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An
Online Journal on
Topicals:
-
Formulation
- Processing
- Intra-Dermal and
Trans-Dermal Vehicles
- Nano-Encapsulation
- Nano-Emulsion
- Topical Medicinals
- OTC
- Skincare
- Naturals
- Cosmeceuticals
- NanoBioTech
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The
Formulator's Bookshelf
This month we have
chosen to review:
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I think a
good non-fiction book should
answer some questions and suggest other questions, so that the
result of reading the book is not to feel that the problem is
solved
but that the investigation can now advance to a higher, more
interesting, level. Skin (University
of California Press, 2006) met that requirement for me: having
read it, I do have a broader general understanding of skin (thanks
in part to the author's willingness, in a book written for non-scientists,
to
use and explain scientific vocabulary) but I am left wondering
about the many unanswered questions that occured
to
me while I
was reading it.
One of the questions this book raised for me (probably
midway through the chapter on "Sweat") is about the book's own
subtitle, A Natural History. I have
enjoyed visits to several museums of natural history, and I
own several other books that call themselves natural histories
of other subjects, but I had not, until I started wondering
why some topics were discussed in Skin and
others were omitted, wondered what specific promises are being
made
by naming
any collection of information "a natural history."
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As it turns out, labeling anything "natural history" is
a good way to announce that its contents can't be predicted. A natural
history can be the sum of all facts related to a subject, or a non-systematic
study relying on field observation rather than laboratory investigation,
or a genre of scientific material addressed to a non-scientific readership,
or the work of an amateur scientist. The Wikipedia article on Natural
History is worth reading for its discussion of how the usage of the
term has changed; the discussion page associated with the article is
equally interesting, recording the in-progress struggle to create a
clear explanation of an unclear idea.
The author of Skin, Nina G. Jablonski,
is an anthropologist whose primary field of study is skin color. She
begins the book by explaining that she had originally envisioned it
to be focused on skin color, but was persuaded by her editor to expand
its scope to discuss skin more broadly. Within limits she has done
so, but skin color remains the major focus of the book.
Skin is organized into eleven chapters,
preceded by a list of illustrations and followed by a valuable glossary,
notes, a list of references that will make further reading more productive,
and an
index. The chapters are:
- Skin Laid Bare
This introductory chapter, with clear drawings of the multi-layered
structure of skin, is as far as most general-readership discussions
of the
subject attempt to go. Instead of being the destination, the vocabulary
and concepts introduced here are the foundation for the remainder
of the book.
- History
A key question is introduced here: since skin, unlike bones, does
not leave much evidence in the fossil record, how is it possible
for anyone to know how skin has changed in the course of human
evolution? For this purpose, Jablonski points to three characteristics
shared by all primates, human and non-human, and presumably by their
common ancestor: primate skin is thicker in back than in front,
and most of it is covered with hair; primate
skin can produce sweat; primate skin contains melanin. Most non-human
primates are born with dark hair and light skin; the skin
of less-hairy areas darkens when exposed to sunlight, so infant
primates have light-colored faces and hands while adults typically
have dark
skin in those exposed areas.
Adult captive
animals which seldom see the sunlight retain the light faces of
infants, showing that the skin's color change relates to light exposure,
not to the aging process (unlike the greying of hair, which happens
whether or not the animal is exposed to sunlight).
- Sweat
Human bodies are not hairless; we have just as many hair follicles,
distributed in the same way, as other primates. The hairs themselves,
though, are thin and short, allowing
humans to cool more efficiently through the evaporation of sweat
from exposed skin. This chapter explores the features of our skin
that help us keep cool,
including
our unique
reliance on rapidly-evaporating eccrine sweat (thin, watery, produced
in copious amounts) rather than lathery apocrine sweat (milky, viscous,
remaining as a coating on the body) as other mammals do.
- Skin and Sun
- Skin's Dark Secret
- Color
These three chapters explore Jablonski's fascination
with skin color and the ways in which humans have adapted to balance
competing needs for dark skin, which protects itself and the interior
of the body from sun damage, and light skin, which supports the body's
ability to produce
Vitamin
D
in sunlight.
- Touch
In this chapter, Jablonski explores the sense of touch, mediated by
the skin, as an influence in human evolution and social development. Nails
are also part of this discussion: primates have nails, protecting
only the tops of fingers and toes, rather
than claws like other climbing animals, giving us improved sensitivity
in our fingers and toes while trading off some of our ability to
fight.
- Emotions, Sex, and Skin
This eight-page chapter seems unfinished. It revisits some
of the ideas
raised in other chapters (particularly about sweat, touch, and color) but
does not use them to create an organized discussion of the topics
identified in the chapter title.
- Wear and Tear
Subsections of this chapter are devoted to some of the many things
that can go wrong with skin: Birthmarks and Moles; Scabs; Scars;
Bites and Stings; Burns; Dermatitis; Pimples and Acne; Warts; Stretch
Marks; Rosacea; Wrinkles; Shingles; Skin Cancers. With so many problems
listed, only very general information can be provided about each
one.
- Statements
- Future Skin
These final chapters, like the chapter on "Emotions, Sex, and Skin",
relate largely to how skin has been or can be used for social, artistic,
and communicative purposes. Much of the "Statements" chapter returns
to the theme of skin color, discussing how different cultures at
different times have valued light skin or dark skin, often both
for the same
reason that the favored color is seen as a sign of youth, health,
and wealth. In "Future Skin", Jablonski identifies three frontiers
along which "the functions and potential of skin will be expanded"
in decades to come: improvements of skin's ability to repair itself
after injury or disease; expanded communicative and sensory options
through cosmetics and technological implants; creation of skin for
robots, allowing them to simulate human touch.
Skin is thoroughly illustrated
with photographs and drawings; most are in black-and-white, but there
is a section of
color plates. My favorite of the color photos is a close-up of a hippopotumus'
face, showing the "red sweat" it secretes as a sunscreen.
Because Jablonski is an anthropologist and I am not, I was
curious about how closely her ideas reflect mainstream thought among
scientists who study humans. Specifically, I wonder how much support
there is for her explanations of how the variation in human
skin colors evolved, and how
skin color relates to
gender roles. For some insight into this, read Dunsworth's
review of Skin in PaleoAnthropology,
the online journal of the Paleoanthropology Society.
Skin is not about recommending
which lotions and creams to apply to skin, nor about how to correct
skin problems such as those
associated with age (wrinkles) and youth (acne). It's about skin as
a physical object: what it's made of, how it works, how it has changed,
and how we know. It asks and answers some valid questions. It leaves
many other questions unanswered.
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In this issue:
Welcome to the Journal of Topical Formulations
Feature
Article:
Dynamic Synergy as an Approach to Combining Cosmeceuticals
The Formulator's Bookshelf
Sites Worth Seeing
What Does It Mean?
Announcements
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