You may have noticed that your hair texture is not the same as it was in your youth, perhaps becoming straighter, thinner, or even developing an unexpected wave or curl. This change is a common observation, validating that hair is a dynamic part of the body that responds to the biological shifts of aging. The hair that grows from your scalp in your 50s or 60s is chemically and structurally different from the hair that grew in your 20s. These changes are rooted in fundamental biological processes within the body and the hair follicle itself, revealing why hair is capable of becoming wavier as you get older.
The Biology of Hair Shape
The natural shape of a hair strand is determined primarily by the structure of the hair follicle embedded in the scalp. Straight hair tends to emerge from follicles that are nearly circular in cross-section, allowing the hair shaft to grow out uniformly. In contrast, wavy or curly hair is produced by follicles with an oval or elliptical cross-section. This flattened shape forces keratin-producing cells to be distributed asymmetrically within the hair shaft, creating tension and a natural bend. The uneven distribution of keratin proteins dictates the degree of curl or wave a strand will possess.
Hormonal Shifts and Follicle Remodeling
The most significant driver for a change in hair texture over a lifetime is the fluctuation of hormones, which can physically alter the shape of the hair follicle in a process called follicle remodeling. Hormones like androgens and estrogens have receptors within the hair follicle and directly influence its growth cycle and structure. Major life events associated with large hormonal shifts, such as puberty, pregnancy, and menopause or andropause, can trigger permanent or semi-permanent changes to hair texture.
During menopause, a woman experiences a rapid decline in estrogen, leading to a relative increase in androgens. This hormonal imbalance can cause the circular shape of a follicle to subtly flatten into a more elliptical form, causing previously straight hair to develop a noticeable wave or curl. For some individuals, the cumulative effect of decades of hormonal cycles results in a gradual, structural change to the follicle over time.
The alteration in hormone levels also affects the hair growth cycle, often shortening the active growth phase and decreasing hair diameter. This follicular miniaturization, combined with the shape change, leads to hair that is finer and sometimes less dense. The hair that grows back from a remodeled follicle exhibits the new texture dictated by the altered follicular shape.
Changes in Strand Structure and Sebum Production
Beyond the follicle’s structural change, two physical changes in the hair strand itself contribute to the appearance of waviness in older adults. The first is related to hair graying, which involves the loss of melanin pigment from the hair shaft. Gray hair often exhibits a different internal keratin structure and a coarser texture than its pigmented counterpart.
This structural difference means that gray hairs can have an altered diameter and increased porosity, causing them to behave more erratically and appear wavy. The emergence of a significant percentage of gray hair can change the overall texture and manageability of the entire head of hair. A second contributing factor is the natural reduction in the activity of the sebaceous glands with age.
Sebum, the natural oil produced by these glands, coats the hair shaft, providing weight and lubrication. As people age, sebum production naturally decreases, often resulting in hair that is lighter and drier. This loss of natural weight and moisture allows a latent or subtle waviness, previously weighed down by oil, to become more apparent in the absence of sebum’s smoothing effect.