Toronto was set up to be a trading post at the mouth of the Don River and it was originally called York. The Europeans also set up a military outpost. The harbour was the reason why the village was established there. Humans depend on their environment. In Toronto, there are many organizations such as the Toronto Environmental Alliance that are trying to make Toronto a better place and this is a good type of interaction. However, some interactions are negative. The building of expressways is a negative interaction and traffic is also another problem.The Commercial Centre is the biggest in Canada and population grew because of the business opportunities and this has led to building of expressways. Humans always know how to adapt to an environment. Since Toronto is extremely cold during the winter months and hot in the summer, People install furnaces in their houses to stay warm in winter and to have air conditioning in summer.