Summary of Key Features:

• This volume begins with a description of the author’s search for the structural basis for the mammalian cutaneous permeability barrier.
• It follows this with a section on the basis of the barrier in other terrestrial organisms, including plants, insects, amphibia, reptiles, and avians.
• Several chapters then describe the evolutionary forces that led to the development of a highly impermeable barrier, as our newly hairless ancestors encountered the hostile environment of Sub-Saharan Africa.
• It then provides novel theories both for why pigmentation evolved initially, and then receded at northern latitudes.

Background and Rationale for the Book:

Because the skin so rarely ‘fails’ in comparison to our internal organs, such as the lungs, kidneys, heart, and liver, medicine has not fully comprehended the importance of the skin’s permeability barrier, without which life on dry land would not be possible. This treatise represents an attempt to correct this perception—to give the skin its amply deserved recognition, and the right to be placed among the pantheon of important organs.

Focus:

My discussion of the basis for the evolution of cutaneous pigmentation, coupled with a novel hypothesis for its subsequent dilution, injected new views into the current discourse about the basis of skin color. First, I provide new evidence about the role of melanocytes in promoting barrier competence, a view that counters current dogma that pigment dilution occurred to allow for further vitamin D production. Second, I dispute that pigmentation developed to protect against either vitamin D intoxication or against skin cancer. Instead, I argue that pigment dilution occurred in service to metabolic conservation, a concept new to the world of evolutionary biology.

Short Introduction:

Because of its sheer competence, the importance of the skin’s permeability barrier in allowing life in an arid and hostile environment is underappreciated. This volume addresses this regrettable situation, while attempting instead to celebrate the enormous gift of our skin. My studies showed, for the first time, that the entire stratum corneum serves as the barrier, and that this tissue displays a unique two compartment (‘bricks and mortar’) arrangement, with a mixture of three key lipids localized to extracellular domains. The book assesses how the epidermis responds to external stressors, such as tape stripping or detergent applications, as well as to internal stressors, such as psychological stress.

Research Methodology:

I exploited morphological methods, including electron microscopy and freeze fracture technology to elucidate the structural basis for the stratum corneum’s unique ‘bricks and mortar’ architecture. The next step was to identify the types of lipids that account for the skin’s watertight barrier, using standard lipid biochemical methods, including thin layer and gas liquid chromatography. To study how the skin responds to external stressors, I utilized radioisotope incorporation into the three lipid species in response to these insults. Much of my work has been in experimental animals, particularly hairless mice, but I also use cell culture to further elucidate specific metabolic mechanisms.

Peter M. Elias, MD, is a Professor of Dermatology at the University of California San Francisco and a Staff Physician at the San Francisco VA Health Care System, having worked in the laboratory and clinics for over 50 years. He is recognized internationally for research on the function of skin and is frequently invited to speak about his work before professional audiences both in the United States and abroad. For over 40 years, his research has been devoted to the study of many aspects of the skin’s barrier. He is also the recipient of numerous prestigious awards from professional societies and the author of over 700 scientific publications, including four scientific and medical books.

The Miracle of Skin: Surface Matters is available now in Hardback at a 25% discount. Enter code PROMO25 at checkout to redeem.

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