The concept of “growth” extends beyond the simple lengthening of bones, encompassing processes like cellular division, tissue expansion, and constant replacement. While the majority of our organs and skeletal frame cease their developmental increase after adolescence, certain body parts continue to experience morphological changes throughout a person’s life. These exceptions involve specialized tissues that maintain cellular activity, structures designed for constant turnover, or tissues that succumb to the forces of gravity and wear.
Cartilage That Keeps Expanding
The ears and the nose are the most widely recognized body parts that appear to increase in size over a lifetime. Unlike bones, which stop growing when their growth plates fuse, these structures are primarily composed of elastic cartilage, a flexible tissue that remains active. The perception of ongoing growth stems from two distinct biological mechanisms: one involving the cartilage itself and the other relating to the surrounding tissues.
Specialized cells called chondrocytes in the cartilage of the nasal tip and ear lobes continue to produce and replenish the surrounding extracellular matrix (a blend of collagen and proteoglycans). This gradual, microscopic accumulation of new matrix material throughout decades contributes to a subtle increase in overall dimension.
A more significant factor in the perceived enlargement is the degradation of the connective tissues supporting the cartilage. Over time, the skin’s collagen and elastin fibers weaken and lose their structural integrity. This loss of elasticity, combined with the constant, downward pull of gravity, causes the relatively soft cartilage framework to elongate and droop.
This effect is especially noticeable in the earlobes, which lack bony support. The weakening fibers allow the earlobe to stretch, making the ear look longer as a person ages. The nasal structure changes similarly, with the tip of the nose appearing to lengthen as its supporting ligaments weaken and the tissue sags downward.
Continuously Regenerating Structures
Some structures do not “grow” by increasing overall size, but rather undergo continuous production and replacement. Hair and nails are the most obvious examples of this constant regeneration. The visible parts of hair strands and nails are made of keratin, a protein that is technically non-living once pushed out from the skin.
This perpetual output is driven by living tissue beneath the surface: the hair follicle and the nail matrix. The hair follicle cycles through phases of growth, rest, and shedding, constantly manufacturing new hair fibers. Similarly, the nail matrix, located at the base of the nail bed, maintains a high rate of cellular division.
These rapidly dividing cells continuously produce new keratinocytes. As new cells form, they push older cells forward, where they flatten, harden, and die, forming the nail plate. This continuous cellular turnover is designed to replace structures subject to constant wear and tear, ensuring a fresh, functional barrier.
Changes Driven by Gravity and Wear
Many body parts that appear to change dramatically with age are not growing but are undergoing morphological alterations due to degradation and mechanical forces. The feet, for instance, often widen and lengthen over the years, leading to an increase in shoe size. This is not due to bone growth, but rather the cumulative effect of a person’s weight and the constant pull of gravity on the supporting ligaments and tendons.
The ligaments maintaining the arch of the foot gradually lose their tautness and elasticity. As these soft tissues become lax, the arch flattens and collapses slightly, causing the foot to spread out over a larger area. Similarly, the skin across the entire body simply sags rather than grows.
This sagging is a direct consequence of the breakdown of collagen and elastin, the protein fibers that provide skin with firmness and snap-back ability. As the body produces less of these proteins and existing supplies deteriorate, the skin yields to gravity. This effect can make features like the jawline and eyelids appear expanded or drooped.
The teeth and gums also exhibit changes driven by mechanical wear and cellular degradation. Gum recession, where the gum tissue pulls back from the tooth, can make the teeth look longer and more prominent. This is often an effect of inflammation or abrasive brushing over a lifetime, rather than continuous, intrinsic growth. These structural shifts illustrate how the body’s aging process is largely defined by loss of supportive tissue and yielding to external forces, creating the illusion of ongoing growth.