Sometimes the destruction by people of certain territories such as forests, swamps, lakes, and so on, do not affect the environment. But that rarely happens. Having drained the swamp, we destroy the place of residence of dozens of species of insects, lizards, frogs, snakes. Loss of insects can hit the number of birds that fed on insects. Often, after draining the swamps, a lot of mice and rats appear due to the fact that there are no more snakes. This is a chain reaction that destroys food chains, which may include more than a dozen animals.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.