James, I agree that hunter-gatherer minds initially build hunter-gatherer cultures (having no other option), but as those cultures develop technology, their technology alters their lifestyle, their environment and their culture such that it is no longer in harmony with the evolved hunter-gatherer mentality of its members. Initially, cultures adapt. People change their ways as best they can. But time passes, technology progresses and things further change. New lifestyle forces (more sedentary work, more abundant food, the emancipation of women) make it impossible to adhere to a hunter-gatherer lifestyle. The extended family is essentially gone and now the nuclear family is in decline, being replaced by the single-parent family. All that the extended family-and-tribe cultural structure once provided a child must now be obtained from only one parent (largely absentee due to employment) and from popular culture.
Taking only this single example of technologically forced cultural change, it is hard to imagine that this drastic impoverishment of childhood has not taken a toll. One might ask, rhetorically at least, how can such a change NOT contribute to an increase in the number of children who grow up to be dysfunctional adults? How can it NOT contribute to crime, drug abuse, suicide and a general decline in the social skills one needs to function well as an adult in our modern society?
James, I fail to follow your argument re: homeostatic costs. These and other factors limit access to certain places in biological design space, making some morphologies, physiologies and (if we accept evolutionary psychology as valid) psychologies unavailable to us. This would seem, if anything, to favor my argument by implying that human adaptability is limited - that some adaptations that would make us better adapted to modern life are unavailable to us. As for changes in the fitness landscape, one need not wander down the list of traumas to fossil fuels and overpopulation to find plenty of reasons to think that the human fitness landscape looks like a trampoline pummeled by a dozen bouncing kids. Good designs in the fitness landscape come and go at an ever increasing rate.
Even the evolutionary forces that originally shaped us no longer work in our favor. Natural selection dictates that those individuals with the right genes (originally, the genes that made them the best adapted to their environment) will enjoy a reproductive advantage. For modern humans, the right genes seem to be those that increase the probability that the individual will ignore family planning, fail to use birth control options and have more children than they have the resources to care for properly. In contrast, those individuals who seem best adapted to our modern lifestyle, in that they function well, form supportive social connections, are able to earn a livable wage and show concern for the state of the planet, are having fewer or even no children at all. Extend these trends into the future and consider the consequences.
The mismatch between our reproductive drive and finite resources is only one of many such mismatches. How about: a fixed sensory processing rate Vs a constantly increasing information flow; a tribal us-Vs-them mentality versus a host of problems requiring global cooperation; a Paleolithic fight-or-flight response Vs a chronically stressful lifestyle; a fixed need for social support Vs a decrease in the imparting of social skills to the young; a physiology evolved for strenuous daily physical activity Vs a job that requires 12 hours per day at a computer terminal. Obviously, I could go on. And thanks for the comments.