Most of us probably think that the history of life on earth is about simple beginnings and steady progress towards beauty and complexity. Bacteria appeared in some primordial ooze millions of years ago, and evolution slowly churned out better things like rhinoceroses, oak trees, and great white sharks. Stephen Jay Gould, a respected paleontologist and author of numerous books on natural history and evolution, disagrees.
On Tuesday, March 2, Professor Gould gave a lecture before a capacity crowd in Chapin Hall entitled “The Nature and Measure of Excellence: Why Progress Does Not Rule the History of Life and .400 Hitting Disappeared in Baseball.” The talk was the third in the ongoing “Necessity of Failure” lecture series.
In his characteristically animated and provocative style, Gould described what he considers a popular misconception about evolution: that nature has an unstoppable tendency of creating superior and intelligent creatures. To Gould, evolution has nothing to do with “progress” towards some ideal form or function. In fact, Gould said that if you reset the Earth’s clock to time zero, and allowed bacteria to diverge all over again, humans would almost certainly not be part of today’s diversity.
Gould opened the lecture by saying, “failure is not what we don’t know, or what we don’t have; it’s false ways of thinking that constrain our ideas.”
Sir Francis Bacon, the 16th-century English author and naturalist, classified these false ways of thinking, or “idols,” into four groups in his essay Novum Organum (The New Method). Gould focused on Bacon’s “Idols of the Tribe,” or the conceptual “locks” created by the peculiar way the human mind works. In Gould’s eyes, the human tendency to fit patterns to random things observed in nature is an example of an idol of the tribe. Looking into the night sky, our ancestors saw constellations, not clumps of stars.
The problem, Gould claims, is that humans do the same thing for the history of life: presented with fossils of ancient bacteria and modern day diversity, people like to believe that evolution is just one long, smooth pattern of increasing complexity.
Another human foible that Gould criticized is the tendency to see Homo sapiens as the be-all and end-all of the history of life. Gould pointed out that the geological revolution has revealed that humans have only been around for a tiny fraction of the grand scheme of the Earth’s history. To illustrate this humbling concept, Professor Gould referred to an analogy that John McPhee makes in Basin and Range. Namely, if the age of the universe is represented in terms of the old English yard, the distance from King Edward’s nose to his outstretched hand, then all of human history can be contained within a few of Edward’s finger nail filings.
According to popular advertising, said Gould, that is not our only misunderstanding of evolution. Gould showed a number of humorous slides of magazine ads that used the classic icon of evolution-the series of figures progressing from a hairy, stooped over ape to a robust, upright human male. The ape-to-human icon appears in everything from ads for swimwear to laptop computers.
One cartoon went a few steps further, showing the upright man progressively stooping over again into a couch potato watching football on television.
Gould noted that one of the most disturbing things about these ads is that the graphic designers inadvertently depict a lightening of skin color from ape to human. Even if this were unintended, Gould said it demonstrates one popular misconception about race and human biology-lighter skin is an evolutionary step closer to the ideal.
Racist undertones notwithstanding, Gould said the ape-to-human icon is immediately recognizable to the public because we tend to think in linear sequences. Gould said the problem with this way of thinking is that it biases the way people look at the history of life.
“Most people,” he said, “would look at the history of horses as a linear tale of progressive evolution triumphant.”
Starting out as a four-legged mammal the size of a fox terrier, the horse has grown to become the “Man-o-war thundering down the stretch.” But Gould sees horses as an outstanding example of evolutionary failure. The original diversity of small ancestral horses has been reduced to only a single lineage, represented by six species of horses, zebras, and old world asses.
Gould turned to a few less glorious species of mammals-rats, bats and antelopes-to find the real success stories of evolution. Gould asked the audience, “Have you ever seen a picture of the evolutionary success or triumph of these groups?”
A diagram of rodents would show an enormous bushing tree instead of a simple ladder of horses or humans beings.
“That’s life’s little joke,” said Gould. “When a lineage is so depleted that only one branch is left, we see it as the pathway of evolution triumphant.”
Before closing the chapter on horses, Gould returned to human history. Gould pointed out that the six human-like species that once coexisted in Africa have now all been reduced to a single lineage, Homo sapiens. Gould questioned whether human beings really are an example of evolution triumphant after all.
But if humans are the only lineage left, couldn’t you argue that evolution has “weeded out” all of the inferior ancestral hominids in its central drive towards complexity and progress? According to Dr. Gould: no, Homo sapiens got lucky in the random events of history.
To illustrate this, Gould described the standard statistical paradigm called “The Drunkard’s Walk.” Gould asked the audience to imagine a drunken person emerging from a bar and leaning up against a brick wall 30 feet away from a gutter. In his stupor, he stumbles randomly to the left and right across the sidewalk. Given enough time, the drunk inevitably ends up in the gutter even if he staggers equal amounts in either direction.
In the history of life, bacteria are the “brick wall” of lowest possible complexity, while human beings are the “gutter” or furthest distance from the wall. In this analogy, there is no trend that naturally leads to intelligent human beings; the drunkard doesn’t want to reach the gutter, but inevitably falls in because of the randomness of his walk.
Some people might find Gould’s argument a little depressing. Gould did not offer much consolation when, at one point, he lifted up a copy of the Bible to read a passage from Psalm Eight questioning the meaning of human life.
“When I consider Thy heaven, the work of Thy fingers, the moon and the stars, which Thou hast ordained, what is Man that Thou art mindful of?” read Gould.
The psalm’s answer is simply that humans are here and that God chose us as the masters of all the creatures of the Earth.
But Gould, who is normally outspokenly against creationism, only briefly lingered on the topic of religion. “It’s a wonderful institution, and I’m all for it even if it’s very different from science. . .it embodies all sorts of discourses on moral questions and questions of meaning,” said Gould.
At the end of the talk, he then returned to this by paraphrasing Charles Darwin. “The source to answers about questions of morality and meaning is not to be found in nature anyway. Nature’s not about us; we should be happy to be here,” said Gould.
David C. Smith, an ecologist and evolutionary biologist in the Biology department, noted that this statement was confusing in light of the entire lecture.
Said Smith, “It seems to me that the entire talk was stimulating because it was about us. In other words, what [Gould] was talking about was our place in this evolutionary construct and what this does to our image of ourselves. That’s the main reason Darwinian theory had a big impact on Western thought.”
Smith continued, “One way of looking at moral systems and religious views is that they are just part of [the human] phenotype, or the physical expression of our genes, like the color of our eyes and the shape our nose, this is the way our mind works. Many people would argue that anything that’s an expression of what we are pertains to evolutionary biology.”
Gould’s evolutionary arguments are far from settled among biologists and paleontologists, and the audience undoubtedly walked out of Chapin with differing opinions about the lecture. In spite of these mixed reactions, however, Gould has clearly invigorated the field of paleontology and stimulated discourse on the place of humans in the history of life.