The first review of the global impact of humans on tropical forests in the ancient past shows that humans have been altering these environments for at least 45,000 years.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/humans-have-been-altering-tropical-forests-least-45000-years
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/phys
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/forests
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/tropical-forests
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/deforestation
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/agriculture
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/industry
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ecosystems
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/biodiversity