Irreplaceable Perplexity 101

Ms. Cleary has designs on teaching evolution

Hello class. Settle down please, it’s time for today’s lesson. Put that iPod away, Wesley, or Ms. Cleary will take it home with her and you won’t hear Green Day for a blue moon. Melinda, that chirpy ring tone from your cell phone must stop, or Ms. Cleary will use the infernal device to call her cousin Bernie in Barcelona. Your father will emit his own ring tone when he receives your next phone bill.

Dean MacAdam

Now that your attention is riveted on Ms. Cleary, let’s focus on today’s special topic. It has come to Ms. Cleary’s attention that evolution is in the news. Evolution is really happening, as you kids say.

People with inquiring minds in Kansas and Pennsylvania and, well, all sorts of places now question whether life really evolved on this planet as proposed by Charles Darwin and his scientific followers. They want children like you to learn about intelligent design, an all-purpose evolution substitute.

Ms. Cleary suspects that those few of you who still read newspapers or at least glance at Headline News while channel surfing over to the latest WB teen soap opera have heard about this biological brouhaha. Today, Ms. Cleary will answer your questions about the great evolution debate in her capacity as a humble servant of youth.

You may begin.

What’s evolution?

Bless you, you’ve actually been listening, Wesley. Miracles do occur. Class, be warned that you may hear Hollywood actors say of a director, “Oh, he’s so evolved” or speak of an award-winning colleague as “having evolved to a new level.” These people don’t know evolution from an audition for Scream: Part 8.

Over long periods of time and many generations, animals change their forms. Form changes that serendipitously help animals survive tend to last. However, environments change, too, and by so doing, sometimes wipe out groups of animals that busted their tails to evolve in a previous setting. That’s cold. That’s evolution.

All the animals now living on this planet trace their ancestries back billions of years through a variety of creatures that no longer exist, including—at the very beginning—one-celled organisms unlike any that you may happen to run across today. This biological unity and diversity go together like The Captain and Tennille, like marble-fudge ice cream and cellulite, like a Quentin Tarantino movie and the sensation of popcorn chunks rising in your throat. That’s cool. That’s evolution.

Old-school evolution often occurs too slowly for an observer to see. That’s inconvenient for those who limit reality to anything that can be captured on their digital video cameras. For those interested in seeing for themselves, ponder artificial evolution. Consider, for example, dog breeding over the past century or Michael Jackson’s face over the past 25 years.

What’s a missing link?

A missing link, Viola, makes Ms. Cleary’s charm bracelet pinch her wrist. Although the intelligent-design people put a lot of stock in missing links, those wacky creatures tell you squat about evolution. So what if we never stumble over the remains of, say, the last common ancestor of apes and people?

Let’s consider primates, class. The worldwide collection of fossil skulls from ape and human ancestors shows shape changes that occurred over vast stretches of time among related creatures. Was there ever a half-person, half-chimp? That brings a repulsive and unsanitary image to mind.

Since nobody knows what the common ancestor looked like, scientists in their prickly way may never agree that they’ve found it. Many questions remain about the ways in which fundamental shape changes arise and foster the evolution of new types of animals. These aren’t signs that evolution never happened. They’re signs that fascinating turns in evolutionary biology lie ahead for the intellectually curious. By that turn of phrase I mean anyone willing to put down People magazine long enough to read a few books—even paperbacks.

What is intelligent design?

It’s the missing link between creationism and religious instruction masquerading as biology. Yes, class, Ms. Cleary sees a place for missing links after all, and it’s not pretty.

Creationism takes a literal view of the Bible, so it holds that the Earth and all its creatures were created in one fell, divine swoop 6,000 years ago. Fair enough, but that’s a hard sell as must-have information in a sophomore biology course.

Enter intelligent design (ID), an idea that tries to make creationism palatable to adults on school boards who have no scientific training or interests but have the power to tell adults who do have scientific training and interests how to teach science.

Ms. Cleary admits to having a hard time finding anything substantial in the writings of those whom she refers to as IDologues. Much arm waving concerns the concept of “irreducible complexity.” Listen closely, class: Biological cells contain protein-making systems for basic functions, such as clotting blood. IDologues assert that such systems are irreducible, consisting of many parts that work together so closely that the whole operation shuts down if a single component goes missing. So, evolution couldn’t make adjustments part by part.

IDologues also claim that these biological entities are so complex that they must have been designed from the start to work as they do now rather than having evolved from previous forms. Essential biological systems must therefore reflect a designer’s dexterous hidden hand, not evolution. And perhaps nonessential biological facts of life, such as irritable bowel syndrome and male-pattern baldness, reflect the cold, hard slap of a designer’s hand.

Ms. Cleary assigns this argument a grade of F for “forget it.” As physicist Mark Perakh of California State University, Fullerton has pointed out, if the loss of a single part destroys a system’s function, then that system has been poorly designed. Any well-designed system contains features that not only perform their regular roles but can compensate for losses or malfunctions elsewhere. Indeed, scientists are finding that biological systems exhibit just this kind of resiliency and complexity. Biology is messier and more adaptive than IDologues imagine.

Evolution is just a theory, right? Shouldn’t we learn about alternatives to it?

A scientific theory is a wonderful thing, Melinda. It’s not a wild guess or a poor substitute for facts. It’s a framework for making sense of a large number of related observations about the world. Scientists use theories to guide them in designing their experiments. Depending on what the scientists find, a theory can crash and burn or take on unexpected powers of explanation. In other words, theories evolve, and evolutionary theory has gotten stronger over the years.

Don’t misunderstand Ms. Cleary. She has great respect for religion, as you all know. Religions evolve and adapt too. But religions answer big questions that nearly everyone asks about our connection to the universe and the meaning of our lives. Science generates novel questions about us and the world that almost nobody would have thought to ask otherwise. Science sifts nuggets of insight out of humanity’s irreplaceable perplexity and then subjects that knowledge to continuing scrutiny. Ms. Cleary would refer to irreplaceable perplexity as IP, but that sounds vaguely repellent to her.

By the way, there’s plenty of genuine controversy for students of evolution to learn about. Unfortunately, it’s not often taught to them, even in the most scientifically tolerant classrooms.

The controversy concerns not whether evolution exists but how it works. As anyone who has attended a meeting of anthropologists can tell you, these scientists engage in epic battles about the nature of evolution. They make Tony Soprano look like a flower child. You’ll hear these highly educated people trade streetwise yet erudite barbs such as “Hey fossil breath, people today evolved from a direct ancestor in Africa around 200,000 years ago at most,” and “So sorry, matrix for brains, but people evolved simultaneously from populations in Africa, Asia, and Europe over at least the past 1 million years.”

Ms. Cleary has tidied up the scientists’ actual insults so that impressionable young minds won’t be startled.

What is evo devo?

To the best of Ms. Cleary’s recollection, that’s a cover band inspired by a strange 1980s pop group that wore funky flower pots on their heads and danced like geeky robots, singing “Whip it! Whip it good!”

Isn’t evo devo short for evolutionary developmental biology?

Oh yes, thank you, Todd. Ahem. Sometimes Ms. Cleary has flashbacks to her wayward youth.

Evo devo, the study of how changes in genes and individual development contribute to evolution, has advanced greatly in the past 20 years. It’s now known that many different animals—from flies to people to elephants—share a set of genes that governs the formation of their bodies and body parts. As scientists are learning how complex animals are constructed from single cells, they’re discovering that subtle tweaks to body-building genes promote the descent and modification of animals, no steroids required. Such findings promise to expose the inner workings of evolutionary processes originally proposed by Darwin.

The development of individual organisms out of tiny cells is an amazing thing, class. Physical development is as flexible as one of those charming balloon giraffes that Ms. Cleary buys at the state fair each year. The structures that are built by development may suffer when damaged or when parts of them are removed. But flexible developmental processes, not their end products, may well lie at the heart of evolution.

Let’s contemplate the human brain for a moment, class. A child who has half of his or her brain surgically removed to treat severe epilepsy will still grow up to display virtually all the mental and physical faculties of a child with a whole brain. Massive cell reorganization that occurs in the developing half-brain picks up the slack. Brain development is irrepressible, not irreducible.

Did you hear Ms. Cleary, Wesley? Kids with half a brain can succeed. Keep your chin up.

Is it time for lunch yet?

Maintain your focus, Melinda. Goodness knows, it must be hard to think without a wafer-size digital-communications system pressed against your ear.

Ms. Cleary expects that all of you have listened carefully to her little discourse on the evolution wars, although she will not administer a pop quiz next week.

In fact, she will not raise this topic again. After all, this is a Sunday school class. Ms. Cleary simply couldn’t resist doing a little evolutionary preaching today. Don’t be mad. She’s just teaching the controversy.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

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