Why don’t any animals move around on wheels? Are zebras white with black stripes, or black with white stripes? With questions such as these, palaeontologist, evolutionary biologist and scientific disseminator Stephen Jay Gould (September 10, 1941- May 20, 2002) would rouse his colleagues and his readers, then go on to explain some of the more complex ideas of evolution. Like Charles Darwin, Gould devoted himself to understanding all aspects of nature and uncovering enigmas that had tormented his peers since the English naturalist published “The Origin of Species” in 1859. He completed Darwin’s theories with new hypotheses, began three scientific debates that led his colleagues to rethink the ideas of the father of evolution and would become the greatest palaeontologist of the twentieth century.
In the 1970s, during his Ph.D. at Columbia University, Gould and Niles Eldredge were analysing fossils to understand how evolution works, when they both came up against a seemingly irresolvable problem. They did not find gradual changes in species, as predicted by Darwin. According to his theory, organisms of the same species compete with each other and the best adapted to the environment survives and passes its characteristics along to its descendants. In this way, slowly and gradually, changes take place in future generations. Gould and Eldredge found long periods of almost complete stability, unchanged, eventually interrupted by outbreaks of new species that appeared suddenly.
Darwin had already faced the same problem more than a century before, but had argued that the lack of fossils was due to the difficulty of finding them. Gould and Eldredge came to another conclusion and published in 1972 the theory of punctuated equilibrium, which proposed that species take evolutionary leaps and change fundamentally from one moment to the next, after remaining stable for a long time. Thanks to the controversial thesis, Gould earned criticism from such great scientists as evolutionary biologists John Maynard Smith and Richard Dawkins.
But criticism did not intimidate him, and six years later, as a Harvard professor, Gould again shook the foundations of evolution by arguing, together with Richard Lewontin, that the characteristics of some organisms are simply a consequence of the way in which they evolved and not necessarily the result of natural selection, as Orthodox Darwinists believe. In other words, not all the characteristics of living beings represent an evolutionary advantage, but are simply collateral effects of evolution. An example is human reasoning—the ability to solve problems did not interest early hominids, but rather it was the ability to organize themselves for hunting, the notion of space, or skills with tools that they needed. Gould argued that the mechanisms of evolution gave humans that apparently banal ability that, as a bonus, has endowed us with the ability to read, build houses and have a social and spiritual life.
The importance of chance
The idea of forces that, beyond natural selection, moved the evolution of living beings was not well accepted either, but Gould still had another controversial hypothesis. In the book “The Wonderful Life,” published in 1979, the palaeontologist suggests that another very powerful force acts in the evolution of species—chance. He tells the story of a 500-million-year-old fossil from a prehistoric fish-like animal and mentions that if that animal had become extinct sooner than it did, human beings might not exist.
Gould argues that if natural catastrophes occur randomly, a small asteroid that falls at a key moment of evolution has the power to change everything that comes later. According to this theory, evolution is not intentional; it has neither ends nor a general direction towards the most complex, and does not grant a privileged position to the human species.
He used metaphors to elucidate the randomness of events related to speciation. For example, he described evolution as being like a movie that, every time it was restarted, would have a different ending. Thanks to that bold but simple language, he captivated his readers and became one of the greatest scientific disseminators of all time. In one of his last essays, “The Median Isn’t the Message”¸ he used his own illness, an abdominal tumour he suffered from for years, to explain statistics and how it helped him to believe that he could survive longer than the eight months that were assigned him by the doctors. His hypothesis was successful and he was able to fight on for 20 more years with the illness, until in 2002 Stephen Jay Gould passed away at home from a different illness, surrounded by his fossils and his books.