Each year hundreds of thousands of individuals are reported missing in the United States, among them runaways, abducted children and young adults, senior citizens suffering from dementia, and fugitive criminals. Each year law enforcement agencies are charged with the task of locating these individuals, expending time and manpower in searches that may last years and may or may not be successful. Major difficulties in the location of missing persons and fugitives, especially in cases extending over long periods of time, are caused by changes in the facial appearance of these individuals, which result from the natural aging process, rough living, purposeful physical alterations, or a combination of these and still other factors. The following study describes age-related changes occurring naturally in the human face as well as characteristic changes in facial appearance caused by aspects of the environment; alcohol and other drug use; disease; and dental, medical, or cosmetic procedures. These changes, which can accentuate and hasten the normal aging process, are illustrated photographically and demonstrate the variation and complications involved in facial recognition and identification.
Aging: Biology and Chronology
Aging is a highly individual phenomenon. How this process manifests in a given individual is determined, in large part, by genetics and general human variation (Loth and Iscan 1994; Neave 1998; Novick 1988; Orentreich 1995). Like biological development, aging in different people does not take place at a uniform rate (Subtelny 1959), may occur in spurts, and is unpredictable with regard to the specific numerical age of an individual (Bulpitt 1995; Feik and Glover 1998; Loth and Iscan 1994; Neave 1998; White 1991). Differences in the rate of aging between men and women have been documented by many researchers, who attribute the seemingly faster onset of age in females to sex-specific characteristics such as skin thickness (which also varies racially and regionally) and hormonal activity--especially with relation to menopause (Callens et al. 1996; Dumont 1986; Feik and Glover 1998; Neave 1998). In both sexes, however, individual hormonal changes as well as diet, skin pigmentation, and level of physical activity play a significant role in the onset and visibility of physical aging (Kadunce et al. 1991; Landau 1989; Neave 1998; Novick 1988; Orentreich 1995).
The traditional concept of age and aging measures the number of years that have passed since a person's birth. When discussing cutaneous aging, however, it is important to differentiate between a number of different processes occurring on the molecular level, especially as these tend to overlap within the general category of biological aging. Chronologic aging, also called intrinsic or innate aging, refers to the gradual, progressive degeneration of tissues occurring throughout the body during a lifetime and is physically apparent in the skin, the organs, and all bodily systems. These physiological changes manifest within the body at fairly predictable stages in an average individual's life and represent inherited tendencies (Novick 1988; Uiotto 1997; Uiotto et al. 1989). Extrinsic aging or photoaging occurs as a product of exposure to sunlight and specifically involves the degenerative effects of actinic irradiation; only the sun-exposed portions of the body are subject to this type of damage (Kolb 1998b; Uiotto et al. 1989). Because these processes occur independently and simultaneously, the changes caused by extrinsic photoaging enhance and emphasize those produced by innate chronologic degeneration (Novick 1988; Uiotto 1997; Uiotto et al. 1989). It should be noted that depending on the genetics, health, and habits of a given individual, a person's biological age may differ--sometimes significantly--from his or her actual age in years (Feik and Glover 1998; Loth and Iscan 1994; Neave 1998).