How are chemical and physical changes used in First People’s
Traditional preservation methods of natural resources?
Throughout history, there have been many different methods to keep food and other organic materials from spoiling. Each process has a different scientific reason why it works, as well as different types of changes. The preservation methods of the First Nation peoples of British Colombia are no exception. With their use of methods such as curing or tanning hides and smoke-drying foods.
Tanning hides is used to create leather out of different animal skins that otherwise would biodegrade. The term tanning comes from “tannin” a compound that’s acidic nature will help materials resist decay by altering the nature of the proteins in the hide. There are several different methods for tanning, two of those methods were rawhide and brain tanning.
Rawhide is made by soaking hides that have been rubbed raw in lime then stretching it as it dries. Technically Rawhide is not leather but it is usually lumped in with the other forms. it is usually used for things like drum heads that do not need to flex very much, due to its brittle nature. Rawhide is an example of a chemical change due to the high basic nature of the lime.
Brain Tanning is an ecologically sound and sustainable form of aldehyde tanning used by ancient civilizations around the world, including First Nations people on this 
continent. Brain tanned leathers are made by a labour-intensive process that uses emulsified oils, often those of animal brains. Brain tanned hides are known for their exceptional softness and their ability to be washed. This process is much longer, it involves repeatedly soaking the hide between scraping the hide of different things such as the blood vessels, or hair. (For a more detailed description go to brain tanning) Thisis an example of a physical change.
A different preservation method is smoke drying meats. This was done by either by smoking it over a fire or drying it in the hot sun. This was used to help preserve the meats, and to make other foods by rolling the fat into a ball with different berries and nuts. This would be an example of a chemical change.
Links:
http://www.native-art-in-canada.com/braintanning.html