The last unclothed humans to survive in colder temperate regions were in Tierra del Fuego, in the south of Argentina and Chile, died out in the 19th century.Today we cannot survive without correct clothing.
As we can lose up to half our body heat from our head, thanks to the huge blood flow and rapid metabolism of our super-computer brains, a hat is the most important item of clothing. Removing a hat when hot will cool you down; and vice versa.
The area around our heart and thorax – our body core – is the next most important part to protect, with body warmers, sleeveless wind proofs and thermal underwear. If too hot, undoing your shirt to allow air to circulate across your chest is the next thing to do after taking off your hat.
Arms and legs are less important. The body will restrict blood flow to them to maintain core temperature when really cold, creating in turn problems with frost bite in very cold conditions.
It is however vital to respond quickly to sensations of cold, heat and general weakness or any other adverse feeling, and remove or put on clothing well before you feel either cold or hot. It’s very hard to get warm once you do actually feel cold, and the body has to work extremely hard to reduce temperature if you get too hot, with a high risk of heat exhaustion and sudden collapse.
It’s also important to understand that your clothing works best if dry, so don’t allow yourself to sweat heavily. Remove clothing well before this occurs.
Clothes insulate the body; either by retaining body heat, or by protecting the body from the sun. Clothing for hot deserts must do both, from extreme heat by day, and freezing cold once the sun goes down.
The Layer Principle
In cold environments, warm air must be trapped close to the body, which is best done by several thin layers of clothing which are far more effective at retaining layers of warm air near to the body, than one or two thick layers. By removing and adding many thin layers, body temperature can be more effectively controlled.
The outer layer must protect from whatever is the main problem in an environment: soldiers wear shrapnel-proof body armour, nightclub bouncers knife-proof jackets… the wind in the arctic and Antarctic, rain and wind in temperate regions with temperatures above freezing point, and the sun in hot climates.
The innermost layer must absorb perspiration, then allow it to evaporate quickly – called ‘wicking’, through the other layers, to prevent them getting wet and losing their properties of insulation. Outer layers that ‘breath’, like goretex, are vital to allow the final venting off of this moisture.
Intermediate layers are added according to temperature and activity.
Appropriate footwear to the environment is the most vital survival precondition. The comfy brogues or fashionable sling-backs won’t survive a day outside the usual home, car, work scenario. It’s worth thinking about footwear when travelling. Trainers or those heavy boots you were going to wear on the walking holiday might be better worn also on the plane – with the additional advantage of lightening your suitcase.
Footwear must always be well insulated; from the heat of the desert and icy ground like, using well-made rubber liners, goretex outer socks and a combination of thick (preferably woollen) socks, and thin socks.
Wisdom varies on whether the thick outer sock should be closest to the foot, with the thin sock outside to protect it; or vice versa. I personally favour the latter, as the thin sock keeps the thicker one tightly in position.
Generally, the heavier the boot, the more the protection to the feet, and so the better; although for urban situations, the lighter sort of boot or even trainers will suffice. This will of course depend on whether you need to be able to kick people… Some people use trainer-type boots for mountaineering walking, as a break from wearing heavy skiing or climbing boots. I’ve done this myself, but these lighter type of boots don’t last as long.