It is now over one hundred and fifty years since Charles Darwin published “The Origin of Species.” Despite his own gripe that he wasn’t very capable as a writer, the work remains one of the outstanding achievements of science writing – lucid and accessible to scientist and general reader alike. Of course the book was far more than just a good read. It transformed biological science and evolutionary thinking, and it caused a furore in religious circles. However it was the accessibility of the volume that ensured it finding its way onto the shelves and reading lists, and from there into the dinner table and drawing room conversations. Darwin did not invent evolutionary theories (this could be ascribed to the Greeks), however he most certainly substantiated, elucidated and popularised them in a fashion hitherto unseen.
Darwin was fundamentally committed to the central pillar of “The Origin,” namely that life forms mutate over extended periods of time, for example in response to environmental changes. The reason he gave was “that the greatest amount of life can be supported by great diversification of structure”: evolution is driven by the will of all life forms to succeed and grow, despite the best efforts of both the physical world and indeed other life forms to deny them the opportunity. Despite this Darwin was the first to acknowledge that much remained obscure. “I am convinced,” he wrote, “That Natural Selection has been the main but not exclusive means of modification.”
In its time, Darwin’s principles were the subject of much debate between the establishment and the arriviste, the theologian and the scientist. The concept of plants improving over millions of years was generally perceived as acceptable; however “the monkey theory,” that man evolved from – ugh! – animals, proved difficult for many. Not so today, which sees even this previously unthinkable tenet being accepted as central to the street wisdom of the agnostic West. Without demanding an understanding of the arguments that support it, Natural Selection has been accepted on face value by the general population, discounting of course the religious groups that have stuck to their guns since the theory was first espoused.
In 1972, Niles Eldredge and Stephen Jay Gould were graduate students at the American Museum of Natural History in New York, and they were having problems. The trouble was that their chosen species – trilobites and land snails – were showing precious little evidence of any evolution at all, even through the thousands to millions of years’ worth of strata where the species were found. In attempting to resolve this issue, they developed a theory of their own. The pair decided that speciation theory, which had for a while been the subject of discussion in the biological community, was also appropriate for understanding fossil records. Speciation theory is based on the principle that new species are much more likely to develop within an isolated group than the main population, as any mutations have a much better chance of dominating a small population than a larger one. Eldredge and Gould applied this principle to their analysis of the fossil records and came up with “The theory of punctuated equilibrium.” The central principle is that evolution occurs, in the main, very slowly and progressively, with the occasional evolutionary leap caused by small groups of life forms which have somehow become separated from the main population. This theory conveniently fitted the issues that they raised with regard to the near-standstill slowness of ‘normal’ evolution, not to mention the absence of fossil evidence concerning ‘transitional’ lifeforms – neither one species than another. After all, if the subpopulation is so small, the statistical likelihood of discovering any fossils would be close to zero.
Exactly what the circumstances were that caused the sudden jumps in the fossil record, Gould and Eldredge did not know. It could be down to gradual, though relatively fast in geological terms, changes in landscape or weather. Alternatively the occasional cataclysmic event, such as the comet which is reputed to have wiped out the dinosaurs, could have led to the rapid evolutions of all life forms with survival permitted only to those which managed to equip themselves for the aftermath. Us lay people only have to look at the reputations of various closed communities for interbreeding, and their consequences, to see the potential for truth in the theory of punctuated equilibrium.
Eldredge and Gould published their findings in the book “Models in Paleobiology” and, in doing so, knocked the evolutionary establishment on its back. The theory was, to the pair, as much about the equilibrium (“Stasis is data,” wrote Gould) as it was about its punctuation. Despite this it didn’t go down at all wellwith the older folk of institutionalised Darwinism. “Evolution by Jerks,” or “Punk Eek” were terms characterising not only the concepts but also the hostility felt against the authors.
Interestingly, the progress of evolutionary theory has itself followed the patterns put forward by Gould and Eldredge. Both Darwin and the young turks of New York count as small groups working outside the confines of the mainstream. Both put forward theories that fundamentally changed the understanding of the time. Darwin, in particular, created the right to question what had gone before, however conservatism was quick to set in once again. Gould and Eldredge found themselves going up against the accepted beliefs and practices of the paeleontological, Darwinist establishment. It seems that the right to question accepted beliefs has often to be fought for, with the battles won and lost on grounds of human nature and not of science or fact.