Cambrian Explosion Occurs
Geological / environmental event
541 Million BC
The Cambrian Explosion introduces the dominant clades of animals that will populate the Earth, providing a frame of reference for the Nightlight Zone. The Watchers already witness the early animals compete for survival, and die off.
For eons, Earth's oceans were devoid of any complex life. For the majority of its history, the oceans were merely inhabited by bacteria and simple multicellular lifeforms, and the Watchers waited through it all in order to see how they could let life influence their own creations.
The Cambrian Explosion took place soon after the evolution of predation, and it was from that point on the Watchers began observing life on Earth as a frame of reference for how life behaved. They would continue to wait until they had a sufficient idea of this concept, before beginning their own mission.