Monday, July 28, 2008

Evolution isn’t perfect

If nothing else, it's a handy expression. A kluge, Gary Marcus explains, is "a clumsy or inelegant - yet surprisingly effective - solution to a problem"; a piece of jerry-rigging, in other words. Nature is rife with them, the human body no less so, and it's a wonder our brains can function in the modern world at all.

That, at any rate, is the burden of this cheerily blasphemous book, which succeeds in sticking it both to the intelligent design lobby and to some of evolution's biggest cheerleaders.
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Marcus's major opponent here, though it is never named, is adaptationism - the supposition that any trait of any organism must be doing something useful or it wouldn't be there.

"Natural selection tends to cause the selection of superlatively well engineered functional designs," say John Tooby and Leda Cosmides, founders of evolutionary psychology. But if that's so, Marcus asks, how come our memories are so bad?

You can search a computer database; you have to wait until your memory is jogged if you want to remember something in particular.

And why are our wills so weak? Pleasure is supposed to guide us for the good of our genes, but there's nothing genetically beneficial about eating 65 ice-creams and getting diabetes.

Come to that, why are we so gullible? Why is our language so vague and ambiguous? Why are we so bad at sticking to plans, or keeping track of how we know what we know, or generally doing any of the things you'd hope to be able to do with a superlatively well-engineered brain?

Because it was a kluge. Evolution doesn't, in fact, tend to perfection: it goes with what works and tinkers with it later. That's why the retinas of vertebrates seem to be installed backwards, giving us all blind spots in the middle of our visual fields. Eyes like that do the job well enough, and there's no way of flipping the retina while preserving decent vision across intermediate generations. So we're stuck with them.

Likewise the mind: our meagre reasoning capacity is an afterthought, spatchcocked on to the ancestral systems that have the reins where practical decision-making is concerned. If only our higher mental functions could dominate; alas, the lizard- brain parts have seniority.

Marcus brings a schoolboyish brio to the table, exulting in rude spoonerisms and littering the footnotes with links to Derren Brown on YouTube - indeed, the whole thing might have been pitched at a teenage readership.

Nevertheless, if a kluge has to answer some urgent need, it would be hard to argue that this book qualifies.

Another man exercised about our evolutionary shortcomings is the physicist Leonard Mlodinow. Having, intriguingly, been a scriptwriter on the television series MacGyver, Mlodinow presumably knows all about kluges. But there's no substitute for doing things properly; observation shows that people habitually overlook the role of chance in their dealings, and Mlodinow tries to set us straight.

Thus, despite a clever camouflage job designed to play up buzz concepts, The Drunkard's Walk is a straightforward elementary course in probability and statistics.

It's quite a good one, too. Mlodinow is a sensitive teacher, taking the edge off the maths with anecdotes and historical vignettes drawn from the field's roots in Renaissance gambling dens. Where numbers can't be avoided, he plucks them from the worlds of finance and baseball.

And his moral - that we are all taking a drunkard's walk through life, bounced hither and yon by random forces, and that a little light maths instruction should aid acceptance of this fact - is commendable.

The biggest problem is Mlodinow's oddly old-geezerish persona. He makes winking reference to the relative attractiveness to women of Tom Cruise and Danny DeVito, as if Cruise hadn't jumped the shark and DeVito all but vanished from view.

There's outmoded talk about picking up brunettes in bars and a jocular allusion to Nixon. At one point he harrumphs: "Calculating the gross motion of heavenly bodies...is a simple task performed today by precocious high school students as music blares through their headphones." Headphones, indeed. Whatever next?

It must be admitted that Mlodinow lectures well. Once it's over, though, you do half-expect him to tell you to get off his lawn. Perhaps his ancestral systems are giving him gyp.
Posted by Ajay :: 5:44 PM :: 0 comments

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