We didn't, however in our present situation we have little need to change. Why? Because we don't live in "the environment" anymore. We live in houses, drive cars, have vaccines that save the lives of billions, use medicine etc.
[quote]Then why did humans stop evolving?[/quote]
HAHAHAHAHAHAHA
[spoiler]We didn't, and to write a comment like that shows you know virtually nothing about evolution.[/spoiler]
Evolution is a process that takes place over the course of millions of years. The Earth is 4.7 billions years old. Humans are a product of evolution that began with precursors to first life