Both the D'ni people and Humans are, for the most part, unaware of each other's existence beneath and over the surface, and live independently, although there were some rumors that early in history some D'ni disappeared and perhaps fled to the surface, perhaps establishing contact with them.
Before or around 9336 the D'ni Council consented with the decision to reach the Surface and establish official contact with the surface dwellers, although the project was eventually abandoned. It was when the girl Anna discovered the Cleft and the Great Shaft when the D'ni met a human for the first time.
As was the case with other Outsiders, humans were interfertile with the D'ni, as proved with the birth of Gehn. Note that when Atrus met the old man of Channelwood, he identified him as a "human". The old man mysteriously spoke "his language". In this case, it seems that all sentient Outsiders can be considered "humans".
- Ti'ana: The first human to ever set foot in D'ni.
- Gehn (Half human): The first offspring from a human and a D'ni.
- The people of Amad and Leira; Gehn entertained the idea that they were somehow related or descended to the D'ni.
- The Stranger: The protaganist of the Myst series.