[hamilyon2]

The counterargument on the last one (Human-competition threshold) seems weak (and simply wrong) to me. In related link argument for wide range of human abilities rests basically on comatose humans being unable to do anything at all and mutation-adds-random piece-to-machine metaphor.

Mentally-impaired human intelligence level is enough to replace some of the workforce, combined with some actuators and perception abilies of average human.