Forty-seven years have come and gone since Paul Ehrlich made his case for population control. What has been the consequence? Americans are starting to realize, perhaps for the first time, that we are facing a demographic nightmare. Our problem is not too many people but a plummeting birthrate. There are more single women today than those who are married, and the birthrate has been declining steadily. If it were not for immigration, this nation would be below zero population growth.