Humans are incredibly weak by the standards of nature. We lack claws, fangs, coats of fur, heightened senses-all the attributes that animals use to survive in nature. Fortunately for us, we're also smart. That characteristic, combined with our opposable thumbs, has been enough to ensure our rise to the very top of the food chain. Instead of claws, we use knives. Instead of heightened senses, we invent devices like binoculars. And instead of coats of fur, we just have coats. Yes, when it comes to keeping warm in the 21st century, humans have a staggering array of garments to choose from, and some of the materials we use keep us warm even in the harshest climates.

Down, of course, is one of the most traditional materials used in cold weather garments. The term refers to the fine layer of feathers that birds have beneath their tougher exterior feathers. Humans have been using down as a thermal insulator for hundreds of years and interestingly enough, we still are. There are a number of other options for keeping warm today, but many of the coats intended for severe weather still use down as the insulator. Goose down is extremely popular, being warm, lightweight and compressible. Manufacturers like North Face, Patagonia, Marmot, Mountain Hardware and REI all use down in some of their severe weather garments.

As to synthetic insulation options, polyester fibers are very popular. Gore-Tex is probably the most well-known brand name of polyester insulation. The advantage of polyester fibers is that they continue to insulate even when wet; the same cannot be said of down. The pores of polyester fibers are extremely small, making the material wind resistant and adding to an individual's warmth. Other brands of polyester insulation include PrimaLoft Eco and Thinsulate.

Polar fleece, usually referred simply as "fleece," is another material popular for coats. This material is quite soft and has a napped quality, meaning that it is fuzzy. Fleece is not usually used for harsh weather garments like polyester fibers and down. However, it does create a great deal of warmth relative to its weight. This means that fleece garments are ideal for layering, especially since they are highly breathable and perspiration passes readily through the jacket and away from the body. Fleece is a highly versatile fabric, and it is very popular in both jackets and vests for both genders.

Tricot mesh is sometimes used for coats that need to be warm yet breathable. Tricot refers to a plain warp-knit fabric, which has a makeup that allows sweat vapor to escape easily. Garments featuring this kind of fabric are ideal for situations where the wearer is performing vigorous physical exercise in a cold climate. Alpine hiking, snowshoeing and mountaineering are all situations in which tricot mesh can be useful. The individual is going to sweat, and if that perspiration is not allowed to dissipate, then he or she is going to become cold as soon as the exercise is over. Tricot mesh prevents this from occurring.