Normal vital activity of organisms is possible only with a favorable combination of a number of environmental factors. If, in this case, the manifestation of one factor turns out to be insufficient (or, conversely, excessive), then it becomes decisive for the normal life of organisms of this species. Then in the body various changes begin, even mutations, in order to develop biological adaptability to the changed environmental factor.
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.