When life first appeared on Earth, Gaea was placed in charge of maintaining its evolution and ensuring that sapient life would develop. Gaea psychically linked herself to Earth's first life-forms, allowing her to influence their development over billions of years.
During the Triassic Period, Gaea supported the rise of the archosaurs. However, she observed that the first sapient reptilians, later known to humanity as the Serpent People, were not capable of veneration for the environment and were easily swayed into worshiping the Archdevil Set. She decided to let most of the archosaurs to go extinct at the end of the Cretaceous, except for the birds and crocodilians. Some dinosaurs and pterosaurs were allowed to survive in a few isolated parts of the world, including Skull Island and Maple White Land.
When the Valar arrived on Earth, she was very friendly with them and personally trained the Vala Yavanna, who shared with her a desire to protect all living things. Gaea even allowed Yavanna to create the Ents as guardians of forests.
Gaea rarely interacts with humanity, preferring to watch them from a distance, but she is still worshiped by many groups of people across Earth. Worshipers of Gaea tend to support pacifism and environmental protection.
On occasion, Gaea invites young humans to her home on Hope Island to act as protectors of nature, giving them special rings with elemental powers.