Folds and Wrinkles: Identification of Individuals Through Analysis

Folds and wrinkles, the subtle manifestations of skin morphology, offer an extraordinary range of unique identification features. They serve as precise reference points between the identifying model and the subject to be identified. The complexity and individuality of these features allow for remarkable precision in identification.

Folds represent continuous morphological changes in human facial skin, which are primarily associated with aging. At first, these changes appear as fine lines, often visible as smile lines or lip lines, and gradually develop into deeper folds and eventually into pronounced wrinkles. This process is induced by the contraction of muscles and the subcutaneous tissue.

The aging process of the skin can be divided into two categories: chronological aging and photoaging or environmental aging. While chronological aging is a natural process that begins around the age of 25, photoaging is accelerated by external influences such as UV radiation and pollution. Despite individual differences, the aging process of the skin generally begins between the ages of 20 and 30, even if visible signs appear later. This phase is characterized by fine lines and wrinkles, a loss of elasticity and firmness, changes in the subcutaneous fat tissue, and a decrease in the skin’s fat and water content.

As aging progresses, the skin tends to become drier and more susceptible to cracks and pseudo-scars. The epidermis, the outermost layer of the skin, becomes thinner, which makes the underlying blood vessels more prominent. This dryness is due to reduced activity of the sebaceous glands, leading to lower fat production and a loss of skin elasticity. This impairs the skin’s ability to regenerate and can delay wound healing. In addition, muscle tone decreases with age, which further contributes to the formation of folds and wrinkles.

A classic example of the manifestation of folds and wrinkles is the double chin, which forms as a result of the creation of folds below the tip of the chin. These deep structural changes offer a unique opportunity for individual identification, as every line and crease is unique in its shape, size, and position.

In human facial skin, various types of folds and wrinkles can be distinguished, each arising through different mechanisms and in various regions of the face. These include:

• Glabellar lines, also known as frown lines, which result from repeated contraction of the corrugator supercilii and procerus muscles located between the eyebrows. These lines become more visible when we furrow our brows.
• Forehead wrinkles, which develop through repeated contraction of the frontalis muscle that spans the forehead. These wrinkles typically appear horizontally and become more pronounced when we raise our eyebrows.
• Periorbital wrinkles, often referred to as crow’s feet, which occur due to repeated contraction of the orbicularis oculi muscle surrounding the eyes. These wrinkles typically appear in the outer eye region and become more noticeable when we smile or squint.
• Nasolabial folds, which form between the nose and the corners of the mouth. Their appearance is influenced by various factors, including the repeated contraction of the zygomaticus major muscle, which helps us smile, as well as aging processes such as the loss of collagen, elastin, and subcutaneous fat.
• Mentolabial folds, also known as marionette lines, which extend from the corners of the mouth down to the chin. They develop due to aging processes such as the loss of collagen and elastin as well as changes in the position and amount of subcutaneous fat tissue.

These various folds and wrinkles provide unique identification points that can be used in photographic comparisons. Each line and crease is unique in its shape, size, and position, and a detailed examination of these features can contribute significantly to the identification of individuals.

Muscular involvement plays a crucial role in this process. Relevant muscles include the corrugator supercilii and procerus for glabellar lines, the frontalis muscle for forehead wrinkles, the orbicularis oculi for periorbital wrinkles, the zygomaticus major for nasolabial folds, and the depressor anguli oris and mentalis for mentolabial folds. The repeated contraction and relaxation of these muscles leave distinct marks on the skin that are unique to each person.

Additionally, research in the field of the skin microbiome has shown that the diversity of the skin microbiota plays a role in skin aging. Studies have found correlations between certain microbes and the formation of crow’s feet, opening up new avenues for skincare approaches. Technological advances such as Jones Matrix Optical Coherence Tomography (JM-OCT) enable non-invasive visualization of deep skin structures, offering new insights into the mechanisms of wrinkle formation.

In summary, a detailed examination of folds and wrinkles not only provides new possibilities in cosmetic dermatology but also in forensic science and identification technology.

Sources for this article:
University of California – San Diego. (2024). Researchers discover potential microbiome links to skin aging. ScienceDaily.
Medical Xpress. (2024). New analysis reveals how skin microbiome could be associated with wrinkles and skin health.
GitHub. (2024). FG-2024 Papers: Explore a comprehensive collection of research papers on facial recognition.
Biometric Update. (2024). Study finds dorsal hand images as effective as face biometrics for age estimation.
MDPI. (2024). Evaluation of Automatic Facial Wrinkle Detection Algorithms.
Manchester Metropolitan University. (2024). Research: Facial wrinkles detection and inpainting.