Why has intensive/extensive subsistence agriculture developed in seperate areas of the warm moist tropics?

Question

Why has intensive/extensive subsistence agriculture developed in seperate areas of the warm moist tropics?

Answer 1

population growth in those areas and state of the art ag.

processes applied in areas that had no knowledge of this before.

Answer 2

Why not? It is a good idea and there is good communication almost every via the Internet.  Just your question could start it up again in another area of the world.  People will see it , research the topic, and start something good.