There is no reason to believe IQ gains will go on forever. There may remain few who have not absorbed the language of science to whatever degree they can. The trend toward a higher ratio of adults to children in the home may reverse. Any further drop in the birth rate is likely to be outweighed by more solo-parent homes. There must be some saturation point in our willingness to be challenged by more conceptually demanding activities at work and at play. Although IQ gains are still robust in America, they have stopped in Scandinavia (Flynn & Weiss, 2007; Schneider, 2006). Perhaps Scandinavia is more advanced than America and its trends will become universal, at least in developed nations.

The most obvious consequence of the end of IQ gains would be that they would stop killing people on death row. If there were no gains for thirty years or so, no one would have IQs inflated by obsolete norms. Other consequences are less obvious.

If IQ gains were to cease throughout the developed world during the twenty-first century, this could give the developing world a chance to catch up. Its people are overwhelmingly still focused on the concrete and the distribution of scientific spectacles has barely begun.