Why do we get wrinkles? We get wrinkles because skin changes structurally as we age. Collagen becomes less abundant and more fragmented, elastic fibres lose some of their ability to spring back, the skin becomes thinner and drier, and the layer of fat beneath it can change. Repeated facial movement, gravity and ultraviolet radiation from sunlight add extra mechanical and chemical stress, so folds that once disappeared quickly can gradually become permanent lines.
People searching for why wrinkles form, what causes fine lines, why sun exposure causes wrinkles, why skin loses collagen, why some people wrinkle earlier and how facial expressions create lines are asking about anatomy, ageing, connective tissue, genetics and environmental exposure at the same time. Wrinkles are not one defect with one cause; they are the visible result of several slow processes acting on skin over years.
For students, wrinkles are a useful example of how material properties change in living tissue. Young skin can deform and recover because collagen, elastin, water, fat and cellular repair systems work together. Ageing changes that system gradually. The surface still performs its barrier function, but it becomes less able to resist repeated folding and less able to restore its original shape after each movement.
The Short Answer: Skin Loses Support and Elastic Recovery
Wrinkles form when skin no longer returns as completely to its original shape after bending, folding or compression. Ageing changes collagen, elastin, hydration and the organisation of deeper tissue.
Repeated forces then leave progressively more persistent marks. A smile line that was temporary at twenty can become visible at rest decades later because the material underneath has changed.
What Collagen Does
Collagen fibres give the dermis much of its tensile strength. They help skin resist stretching and provide a structural framework for cells, blood vessels and other extracellular material.
With age, collagen production declines and existing fibres accumulate damage. The support network becomes less dense and less orderly, making the skin more likely to crease.
What Elastin Does
Elastin allows skin to stretch and then recoil. It works with collagen rather than replacing it.
When elastic fibres become fragmented or abnormal, skin does not spring back as efficiently after facial movement, pressure or gravity. Reduced recoil contributes to sagging as well as wrinkles.
Why Skin Becomes Thinner With Age
The epidermis and dermis change with age. Cell turnover slows and some supporting layers become thinner.
A thinner surface provides less structural depth between the outside world and underlying tissues, so folds and vessels can become more visible.
Why Skin Becomes Drier
Oil production and the skin’s ability to retain water can decline with age. A drier outer layer is less plump and can make fine lines look more obvious.
Hydration changes appearance, but dryness is not the whole cause of deep wrinkles. Moisture can soften the surface while deeper structural ageing remains.
Why Facial Expressions Create Lines
Smiling, squinting, frowning and raising the eyebrows fold skin repeatedly along predictable paths. In young skin those folds usually disappear when the muscles relax.
As elastic recovery weakens, the repeated fold becomes a preferred crease. Dynamic lines gradually become static lines that remain visible even when the face is neutral.
Why Crow’s Feet Form
The circular muscle around the eye contracts during smiling and squinting. The thin skin at the outer eye folds into radiating lines.
Because this region has little deep padding and receives frequent sun exposure, those temporary lines often become persistent earlier than lines in thicker skin.
Why Forehead Lines Form
The frontalis muscle lifts the eyebrows and repeatedly folds forehead skin horizontally.
Over years, the same mechanical pattern is repeated thousands of times. Reduced collagen and elasticity allow those fold lines to become established.
Why Frown Lines Form
Muscles between the eyebrows pull the brows inward and downward during concentration, glare, anger or habit.
The skin repeatedly compresses vertically in the same region, creating the paired grooves often called frown lines.
Why Sunlight Accelerates Wrinkling
Ultraviolet radiation damages DNA and connective tissue and changes enzymes that remodel collagen. Chronic exposure accelerates the breakdown of collagen and produces abnormal elastin.
This process is called photoageing. It can make exposed skin wrinkle, roughen and change pigment earlier than skin that receives less ultraviolet exposure.
UVA and UVB Are Different
UVA penetrates more deeply into skin and contributes strongly to photoageing, while UVB has higher energy at the surface and is a major cause of sunburn and direct DNA damage.
Both can contribute to cumulative skin damage. The distinction explains why wrinkle prevention and skin-cancer prevention overlap but are not identical questions.
Why Sun-Exposed Skin Ages Differently
Compare a chronically exposed forearm or face with skin usually protected by clothing. The exposed region often develops more uneven pigment, roughness and deeper wrinkling.
The comparison demonstrates that intrinsic ageing and environmental ageing operate together. Genes set a baseline, while exposure changes the rate.
Why Smoking Accelerates Wrinkles
Smoking exposes tissues to oxidants and reduces healthy blood-vessel function. It is associated with accelerated collagen breakdown and characteristic facial wrinkling.
Repeated lip movement during smoking can add mechanical lines around the mouth, but the broader effect is biological damage to skin structure.
Why Air Pollution Is Discussed
Air pollution contains particles and reactive chemicals that can increase oxidative stress and inflammation at exposed skin surfaces.
The effect is smaller and more variable than age or ultraviolet exposure but contributes to the idea that skin ageing reflects cumulative environment as well as genetics.
Why Genetics Matters
Genes influence collagen structure, skin thickness, pigmentation, facial anatomy and repair systems. These inherited traits affect when and where wrinkles become visible.
This is why siblings can share ageing patterns even when lifestyles differ, while people of the same age can look very different.
Why Skin Pigment Changes Photoageing Risk
Melanin absorbs ultraviolet radiation and provides some natural protection from UV damage. More melanin generally reduces some forms of photoageing.
No skin tone is immune to ultraviolet injury. Darker skin can still develop wrinkles, pigment changes and skin cancer, although patterns and timing can differ.
Why Wrinkles Are Not Just “Old Skin”
Ageing includes many processes: altered collagen, elastin, fat, bone, muscle, hydration and cell signalling. Wrinkles are one visible output of that larger system.
Two people with similar wrinkles can have different combinations of causes, which is why appearance alone cannot reveal the exact biological history.
Why Fat Under the Skin Matters
Subcutaneous fat gives the face volume and supports the overlying skin. Ageing can reduce or redistribute facial fat pads.
When support shifts, skin can fold or sag differently even if the skin itself has not lost the same amount of collagen everywhere.
Why Facial Bones Matter
The skull and facial skeleton also remodel with age. Changes around the eye sockets, cheeks and jaw alter the framework supporting skin and soft tissue.
Wrinkling and sagging are therefore partly architectural. The covering changes, but so does the structure beneath it.
Why Gravity Matters
Gravity continuously pulls soft tissue downward. Young connective tissue resists this force effectively.
As elastic recovery and structural support decline, gravity contributes more visibly to folds, jowls and deeper creases.
Why Sleeping Position Can Create Temporary Lines
Pressing the face against a pillow folds skin in directions different from ordinary facial expression. Younger skin usually smooths quickly after pressure stops.
With age, repeated compression may leave longer-lasting sleep lines because the tissue has less elastic recovery.
Why Dehydration Can Make Lines Look Worse
Temporary dehydration can reduce skin surface plumpness and make fine lines appear more obvious.
Rehydration can improve that temporary appearance, but drinking extra water cannot rebuild lost collagen or erase established structural wrinkles.
Why Moisturisers Make Fine Lines Look Better
Moisturisers reduce water loss and increase hydration of the outer skin layer. A hydrated stratum corneum swells slightly and becomes smoother.
This optical and mechanical improvement can soften fine lines temporarily without reversing deeper dermal ageing.
Why Retinoids Are Discussed
Topical retinoids influence skin-cell turnover and collagen-related pathways and are among the better-studied treatments for photoaged skin.
They can irritate skin and are not appropriate for every person or circumstance. Treatment decisions belong in a skincare or medical context rather than being reduced to one universal product recommendation.
Why Sunscreen Matters More Than “Anti-Wrinkle” Marketing
Daily ultraviolet exposure is one of the strongest modifiable drivers of photoageing. Reducing cumulative UV dose slows future damage.
A product that moisturises existing lines may improve appearance, while sun protection addresses one of the processes creating additional damage over time.
Why Wrinkles Differ Around the Mouth
The mouth moves constantly during speech, eating and expression. Skin around the lips also has different thickness and fat support from the cheeks.
Smoking, sun exposure and age can therefore produce distinctive vertical and radial lines around the mouth.
Why Neck Wrinkles Form
The neck bends repeatedly and is often exposed to sunlight while receiving less deliberate skincare than the face.
Skin and underlying support also differ from the cheeks, so horizontal neck lines and loose folds can become prominent with age.
Why Hands Show Age
The backs of the hands have relatively thin skin and receive substantial sun exposure. Fat and collagen loss make tendons and veins more visible.
Wrinkling there reflects the same combination of intrinsic ageing and environmental exposure seen on the face.
Why Wrinkles Can Appear Earlier in Outdoor Workers
High cumulative ultraviolet exposure accelerates photoageing. Someone who spends decades working outdoors can therefore develop deeper wrinkles earlier than a person with less exposure.
The effect demonstrates dose over time: small exposures repeated daily can matter more than occasional intense exposure alone.
Why Tanning Beds Age Skin
Tanning devices expose skin to ultraviolet radiation, often with substantial UVA. The tan is evidence of a pigment response to injury.
Repeated artificial UV exposure accelerates photoageing and increases skin-cancer risk, so the cosmetic short-term darkening comes with long-term biological cost.
Why Repeated Squinting Matters
Bright light, uncorrected vision problems or habit can increase how often the eye region folds.
Mechanical repetition alone does not create all wrinkles, but it reinforces lines when skin structure has already become less resilient.
Why Wrinkles Can Be Asymmetric
Faces do not receive identical sunlight, sleep pressure, muscle use or anatomy on both sides. Driving position, window exposure and habitual expressions can create unequal cumulative stress.
Small differences repeated for years can become visible asymmetry.
Why Men and Women Can Age Differently
Hormones, skin thickness, facial hair, fat distribution and menopause-related changes influence skin ageing.
There is large overlap between individuals, so sex-based averages cannot predict one person’s wrinkle pattern precisely.
Why Menopause Can Accelerate Skin Change
Falling estrogen affects collagen, hydration and skin thickness. Some people notice faster changes in texture and elasticity around menopause.
Hormonal influence adds to rather than replaces the effects of chronological ageing, sun exposure and genetics.
Why Stress Can Affect Skin Without Being a Direct Wrinkle Switch
Chronic stress can influence sleep, inflammation, hormones and behaviour such as smoking or reduced self-care.
These pathways may contribute indirectly to skin ageing, but one stressful week does not mechanically create permanent wrinkles overnight.
Why Poor Sleep Can Change Appearance
Sleep affects fluid distribution, inflammation and tissue repair. Short-term sleep loss can make the face look tired or puffy.
Long-term lifestyle patterns may influence ageing, but temporary lines after a bad night are not the same as permanent structural wrinkles.
Why Weight Loss Can Reveal Wrinkles
Loss of facial fat reduces volume beneath the skin. If skin elasticity is limited, the surface may look looser or more folded.
The wrinkle did not necessarily form because the weight loss damaged skin; a previously supported fold can simply become more visible.
Why Rapid Weight Change Can Matter
Skin adapts gradually to changes in underlying volume. Rapid expansion or contraction gives connective tissue less time to remodel.
This is one reason large body-size changes can alter skin laxity even when the person is otherwise healthy.
Why Wrinkles Are Different From Scars
A wrinkle is a fold or crease in otherwise continuous skin, while a scar is tissue produced after injury changes normal architecture.
Both involve collagen, but the collagen arrangement, cause and biological history differ.
Why Wrinkles Are Different From Stretch Marks
Stretch marks are dermal scars associated with rapid stretching and hormonal influences. They often appear as coloured or pale linear bands.
Wrinkles arise mainly from ageing, folding and support loss rather than the same acute expansion mechanism.
Why Wrinkles Can Look Deeper in Dry Light
Side lighting creates shadows along skin creases, making texture look stronger. Soft frontal light reduces those shadows.
Photography therefore changes perceived wrinkle depth without changing the skin itself.
Why Cameras Can Exaggerate Texture
Sharpness, contrast, lens distance and image processing alter how fine surface detail is rendered.
A highly detailed close-up can make ordinary pores and lines look dramatic, which is why appearance should not be treated as a precise medical measurement from one photograph.
Why Wrinkles Are a Materials-Science Problem
Skin behaves as a viscoelastic material: it responds to force over time, partly like an elastic solid and partly like a time-dependent material.
Ageing alters that viscoelastic behaviour, so the same facial movement produces a different degree of recovery at different ages.
Why Wrinkles Are a Repair-System Problem
Connective tissue is continually remodelled by cells such as fibroblasts. Damage and repair happen simultaneously.
Ageing and UV exposure shift the balance so breakdown can exceed rebuilding, gradually changing the extracellular matrix.
Why Wrinkles Are an Evolutionary Trade-Off
Natural selection strongly favours skin that protects the body through reproductive years, heals wounds and permits movement. Perfect lifelong smoothness provides little survival advantage.
Ageing therefore reflects biological maintenance limits rather than a design goal of keeping cosmetic appearance unchanged forever.
Why Wrinkles Are Not a Disease
Wrinkles are a normal feature of ageing and environmental exposure. They do not require treatment simply because they are present.
Medical evaluation is appropriate when a skin change is suspicious for disease, but ordinary wrinkles are an appearance change rather than an illness.
Why Some Wrinkles Carry Social Meaning
Cultures can associate wrinkles with age, wisdom, fatigue, beauty, stress or status. These meanings vary historically and socially.
The skin line itself is biological; the value assigned to it is cultural.
Why “Anti-Ageing” Is an Inexact Phrase
No skincare product stops the biological ageing of the entire body. Some interventions can reduce photoageing, improve hydration or alter the appearance of specific lines.
Clear language distinguishes slowing one process from reversing ageing as a whole.
Why Prevention and Treatment Are Different
Preventing additional UV damage is not the same as changing lines that already exist. Moisturisers, retinoids, procedures and sun protection act through different mechanisms.
Understanding the mechanism prevents one product from being expected to perform every job.
Why Skin Cancer Prevention and Wrinkle Prevention Overlap
Ultraviolet exposure contributes both to photoageing and to mutations that can lead to skin cancer.
Sun-protective behaviour therefore has a health rationale far beyond cosmetic appearance.
Why Wrinkles Are a Good Evidence Lesson
A person may credit one cream, supplement or habit for looking younger, but ageing is slow and photographs are sensitive to light, expression and camera settings.
Strong conclusions require controlled comparisons rather than before-and-after anecdotes alone.
Why Wrinkles Are a Good Systems-Thinking Lesson
The visible line reflects epidermis, dermis, fat, bone, muscle, hydration, genes and environment.
No single layer owns the wrinkle, which is why the best explanation combines mechanics, cell biology and long-term exposure.
What Students Should Be Able to Explain
A strong answer should connect collagen, elastin, repeated folding, ultraviolet radiation and age-related repair changes.
If a learner can explain why moisturiser can soften appearance without rebuilding deep collagen, and why sunlight accelerates ageing without being the only cause, the concept has become transferable.
Common Myths About Wrinkles
Wrinkles are not caused only by dehydration, facial expressions do not act alone, and one miracle cream cannot stop all mechanisms of skin ageing.
Genetics, intrinsic ageing and ultraviolet exposure remain central, while lifestyle and treatment modify rather than erase the process.
Frequently Asked Questions
Why do wrinkles become permanent? Skin loses structural support and elastic recovery. Why does the Sun matter? UV damages collagen and elastin and accelerates photoageing. Why do smile lines deepen? Repeated folding acts on increasingly less resilient tissue.
Can hydration remove wrinkles? It can temporarily plump the surface and soften fine lines but cannot reverse all deeper structural changes.
Where to Go Next
For authoritative background, see Mayo Clinic’s wrinkles overview and the National Institute on Aging guide to skin and ageing.
We get wrinkles because skin is a living material that changes with time. Collagen, elastin, hydration, fat, bone, muscles and ultraviolet exposure all reshape how the surface responds to thousands of repeated movements across decades.
Why Wrinkles Deepen With Repeated Motion
Every facial movement creates temporary stress in skin and connective tissue. When the same movement is repeated thousands of times, the same fold lines receive the same mechanical load. Young tissue redistributes that load efficiently, but older tissue has less collagen support and elastic recoil, so the fold becomes mechanically favoured and increasingly visible.
This is why dynamic lines often become static lines. The motion does not suddenly damage the skin in one moment; it creates a repeated pattern that gradually becomes encoded in the changing material properties of the face.
Why Wrinkles Often Follow Facial Anatomy
Wrinkle patterns are strongly influenced by where muscles attach, where skin is thin, how fat pads are arranged and where underlying bone changes direction. The face therefore has preferred fold lines, much like fabric folds repeatedly along the same seams.
This is why forehead lines tend to run horizontally while glabellar lines between the brows tend to run vertically. The geometry of muscle force determines the geometry of repeated folding.
Why Skin Around the Eyes Wrinkles Early
Periorbital skin is thin and moves constantly during blinking, smiling and squinting. It also has relatively little subcutaneous padding compared with the cheeks. Those features make small changes in collagen and elasticity especially visible.
Sun exposure adds further stress because the eye region is chronically exposed. Sunglasses can reduce squinting and UV exposure, addressing both a mechanical and environmental contributor at once.
Why Wrinkles Around the Mouth Can Be Deep
The lips and surrounding muscles move during speech, chewing, drinking and facial expression. The mouth region therefore experiences repeated folding in several directions every day. Age-related changes in fat and dental support also alter the way the skin drapes around the lower face.
That is why lines around the mouth can reflect more than skin ageing alone. Teeth, bone, muscle and soft tissue all contribute to the final surface shape.
Why Loss of Facial Volume Changes Wrinkles
Ageing can reduce or redistribute fat beneath the skin. When volume decreases, the skin that once stretched smoothly over a fuller structure may fold more easily. This is especially noticeable around the temples, cheeks and lower face.
The process is similar to a fabric cover becoming looser when the padding beneath it shrinks. The skin itself may also have changed, but support loss makes those changes more visible.
Why Bone Remodelling Changes the Face
Facial bones continue remodelling throughout adulthood. The eye sockets can enlarge slightly, the maxilla can change and the jawline can lose some structural prominence. These deep changes alter the framework that supports soft tissue.
Wrinkles therefore belong to a three-dimensional ageing process. Focusing only on the skin misses changes occurring in fat, muscle and bone underneath it.
Why Collagen Becomes Less Organised
Collagen fibres are continually remodelled by enzymes and cells. With age and UV exposure, breakdown increases and newly produced collagen may not replace the original architecture perfectly. Fibres become fragmented and less mechanically efficient.
The result is not simply “less collagen” but a network with poorer organisation and strength. Material quality matters as much as quantity.
Why Elastin Can Become Abnormal After Sun Damage
Chronic ultraviolet exposure can produce abnormal accumulations of elastic material in the dermis, a process associated with solar elastosis. Although the tissue may contain abundant elastin-like material, it does not behave like healthy elastic fibres.
This is a useful reminder that “more” of a structural material does not automatically mean better function. Organisation and molecular quality determine performance.
Why Repair Slows With Age
Fibroblasts, keratinocytes and other skin cells remain active throughout life, but their responses change with age. Cell signalling, matrix production and wound-healing speed can decline.
Damage therefore accumulates because the balance between wear and repair shifts. Wrinkles are one visible consequence of that slower maintenance system.
Why Repeated UV Exposure Is Cumulative
One brief period of sunlight does not create all future wrinkles, but ultraviolet damage adds up across years. DNA changes, collagen breakdown and pigment alterations accumulate gradually.
This cumulative process explains why daily habits matter. Small differences in exposure repeated thousands of times can eventually produce large differences in visible ageing.
Why Sunscreen Cannot Reverse Every Existing Wrinkle
Sunscreen reduces future ultraviolet exposure when used correctly, but it does not rebuild all previously lost collagen or reverse every structural change in older skin.
Its greatest value is preventive: lowering the rate of additional photoageing while other treatments, if desired, address existing appearance through different mechanisms.
Why Dryness and Wrinkles Are Easy to Confuse
Dry outer skin develops fine surface lines and rough texture that can resemble early wrinkling. Moisturiser may improve these lines quickly because the issue is partly water content in the stratum corneum.
Deeper wrinkles respond less dramatically because they involve dermal structure and facial anatomy, not only surface hydration.
Why Skin Can Look Younger After Moisturising Without Becoming Biologically Younger
Hydrated skin reflects light more evenly and its outer cells swell slightly, reducing fine surface irregularities. The visual change can be immediate.
This is a cosmetic improvement rather than reversal of chronological age. Appearance and underlying biological history should be kept conceptually separate.
Why Facial Massage Does Not Rebuild Deep Collagen Instantly
Massage can temporarily change blood flow, fluid distribution and muscle tension. Those effects may alter how the face looks for a short period.
Deep connective-tissue remodelling occurs over much longer timescales. Claims of instant collagen rebuilding confuse temporary mechanical effects with slower cellular biology.
Why Wrinkles Differ Between Individuals of the Same Age
Chronological age is only one variable. Genetics, UV exposure, smoking, pigmentation, facial shape, hormonal history, weight change and skin care all influence visible ageing.
Two people born on the same day can therefore have very different wrinkle patterns without either being biologically “older” in every sense.
Why Wrinkles Are a Better Age Estimate in Populations Than Individuals
Across large groups, wrinkles generally increase with age. For one person, however, the relationship is noisy because environmental and genetic variation is large.
This is a statistical lesson: a trend can be real at population level without being precise enough to predict one individual accurately.
Why Wrinkle Treatments Work Through Different Mechanisms
Moisturisers change surface hydration, retinoids influence cell and collagen biology, neuromodulators reduce muscle contraction, fillers replace volume and energy-based procedures stimulate tissue remodelling.
Because each targets a different part of the system, treatment choice depends on which kind of line or structural change is being addressed.
Why One Treatment Cannot Fix Every Wrinkle
A line caused mostly by repeated muscle contraction is biologically different from a fold caused by volume loss or a rough surface caused by photoageing.
Expecting one product to solve all three mechanisms ignores the anatomy producing each visible feature.
Why Wrinkles Are a Good Example of Cumulative Exposure
Skin ageing demonstrates how small repeated inputs become large long-term outcomes. UV radiation, facial movement and environmental stress rarely create dramatic immediate damage, but their effects accumulate over decades.
The same principle appears in learning, finance and engineering: repeated small differences can dominate one-off events when the timescale is long enough.
The Big Picture
Wrinkles are the surface expression of ageing across several layers at once. Skin becomes thinner and drier, collagen loses strength, elastin becomes less effective, fat and bone support change, and repeated motion keeps folding the same regions.
Ultraviolet exposure accelerates many of these changes, while genetics determines much of the baseline. The final face is therefore a record of biology, movement, environment and time interacting rather than one simple cause.
Why Skin Cannot Stay Perfectly Smooth Forever
Living tissue is continuously exposed to sunlight, oxygen, movement, temperature change and mechanical stress. Repair systems compensate impressively, but they are not perfectly lossless. Small imperfections accumulate over decades, especially as cell turnover and connective-tissue maintenance slow with age.
Wrinkling is therefore one visible consequence of long-term maintenance limits rather than evidence that the skin suddenly “failed.”
Why Facial Movement Is Still Valuable Despite Wrinkles
Smiling, frowning and squinting create lines, but those movements are essential for communication, vision and social life. Avoiding expression entirely would sacrifice important functions for a cosmetic goal.
This is another biological trade-off: structures are built to work, not to remain visually unchanged. The ability to move the face is far more useful than preserving a perfectly smooth surface forever.
Why Wrinkles Can Reflect a Life of Expression
Repeated expressions leave patterns because muscles use familiar routes. Over decades, those patterns can become part of an individual face.
The biology is mechanical, but people often attach social meaning to those lines because they arise in places associated with smiling, concentration or squinting.
Why Wrinkles Are Not a Reliable Measure of Health
A person with many wrinkles can be physically healthy, while someone with smooth skin can have significant illness. Wrinkle depth mainly reflects skin ageing, anatomy and exposure history.
Visible ageing should therefore not be treated as a direct score for cardiovascular fitness, intelligence, energy or overall biological health.
Why the Same Skin Can Look Different From Day to Day
Hydration, swelling, sleep, lighting, temperature and facial expression can change the appearance of lines without changing the underlying connective tissue dramatically.
This is why short-term photos are a poor way to judge long-term skin ageing unless conditions are standardised carefully.
What Students Should Remember
The durable model is simple: collagen supports, elastin recoils, water and fat provide volume, muscles repeatedly fold the surface, and ultraviolet radiation accelerates structural damage. Age changes every part of that system.
Once those mechanisms are connected, wrinkles become a predictable outcome of material ageing rather than a mysterious sign that appears from nowhere.
The final lesson is that wrinkles are created by interaction, not by one culprit. Age changes the material, expression applies repeated force, ultraviolet exposure accelerates damage, and anatomy determines where folds concentrate. Good explanations keep those layers together instead of reducing every line to dryness, stress or one habit. That systems view is why wrinkles vary so widely between people who are the same chronological age.
Wrinkles are therefore best understood as a long-term record of tissue ageing, repeated movement and environmental exposure acting on the same living material over decades.
The process is gradual, cumulative, mechanical, chemical and biological at once.