Kluge: The Haphazard Construction of the Human Mind (Houghton Mifflin; 2008)

HUMAN BEINGS HAVE INTELLECTUAL skills of unparalleled power. We can talk, we can reason, we can dance, we can sing. We can debate politics and justice; we can work for the betterment not just of ourselves but our species. We can learn calculus and physics, we can invent, educate, and wax poetic. No other species comes close.

But not every advance has been to the good. The machinery of language and deliberative reason has led to enormous cultural and technological advances, but our brain, which developed over a billion years of pre-hominid ancestry, hasn't caught up. The bulk of our genetic material evolved before there was language, before there was explicit reasoning, and before creatures like us even existed. Plenty of rough spots remain.

In this book, we've discussed several bugs in our cognitive makeup: confirmation bias, mental contamination, anchoring, framing, inadequate self-control, the ruminative cycle, the focusing illusion, motivated reasoning, and false memory, not to mention absentmindedness, an ambiguous linguistic system, and vulnerability to mental disorders. Our memory, contextually driven as it is, is ill suited to many of the demands of modern life, and our self-control systems are almost hopelessly split. Our ancestral mechanisms were shaped in a different world, and our more modern deliberative mechanisms can't shake the influence of that past. In every domain we have considered, from memory to belief, choice, language, and pleasure, we have seen that a mind built largely through the progressive overlay of technologies is far from perfect. None of these aspects of human psychology would be expected from an intelligent designer; instead, the only reasonable way to interpret them is as relics, leftovers of evolution.

In a sense, the argument I have presented here is part of a long tradition. Gould's notion of remnants of history, a key inspiration for this book, goes back to Darwin, who started his legendary work The Descent of Man with a list of a dozen "useless, or nearly useless" features

— body hair, wisdom teeth, the vestigial tail bone known as the coccyx. Such quirks of nature were essential to Darwin's argument.

Yet imperfections of the mind have rarely been discussed in the context of evolution. Why should that be? My guess is that there are at least two reasons. The first, plain and simple, is that many of us just don't want human cognition to turn out to be less than perfect, either because it would be at odds with our beliefs (or fondest desires) or because it leads to a picture of humankind that we find unattractive. The latter factor arises with special force in scientific fields that try to characterize human behavior; the more we stubbornly deviate from rationality, the harder it is for mathematicians and economists to capture our choices in neat sets of equations.

A second factor may stem from the almost mystifying popularity of creationism, and its recent variant, intelligent design. Few theories are as well supported by evidence as the theory of evolution, yet a large portion of the general public refuses to accept it. To any scientist familiar with the facts — ranging from those garnered through the painstaking day-to-day studies of evolution in the contemporary Galapagos Islands (described in Jonathan Weiner's wonderful book The Beak of the Finch) to the details of molecular change emerging from the raft of recently completed genomes — this continued resistance to evolution seems absurd.* Since so much of it seems to come from people who have trouble accepting the notion that well-organized structure could have emerged without forethought, scientists often feel compelled to emphasize evolution's high points — the cases of well-organized structure that emerged through sheer chance.

Such emphasis has led to a great understanding of how a blind process like evolution can produce systems of tremendous beauty — but at the expense of an equally impassioned exploration of the illuminating power of imperfection. While there is nothing inherently wrong in examining nature's greatest hits, one can't possibly get a complete and balanced picture by looking only at the highlights.

The value of imperfections extends far beyond simple balance, however. Scientifically, every kluge contains a clue to our past; wherever there is a cumbersome solution, there is insight into how nature layered our brain together; it is no exaggeration to say that the history of evolution is a history of overlaid technologies, and kluges help expose the seams.

Every kluge also underscores what is fundamentally wrongheaded about creationism: the presumption that we are the product of an all-seeing entity. Creationists may hold on to the bitter end, but imperfection (unlike perfection) beggars the imagination. It's one thing to imagine an all-knowing engineer designing a perfect eyeball, another to imagine that engineer slacking off and building a half-baked spine.