By 1973 we had recognized that excessive crowding of mice can culminate in all subjects becoming so autistic that none could exhibit behaviors essential for species survival. We also had developed a technology that recorded the movement of each rat in a population by its identity as it moved through a complex compartmentalized habitat over its lifetime. These two developments were incorporated into a 1973-1986 set of experimental rodent population studies. Dissolution of residential stability marked the course of origin of an extinction-producing irreversible universal autism, one that might also characterize humans during the next century. Our studies with rats, utilizing the new technology, reveals that acquisition of collaborative social roles modifies contact rate and intensity of status interactions sufficiently to ameliorate pathologies accompanying crowding. A just completed restructuring of the data base of the space-time course of duration and change of behavioral states now permits a more precise delineation of how crowding induces fragmentation of behavior and withdrawal, whereas cooperation leads to longer and more complex behaviors as more effective communication develops.
