etbe: Singularities are, historically, dime-a-dozen. Overwhelmingly the most frequent of them are out-and-out collapses, including mass starvation and massacres. Development of tools and weapons did not "immediately" vault early humans to the top of the food chain; that happened more than a million years later, so must be traced to some other cause. The effect of agriculture was certainly unpredictable: except in the last century in rich countries, its main effect was a grossly-expanded but seriously malnourished population.

As developments likely to have surprising effects, the greatest currently may include (1) systematic, radical climate change, (2) systematic elimination of ocean food sources by factory fishing, (3) systematic elimination of river outflows, (4) systematic elimination of broad swaths of animal and plant species, some of which, necessarily, are linchpins in ecological systems we depend on, (5) uncontrolled deployment of nuclear weapons, (6) television-driven religious indoctrination, (7) agricultural use of antibiotics driving development of resistant bacteria.

You want a singularity? You might well get one in your lifetime, but I predict you won't like it.