John Francis, an environmentalist who stopped riding motorized vehicles for 22 years and spent 17 years voluntarily silent, will be the keynote speaker at Purdue’s Ecological Sciences and Engineering Symposium.

His speech titled “Urban Rise: Footprints of a Global Civilization” is in conjunction with the Discovery Park Lecture Series and will take place at 7 p.m. Oct. 16 at the Hall for Discovery and Learning Research, Room 131.

The presentation is free, but seating is limited so people are encouraged to register beforehand at purdue.edu/esesymposium.

Symposium co-chair and graduate student Lauren Logan said the symposium will touch on topics including urbanization, resource consumption, rural depopulation and policy platforms.

“It is imperative that we as a species understand our role within urbanization and face the consequences, both good and bad, of our actions,” Logan said.