A gerund is a nonfinite verb form used as a noun. It consists of the present participle of the verb and functions in the ways other nouns function:
A variety of experiments were loaded
onto the Viking spacecraft in the hopes of detecting the
telltale signs of microbial life: growth, food consumption, and waste
--Kai Wu, "Artificial Life," SciTech Magazine (modified)
Giving machines the ability to replicate and mutate allowed for further complexity and would unleash the powerful and unpredictable forces of evolution.
--Kai Wu, "Artificial Life," SciTech Magazine
Use the possessive case form for a noun or personal pronoun that modifies a gerund.
Modern society's altering the hydrology of the Everglades has profoundly affected the ecology of the region.
--Norman Boucher, "Back To the Everglades," Technology Review (modified)