Thanks for the clarification of the point about life. The fact that you make a distinction between life in the broad sense of our existence and life in the biologist's sense of adaptive complexity is precisely why critics such as I have such serious reservations about sociobiology. Why try to explain the magisterial bylaws that cannot recognize the existence of the magisterial?
This is another way of saying that much of the disagreement between us centers on what counts as an explanation of human thought and behavior. Recognizing the rather huge gap in our understanding of people, you propose hypotheses that, in your view, might guide us toward researchable problems using the insights of evolutionary psychology and artificial intelligence. No one knows, of course, whether those hypotheses will bear fruit. My sense is that, even if successful, the explanations they uncover will exist at such a level of generality that huge gaps in our knowledge of how specific individuals think and act will remain. Social scientists, including historians, tend not to be interested in people in general; we are far more fascinated with actual persons. I would love to know more about how American voters make up their minds between competing ideologies, for example. The only way to find out is to get to know the people whose thinking I want to understand. Explanations at the level of universal algorithms, however fascinating, are not what I am after.
Consider an example. Suppose we want to understand not how the mind works, but how Steven Pinker's mind works. Fortunately this particular human being has written a book that reveals a great deal of how his mind does work. Reading that book, we learn that Steven Pinker is very much a product of his culture. Indeed, his book is filled with wonderful references to films, novels, TV programs, and music. It becomes clear to me that for this particular individual, culture plays a major role in how he thinks. Pinker, some of whose thoughts can surely be attributable to the way his mind evolved biologically and some to the brute calculative ability of his neural synapses, is also a person who reaches for the cultural tools around him to help him make sense of the world. So yes the capacity for culture, as you put it in your letter, may itself have an explanation. But in the meantime it works wonders, helping, among things, to produce a book called How the Mind Works.
Evolutionary psychologists like to say that their explanations are the truly scientific ones, especially when compared with the fuzzy thinking they encounter among social scientists. Yet, oddly for an approach so scientific in self-conception, there is remarkably little empirical data in books written from such a perspective, including, alas, yours. I find it hard to imagine a science of human behavior that seems so uninterested in actual human beings, but that may be because, for me, the social sciences are not about finding laws that apply to all people throughout all history but in understanding particular people at particular times. The point of my criticism of your book was that you should search for the general laws--who knows, you may (although I doubt it) even find them? Meanwhile, let others try to explain the particular and the concrete. Infanticide may serve some adaptive function. But that explains little or nothing about why a particular Brazilian peasant, facing the prospect of a mouth that will go unfed, breaks down and kills her baby. If only evolutionary psychologists respected such different levels of explanation, I would have no quarrel with them.