thickening of orbital fat tissue may cause the eyes to appear more deeply set. Loss of collagen leads to loose skin that can create exaggerated bone protrusions and hollows. Declining muscle tone also contributes to a more sunken, lean look in the face.
Degenerative bone conditions
Age-related conditions like osteoporosis and osteomalacia (weak, soft bones) are associated with changes to the shape and density of cranial bones. Osteomalacia causes thinning of the inner bone tissue, enlargement of the marrow cavities, and porosity (tiny holes). Osteoporosis makes the temporal bones especially prone to depressions.
How much shifting occurs?
Overall, the skull undergoes up to 4 millimeters (0.16 inches) of shape change from young adulthood to old age. The specific amount and nature of shifting varies between individuals based on factors like:
- Genetics
- Bone density
- Tooth loss patterns
- Facial fat distribution
- Environmental exposure
- Nutrition
- Presence of bone disorders
People with thicker cranial bones and good bone preservation into old age will likely experience less dramatic shape changes. Malnourishment, tooth loss, smoking, osteoporosis, and other factors can accelerate bone resorption and tissue changes for a more drastic shift.
Key skull changes
Though subtle on an individual basis, some patterns of skull change with aging include:
Brow ridge
The brow ridge becomes more pronounced, likely due to bone resorption in the surrounding areas.
Orbit shape
The bony eye sockets (orbits) increase in overall size and become more rectangular due to bone resorption.
Nasal aperture
The nasal cavity opening in the skull grows wider and taller. The nasal septum between the left and right sides of the cavity also gradually resorbs.
Inferior orbital margin
The lower edge of the eye sockets loses definition and appears flattened.
Zygomatic arches
The cheekbone arches recede backwards due to maxillary resorption after tooth loss. This causes the cheeks to appear more sunken.
Anterior nasal spine
The small bony projection at the lower end of the nasal cavity becomes longer and more hooked.
Maxilla and mandible
These jaw bones shrink vertically and experience gradual resorption of the alveolar margins where teeth are set. The mandible body takes on a more square shape.
Sex differences
Research shows some subtle differences in skull shape changes between males and females. For example, males tend to show:
– More rounding of the supraorbital margin (above the eyes)
– Broader nasal aperture
– Larger mastoid processes behind the ears
– More pronounced inion (external occipital protuberance)
These variances likely relate to the already present sexual dimorphism (physical differences between sexes) in facial features and muscle attachments. But overall, the extent of skull change is generally comparable in males and females.
Does skull shape stabilize after a certain age?
The most rapid shifts in skull shape tend to occur from early to middle adulthood as tooth loss progresses and tissue elasticity declines. However, gradual bone changes continue through the 70s, 80s, and 90s. Very advanced age brings some stabilization as bone loss plateaus. But degenerative bone conditions like osteoporosis can persist and cause ongoing diminishment.
Facial bone loss after tooth extraction can occur at any adult age. According to one study, the maxillary and mandibular bones reduced around 1 millimeter for each decade after the 20s. This gradual resorption continues as long as teeth are missing. So there may not be a point at which the jaw bones remain static.
Can skull shape accurately determine age?
Because there is considerable individual variation in the rate and degree of skull change, researchers caution against overestimating the accuracy of skull shape for determining age. Bony landmarks like the amount of cranial suture closure can provide a general age range. But many other factors like nutrition and bone disorders also affect the skull.
Overall, skull shape changes offer clues but not definitive proof of an individual’s age. In anthropological analysis, archaeologists combine skull assessment with other skeletal traits to estimate age ranges. But there is no precise formula.
Does the skull continue changing shape once fused?
The 8 neurocranial bones that form the brain case fuse together completely during early childhood. Sutural growth and minor shifting still occurs after fusion to allow the brain to expand to its full adult size. But after the completion of brain growth, the neurocranium remains static in adults and does not undergo further shape changes with age.
In contrast, the facial bones remain unfused throughout life, allowing for gradual resorption. So most age-related skull shape changes occur only in the facial bones, while the neurocranium maintains its overall size and configuration after maturity.
Can skull shaping affect health and function?
Extreme skull distortion, such as intentionally binding an infant’s soft cranial bones, can negatively impact health and function. However, the subtle skull shape changes associated with normal aging don’t appear to affect the brain or senses in a significant way.
For example, the gradual enlargement of the nasal cavity doesn’t hinder breathing and air flow. The brain still has ample room within the stable neurocranium as the facial bones shift. Vision and hearing are not impaired by incremental orbital or ear bone changes over decades. In the absence of major bone disease, minor age-related skull shape shifts pose no real health risks.
Conclusion
While the neurocranium remains static after maturity, the facial bones of the skull do undergo gradual reshaping as we age. Bone resorption, tooth loss, tissue changes, and some degenerative bone disorders all contribute to subtle skull alterations over time. People experience different rates of change based on genetics, health, and other factors. However, certain patterns like increased orbital size, maxillary reduction, and nasal enlargement are commonly seen to a small extent in older populations. Anthropologists can consider skull shape as one of many clues about an individual’s age, but it is not an exact indicator. Overall, normal age-related skull changes do not impair function or health.
| Decade | Skull Changes |
|---|---|
| 20s | Cranial sutures finish fusing together; skeletal maturity reached |
| 30s | Gradual bone resorption begins, subtle changes start |
| 40s | Nasal aperture enlargement may begin |
| 50s | Tooth loss accelerates bone reduction in jaws |
| 60s | Orbital shape change more noticeable |
| 70s | Ongoing resorption leads to sunken appearance |
| 80s | Bone loss plateaus but degeneration can persist |