Copyright 1996 Star Tribune
Star Tribune

October 6, 1996, Metro Edition

SECTION: News; Pg. 25A

LENGTH: 1714 words

HEADLINE: Variation on an evolutionary theme

BYLINE: Jim Dawson; Staff Writer

For most people, including scientists, evolution is a natural law that drives life from simple organisms to more complex life forms, topped off by humans. Wrong, says Harvard paleontologist Stephen Jay Gould. We got to where we are by chance. If the process were started over, the odds are very slim that humans would be here to worry about it.

Bow to the mighty bacteria, mourn the noble horse and, most of all, remember that baseball season back in 1941 when Ted Williams hit .406, for it probably won't happen again.

These items might seem to have nothing to do with each other, but in the mind of Harvard paleontologist Stephen Jay Gould, they are all examples of a reality that we fail to see, even though our very existence is evidence of that reality.

Welcome to another mind-altering book by Gould, a leading scholar on what Charles Darwin really meant with his theory of evolution in his 1859 book, "The Origin of Species." The world didn't respond well to Darwin's dethroning of humans as God's chosen species, but evolution has become the solid, well-supported underpinning of modern science.

Now, Gould reveals in his book " Full House" what he believes is a deeper truth about evolution, one that runs against the standard notion that evolution is progressive and steadily marches from simple life forms to more complex organisms like us.

The idea Gould presents is that in populations of people, bacteria or almost anything else, the constant attempt to find an "average" or "typical" individual is misguided.

Progress is not a trend

Reality is in the variation and the difference, Gould says, and inherent in this view is "the argument for denying that progress defines the history of life or even exists as a general trend at all. Within such a view of life-as-a-whole, humans can occupy no preferred status as a pinnacle or culmination."

This might all seem a bit distant from everyday life, but the implications affect not only the standing of human beings "at the top" of what many view as the ladder of life, but such lesser things as why nobody is likely to hit .400 again in baseball.

"Darwin's take on evolution holds that adaptation to the natural environment, not progress, was the mechanism," Gould said in an interview last week. "Yet, we assume that evolution must be progressive."

This view of evolution as progressive, constantly pushing life to a higher rung on the ladder, looks true at first glance. There were the bacteria, the jellyfish, the vertebrates and, finally, us, standing at the very top looking down on the rest.

"The bias of progress is so ingrained in us that it's hard to get around," Gould said. "People are not willing to challenge the notion of progress."

What this is, according to Gould, is a view of the world, when tied to the story of evolution, that is slanted to "validate traditional human arrogance."

"It's a very simple argument I'm making," Gould said.

The argument's roots reach back to 1982, when Gould, then 40, developed abdominal mesothelioma, an "invariably fatal" cancer. He, like any good professor, went to the Harvard medical library after recovering from the shock of the diagnosis and found what he calls the "brutal message: Mesothelioma was incurable with a median life expectancy of eight months following diagnosis.

Chance on the curve

Gould, with his statistical training and years of analyzing natural systems, was suspicious of the eight-month death sentence and realized there must be great variability hidden in the numbers. He drew up a classic bell curve, with the left half representing the cancer victims dying within eight months. Those who made up the right half of the curve stretched out far into its "tail," meaning they lived long past eight months.

"The variation was markedly right skewed, with a few people living a long time," he said. "I saw no reason why I shouldn't be able to reside among these inhabitants of the right tail."

Thanks to good fortune and an experimental treatment that worked, he is probably cancer-free today.

The experience got Gould thinking about variations in systems and whether an "average" number really represents reality.

So he turned to baseball, a system that has undergone fairly minor changes and has historical statistics on almost everything that can be measured.

His goal was to try to solve the mystery of why the .400 hitter has disappeared, and along the way see if it confirmed his growing suspicion that the standard view of evolution is wrong.

A durable average

He found a number of interesting facts about baseball, such as the overall batting average for the entire history of the game has not varied much from .260. More important, he found that as the overall skill of baseball players improved and as the entire game moved toward the limit of human performance, the variability in batting averages shrank.

Pitchers certainly were better, as were fielders. But so were batters, and as the overall league batting average wasn't changing much, the balance of the overall game seemed remarkable, Gould said.

So what happened to the .400 hitter?

The problem, Gould said, was that we think of .400 hitting as a "thing," an individual piece that is an indicator of a decline of great hitting. It is nothing of the sort, he contends. Such heroic hitting is simply one variable in a system made up of many variables, and as the system has stabilized with highly skilled players, the extremes in variation have predictably diminished.

"The best hitters of today can't be worse than .400 hitters of the past," he writes in his book. "But the average player has moved several feet closer to the right wall [representing the upper limit of human performance] and the distance between the ordinary and best has decreased, thereby erasing batting averages as high as .400. Ironically, therefore, the disappearance of .400 hitting marks the general improvement of play, not a decline in anything."

To further examine the role of variability in systems, Gould turned to the evolution of horses. Scientists have traditionally charted the evolution of horses over millions of years from very small, multitoed creatures to the big, modern, hoofed species.

The last of the horses

The true view, Gould says, is that the modern horse is the endpoint of an "unsuccessful lineage." It is not the triumphant ultimate achievement of horse evolution, but the last surviving "twig" on a many-branched evolutionary bush that once had many species filling the world. The horse is, in Gould's words, "a relic of former glory."

The evolution of horses was once a system filled with variation from big to little. The many species have all but died out, leaving just one major line to linger. Hardly, in Gould's view, the mark of a progressive system.

Finally, we come to bacteria, the simplest and most dominant life-form on the planet. They come in seemingly infinite varieties, and they have had billions of years to evolve. Yet, they remain as the simplest form of life, incredibly varied, but not climbing the ladder of evolution.

They mark what Gould calls the "left wall" in life - if an organism got much simpler, it wouldn't be life. So, through pure variation and randomness, the only thing allowed in the system is greater complexity, Gould says. The system isn't directed, or biased, in that direction, it just can't go the other way.

Random acts of progress

Yet, most of the simple creatures have stayed simple. The "vaunted progress of life is really random motion away from simple beginnings, not directed impetus toward inherently advantageous complexity," Gould writes.

The lesson that should be learned, he concludes, is we should "treasure variety for its own sake." After all, Gould points out, if we look at the world as it is, not as we want it to be, then we live and always have lived in the Age of Bacteria, not the Age of Man.

Stephen Jay Gould is a professor of zoology and a professor of geology at Harvard University, and the curator for invertebrate paleontology at the university's museum of Comparative Zoology. His new book " Full House, " one of more than 15 he has written, explores the idea that variability - not complexity - is the true measure of excellence, and that evolution is not progressive.

He is also a baseball fanatic.

How the .400 hitter became extinct

Early baseball players, as a group, were not as talented as their modern counterparts. Nor were they nearly as close to the limit of human performance, as represented by the dotted line in the bell-curve diagrams. Gould's detailed studies of baseball statistics indicate that as the overall quality of players has improved, raising the height of the curve. But the extremes of batting averages - the left and right "tails" on the curve - have narrowed. There are still great hitters in baseball, perhaps better than the .400 hitters of the past. But there is less difference between the "ordinary" and the "best" players reducing extremes in variability and making it almost impossible to hit .400. Gould also points out that in 100 years, baseball has been a remarkably balanced system. The mean batting average of players at bat at least twice a game has always been very close to .260.

The nature of major league batting

As baseball batters developed increasingly higher skills during the first 100 years of professional baseball, the variations in batting averages declined in a regular fashion, as is shown by the chart atright. The pattern shows "regularity with a vengeance," said scientist and author Stephen Jay Gould, and is like a law of nature governing America's pastime. It also explains why batting .400 has become extinct in modern baseball. The numbers along the bottom axis reflect standard deviation and not specific batting averages. Each dot represents the variation in the overall batting average for that year. The higher the number, the greater the variation for that year.

Chart adapted from " Full House" by Stephen Jay Gould