I'm puzzled by your statement that "social scientists, including historians, tend not to be interested in people in general; we are far more fascinated with actual persons. ... Explanations at the level of universal algorithms, however fascinating, are not what I am after."
Surely what makes social scientists different from journalists or biographers is that they seek explanations of their observations that have some degree of generality and predictive power, or that at least give insight into why something happened and don't just note that it happened. And to do that, one can't avoid invoking a theory of human nature. Some social scientists may not call attention to the theories they tacitly use to make sense of their observations, but they still use them.
Of course one can't understand John without knowing something about John. But no social scientist or historian begins to study John from scratch, as if he were a newly discovered organism brought back from Mars. They interpret his words and actions by imputing goals to him, based on a general understanding of what makes people tick. Most obviously, everyone assumes that John has beliefs and desires; that John's desires include knowledge, comfort, happiness, and longevity for him, his relatives, his friends, and his tribe or nation; that John would rather be wealthy than poor, respected than reviled, sexually active than celibate; and that if John renounces one of these motives, it is in exchange for the satisfaction of one of the others. Everyone assumes that John will strive for these goals by seeking information about the motives and knowledge of the people he deals with, and by trying to predict and manipulate their behavior. Without these assumptions, history and social science would never get started. I suppose one can be complacent about how and why the assumptions happen to be true of Homo sapiens, the way that fish are unaware of the existence of water or children assume that milk just comes from the store. But why should people want to blinker their intellectual curiosity in this way?
And these are just the uncontroversial bits of the psyche. Beyond them we get to features that don't just need to be explained; there is genuine disagreement as to the facts. Are people driven by a motive of class and gender solidarity? Is our perception of reality socially constructed? With the right upbringing, could people be indiscriminately unselfish? Are men and women different only because of differences in child rearing and media stereotypes? Do men seek power so as to symbolically kill their fathers? Out of economic interests alone? Because status and power are rewarding in themselves? Historians and social scientists cannot--and do not--avoid taking stands on these questions, which are about competing scientific theories of human emotion and cognition. A major theme of How the Mind Works is that the theories of human nature that many social scientists invoke, implicitly or explicitly (including associationism, behaviorism, romanticism, psychoanalysis, and Marxism), are wrong.
You make one claim that is wildly off-base: "There is remarkably little empirical data in books written from [the evolutionary psychology] perspective, including, alas, yours." I didn't present tables of numbers, because it isn't that kind of book, but there is hardly a topic that is not backed up by data. The bibliography lists 125 empirical reports in the primary scientific literature, and another 170 books and articles that summarize empirical literatures. I describe laboratory studies of vision, memory, disgust, imagery, beauty, music, humor, prejudice, reasoning, and many aspects of infant and child psychology; questionnaires and field studies on fear, sexuality, laughter, happiness, risk, self-deception, and the delay of gratification; statistics on homicide, marriage, incest, polygyny, promiscuity, and religious belief; ethnographic surveys; experiments on neural development; case studies from the neurological clinic; and many others. Are we talking about the same book?
I sometimes get the impression that you see a fundamental divide between science, which ought to restrict itself to the physical world (and perhaps lower-level psychology such as perception), and "humanistic social science," the only acceptable way to approach society and the arts. When scientists cross the divide, you seem to see them as imperialists or carpetbaggers.
Now, I completely agree that we need multiple levels of analysis--if I were a greedy reductionist, I would be studying neurons and molecules, not perception and behavior. Similarly, I don't see psychology (evolutionary or otherwise) as ever coming close to supplanting social science and history.
But I do think that all knowledge is connected; academic divisions are for the convenience of deans. Levels of analysis, from human history to quarks, have to be systematically related: the most basic units at one level explicable from interactions in the level below. The history of science is littered with long-forgotten dichotomies between allegedly unbridgeable realms--planetary vs. terrestrial, physical vs. chemical, inorganic vs. biological, physiological vs. psychological. The dichotomy between human biology and social science, conceived of as two encapsulated monads, will surely join them.