Charles Dickens (Charles Dickens) famous opening line of 1859 novel “This is the best time. This is the worst time” The story of two cities Refers to the period of the French Revolution. But he can equally well describe his contemporary Charles Darwin’s experience of natural selection evolution theory. Darwin was born at the best time in 1809, when conditions were very favorable for his theory to flourish, but he died at the worst time in 1882 because there was a real danger of being strangled soon. Darwin’s nemesis was the famous physicist Lord Kelvin, and the weapon used to deal with him was the age of the earth.
Various evolutionary theories predate Darwin, but no matter which version is preferred, one thing is clear: it takes a long time to produce results. Exactly how long is difficult to determine, but it is believed to take tens of millions of years or hundreds of millions of years.Since 1650, the main theories about the age of the earth are based on Bishop Arthur, Isaac Newton, and many other scholars use various text sources and believe that it is about 6000 years old.
Geological and biological theories must adapt to this short time frame.Geological theory is called Catastrophe theory Suppose that the main features such as the Grand Canyon and the Himalayas appeared due to sudden violent turbulence. When it comes to biodiversity, Special creation, The belief that organisms are immutable and specially designed to adapt to the biological niche in which they are located is the dominant idea.
Such a short time window makes it impossible for anyone to credibly propose the emergence of new species through the slow evolutionary process. But around 1785, as geologists and paleontologists began to use the characteristics of the earth itself (such as erosion, sedimentation, strata, and fossils embedded in it) to estimate the age of the earth began to change fundamentally. Its age.Theory of Uniformism, The main geological feature is caused by the very slow accumulation of small changes, progress has been made and finally reached its zenith in Charles Lyle’s epic three-volume work Principles of Geology In 1830, it consolidated the idea that the earth has existed for hundreds of millions of years or even longer, so that it seems impossible to determine the actual age.
Darwin was also an avid student of geology, was familiar with Lyle’s work (they later became close friends), and carried the first two volumes of his book with him during his five-year voyage around the world Beagles From 1831 to 1836, his theory of evolution sprouted while observing patterns of species wherever he went. Darwin learned from his research on pigeons that even deliberate breeding for specific characteristics takes a long time to produce them. But how long does it take? He felt that it would take at least hundreds of millions of years. The work of Lyle and other geologists allowed him to assume that there was enough time for the work of natural selection.
Darwin also matured when the idea of the immutability of species began to fall apart. Although Darwin accepted the teaching and acceptance of the still dominant special theory of creation, he was also familiar with the general idea of evolution.His grandfather Erasmus Darwin published a book in 1794 Zoonotic diseases Explore primitive evolutionary ideas. Jean Baptiste Lamarck published his own model of how evolution works in 1802.The various models proposed for evolutionary mechanisms, such as Lamarckian evolution, orthodontics, and use-abandonment, all suggest a certain degree of evolution Teleological, There is a Directionality Inherent in the process.
The new geology opened a very long window of time, allowing Darwin and his co-creator Alfred Russell Wallace to work independently and develop new core insights nature By showing how diversity is naturally produced through the process of Malthusian population selection pressure, without any mysterious mechanism leading the process to any specific goal, a selection different from other evolutionary models can be formed.
According to their theory, evolution is driven by chance, because how organisms evolve depends on the chance factors and the environment that existed at the time. If we time again, we will get completely different results from humans, because we know them, they may not appear. . Their work was first presented in a joint paper in 1858.Darwin’s main work Origin of Species A year later, a fiercely contested compilation was published, which brought together a large amount of evidence to help establish the theory of evolution as a fact.
The fundamental change in human status implied by their model, from being specifically created in the image of God to another accidental by-product of the evolutionary process, like all other species, is a direct source of controversy because it challenges a key religion. People are a special creed. This is why even when evolution is accepted, natural selection will cause such opposition.Many scientists at that time believed in religion and believed Theistic evolution In other words, a supernatural institution is directing this process to produce the desired result.
Although all evolutionary models take a long time, nature Selection takes longer than any time guide Selection process. Therefore, the younger the earth is, the more likely it is that natural selection is not a mechanism. It was a physicist led by the famous Kelvin, who himself was a theistic evolutionist who led the charge against the young earth, although it must be emphasized that “young” at the time meant about 100 million years or less. Even religious scientists at the time gave up the idea that the earth was only 6000 years old.
Starting around 1860, Kelvin and other physicists began to use the nebula hypothesis proposed by Emmanuel Kant and Pierre Laplace around 1750 to estimate the age of the earth and the sun. The model regards the earth and the sun as a cloud of rotating particles at the beginning, these particle clouds merge under the action of gravity to form a molten ball, and then the earth solidifies and cools. Kelvin uses the laws of thermodynamics and other physical principles to estimate 2 to 400 million years. By 1879, the upper limit of the earth had dropped to about 100 million years, while the upper limit of the sun was even shorter, at 20 million years, which is far lower than the 200 million years required for natural selection to function. Since physics was considered the most rigorous science at the time, the situation of natural selection looked terrible.
When Darwin died in 1882, he was mourned as a great scientist. He completely changed our understanding of how the great biodiversity we see around us was produced, and overturned the idea that they were unchangeable. However, due to the shrinking age of the earth, a large cloud was shrouded in the natural selection mechanism at the time of his death. Darwin’s last sentence on this topic written in 1880 two years before his death expressed a sad hope that future development might coordinate the needs of natural selection with the needs of physical computing.
“Regarding the passage of time since our planet was integrated into the assumed quantity of organic changes, it is not enough, and this objection, as [Lord Kelvin], May be the most serious one so far. I can only say that, first of all, we don’t know what the rate of species change in years is, and secondly, many philosophers are still unwilling to admit that we know enough about the constitution of the universe and the interior of our planet. Information to safely guess its past duration. “
Facts have proved that Darwin was foresight, and the improvement of the knowledge of the earth’s interior may change the calculations that benefit him, but he seemed to be grasping the straw at the time. In fact, in the recent past, the problem has become worse because Kelvin and others have made new calculations that have led to a further decrease in the age of the earth. Therefore, by 1895, the general physics view was that the age of the earth was within this range of 20-40 hundred. Ten thousand years. Natural selection seems doomed to failure.
But physicists are now encountering stronger opposition from other disciplines. Geologists insist that their model is based on accumulated evidence of deposition and erosion. Although not as rigorous as the physical model, it is perfect enough that they are confident of the 100 million-year lower limit. Paleontologists also believe that the fossil record is inconsistent with the shorter age of physicists. Both groups argued that the physicist must have made a mistake somewhere, even if they could not point out the specific flaw.
Starting in 1895, this deadlock began to be broken, when Kelvin’s former assistant physicist John Perry challenged the latter’s hypothesis that the earth is a rigid and uniform object, saying that there is little evidence to support it.By introducing inhomogeneity and convection in the interior of the earth, he discovered that Kelvin’s estimate of the age of the earth may change The coefficient is 100, Move the upper limit into Billions year. Other physicists have joined a similar upward shift, which encourages geologists, paleontologists, and biologists to ignore physicists’ arguments about a young earth.
The discovery of radioactivity changed this picture decisively because it led to a new method of measuring the age of the earth, allowing scientists to calculate the age of rocks.As the oldest rock that can be found is located Lower limit Regarding the age of the earth, the race to find older and older rocks using this method is underway, and the record is rapidly declining, resulting in an age of 141 million years by 1905, 1.64 billion years by 1911, and 1.9 billion years by 1935. , To 3.35 billion years to 1947, to 4.5 billion years in 1953, this is the current consensus.
Kelvin died in 1907 at the age of 83. It was not clear at the time whether he accepted his estimate and was no longer valid. But Darwin hoped that Kelvin would be proven wrong, and eventually proved that there was enough time for natural selection to work, which was realized 30 years after his death. His theory now has all the time it needs.
This is an opinion and analysis article; opinions expressed Author or author Not necessarily those Scientific american.