As the temperature drops, the coats and scarves come out and you probably barely think about heat -unless you leave your coat behind! Have you ever wondered about how we keep the heat or why we need it? Or how animals and humans differ? What would you need to survive in the extreme cold?
All creatures have an optimal temperature their body needs to achieve proper function. Warm-blooded creatures (endotherms) can regulate their body so it stays at a constant temperature. So naturally if you were in an extremely cold environment your body will have to work overtime to stay warm! How is the heat escaping?
On the Move
Heat radiates out and diffuses from an area of high concentration (your body) to areas of lower concentration (everywhere else) through either conduction or convection. Conduction is transfer of heat between two solid surfaces. So, if you sit in the snow heat will escape via your direct contact with the snow. Convection is the transfer of heat between a mass (i.e. you) and a moving fluid or gas. So, if you are standing outside and an icy wind blows past you, it is pulling heat away from you. Same thing is true if you jumped in the Arctic Ocean. Your heat will escape in the passing chilly water.
The heat from a warm-blooded human or polar bear in the Arctic is constantly trying to escape and move away from the body through these two mechanisms. The goal in these extreme environments is to either contain your body heat and stop its movement, or at least slow it down so the internal body mechanisms can keep up with production.
Capture the Heat
What are some ways your body stays warm and what are some things you can do?
- Fuel your fire – make sure you are well fed and hydrated so your body can burn extra calories to maintain your core temperature.
- Shivering – This is actually a warning that you are too cold. Your muscles spontaneously contract to burn calories and generate heat to increase or maintain your core temperature. If you are shivering, you should get somewhere warm or put on more layers. It is one of the last lines of defense your body has to prevent hypothermia.
- Layer up – Adding clothing layers traps air and slows the transfer of heat. This insulation, especially if your coat is waterproof, is a powerful way to keep the heat in.
- Shelters – such as igloos in the artic, or your own house are designed to trap heat and keep you and your environment warm.
Animals versus Humans – how do they capture the heat? What do you think makes animals and humans different when it comes to the cold? Animals have evolved many different adaptations to allow them to cope with extreme cold.
Polar bears have both an extra layer of fat and special fur. Their special coat features two types of fur: long oily guard hairs and short insulating hairs. Together these different types of hair help the polar bear stay warm. The oily guard hairs are hollow allowing them to trap warmth and bring it close to the skin. They also provide an oily outer layer which prevents the polar bear from getting wet and losing heat via convection. The shorter insulating hairs help polar bears stay warm by trapping heat close to the skin. Under their fur, polar bears have black skin which is good for absorbing the rays of the arctic sun. Plus, their coat is white, which is helpful for camouflage, and reflects light making it a poor conductor of heat.
Whales, seals, walruses are all examples of marine mammals that use blubber to stay warm. Blubber is just an extra layer of insulating fat, which keeps their internal heat from escaping. Having blubber means those animals can swim in the cold arctic ocean without getting a cold or hypothermia.
Otters are an interesting marine mammal that can survive in the icy ocean, but don’t have blubber. Otters have a super dense, double-layered coat of up to a million hairs per square inch! That fur is designed to be water-proof and capture pockets of air. All that air makes them float and works just as well as a layer of blubber.
Humans on the other hand must add something to their body to stay warm. The simplest solution for early humans was to wear the skins and pelts of these animals. We basically borrowed the animal adaptations by making clothes out of animal skin – everything from seal and caribou to rabbit and bear. Eskimos even make waterproof parkas from the skins of marine mammals.
Modern fabric technology:
Scientists and engineers have been able to replicate these animal adaptations in a variety of ways.
- Fleece is similar to wool and very efficient at keeping you warm by trapping air and adding insulation to your layers. Guess what – it’s made of plastic polymer! Its polyester fiber can even be made from recycled bottles.
- Nanowire tech – a newer technology that features special metallic fibers that trap air and can even be used to generate heat when a charge is run through them.
- Adaptable smart fabric –Astronauts wear a temperature regulating suit under their space suit that circulates liquids and helps them maintain a constant temperature. Scientists have been studying a way to create something similar to this for everyday use. Imagine wearing a light weight shirt that adjusts to the temperature no matter where you are. Almost like having a central air system right next to your skin.
- Synthetic furs and fabrics- Also we can spare the rabbits and other animals and manufacture faux fur and other coverings that keep the adaptation and hold the slaughter.
Bundle up your layers and stay warm this winter just like a polar bear!