Elias and Williams: The Inside-Out of Skin by dermatologists and skin researchers Peter M. Elias, M.D. and Mary L. Williams, M.D.

The Skin’s Many Barriers and Climate Change

October 9, 2020 By Mary L Williams, M.D.

Skin’s Many Barriers And How Climate Change May Affect Them

Skin has many barriers: it keeps us waterproof, it holds back invading microorganisms, and it protects us from mechanical injury, from toxic rays of sunlight and foreign chemicals in our environment. Each of skin’s many barriers may be impacted as our environment changes as a result of global warming. To understand how skin will have to adapt to climate change we need to consider how these barrier’s work to keep us well.

The Skin’s Water Barrier Came First

Life on our planet began in its seas – a warm womb with a salinity that is close to that of a cell’s interior. But upon leaving the osmotic neutrality of the seas for life on land, our fish-like ancestors, the fishapods, suddenly would have encountered an entirely different world. There they faced a steep osmotic gradient between the much drier air outside and their water-based interior. They now required a water-proof covering to prevent the otherwise inevitable dehydration.

With that first step onto dry land – dawned a new evolutionary imperative, for them and for all their progeny who would follow.  They required a means to prevent the loss of water from their cells into the arid atmosphere that now surrounded them. 

Thus, before the grand experiment of terrestrial life could truly begin, this imperative – the need for a water barrier – had to be solved.

Indeed, all land dwelling species have had to evolve a water barrier on their external coverings (or ‘integuments’) – from the cuticles coating the leaves of plants, to the exoskeletons of insects, or to the scales of reptiles and to our human skin – in order to maintain their water-based way of life in a dry world. 

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