Phenotype of Normal Hairline Maturation




Hairlines change shape with age, starting at birth. A good head of hair is frequently present some time after ages 3 to 5 years. The look of childhood has its corresponding hairline, and, as the child grows and develops into adulthood, facial morphology migrate changes from a childlike look to a more mature look. This article discusses the dynamics of hairline evolution and the phenotypic variations of the front and side hairlines in men and women. A modeling system is introduced that provides a common language to define the various anatomic points of the full range of hairlines.


Key points








  • Hairlines have characteristic shapes in boys and girls and change predictably as children develop into adulthood.



  • The hairline in male and female children is traditionally concave in shape in all races.



  • The upward movement of the female hairline leaves a widow’s peak in 81% of women.



  • The concave shape of the male frontal hairline transitions to a convex shape between 18-29 years of age.



  • The maturing recession of the temple mounds leaves a temple peak behind in boys and girls.



  • Recession of the temple mound upwards and laterally in men leaves a balding corner.



  • The leading edge of hair direction in the juvenile hairline is different than the hair direction in the mature hairline in adult men and some women.






Introduction


This article applies observational science to the process of how the hairline develops from childhood to adulthood in men and women. It also includes a summary of 1051 children from school yearbooks, aged 5 to 10 years and 15 to 18 years in boys and girls whose hairlines were not hidden by styling. It adds a missing link to the insights by Norwood and Shiell and Hamilton in their respective seminal articles on balding in men and women; however, this article’s main focus is not about balding, but about the visual changes in the hairlines that are seen as humans age. What is seen in hairline changes results from environmental events (eg, traction alopecia), age, and hormones as they influence the genetics that code the various parts of the anatomic hairline. These genetics are evident in the phenotype of the hairline’s evolution at each point in time. The available medical information on hairline evolution approaches hairline change as if it reflects a disease process or a genetic abnormality.


This article:



  • 1.

    Provides physicians with a better understanding of how to educate the patient to better understand the changes seen in their hairlines


  • 2.

    Will help decide whether the hairline changes are typical or not


  • 3.

    Provides the physician with a more precise understanding of the genetic influences of the phenotype of hairline evolution from childhood to adulthood


  • 4.

    Provides the hair restoration surgeon a foundation on which to design a hairline appropriate to meet each individual’s needs, specific to their age and sex



People often ask or comment about their hairlines:


Is my hairline receding or getting thin? Am I seeing my hairline rise? Do changes in my hairline mean that I am balding like my father or mother? I don’t like the shape or position of my hairline. Is there something I can do about it?


With genetic balding already affecting up to 50% of the male and female population over their lifetimes, perceptions of what is abnormal are often preprogrammed by the genetic hair loss patterns of people’s parents or grandparents. An uneven or eroding hairline creates a fuzzy, ill-defined border to the face, but a full leading hairline edge makes a statement that reflects a youthful, well-framed, and healthy image; an image that many people desire.




Introduction


This article applies observational science to the process of how the hairline develops from childhood to adulthood in men and women. It also includes a summary of 1051 children from school yearbooks, aged 5 to 10 years and 15 to 18 years in boys and girls whose hairlines were not hidden by styling. It adds a missing link to the insights by Norwood and Shiell and Hamilton in their respective seminal articles on balding in men and women; however, this article’s main focus is not about balding, but about the visual changes in the hairlines that are seen as humans age. What is seen in hairline changes results from environmental events (eg, traction alopecia), age, and hormones as they influence the genetics that code the various parts of the anatomic hairline. These genetics are evident in the phenotype of the hairline’s evolution at each point in time. The available medical information on hairline evolution approaches hairline change as if it reflects a disease process or a genetic abnormality.


This article:



  • 1.

    Provides physicians with a better understanding of how to educate the patient to better understand the changes seen in their hairlines


  • 2.

    Will help decide whether the hairline changes are typical or not


  • 3.

    Provides the physician with a more precise understanding of the genetic influences of the phenotype of hairline evolution from childhood to adulthood


  • 4.

    Provides the hair restoration surgeon a foundation on which to design a hairline appropriate to meet each individual’s needs, specific to their age and sex



People often ask or comment about their hairlines:


Is my hairline receding or getting thin? Am I seeing my hairline rise? Do changes in my hairline mean that I am balding like my father or mother? I don’t like the shape or position of my hairline. Is there something I can do about it?


With genetic balding already affecting up to 50% of the male and female population over their lifetimes, perceptions of what is abnormal are often preprogrammed by the genetic hair loss patterns of people’s parents or grandparents. An uneven or eroding hairline creates a fuzzy, ill-defined border to the face, but a full leading hairline edge makes a statement that reflects a youthful, well-framed, and healthy image; an image that many people desire.




Hairline analysis group


We observed and analyzed the hairlines of 1051 adolescent and preadolescent boys and girls by analyzing school yearbooks. These measurement processes were limited by (1) hairline styles that often obscured the hairline, and (2) a single view of the subjects; these subjects were therefore omitted from the study. We supplemented these data by observing school athletic team photographs and swim teams photographs by performing Internet searches for schools all over the world, by observing children at school graduations and in recreation areas, and at social events ( Table 1 ).



Table 1

Survey from school yearbooks in 1051 children


























































Sex Age (y) # Subjects WP (%) TP (%)
Boys 5 38 0 0
Boys 5–10 170 6 0
Boys 15–17 374 36 14
Boys 18 51 14 16
Girls 5 28 8 0
Girls 6–10 56 11 0
Girls 15–17 281 31 19
Girls 18 53 11 25

Abbreviations: TP, temporal peak; WP, widow’s peak.


Widow’s Peak and Temple Peak


It is apparent from the children studied in these yearbooks and from the multiple other observational and media sources (television, sports events, Olympic events from the 2012 Olympic Games) that male and female hairlines are similar in prepubertal children; all children start with a concave shaped hairline (ages 3–5 years). The leading central edge of the juvenile hairlines is always at the highest wrinkle of the furrowed brow. At the lateral temple borders, the forehead is narrowed in young children because of the presence of lateral temple mounds that help establish the concave shape. Widow’s peaks are rare in boys and girls between the ages of 5 and 10 years, whereas the incidence increases in teenage girls and boys. The widow’s peak never extends below the highest crease of the furrowed brow (in children or adults) and, when it appears, it indicates a rising frontal hairline around it. The lateral temple mounds crowd the lateral borders of the forehead of young children, women, and some men, and there is rarely a temple peak in juvenile or female hairlines while the temple mounds are present. As the lateral temple mounds recede laterally and posteriorly, a temple peak often appears. Both the widow’s peak and the temple peak are remnants of the midline juvenile hairlines and the lateral temple mound of the concave hairline.


Genetics, Hormones, Environment


Most prepubertal children have concave shaped hairlines. In most, there is little distinction between the hairlines of boys and girls until these children near puberty, when we believe hormone changes trigger genetic changes. These changes vary widely as children transition into adolescence and become young men and women. Although a great deal has been written about the importance of hair as a sign of health and vitality, subtle changes that show erosion of youthful hairlines greatly affect how people feel about themselves. The interplay between genetics, hormones, and possibly environmental factors (eg, traction on the hair from styling) can affect these changes.


There is little doubt that the hairlines we have studied can be influenced by traction brought on by pulling the hair back. Traction alopecia has been directly linked to hairline hair loss in African American children who have routinely worn tight braiding. This braiding has been known to produce a loss of some or all of the frontal and temple mound hair in a significant number of these children. What is unclear are the effects of the pony tail as a contributing factor affecting the evolution of what is seen in the hairlines of these girls. Considering that similar changes are seen in boys to a lesser degree, we think that styling adjuncts like the pony tail only rarely cause hairline alopecia. We were unable to distinguish the hairlines in the girls who did or did not routinely wear pony tails, and this reflects a limitation of the study and could affect the validity of some of our conclusions.




Hairline model system


To develop language in order to define the various anatomic points of the hairline, the authors developed a modeled system, illustrated in Fig. 1 , with the full range of hairlines. This model system can be applied to men and women of all ages and of all races.




Fig. 1


Hairline locations.


The border of the face is framed by the upper frontal hairline and lateral temple mounds. The anatomic location of the edges of these two structures need to be defined in order to understand the age-related standard, if there is a standard. We created a modeled system to be able to work out the changes in hairlines that we see. There are 3 critical areas that define a hairline:



  • 1.

    A point where the central leading edge of the upper crease of the furrowed brow can easily be identified (point A)


  • 2.

    Lateral leading edge of the upper temple hairline (point B)


  • 3.

    Lateral temple mounds on the side of the forehead (point C)



The image of a face changes as a hairline recedes superiorly and laterally. As children, everyone has a hairline defined by points A1, B1, and C1 producing a hairline that is originally concave in shape (see Fig. 1 ).

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Aug 26, 2017 | Posted by in General Surgery | Comments Off on Phenotype of Normal Hairline Maturation

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