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Here’s a question for neo-Darwinists: “If someone could prove to you that the Earth was ten or even one hundred times younger than the currently accepted figure of 4.54 billion years, would you give up your belief in evolution by natural selection? Or putting it another way, what’s the youngest age that you, as a Darwinian evolutionist, would accept for the age of the Earth? How low would you go?”
In my previous post, A hypothetical question for neo-Darwinists, on the age of the earth, I challenged neo-Darwinian evolutionists to provide an estimate (to the nearest order of magnitude) of how much time it should take for evolution by natural selection to generate complex life-forms like ourselves from the earliest life-forms. Not surprisingly, no Darwinist was brave enough to submit an estimate.
But let that pass. The question I have posed in today’s post is one that any Darwinist should be able to answer. No mathematical calculations are required; all I am asking evolutionists is what they would be prepared to believe. Here’s my challenge: think of a number that represents the minimum amount of time (in years) in which you’d be prepared to accept that life could have evolved from the earliest living thing to complex animals, including ourselves. Write that number down, and please, don’t read any further until you have done so.
The diversity of estimates for the age of the Earth in the 1920s
Now, I’d like readers to have a look at the following passage, from Chapter 2, section 2 of H. G. Wells’ Outline of History (Macmillan, New York, 1921; first edition, 1920). I should point out that Wells was a trained biologist and an ardent supporter of Darwinism, and that he claimed to have had a great deal of assistance from scientists, historians and other specialists in writing his Outline of History (not to mention his liberal use of a manuscript written in 1919 by a Canadian author named Florence Deeks):
Speculations about geological time vary enormously. Estimates of the age of the oldest rocks by geologists and astronomers starting from different standpoints have varied between 1,600,000,000, and 25,000,000. That the period of time has been vast, that it is to be counted by scores and possibly by hundreds of millions of years, is the utmost that can be said with certainty in the matter. It is, quite open to the reader to divide every number in the appended time diagram by ten or multiply it by two; no one can gainsay him. (1921, p. 10)
On page 11, Wells provides two time-scales: one based on a high estimate of 800 million years for the age of the Earth, with life originating 600 million years ago, and the Cenozoic era, or “age of the mammals,” some 40 million years ago, and the other based on a low estimate of 80 million years with life originating 60 million years ago, and with the age of the mammals commencing just 4 million years ago. Think about that: just 60 million years to get “from goo to you,” and a mere 4 million years to get “from shrew to you.” (Although the first mammals appeared in the late Triassic, modern placental mammals are currently believed to have evolved from shrew-like creatures which appeared shortly after the extinction of the dinosaurs, which marks the beginning of the Cenozoic era.) However, if Wells had drawn a time-scale for a 25,000,000-year chronology, which, in his own words, “no one can gainsay” – at least, not in 1921, when he wrote his book – then life would have evolved over a period of less than 20 million years, and the “age of the mammals” would have commenced a mere 1.25 million years ago. I hope my readers will agree that even in Darwin’s day, the absurdity of supposing that evolution could have taken place over such a short timescale would have been readily apparent.
Bear in mind, please, that there is a 64-fold disparity between the highest and the lowest estimates of the age of the Earth, as quoted by H. G. Wells. And bear in mind also that the Scopes trial was held in 1925, just a few years after the publication of Well’s Outline of History.
The scientific consensus regarding the age of the Earth in the nineteenth century
In my previous post, I narrated the story of how William Thomson, the most highly esteemed physicist of his day, who was later made Lord Kelvin, estimated the age of the Earth at 100 million years or so – a number that caused Darwin and his disciples to suffer a great deal of discomfiture, as they realized that there was no way to fit the entire course of life’s evolution into such a short period. Luckily for them, they were subsequently given some extra breathing space by geologists. Wikipedia takes up the story in its article on the age of the earth. To begin with, it describes how well-supported Lord Kelvin’s estimate was, in the nineteenth century. Indeed, Darwin’s own son, the astronomer George H. Darwin, came up with estimates which supported Kelvin’s figure:
In 1862, the physicist William Thomson published calculations that fixed the age of Earth at between 20 million and 400 million years. He assumed that Earth had formed as a completely molten object, and determined the amount of time it would take for the near-surface to cool to its present temperature. His calculations did not account for heat produced via radioactive decay (a process then unknown to science) or convection inside the Earth, which allows more heat to escape from the interior to warm rocks near the surface…
The physicist Hermann von Helmholtz (in 1856) and astronomer Simon Newcomb (in 1892) contributed their own calculations of 22 and 18 million years respectively to the debate: they independently calculated the amount of time it would take for the Sun to condense down to its current diameter and brightness from the nebula of gas and dust from which it was born. Their values were consistent with Thomson’s calculations. However, they assumed that the Sun was only glowing from the heat of its gravitational contraction. The process of solar nuclear fusion was not yet known to science.
Other scientists backed up Thomson’s figures as well. Charles Darwin’s son, the astronomer George H. Darwin, proposed that Earth and Moon had broken apart in their early days when they were both molten. He calculated the amount of time it would have taken for tidal friction to give Earth its current 24-hour day. His value of 56 million years added additional evidence that Thomson was on the right track.
The last estimate Thomson gave, in 1897, was: “that it was more than 20 and less than 40 million years old, and probably much nearer 20 than 40”.
Radioactivity to the rescue?
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The lead isotope isochron that Clair Patterson used to determine the age of the solar system and Earth (Patterson, C., 1956, Age of meteorites and the earth, Geochimica et Cosmochimica Acta 10: 230-237). Image courtesy of jmpalin and Wikipedia.
The discovery of radioactivity overturned these estimates, but it took a few decades for the science of radiometric dating to become established and to win scientific acceptance, thanks in no small measure to the indefatigable efforts of the geologist Arthur Holmes (pictured at top, courtesy of Wikipedia):
In 1896, A. Henri Becquerel discovered radioactivity. In 1898, Marie and Pierre Curie discovered the radioactive elements polonium and radium. In 1903 Pierre Curie and his associate Albert Laborde announced that radium produces enough heat to melt its own weight in ice in less than an hour.
Geologists quickly realized that the discovery of radioactivity upset the assumptions on which most calculations of the age of Earth were based. These calculations assumed that Earth and Sun had formed at some time in the past and had been steadily cooling since that time. Radioactivity provided a process that generated heat. George Darwin and John Joly were the first to point this out, also in 1903…
The pioneers of radioactivity were chemist Bertram B. Boltwood and the energetic [Ernest] Rutherford… Boltwood did the legwork, and by the end of 1905 had provided dates for 26 separate rock samples, ranging from 92 to 570 million years. He did not publish these results, which was fortunate because they were flawed by measurement errors and poor estimates of the half-life of radium. Boltwood refined his work and finally published the results in 1907… His studies were flawed by the fact that the decay series of thorium was not understood, which led to incorrect results for samples that contained both uranium and thorium…
Although Boltwood published his paper in a prominent geological journal, the geological community had little interest in radioactivity. Boltwood gave up work on radiometric dating and went on to investigate other decay series. Rutherford remained mildly curious about the issue of the age of Earth but did little work on it.
Robert Strutt tinkered with Rutherford’s helium method until 1910 and then ceased. However, Strutt’s student Arthur Holmes became interested in radiometric dating and continued to work on it after everyone else had given up. Holmes focused on lead dating, because he regarded the helium method as unpromising. He performed measurements on rock samples and concluded in 1911 that the oldest (a sample from Ceylon) was about 1.6 billion years old. These calculations were not particularly trustworthy. For example, he assumed that the samples had contained only uranium and no lead when they were formed.
More important research was published in 1913. It showed that elements generally exist in multiple variants with different masses, or “isotopes”. In the 1930s, isotopes would be shown to have nuclei with differing numbers of the neutral particles known as “neutrons”. In that same year, other research was published establishing the rules for radioactive decay, allowing more precise identification of decay series.
Many geologists felt these new discoveries made radiometric dating so complicated as to be worthless. Holmes felt that they gave him tools to improve his techniques, and he plodded ahead with his research, publishing before and after the First World War. His work was generally ignored until the 1920s…
Holmes’s persistence finally began to pay off in 1921, when the speakers at the yearly meeting of the British Association for the Advancement of Science came to a rough consensus that Earth was a few billion years old, and that radiometric dating was credible. Holmes published The Age of the Earth, an Introduction to Geological Ideas in 1927 in which he presented a range of 1.6 to 3.0 billion years. No great push to embrace radiometric dating followed, however, and the die-hards in the geological community stubbornly resisted. They had never cared for attempts by physicists to intrude in their domain, and had successfully ignored them so far. The growing weight of evidence finally tilted the balance in 1931, when the National Research Council of the US National Academy of Sciences decided to resolve the question of the age of Earth by appointing a committee to investigate. Holmes, being one of the few people on Earth who was trained in radiometric dating techniques, was a committee member, and in fact wrote most of the final report.
The report concluded that radioactive dating was the only reliable means of pinning down geological time scales. Questions of bias were deflected by the great and exacting detail of the report. It described the methods used, the care with which measurements were made, and their error bars and limitations…
An age of 4.55 ± 0.07 billion years, very close to today’s accepted age, was determined by C.C. Patterson using uranium-lead isotope dating (specifically lead-lead dating) on several meteorites including the Canyon Diablo meteorite and published in 1956.
To sum up: the scientific consensus regarding the reliability of radiometric dating is barely eighty years old. Neo-Darwinian evolutionists would presumably concede that their theory requires billions of years for it to work. By their own admission, then, there must have been reasonable doubt about the validity of Darwin’s theory of evolution – or, indeed, any other theory which postulated that life had evolved as a result of an unguided process – until as recently as eighty years ago.
Feet to the fire: five questions for neo-Darwinists
I’d like to finish off with five challenging questions for neo-Darwinian evolutionists, and I’d like some honest answers, please:
(1) In view of the fact that the best science of the day supported an estimate of the age of the Earth of no more than 100 million years, which was far too short a time-frame for Darwinian evolution to generate complex animals from the first living cell, will you concede that until 1903 (when geologists realized that these scientific estimates were flawed), Darwin’s theory of evolution could at best have been regarded as a highly speculative hypothesis, which a prudent scientist would have probably rejected?
(2) In view of the fact that radiometric dating did not win general scientific acceptance until 1931, will you also concede that between 1903 and 1931, a prudent scientist would have been perfectly justified in withholding his or her assent to Darwin’s theory of evolution, and in continuing to entertain the hypothesis that (at least some) life-forms had been designed by an intelligent being?
(3) In view of the fact that the Scopes trial was held in 1925, will you concede that the reporters at the 1925 Scopes trial, most of whom displayed a consistent bias against fundamentalism in their news stories, were guilty of a rush to judgement in their public endorsement of evolution?
(4) In view of the fact that Professor Gregory Chaitin, a world-famous mathematician and computer scientist, conceded in his talk, Life as Evolving Software, given on 2 May 2011, that according to current toy models of Darwinian evolution, the evolution of complex life-forms from the simplest living cell should take not billions of years but quintillions of years (as I described in my previous post and at greater length in my earlier post, At last, a Darwinist mathematician tells the truth about evolution, will you concede that it is reasonable for modern-day Intelligent Design theorists to doubt the Darwinian theory of evolution and to entertain the hypothesis that life was designed by an intelligent being?
(5) In view of the fact that the world-renowned evolutionary biologist, Dr. Eugene Koonin, has estimated in his peer-reviewed paper, The Cosmological Model of Eternal Inflation and the Transition from Chance to Biological Evolution in the History of Life, (Biology Direct 2 (2007): 15, doi:10.1186/1745-6150-2-15) that the probability of even a simple life-form evolving in a region the size of the observable universe, within the time available, is less than 10-1,018, in 1 in 1 followed by 1,018 zeroes, and in view of the fact that the multiverse is a highly speculative hypothesis for which no experimental evidence exists, will you concede that the Darwinian theory of evolution must also revert to the status of a highly speculative hypothesis, until solid scientific evidence of the existence of the multiverse is forthcoming?
That concludes my questions for today.