Likely singularities

Agriculture seems to be a pretty good example of a worldwide singularity.
The pre-agriculturalists could not have predicted anything much about the
lifestyles of the agriculturalists. It wasn't nice, either for the fading
hunter-gatherers or the agriculturalists: they got much higher population
densities, but it took ten thousand years for human health and lifespans
to regain their probable pre-agriculture norms.