There wasn’t an event that triggered the evolution of humans
—
Let’s not count the eruption of Mt. Toba in 72,000 BC, which decimated the human population at the time ...
I should have been more specific. There wasn’t a single event that triggered human evolution, since that would imply that human evolution was static until and when such an event occurred. The processes of evolution are ongoing. An event such as an eruption that wipes out a large population, leaving pockets of survivors here and there, would not change the overall pace of evolution. Rather, the different pockets of survivors would each evolve in their own direction, rather than in the direction of the larger group.