The timeline in the show says "the fall of Shady Sands" which was an event from 2277 to ~2281.
We can assume "the fall" started when the NCR decided to siphon water from Vault 33.
We know Moldaver was there, and fell in love with Rose (Lucy's mother) during that time.
Some time after, Hank (Lucy's father), arrived and failed to convince Rose to return to the Vault, but took Norm and Lucy from Rose, before detonating the Nuke.
The NCR is certainly aware of the risks involved with fucking with the Vaults. They must have been desperate to choose to siphon water from a functional vault without knowing what is inside.
My best guess is the NCR made a choice to grow Shady Sands as fast as possible without considering how to provide resources for everyone.
I'm pretty sure the ants are using a memory palace (method of loci).
It's simple, they just remember all their siblings born after them, until they arrive at their food. So once they reach Jant they know the food is close. Simply count backwards until they reach Trant and they're home.
Majority of male hyenas had a docking fetish, and evolution facilitated their needs.