Charles Dickens (Charles Dickens)’s famous opening line of 1859 novel “This is the best time and the worst time” A Tale 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 in the best time of 1809, when conditions were very favorable for his theory to flourish, but he died in 1882 at the worst time because there was a real danger of being stifled soon. Darwin’s nemesis is the famous physicist Lord Kelvin, and the weapon against him is 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 ArthurUsing various text sources, Isaac Newton and many other scholars believe that it is about 6,000 years old.
Geological and biological theories must adapt to this short time frame.A geological theory called catastrophe Suppose that the main features such as the Grand Canyon and the Himalayas appeared due to sudden violent turbulence. When it comes to biodiversity, the idea of special creation is the popular view that organisms are immutable and are specifically designed to adapt to the biological niche in which they are located.
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 and strata, and fossils embedded in it) to estimate the age of the earth, the perception of the age of the earth began to develop fundamentally. The change. age.Uniformitarianism, that is, the main geological features are caused by the very slow accumulation of small changes. This theory was developed and eventually formed Charles Lyle’s three-volume epic poem 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 when he took the HMS on a five-year global voyage. Beagles Between 1831 and 1836, his theory of evolution sprouted when he observed the patterns of species in different locations. 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, in situ occurrence, and use-abandonment, all imply a certain degree of teleology: the existence of inherent directionality is in progress.
The new geology opened an extremely long window of time, allowing Darwin and his co-creator Alfred Russell Wallace to work independently to develop new insights at the core of 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.
Their theory believes that evolution is driven by chance, because how organisms evolve depends on accidental factors and changing environments, which suggests that if we time again, we may get completely different results that humans may never have. Their work was first presented in a joint paper in 1858.Darwin’s main work Regarding the origin of species, Published a year later is a compilation of fierce controversy over a large amount of evidence that helps to 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. The creed believes that human beings are special. This is why even when evolution is accepted, natural selection will cause such opposition. Many scientists at that time were devout and believed in theistic theory of evolution, that is, there was a supernatural force guiding this process to produce the desired result.
Although all evolutionary models take a long time, nature Selection takes longer than any guide Selection process. Therefore, the younger the earth is, the more likely it is that natural selection is not a mechanism. The physicist led by the famous Kelvin himself was a theistic evolutionist and the leader of the young earth, although it must be emphasized that at the time “young” meant about 100 million years or less. Even religious scientists have abandoned the idea that the earth is only 6000 years old.
Starting around 1860, Kelvin and other physicists began to use the nebula hypothesis proposed by Emmanuel Kant and Pierre-Simon 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 is considered the most rigorous science, the situation of natural selection looks 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 final words on this topic, written in 1880 two years before his death, expressed a sad hope that future developments might reconcile the demands of natural selection and physical calculations:
“Regarding the amount of organic change since our planet was integrated to make assumptions, the passage of time is not enough, and as [Lord Kelvin], May be the most serious one so far. I can only say that first of all, we don’t know the rate of species change in years. Second, 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 has the foresight, and the improvement of the knowledge of the earth’s interior may change the calculations that benefit him, but at the time he seemed to be grasping the straw. In fact, in the near future, the problem has become worse because Kelvin and others have made new calculations that have caused the earth’s age to decrease even more. Therefore, by 1895, the general physics view was that the earth’s age was between 20-4000. 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 gone wrong 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 into the interior of the earth, he discovered that Kelvin’s estimate of the age of the earth can be changed by as much as 100 times, turning 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 the situation decisively. It enables scientists to calculate the age of rocks, thus opening up a whole new way of measuring the age of the earth. Since the oldest rocks that can be found set a lower limit for the age of the earth, people began to use this method to find older and older rocks. The rapid decline in records resulted in an age of 141 million years in 1905, 1.64 billion years in 1911, 1.9 billion years in 1935, 3.35 billion years in 1947, and 4.5 billion years in 1953. This is the current Where the consensus lies.
When Kelvin died in 1907 at the age of 83, it was unclear whether he accepted that his estimate was no longer valid. But Darwin hoped that Kelvin would be proved wrong, and eventually proved that there was enough time for natural selection to work, which was realized 30 years after Darwin’s 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.