An indefinite period of human regression could result from the gradual collapse of earth life support systems (caused by population increase, exhaustion of resources and environmental breakdown), accompanied by political chaos. The same eventuality might result from another global war, fought with either strategic or tactical nuclear weapons or other means of mass destruction. In the case of nuclear warfare, radiation could cause genetic deformations reducing societies to the animal level.
Biblical creation theories, for example, may be interpreted to indicate that post-Eden, man entered the indefinable period of regression that will now end in near self-destruction. However, it can also be argued, biblically and genetically, that he will eventually recover and reach higher stages of development.