Having banished a C-Span crew who were busily setting up under the misapprehension that they would be allowed to record the proceedings, Stephen Jay Gould trudged to the podium of the Natural History Museum’s Geological Lecture Hall carrying a heavily laden canvas tote bag. The tote contained his latest book, “The Structure of Evolutionary Theory,” plus several of his earlier volumes.
Gould, the Alexander Agassiz Professor of Zoology, spoke March 23 about the central thesis of his book, then signed copies at a reception afterward. Gould said that he has been working on the 1,433-page opus for more than 20 years and that when he was diagnosed with cancer in 1982, he believed that he had “almost zero chance of finishing it.”
But finish it he did, not in time for the millennium as he had hoped, but in time for his mentor, the 97-year-old Ernst Mayr, Gould’s predecessor as Agassiz Professor of Zoology, to see it in print.
“It’s my greatest joy that I’ve finished this while Ernst is still with us. We’ve been talking about it for a long time.”
Mayr was the first of two people Gould thanked in his opening remarks, risking comparison with an Academy Award acceptance speech, “which,” he said, “I loathe.”
The second was his assistant Agnes Pilot, who, Gould said, has typed every word he has ever written and put off retirement until she finished the book.
“I don’t usually do this Agnes, but for you and only for you,” Gould said as he handed Pilot a signed copy of the book.
Gould went on to summarize the massive book’s thesis in a couple of short sentences.
“Is the pure form of Darwinian logic adequate to account for everything? My argument is that it is not,” he said.
One of the ways Gould departs from strict Darwinism is through his theory of “punctuated equilibrium,” the notion that organisms evolve in sudden jumps followed by long periods when little or no change takes place. This idea contradicts orthodox Darwinism, which posits slow, uniform change over long periods of time, brought about exclusively through the mechanism of natural selection.
Gould also diverges from Darwin in his notion that natural selection can work on the level of species, not just individuals. Darwin, he explained, insisted that natural selection only affected individual organisms because he was trying to overthrow the theological argument of intelligent design, the idea that the intricate adaptation of life forms to their environment implied the existence of a Creator.
Darwin’s model of how natural selection worked, Gould said, was influenced by the theories of Adam Smith, the 18th century economist who introduced the metaphor of the “Invisible Hand,” the mechanism that brings about equilibrium in the economy through the unregulated struggles of individuals to maximize their gains.
In a similar fashion, individual organisms, engaging in the struggle for existence, live longer and reproduce more successfully when they possess characteristics that help them to better exploit the environment. Thus, organisms with these successful characteristics tend to predominate in the population.
According to Gould, however, species can be regarded as individuals under certain circumstances, because, like individuals, they are born, persist over time, give birth to progeny (subspecies), and die (become extinct).
Gould also calls into question the adequacy of Darwin’s theory to explain the observed data. While orthodox Darwinists believe that natural selection, operating slowly and steadily over time, can account for all the variations in living organisms from the earliest fossil records to the present, Gould denies that this is the case.
“In the last 20 years, the bottom has fallen out of this idea,” he said.
The most dramatic piece of evidence suggesting that other forces contribute to evolutionary change is the discovery that the extinction of the dinosaurs was caused by a giant meteor striking the Earth, resulting in global dust clouds that interrupted environmental cycles and caused many life forms to die out, Gould said.
“If it weren’t for that event, the dinosaurs would still be in charge.”