Why do we age?

Why Does Skin Age?

Skin ages for two overlapping reasons. Intrinsic aging is the built-in, genetically timed slowdown that happens to everyone: cells renew more slowly, the skin makes less collagen and oil, and the support structure underneath thins. Extrinsic aging is caused by the environment, mainly sunlight, along with pollution and lifestyle habits, and it speeds up and deepens the visible changes. Researchers estimate that most of what we see on an aging face comes from the second group, which is good news, because that part can be influenced.

Intrinsic Aging: The Clock You Cannot Stop

Intrinsic, or chronological, aging happens even on skin that never sees the sun, such as the inner upper arm. Over time:

  • Collagen and elastin decline. These proteins form the support network of the dermis. As fibroblasts, the cells that build them, become less active, skin gradually looks thinner, less firm, and less springy. A 2021 review of skin collagen across the life stages (Reilly and Lozano, Plastic and Aesthetic Research) reports that from early adulthood, fibroblasts become less active and collagen production declines by about 1.0% to 1.5% a year.
  • Cell renewal slows. The outer layer turns over more slowly, so dead cells linger on the surface and skin can look duller and feel rougher.
  • The barrier weakens. A 2015 review of aging human skin by Rinnerthaler and colleagues describes how aging skin loses some of its antioxidant capacity and barrier function, so it holds water less well and can feel drier.

Hormones and Midlife Changes

For women, the drop in estrogen around menopause is one of the biggest intrinsic shifts. A 2007 review by Calleja-Agius, Muscat-Baron, and Brincat reports that as much as 30% of skin collagen is lost in the first five years after menopause, and that total collagen content declines by an average of 2.1% per postmenopausal year over 15 years. This is why many women notice a faster change in firmness and dryness during this period. We cover this in more depth in Estrogen and Aging Skin.

Extrinsic Aging: The Part You Can Influence

Extrinsic aging comes from outside the body, and sunlight is by far the largest factor.

  • Ultraviolet (UV) light. In a 2013 study of 298 women aged 30 to 78, Flament and colleagues compared sun-seeking and sun-avoiding groups and concluded that UV exposure seems to be responsible for about 80% of visible facial aging signs, including wrinkles, sagging, and uneven pigmentation.
  • Free radicals and oxidative stress. UV, pollution, and normal metabolism create unstable molecules that wear down collagen and other skin structures. Read more in What Are Free Radicals?
  • Air pollution. In a 2010 study of 400 women aged 70 to 80, Vierkötter and colleagues found that higher traffic-related particle exposure was associated with about 20% more pigment spots on the forehead and cheeks.
  • Repeated expressions. Squinting, frowning, and smiling fold the same areas over and over, which is why expression lines form first around the eyes, forehead, and mouth.

What You Might Notice, Decade by Decade

Everyone ages on their own timeline, depending on genetics, skin tone, and sun history, but this is a common pattern:

  • 20s and 30s: the first fine lines around the eyes, a little less glow, and early sun spots on skin that has had a lot of sun.
  • 40s: expression lines that stay when the face is at rest, more visible pores, uneven tone, and drier skin.
  • 50s and beyond: noticeable loss of firmness along the jaw and neck, thinner-looking skin, deeper lines, and more dryness, often speeding up around menopause.

What This Means for Your Routine

You cannot stop the clock, but you can slow the visible effects of extrinsic aging. The strongest evidence is for daily sunscreen. In a randomized trial of 903 adults under 55 in Nambour, Australia, Hughes and colleagues found that people who applied sunscreen daily showed no detectable increase in skin aging over 4.5 years, and had 24% less skin aging than people who used sunscreen only when they chose to.

  1. Morning: gentle cleanser, an antioxidant serum (such as vitamin C), moisturizer, and a broad-spectrum SPF 30 or higher, reapplied when you are outdoors.
  2. Evening: cleanse to remove sunscreen and pollution, then a targeted serum. Peptides such as Matrixyl 3000 support the look of firmer skin, and retinol supports smoother texture. Finish with a moisturizer that suits your skin type.
  3. Weekly: gentle exfoliation with an alpha hydroxy acid to help the look of dull, rough skin, unless your skin is sensitive.

Our 20% Matrixyl 3000 Collagen Serum is a good evening step for the look of fine lines and firmness. For food and lifestyle ideas, see our guide to natural ways to increase collagen. If your skin is sensitive, patch test new products on the inner arm for 24 hours and introduce one active at a time at its lowest recommended rate.

Frequently Asked Questions

Why do we age?

We age because of a genetic slowdown in cell renewal and collagen production, called intrinsic aging, plus damage from the environment, called extrinsic aging. Sunlight is the largest outside factor. Hormonal changes, especially menopause, also speed up visible changes in skin.

At what age does skin start to show aging?

Many people notice the first fine lines and changes in glow in their late 20s or 30s, especially around the eyes. How early and how much depends on genetics, skin tone, and how much sun the skin has had. Changes in firmness usually become more visible in the 40s and 50s.

What is the main cause of skin aging?

For visible facial aging, sunlight is the main cause. A 2013 study of 298 women concluded that UV exposure seems to be responsible for about 80% of visible facial aging signs. Intrinsic aging and hormones account for much of the rest.

Can you slow down skin aging?

Yes, you can slow the visible signs. In a 4.5-year randomized trial of 903 adults, daily sunscreen users showed no detectable increase in skin aging and had 24% less skin aging than occasional users. Antioxidants, peptides, and retinol add further support for the look of smoother, firmer skin.

Does menopause make skin age faster?

Many women notice faster changes during menopause because estrogen supports skin collagen and moisture. A 2007 review reports that up to 30% of skin collagen can be lost in the first five years after menopause. Moisturizers, peptides, and sun protection help support the look of firmness during this time.

Do genetics decide how I will age?

Genetics set your intrinsic timeline, including skin tone and how quickly collagen declines. However, research suggests that sun exposure accounts for most visible facial aging, so daily habits play a very large role. Two people with similar genes can look very different depending on their sun history.

Sources

  • Flament F, Bazin R, Laquieze S, Rubert V, Simonpietri E, Piot B. Effect of the sun on visible clinical signs of aging in Caucasian skin. Clin Cosmet Investig Dermatol. 2013;6:221-232. doi:10.2147/CCID.S44686
  • Hughes MCB, Williams GM, Baker P, Green AC. Sunscreen and prevention of skin aging: a randomized trial. Ann Intern Med. 2013;158(11):781-790. doi:10.7326/0003-4819-158-11-201306040-00002
  • Calleja-Agius J, Muscat-Baron Y, Brincat MP. Skin ageing. Menopause International. 2007;13(2):60-64. University of Malta repository
  • Vierkötter A, Schikowski T, Ranft U, et al. Airborne particle exposure and extrinsic skin aging. J Invest Dermatol. 2010;130(12):2719-2726. doi:10.1038/jid.2010.204
  • Reilly DM, Lozano J. Skin collagen through the lifestages: importance for skin health and beauty. Plastic and Aesthetic Research. 2021;8:2. doi:10.20517/2347-9264.2020.153 (review; the 1.0% to 1.5% yearly figure cites Tobin 2017, J Tissue Viability, and Oikarinen 1990, Photodermatol Photoimmunol Photomed)
  • Rinnerthaler M, Bischof J, Streubel MK, Trost A, Richter K. Oxidative stress in aging human skin. Biomolecules. 2015;5(2):545-589. doi:10.3390/biom5020545

These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

About the Author
Written by Kari Thomas, cosmetic formulator and founder of Skin Perfection.