Environmental system

4. The great increase in production of food grains and better management techniques.
5. One of the first conservation thinkers.
7. One of the first Demographers.
9. A day where people collect garbage, plant trees, sign petitions.
10. Link the water contaminated because of a bomb that cause the outbreak of cholera in Londres.
11. Nobel prize winner for his micro-credits system.
15. America's first environmentalist.
16. Marin biologist who put in march the modern ambiental consciousness.
17. American environmentalist who warned of the dangers of overpopulation.
18. Scientist, meteorologist, writer famous for the Gaia hypothesis.
20. Published more than 300 articles about nature.

1. Danish economist focused on the development of agriculture and its relation to population growth.
2. Published "Walden" and "Civil disobedience".
3. Evolution Homosapiens.
6. Get the independence of India.
7. recieve the Nobel prize.
8. Implement ational parks and national forests in the United States.
12. Lider of the movement "New thinking".
13. Notable figure in science and therapeutic medisin.
14. The first African American woman
19. Discover the cure and create Inmunity to Viruela.