Precise adaptation, with each part finely honed to perform a definite function in an optimal way, can only
lead to blind alleys, dead ends, and extinction. In our world of radically and unpredictably changing environments,
an evolutionary potential for creative response requires that organisms possess an opposite set of attributes usually
devalued in our culture: sloppiness, broad potential, quirkiness, unpredictability, and, above all, massive redundancy. The
key is flexibility, not admirable precision. Ironically, then, to make us at all, evolution must work by processes
contrary to the prejudicial hopes that we invest in Darwin’s legacy to validate our traditional status as lords of all
by right of residence atop life’s pinnacle. Going even further, humans could arise only because evolution disproves
what we have so long promulgated as our natural right and status
Evolution works like the Nairobi market, not like the throwaway society of the wealthy West. You
can evolve further only by using what you have in new and interesting ways. Organisms have no equivalent to currency for acquiring
something truly new; they can reconstruct only from their own innards.
any biological adaptation also produces a host of structural by-products, initially irrelevant to the organism’s
functioning but available for later co-optation in fashioning novel evolutionary directions. Much of evolution’s
creative power lies in the flexibility provided by this storehouse of latent functional potential.
All biological structures (at all scales from genes to organs) maintain a capacity for massive redundancy--that
is, for building more stuff or information than minimally needed to maintain an adaptation. The extra material then
becomes available for constructing evolutionary novelties because enough remains to perform the original, and still necessary,
function.
In organs and body parts, the principle of redundancy finds primary expression in the concept of overdesign,
or margin of safety. Two (or more) structures often perform the same basic function. This generosity may benefit an organism
in the immediate present ( just as a spare tire saves many a driver), but extra capacity also permits creative evolution in
novel directions--because the spare tire can turn into something marvelously different, and the car still runs.
As a general statement, natural selection operates to produce a better fit of organism to prevailing local
environment. In most cases this fit entails greater specialization and consequent loss of flexibility. ( Therefore, in the
key argument of this essay, flexibility must arise as an unintended side consequence of natural selection--that is, from such
structural principles as latent potential and redundancy.) But if better local adaptation can sometimes arise by increased
flexibility, then natural selection might also operate directly toward such a result. The unique cognitive abilities imparted
to us by our large brains, particularly our capacity for learning, may have placed us in an unusual situation favoring direct
selection for flexibility. The basic argument has a long pedigree (an oldie but goodie in my book), dating at least
(in a pre-evolutionary version) to the great seventeenth-century English philosopher John Locke.
In summary, then, Homo sapiens, this most peculiar, powerful, and dangerous of current species, originated
because evolution’s sloppy flexibility permits complex creatures to arise--and not (as we might like to believe) because
we were meant to appear as a natural result of inevitable improvement constructed by a process (natural selection) that continually
makes successful creatures better and better. We are here because distant unicellular ancestors evolved multiple copies of
many genes, thereby allowing some to change while others retained needed functions. We are here because the fins of ancestral
fishes held latent potential for transformation to the different role of bearing weight on land; because reptilian ear bones
could be co-opted to become mammalian hearing bones; and as a result of a thousand other quirky and unpredictable transitions
based on the inherent potential of anatomic structures to work in ways that were not the selected function of their original
design. And we are here because our odd mentality set an unusual context that placed an explicit selective value upon flexibility.
Every complex species owes its unpredictable existence to the sloppy sources of evolution’s creativity. We are
quirky, if glorious, accidents not to be repeated on this planet. May we, then, take some care for our own fragility.
