While the bony skull largely stops increasing in overall size by early adulthood, various other changes occur that can significantly alter the appearance of the head and face over time. These transformations are influenced by biological processes, the continuous evolution of facial features, and other factors that contribute to perceived changes in size and shape.
Skull Development and Maturation
The development of the human skull begins in infancy with multiple separate bony plates connected by flexible fibrous joints called sutures and soft spots known as fontanelles. These structures allow for rapid brain growth during early childhood. The posterior fontanelle typically closes first, often by 1 to 2 months of age, while the larger anterior fontanelle, or soft spot, usually closes between 7 and 19 months, though it can remain open until about 26 months.
As a person matures, these sutures gradually ossify and fuse, forming a solid, protective casing for the brain. While many skull sutures fuse by early adulthood, generally around 20 to 25 years of age, others can continue this process of ossification and fusion into the third or even fourth decade of life. Once these sutures have largely fused, the overall expansion of the bony skull ceases.
Changes in Facial Features
While the bony skull’s overall size stabilizes, certain facial features continue to undergo noticeable changes throughout life. The nose and ears, for instance, are primarily composed of cartilage, a flexible tissue that differs from bone in its growth patterns. This cartilage continues to change over time; ears, for example, can increase in circumference by approximately 0.22 to 0.51 millimeters per year due to collagen changes, reduced skin elasticity, and gravity. Nasal growth largely completes by late adolescence (age 16 in females, 18 in males), but alterations in its soft tissues and cartilage can lead to a perception of increased size with advancing age.
Beyond cartilage, the underlying facial bones also experience subtle remodeling as a person ages. Studies show that eye sockets can enlarge, and the jawline might undergo changes in its angle or recede due to age-related bone loss. These transformations in the facial skeleton contribute to alterations in facial contours and overall appearance, not an increase in overall head size.
Factors Influencing Perceived Changes
Several non-growth-related factors significantly influence the perception that one’s head or face is changing or growing older. The skin’s elasticity diminishes with age, due to reduced collagen and elastin production. This loss of elasticity contributes to sagging and drooping of facial tissues, particularly around the cheeks, jawline, and neck. Gravity also plays a role, exerting a constant downward pull that can alter facial contours and exaggerate sagging.
Changes in facial fat distribution further contribute to these perceived alterations. Fat pads in the upper and mid-face can diminish, creating hollowed areas, while fat may shift or accumulate in the lower face, forming jowls. Additionally, changes in hair thickness or hairline, such as receding hairlines or general thinning, can modify how the head’s shape or size is perceived. These collective changes in soft tissues and fat create the impression of a changing or “growing” head, distinct from any actual expansion of the bony skull.