You say that you have met people who claim that by evolution we are approaching a higher stage of existence. That is true in one sense, that anyone who takes to Krishna Consciousness may elevate himself to the highest status of life. Krishna mentions many types of higher beings in Bhagavad-gita, such as demigods and those who dwell on higher planets. We have information that there are 8,400,000 species of life. Out of these, 400,000 species are considered human life. Of these 400,000, how many species do we find in our experience? Not many, probably less than 1,000, so we must conclude that there are hundreds of thousands of higher and lower types of human forms. But this does not mean that automatically one body evolves into a higher body.
Letter to Upendra, 8 December, 1971