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T
To Afford Protection Against Climate
and Weather
Ian Gilligan
Department of Archaeology, University of
Sydney, Sydney, NSW, Australia
Synonyms
Apparel;Attire;Garment;Clothing is distin-
guished from terms like adornment, costume and
dress which encompass body painting, cosmetics,
scarification and tattooing
Definition
Humans invented clothes as artificial protection
from cold to compensate for the loss of body fur
which became a critical survival issue during the
Pleistocene ice ages. The physiological function
of clothing as thermal insulation is reviewed,
along with archaeological evidence for the devel-
opment of complex clothes and later textile fabrics
as adaptations to changing climates.
Introduction
Adaptation to the thermal environment is crucial
to the survival of all living things. Extremes of
heat and cold exert selection pressures on animal
species, resulting in both biological and behav-
ioral adaptations to climate.
Primates are generally adapted to life in warm
climates and early hominins evolved in the tropics
of Africa. A number of unusual traits –upright
posture, sweating, and the loss of body fur –may
reflect adaptation to the dry heat of the African
savanna (Ruxton and Wilkinson 2011).
Human evolution is an enigma in this regard.
Loss of fur –biological nakedness –deprives a
mammal of natural protection against cold
weather, yet Homo sapiens evolved in the envi-
ronmental context of the Pleistocene ice ages.
Human nakedness mystified Darwin: he could
see no advantage in terms of natural selection
and suggested it might be a case of sexual selec-
tion (Darwin 1871).
Hominins began to spread outside the tropics
during warm interglacials. Over the last million
years, they developed a series of behavioral adap-
tations to compensate for their biological vulner-
ability to cold. The main strategies were control of
fire, use of shelter, and the manufacture of cloth-
ing. Fire was utilized as early as 800,000 years
ago (Walker et al. 2016). While fire and shelter
facilitated a hominin presence in cooler climates,
only clothes could provide the portable protection
necessary for a sustained occupation of cold
climates.
#Springer International Publishing AG 2016
T.K. Shackelford, V.A. Weekes-Shackelford (eds.), Encyclopedia of Evolutionary Psychological Science,
DOI 10.1007/978-3-319-16999-6_3010-1
Human Cold Tolerance
The human body begins to react to cold at an air
temperature of +27 C(80F). At +20 C, the
metabolic rate begins to climb to generate extra
heat, and shivering (a sign of failure) starts at
+13 C. This susceptibility is due mainly to lack
of fur: rabbits for example can survive at 45 C
but when shorn,they start to struggle at0 C. People
can become acclimatized to cold, as seen among
those who work in Antarctica: after a few months
they manifest an attenuated metabolic response to
cold exposure. Clothing plays a paradoxical role:
with regular use of clothes from birth, humans
habituate to a warm microenvironment and hence
become more sensitive to cold. For this reason,
hunter-gatherers who are routinely naked have bet-
ter cold tolerance. The safe naked limit for brief
exposure (up to an hour or two) is around 0 C,
extending to as low as 5C for foragers like
Australian Aborigines who led a traditional life-
style without clothes. By mammalian standards,
human physiological adaptations to cold are dis-
tinctly inferior (Jessen 2001).
Hypothermia
The core temperature of the human body must
remain within a few degrees of 37 C. Hypother-
mia begins at 35 C and at 33 C people begin to
experience blurred vision and lose consciousness.
Below 30 C is severe hypothermia when blood
pressure falls and the heart rate slows, with car-
diac arrest inevitable by 15 C. Depending on
variables like age, physical fitness and alcohol
consumption, as well as environmental conditions
such as wind, survival times for humans with
hypothermia vary between 1.5 and 12 hours. At
an air temperature of 10 C, the survival time for
people without clothes is 3–6 hours (Dettmeyer
et al. 2014).
Frostbite
Frostbite is the other main danger, though it is less
commonly fatal. Frostbite primarily affects
extremities like fingers, toes, and ears, and it can
cause tissue loss and gangrene, which sometimes
leads to infection and death from septicaemia. As
with hypothermia, the safe exposure times are
determined by wind as well as air temperature.
At an air temperature of 15 C and a wind speed
of 40 km/h, symptoms of frostbite can develop
within 30 minutes (Ducharme and Brajkovic
2005).
Climate Variables
Air temperature and wind are the most salient
aspects of climate, along with moisture (rain,
snow and humidity); intensity of solar
radiation –which varies with latitude –and
cloud cover are additional factors. Seasonal and
diurnal ranges need to be taken into account when
using mean annual values from meteorological
data. Also relevant when considering evolution-
ary adaptations are the likelihood of extreme con-
ditions, which may occur infrequently but which
may ultimately determine survival chances.
Temperature
When the temperature of the environment is lower
than skin temperature (typically 35 C), heat is
lost from the skin surface to the surroundings.
Thermal conductance increases from gaseous to
liquid and solid states: water for example has
24 times the thermal conductance of air. Skin
cools more rapidly in liquids and more so when
in contact with solid surfaces –hence liquids and
solids feel colder (and cause more rapid heat loss)
than air at the same temperature. This differing
conductivity is the basis of thermal insulation with
clothes, which trap air near the skin; this is also
why moisture is a major problem for clothes.
The thermal comfort zone for modern humans
with clothes is generally 21–24 C. Infants are
more susceptible to cold, and when naked they
can begin to develop hypothermia at 33 C.
Wind Chill
Any movement of air against the skin surface
removes body heat, and the presence of moisture
(either on the skin or in clothes) exacerbates heat
loss with wind due to evaporative cooling. At low
air temperatures, the cooling effect of wind is
exaggerated: even moderate wind speeds increase
the dangers at sub-zero air temperatures, as seen
2 To Afford Protection Against Climate and Weather
with the wind chill index (Osczevski and
Bluestein 2005). Superior protection from wind
is afforded by fitted (or ‘tailored’) garments.
Environmental Moisture
The thermal conductance of fluids means that
moisture in any form compromises the thermal
effectiveness of clothes. Moisture also displaces
air, and its evaporation extracts heat from the
skin –which is how sweating operates as a
cooling mechanism in warm climates. Even in
cold climates however, perspiration still occurs
and its production increases with physical activity.
Higher levels of relative humidity in the environ-
ment will reduce the capacity of air to absorb
sweat and thus impede the evaporation of sweat.
Humidity therefore reduces the cooling capacity
of sweating and when wearing clothes, it causes
sweat to accumulate. For these reasons, clothing
functions best in dry climates.
Clothing Physiology
The insulation value of clothing as protection
from cold derives from trapping still air close to
the skin surface; all other considerations (such as
the material) are secondary. Clothes are of limited
value as insulation from heat in hot climates:
garments can protect from direct solar radiation
but any such benefits are outweighed by impedi-
ments to convective and evaporative cooling. To
reduce the disadvantages, clothes in warm cli-
mates should be loose and made from light
woven fabrics, with a minimum number of layers.
Principles
Fitting refers to the shaping of a garment to
closely enclose the body. Insulation is further
improved with separate cylinders to enclose the
limbs (which have a relatively greater surface area
and hence higher potential for heat loss). Not only
does this result in improved trapping of air, fitting
provides more protection from wind penetration
and wind chill.
Layers provide additional insulation, since the
inner layers are protected from air movement.
Modern garments are generally fitted and layers
require fitting (at least for inner garments), so the
emphasis with cold weather apparel is on layers.
Clothing zones are defined based on the minimum
number of layers required: the Arctic region for
example is designated as a four-layer
clothing zone.
Woven fabrics allow perspiration to escape
through the material whereas animal skins and
furs are less permeable. Leather may be favored
for footwear due to its durability but sweat is
always an issue, so running shoes for instance
are made from woven material.
Measuring the Thermal Value
Thickness gives an approximate measure of insu-
lation, corresponding to the amount of trapped air.
For example, a 50 mm four-layer assemblage can
enclose nearly half that radius of trapped air.
Clo units are the commonest scientific
measure:
1 clo ¼0:155m2KW1
(m
2
=surface area, K =
Kelvin, W =watts)
One clo unit corresponds to a typical modern
garment assemblage (e.g., shirt and trousers, with
underwear) for a person to be comfortable in a
room at an air temperature of 21 C, with modest
air movement (0.1 m/s) and low relative humidity
(<50 %). In general, each clo unit corresponds to
a complete layer of clothes, and a full four-layer
ensemble suitable for Arctic winter weather pro-
vides ~ 4 clo of insulation.
Climate and Clothing Evolution
Archaeological evidence indicates that hominins
began to use simple clothes by the Middle Pleis-
tocene, around 800,000 years ago. The materials
were animal skins and furs and the basic Paleo-
lithic technology was the stone hide-scraper.
Toolkits dominated by scrapers became more
common in middle latitudes as hominins occupied
colder environments during glacial episodes from
400,000 years ago.
To Afford Protection Against Climate and Weather 3
Complex clothes (fitted garments with the
option of multiple layers) required further techno-
logical innovation: dedicated cutting tools (stone
blades) and hide-piercing implements (awls and
later eyed needles, often made from animal
bones). These toolkits were a prerogative of
H. sapiens and complex clothing was developed
in cooler parts of Africa during a cold phase
75,000–60,000 years ago. Toolkits with blades
and awls accompanied the subsequent spread of
modern humans into northern Eurasia from
45,000 years ago. Complex clothing gave modern
humans an advantage over Neanderthals, whose
scraper-dominated toolkits suggest they had only
simple clothes (Gilligan 2007). By 28,000 years
ago as the climate deteriorated towards the Last
Glacial Maximum (LGM), modern humans with
these clothing-related tools –including eyed
needles –had reached northeast Siberia (latitude
70N), when the average winter temperature is
estimated at 50 C (Kuzmin and Keates in
press).
Textiles became the optimal material for
clothes with global warming from 12,000 years
ago, notably in agricultural communities where
fiber resources such as wool, flax, and cotton
were domesticated. Wind penetration was less of
an issue whereas the woven structure allowed
sweat to disperse (e.g., Tang, Chau, Kan, and
Fan 2015)–a critical consideration in climates
that were warmer and more humid.
Conclusion
The thermal properties of clothing were crucial to
the evolutionary success of hominins, and the
development of complex clothes allowed
H. sapiens to spread into every climate zone on
earth. Clothing is a behavioral compensation for
biological nakedness and a uniquely human adap-
tation to past climate change.
Cross-References
▶Clothing
▶The Savanna Hypothesis and Landscape
Preferences
References
Darwin, C. R. (1871). The descent of man, and selection in
relation to sex (Vol. II). In two volumes. London: John
Murray.
Dettmeyer, R. B., Verhoff, M. A., & Schütz, H. F. (2014).
Forensic medicine: Fundamentals and perspectives.
Heidelberg: Springer.
Ducharme, M. B., & Brajkovic, D. (2005). Guidelines on
the risk and time to frostbite during exposure to cold
winds. Paris: NATO Research and Technology
Organisation.
Gilligan, I. (2007). Neanderthal extinction and modern
human behaviour: The role of climate change and
clothing. World Archaeology, 39, 419–514.
Jessen, C. (2001). Temperature regulation in humans and
other mammals. Berlin: Springer.
Kuzmin, Y. V., & Keates, S. G. (in press). Siberia and
neighboring regions in the Last Glacial Maximum:
Did people occupy northern Eurasia at that time?
Archaeological and Anthropological Sciences. DOI
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Osczevski, R., & Bluestein, M. (2005). The new wind chill
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Tang, K. P., Chau, K. H., Kan, C. W., & Fan, J. T. (2015).
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