Stephen Jay Gould: The Interview

"Staggering our certainties" about humanity's place at the top of the heap

Published September 23, 1996 7:00PM (EDT)

In the popular mind, Darwin's great discovery was that apes were our ancestors. To Stephen Jay Gould, that's not the half of it. The Darwinian ideas that people really have a hard time embracing, he maintains, are the implications of natural selection -- a theory that explains the development of Homo sapiens without reference to any sort of divine plan or vision of progress.

Woven through much of Gould's writing, and at the heart of his new "Full House," is an insistent demand that we "cash out" the deepest implications of Darwin's insights -- and begin to comprehend that our species, far from being the pinnacle of some inevitable trend in nature toward greater complexity, is simply a tiny accident occurring on a minor side-branch of the evolutionary tree.

In his 1991 "Wonderful Life," which is a sort of companion to "Full House," Gould used the example of the Cambrian explosion of species found in the fossils of the Burgess Shale to demonstrate that "contingency" -- accident, happenstance, the particular way that events unfold -- plays a central role in determining the fate of species. Rewind the tape of events to play evolution out once more, Gould argues, and the odds are against anything like Homo sapiens developing. We're here because we're here -- not because we had to be here.

"Full House" turns from the fossil record to the nature of statistics. Gould takes up a series of apparently unrelated and seemingly abstruse questions -- from the disappearance of the .400 batting average in recent decades to the likelihood of his own surviving an episode of stomach cancer -- and weaves them into an impassioned critique of the progressive view of evolution.

Ever since Plato, Gould argues, we've tried to understand events by identifying linear trends based on shifting averages. But in evolutionary terms, there are no averages -- just individual variations. If we focus on the spectrum of variations rather than averages and trends, we are less likely to be led astray by minor events taking place at statistical extremes -- and less likely to conclude that we are the culmination of a trend toward complex life. On Gould's graph of the distribution of complexity among life forms (see illustration below), humanity exists at "the right tail," not the top of the heap.

In other words, though decades of popular mythology has enshrined a picture of evolution as "the rise of man," a progress from teeny bacteria to brainy self-conscious mammals, the bacteria never went away -- and, according to Gould, they remain by far the most significant form of life.

It takes a careful writer to make statistical issues like these comprehensible to the general reader -- and a charming one to keep them exciting. Gould, fortunately, is both.

"Full House" tries to persuade people that there is no progress inherent in evolution. But the subtitle, "The Spread of Excellence from Plato to Darwin," sounds pretty progressive itself.

It's a pun. I'm talking about variation contracting and expanding. And then "from Plato to Darwin" is also a pun, something of an in-joke, because it's not a chronological history, it's a contrast of a Platonic and Darwinian approach. It's a little cryptic, but that's exactly what it's talking about -- measuring excellence by spread.

The main point is that we're very hung up on trends -- we make the mistake of interpretation in the Platonic mode, abstracting a system by a single number and seeing how it moves.

You ask your readers to look at things in terms of the spread of variations rather than in terms of averages or essences. That seems like an enormous shift for people, because one of the ways we learn is by looking at lots of individual examples and then generalizing from them.

It is difficult -- there is a strong bias, and Plato is its embodiment. The problem in all of the examples is just to reconceptualize, to get people to take up Darwin's insight that variations are irreducible -- that's the reality itself.

I love the .400 hitting example because it just makes so much sense once you get it. Everyone is always talking about .400 hitting -- and there's an enormous variety of explanations, but they're all based on the same assumption, which seems commonsensical, namely, that .400 hitting once existed and went away, so something bad has affected hitting. Maybe it's that pitching's gotten better, faster, but something bad has happened, either absolutely or relatively. And yet everybody knows that doesn't make sense because everything gets better in sports.

The whole thing is based on a misperception -- misconstruing the number 400 as an entity, as a measure of excellence. People have always assumed that hitting must have gotten worse, either absolutely or relatively, because it disappeared. I argue that if you study things in terms of spread, decreasing spread, that you will understand that the decline of .400 hitting is, ironically, measuring the increasing excellence of play.

And I've never had any of the major baseball statisticians reject this idea, once they see what I'm saying. The history of life example will not have as much acceptance, because the prejudice is too deep. I don't think it's as deep as creationist prejudices were in the 19th century, but I don't think I'm going to convince everybody. They'll at least see what I'm saying. Maybe they'll have a renewed appreciation for bacteria. But they may still say, "Well, look, I don't care, I'm just interested in that right tail. That right tail is where it's at! That's where we are, and consciousness is transforming the planet and wiping everything else out. I understand that it can be produced entirely by random motion, but it's there, and I don't care about all this other stuff."

When Darwin wrote letters to people he knew he wasn't going to convince, what he would say -- I love his phrase -- was: "My only hope is that at least it may stagger you in your certainties."

If the reader really does take your argument to heart, it has implications across the map, not just for evolution but for the way we look at everything.

Well, some trends really are things moving somewhere. That's why I have that discussion of cultural evolution. Human technology can be seen as progressive in terms of its complexity -- that doesn't mean it's good, that's another issue. I'm not saying that every single trend has to be reconceptualized -- but there's a lot of puzzling situations where we do.

When I finished "Full House" I started to think of other directions you could turn this way of thinking toward: the book market, for example. We tend to focus on best sellers or the books we think are best written, but if you study the spread of variation in its population, you'd probably pay a lot more attention to romances and self-help books.

So often, we characterize a whole system by an extreme value that intrigues us. And that value often is moving somewhere, simply because of the variation -- an extreme value's gotta move if the variation's expanding and contracting.

Thinking in terms of trends is at the root of the way the media work.

I think it's very deep. Humans are storytelling creatures. That is constitutional, and at least in this culture we like our stories to go in certain ways. We don't like stories like the Book of Ecclesiastes, where all rivers run into the sea, and the sea isn't full, and there's nothing new under the sun! I mean, those are stories, but we like stories that go somewhere, and therefore we love trends. A trend is the ultimate story that goes somewhere, in its simplest form: something gets better, we rejoice, or something gets worse, and you lament.

At the end of the introduction to "Full House," you say to the reader, "Let's have a whale of an argument." Why do you anticipate such resistance?

Darwin's revolution is a curious one -- it never got completed. Freud said that great revolutions have two parts: one is when we accept the physical reconstruction of the earth, and the other is when you buy its implications for human status. And that in a way is the harder one. Copernicus's revolution has achieved both parts, but Darwin's never achieved the second part. Because it's in many ways the most disturbing of all revolutionary messages.

"Wonderful Life" is the argument for contingency -- a particular pathway didn't have to happen and wouldn't again if you could replay it. Then there's the argument in "Full House" -- that the expansion of the right tail, the complex end of the distribution of life, where we are, can be produced by random motion on the drunken walks model. You put those two together, people really don't want to accept that.

"Full House" talks about the abstract generality of life's distribution, this right-skewed distribution with an extending right tail. There's nothing about that that encourages any belief in a principle of progress or even a trend of progress. Because systems in random motion that begin, as life must, near the left wall of minimal complexity have to develop that way if they increase in diversity at all.

And then your only solace is to say, "Okay, but at least here I am on the right tail. So even though I accept what you say, at least you're allowing that something like me had to arise, because there has to be a right tail. So it may be parochial, but I'll just focus on the right tail." And then the other theme of contingency comes along and says, maybe there has to be a right tail, but you don't have to be on it -- and you could build that right tail a hundred times again starting from the bacterial mode of pre-Cambrian times, and you'd never get a sentient being anything like you again!

And that upsets people.

What I really want is for people to understand the argument and see that it makes sense. It's not at all original. People like Ernst Mayr and other great historians of Darwinism have often said that in a way the deepest revolution that Darwin tried to make is precisely that -- to break through the Platonic restraints and to get people to see that variation is ultimate reality. That's a big difference, particularly for practical biology.

Before Darwin if you picked up a handful of snails at the seashore and they varied... It's hard. This is what Foucault and other people write about so well: how do you get into the mindset of a very different worldview? It's almost impossible. But I guess in 1800 you'd pick up a pile of shells and you'd recognize that they were different, but you would see those differences in Plato's sense literally as accidents -- in the Platonic sense of accidental, that is, as varying degrees of departure from an essence, because of the slings and arrows of outrageous fortune of an individual life.

That's why there are all these old tales in scholastic philosophy about the brothers who were arguing about how many teeth there were in the mouth of a horse. And the young novitiate says, why don't we go out and count old Dobbin's teeth? And they practically throw him out, because that's ridiculous -- old Dobbin's teeth has nothing to do with how many teeth there are in a horse's mouth! But I guess that's how you would have looked at it. Whereas today, I assume that a biologist just looks at those snails differently. When I look at snails, some are big and some are fat, I might calculate an average, but I know that the average is the abstraction.

The story about the discovery of bacteria on a Mars rock must have broken right about the time "Full House" rolled off the presses.

That was great, I loved that! My suspicion is that it's not true. It's probably inorganic. But the point is that it's a very well-written article, the authors are quite cautious, they give all the alternative interpretations. They were right to publish it. I wouldn't bet on it, but I wouldn't bet very strongly against it. And of course it's clearly very much in line with what I'm arguing.

Among non-scientists, I think there was a kind of disappointment: oh, it's just bacteria...

In a way it's the same error. Either you say it's bacterial and you say, so what? Or you say it's bacterial and you get thrilled because you think it means people tomorrow -- geologically tomorrow. That is, people will be thrilled by it, because they think bacteria means little green men, next day. It's as though there's three steps: non-life, bacterial life, and little green men! For me, and for most scientists, the difference between step one and step two is very small -- once you have the right conditions, you're going to get bacterial-grade life. But then the step to consciousness is very chancy and contingent and may never happen. But I think for most people the step between non-life and life isn't inevitable -- but once you get there, it will necessarily march on and up.

If you could persuade a whole group of people to absorb the implications of Darwin's ideas, would that affect their social and political views?

Oh I suppose. I don't think our immediate politics come out of our very broad philosophies. But our broad philosophies are not irrelevant. If everybody grew up with the "Full House" perspective, I think you would have a different attitude towards most other creatures. You wouldn't see yourself as sitting atop a pile, and having dominion, or ruling by right, or any of the Biblical metaphors that few of us take literally today, but that I think we still live by.

Creationism is still with us. Do you think it's a permanent feature of the landscape?

As long as there are millions of people who believe it and have lots of money. What's permanent, in geological terms? But as long as our society is organized this way, yeah, I think it is. Because it's not an intellectual issue. It's an interesting phenomenon of American socio-cultural history. As long as you have this enormous pluralism within Protestantism, as long as some of our traditional divisions like rich and poor, north and south, and rural and urban persist, you're going to get this hard-line fundamentalism. And it's never going to be majoritarian, though it might be locally, but it's gonna be at least locally potent.

How do you view the new science of modeling life processes like evolution on computers?

You're talking to a man who still writes on an upright typewriter. Artificial life I find interesting, I've read a little of the literature. But I don't know how much it's going to teach us about actual life. It does allow you to iterate a set of simple rules and see what happens. That's not how the world out there works, but that's an interesting thing to do. Natural selection in its pure algorithmic form doesn't happen out there either, but you can do it on the computer. I think it's a very valuable approach. It would be a danger only if people thought that's how the world worked.

You're known as a writer who can explain complex things to an intelligent lay audience. Do you ever find yourself worrying about oversimplifying things?

I don't do that. I think that's a real challenge -- the kind of thing Carl Sagan does in Parade. I sort of operate at one end of what's called popular science. Not because I don't appreciate the other end, I just wouldn't do it well, somehow. But the end I operate on really doesn't sacrifice any complexity -- except complexity of language, of course, complexity of jargon. But I like to think that my stuff is as conceptually complex as I would know how to write it for professional audiences.

And as I've always said, that is a tradition -- that is part of the humanistic tradition. That's what Galileo did when he wrote his two books as Italian dialogues and not as Latin treatises. That's what Darwin did when he wrote "The Origin of Species" for the general reader. I think a lot of people that pick up "The Origin of Species" see it's quite a charming book and assume it's a popular version of some technical treatise. There's no technical treatise -- that's it! That's what he wrote.

The Victorian era also had its tradition of the gentleman scientist.

Yes indeed, and it was gentlemen, and it was still a very small percentage of the population. You know, there's this myth of the golden age -- everybody wasn't educated, just a few percent of wealthy males, but they were the opinion makers. "The Origin of Species" was published in an edition of 1200, I think. It wasn't a large absolute number. And it was one of the great publishing sensations of the 19th century. But I think by the end of the century the last edition was only in its 40th thousand -- they used to list them by the thousand. You know, that's a good sale, but it wouldn't get you on the bestseller list today!

By Scott Rosenberg

Salon co-founder Scott Rosenberg is director of He is the author of "Say Everything" and Dreaming in Code and blogs at

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