1266 THE STRUCTURE OF EVOLUTIONARY THEORY
we so often construct invalid dichotomous taxonomies in our real world of complex
continua, but primarily because we so often impose another conceptual module for
moral judgment upon our pairings (the Manichean good vs. bad), and then proceed to
identify one side of the dichotomy (including ourselves and our preferences) as
righteous, and the other side (including "foreigners" and competitors) as worthy of
anathematization or even ripe for burning. (I need hardly add that yet another aspect
of human mentality, our capacity to devise grisly means of death and torture, and our
technological ability to apply such means to large numbers of people in short periods
of time, makes our innate preferences for dichotomization particularly dangerous.)
Now I am perfectly willing to believe that our brain's preference for
dichotomization arose as a highly adaptive attribute in a very distant and ancient
small-brained ancestor that, to enhance its prospects for survival, needed to make
limited, quick, and twofold decisions that exhausted the maximal capacity of its
judgment in any case: mate or wait, eat or sleep, fight or flee. But, whatever the
adaptational basis of origin, dichotomization then persisted throughout the
subsequent phylogeny of vertebrates as a historical constraint that became more and
more quirky, and more and more limiting, as the brain enlarged into the much more
sophisticated instrument of a lineage that eventually generated our exalted, but
curiously freighted, selves.
- At the level of immediate reasons for persistence and flourishing of the
hunter-gatherer common ancestor of Homo sapiens in Africa, many distinctive
mental attributes of our species, including major features of "human nature" that
define our evolutionary success, must have arisen as nonadaptive spandrels (later
exapted, in several cases, as vital bases of our current domination), and not as
primary adaptations (the central theme of Chapter 11). This conclusion necessarily
follows from the previous argument that, at the level of maximal natural complexity
represented by the human brain, consequential spandrels must, at least in number,
overwhelm the primary adaptations that generate them. Therefore, in terms of
exaptive potential for evolutionary futures, the brain includes more cooptable
spandrels than primary adaptations. Any "evolutionary psychology" that neglects the
nonadaptational origin of many features now useful (or at least used, however
dubiously), and that limits the domain of evolutionary inquiry to arguments (often
speculative) about initial adaptive causes and benefits, will become more misleading
than enlightening in restricting investigation to such a narrow scope of inquiry. We
must abandon the largely unconscious bias of an overly strict Darwinian approach
that equates all "evolutionary" explanation with adaptationist analysis.
THE UBIQUITY OF SPANDRELS UNDER A HIERARCHICAL CONCEPTION
OF EVOLUTIONARY LEVELS AND CAUSALITY. If Darwin's own view of
natural selection as a single-level process operating on organisms had prevailed,
spandrels would still be pervasive in nature and important in evolutionary theory.