Species as Individuals in the Hierarchical Theory of Selection 701
elements—an important input of raw material for generating "organized adaptive
complexity" at a higher level. Organisms are good at building complex
adaptations. Species are good at forging temporal trends of geological duration,
and their efforts largely regulate the relative diversity among phyla (why so many
beetles, and so few pogonophorans). To say (as Dawkins, Williams, and other
detractors often do) that species selection must be unimportant because such a
process can't build organismal complexity reminds me of the cook who didn't like
opera because singing couldn't boil water.
THE DEME-INDIVIDUAL This kind of individual has borne the brunt of the
general argument about higher-level selection ever since Darwin awarded the idea
a strictly limited amount of conceptual space in trying to puzzle out the origins of
human altruism (see pp. 133-137). The subject has been extensively reviewed and
controverted (Wynne-Edwards, 1962, vs. Williams, 1966, for an early and
generally unacceptable version; Wade, 1978, 1985; D. S. Wilson, 1980,
1983,1989; Wilson and Sober, 1994; Sober and Wilson, 1998, for reviews). I shall
therefore provide only an idiosyncratic sketch here, for the terms and concepts of
this discussion permeate the chapter, while my own interest as a paleontologist
flows to the still higher levels that have not been extensively studied.
In a curious way, the development and acceptance of hierarchy theory has
been impeded because the classical treatment of this subject has been focussed so
strongly, indeed almost exclusively, on this level—and demes are the hardest of all
individuals to validate and justify within the evolutionary hierarchy. All other
individuals build better boundaries (to retain their own subparts, or lower-level
individuals, and to exclude the subparts of other individuals at their level), and
experience less difficulty in remaining sufficiently stable for the requisite time
until reproduction. But demes are especially vulnerable to the classic objection (see
p. 647) that, lacking strong internal mechanisms for coherence, their individuality
may be too fleeting and subject to change by loss or invasion—as in Dawkins's
well-formulated and memorable image of dust storms in the desert or clouds in the
sky. Indeed, as I argued previously (p. 648), the classic defense of interdemic
selection depends upon the identification of plausible conditions that would allow
such adventitious groups to remain stable long enough to act as units of selection.
The centering of the general argument for higher-level selection upon demes has,
by false and unfortunate implication, led to the widespread impression that any
kind of supraorganismal selection must face the same difficulties—perhaps with
problems growing ever more intense as individuals become more inclusive. But
this argument, based on illogical assumptions about linear extrapolation, does not
hold because demes (in most circumstances) are uniquely unstable in the
evolutionary hierarchy. Species, for example, usually attain as much stability and
coherence as organisms, though by different mechanisms (see pp. 703-705).
Group selection has traditionally been invoked under our organismic biases as
an explanation for bodily behaviors—with altruism as a paradigm,