Evolution-3: Natural selection and the age of the Earth


(See part 1 and part 2.)

It is clear that many people find it hard to accept Darwin’s theory of evolution by natural selection. One reason is of course because it completely undermines the need to believe in a creator, making god superfluous when it comes to explaining the nature and diversity of life, and thus people may have a negative emotional reaction that prevents them from seeing the power of the theory. As I have discussed earlier, people are quite able to develop quite sophisticated reasons to believe what they want and reject what they dislike.

Another reason that Darwin’s ideas were so hard to accept is because, as Daniel Dennett says in his book Darwin’s Dangerous Idea (1995), he turned the whole model of how things come to be on its head. Up until then, people had thought that to make anything always required a more complex thing. Simpler things never made more complex things. You did not find a horseshoe making a blacksmith, for example. But what Darwin was suggesting was that a very simple mechanism, natural selection, could result in simpler things becoming more complex without an external agent, but just from the ground up, as it were. What is worse was that, according to Darwin’s theory, intelligence, which had been thought as a precursor to creation and often used synonymously with god, turned out to be something that occurred much later in life’s evolution. In other words, intelligence itself came into being by a non-intelligent mechanism. These ideas made people who thought of human beings as possessing some special divine qualities uncomfortable, to put it mildly.

People find it hard to accept the fundamental idea of evolution that very small changes, if cumulative over very long times, can result in big changes. This should not be an entirely foreign concept, especially to those with savings accounts who are familiar with the way that interest grows when compounded. If you keep some money in a savings account at a rate even as low as 1%, it will double in 70 years, quadruple in 140 years, become eight times as much 210 years, and so on, becoming over a thousand times as large in 700 years, and over a million times as large in 7,000 years. But therein lies the difficulty. People do not fully appreciate the power of compounding because they tend not to be able to grasp time scales much longer than their own life spans.

The mathematics and statistics that are relevant to understanding how natural selection works does not come easily to people, partly because we do not have a firm intuitive grasp of geological time scales which are so large as to be almost impossible to comprehend. I once had a college first year student say that she did not think evolution could have happened. I asked her why and she said that when you saw the images drawn on ‘ancient’ Egyptian inscriptions, those people looked just like us today. So in her view, since there had been no visible evolutionary change over what to her was an enormous length of time, this disproved evolution!

It is not easy to grasp that even written language only goes back 5,000 years or so. When we factor in that the more appropriate unit of time for evolutionary change is the generation (which for humans is about 20 years), we see that written language emerged only 250 generations ago. It is hard for us to even imagine what life was like back then. Even the Vietnam war, which was just one generation ago, seems like ancient history to college students today, almost obscured by the murky mists of time.

So it is almost impossible to wrap our minds even around the fact that the common ancestor of humans and chimpanzees lived 300,000 generations or 6 million years ago, even though that itself is a blip compared to the origin of life itself (over 3 billion years ago) or age of the Earth (4.5 billion years ago). When we realize that the lifetime of a generation for many species is usually much less that 20 years, and is often measured in months and even days, the number of generations that have been available for evolutionary change to take place is staggeringly huge.

Although he could not quantify it at that time, Darwin knew that his theory of natural selection required very long time scales in order to be feasible. But he was born at a time when Biblical cosmology was dominant and the idea of an Earth that was less than 10,000 years old was widespread. This would not have been long enough for his ideas to work and it is unlikely that he would have hit upon his great discovery if not for having been born at a fortuitous time. In another example of how science is deeply interconnected in its theories, Darwin’s theory was made possible because of the work of his contemporary and later friend, geologist Charles Lyell and his theory of uniformitarianism.

Prior to Lyell, ideas in geology were strongly influenced by the book of Genesis and it was believed that the Earth had had a series of catastrophes (floods, volcanic eruptions, earthquakes, etc.) that had produced its major geologic features. The advantage of this theory of catastrophism was that it enabled people to believe that the Earth was quite young, since it made it plausible that major geological fractures like the Grand Canyon and Niagara Falls could come into being suddenly.

Lyell in his three volumes The Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth’s Surface, by Reference to Causes now in Operation (published over the years 1830-33) advanced evidence that the Earth had been around for a very long time and in particular, from his study of fossils, that human beings were much older than had been thought. Darwin read the first volume of this work on his life-changing trip on the Beagle (which lasted from 1831 to 1836) and it opened his eyes to a new way of seeing the diverse life forms in the exotic faraway places he visited. Lyell’s work not only gave Darwin the large window of time necessary to fit his own theory, it also was a precursor of Darwin’s central idea that very small changes, accumulated over very long times, could produce dramatic effects.

Although Lyell’s estimate of the age of the Earth was only about 250 million years, smaller in comparison to current estimates by a factor of almost twenty, this was still a huge increase from earlier ideas, and Darwin saw in it an opening that the Earth was possibly very old, old enough that made it possible for the evolution of life as he saw it to occur and it encouraged him in his work. But after Darwin published his landmark On the Origin of Species in 1859, the old Earth theory of Lyell received a major setback when in1864, one of the most eminent physicists of that time, William Thomson (later Lord Kelvin), said that his calculations of the rate of cooling of the Earth’s magma suggested that the Earth became a solid body between 20 and 400 million years, a disturbingly low lower limit. But it got worse, with later calculations reducing even the upper limit to much less than what Lyell had proposed, coming down to about just 10 million years. This was much less than what Darwin needed for his theory to work, and Thomson in 1868 explicitly challenged the validity of natural selection on these grounds. (David Quammen, The Reluctant Mr. Darwin (2006), p. 211.)

While this was undoubtedly a setback, Darwin doggedly persevered, accumulating more biological evidence for his theory, confident that future work in physics would vindicate him that the Earth was much older. But conclusive support on this question would only come after his death in 1882. Following the discovery of radioactivity, Rutherford and others in 1907 found evidence of rocks that were 1.6 billion years old. Further studies since then have increased the age to the current estimates of 4.5 billion years, more than enough for the theory of evolution to work.

Once again, we see how the interconnectedness of science can provide powerful constraints when it comes to constructing new theories, because theories in one area (such as biology) have to be consistent with theories in seemingly disparate areas (like physics and chemistry and geology). When creationists attack the theory of evolution and try to replace it with ad hoc theories of great floods, they are also severing ties with an entire network of scientific theories, and adding on yet more ad hoc hypotheses to fill in the obvious gaps does not help. When they reject a comprehensive theory like the theory of evolution by natural selection without replacing it with another one that is consistent with the findings of other scientific theories, they are pretty much rejecting the foundations of modern science.

As the philosopher of science Pierre Duhem wrote long ago in his book The Aim and Structure of Physical Theory (1906): “The only experimental check on a physical theory which is not illogical consists in comparing the entire system of the physical theory with the whole group of experimental laws, and in judging whether the latter is represented by the former in a satisfactory manner.” (emphasis in original)

POST SCRIPT: The Lion Sleeps Tonight

Hank Medress, vocalist of the group the Tokens, died last week at the age of 68. Here he is singing their big hit The Lion Sleeps Tonight.

Comments

  1. Ross says

    Interesting that Lyell’s work was anticipated by that of the 17th-century Danish scientist, Nicholas Steno, as described in the recent book, “The Seashell on the Mountaintop,” by Alan Cutler. Steno couldn’t accept the evidence he discovered, however, because of his devout religious beliefs, and unable to reconcile his scientific observations with the biblical view of creation, he essentially went mad and ended his days as a hermit. The evidence was there two centuries before Darwin and Lyell, but no one was ready for it.

  2. James Collins says

    Poor Mr. Lyell, It’s so sad that he never learned about the truth of so-called evolution.

    If only he had lived during a time when biology could be studied under a powerful microscope, and if he could have know the complexity of the cell and it’s DNA, he obviously would have come to his senses, and quickly rejected Darwin’s evolution.

    Many people, when they can’t provide evidence for their theory, adopt the strategy of falsehood. Such is the case with many of those who have fallen victim to the propaganda of renowned evolutionists.

    If evolutionists want to end the arguments all they have to do is, get their brilliant heads together and assemble a ‘simple’ living cell. This should be possible, since they certainly have a very great amount of knowledge about what is inside the ‘simple’ cell.
    After all, shouldn’t all the combined Intelligence of all the worlds scientist be able the do what chance encounters with random chemicals, without a set of instructions, accomplished about 4 billion years ago,according to the evolutionists, having no intelligence at all available to help them along in their quest to become a living entity. Surely then the evolutionists scientists today should be able to make us a ‘simple’ cell.
    If it weren’t so pitiful it would be humorous, that intelligent people have swallowed the evolution mythology.
    Beyond doubt, the main reason people believe in evolution is that sources they admire, say it is so. It would pay for these people to do a thorough examination of all the evidence CONTRARY to evolution that is readily available: Try answersingenesis.org. The evolutionists should honestly examine the SUPPOSED evidence ‘FOR’ evolution for THEMSELVES.
    Build us a cell, from scratch, with the required raw material, that is with NO cell material, just the ‘raw’ stuff, and the argument is over. But if the scientists are unsuccessful, perhaps they should try Mother Earth’s recipe, you know, the one they claim worked the first time about 4 billion years ago, so they say. All they need to do is to gather all the chemicals that we know are essential for life, pour them into a large clay pot and stir vigorously for a few billion years, and Walla, LIFE!
    Oh, you don’t believe the ‘original’ Mother Earth recipe will work? You are NOT alone, Neither do I, and MILLIONS of others!

  3. Thought Shaman says

    It appears that James Collins is working off a standard response and doesn’t bother to read any responses to his questions. Much of his post is the same as what it was a few days ago, to which I responded about advances in the biological field.

  4. says

    Yes, James seems to be spamming anyone mentioning evolution. I just did a google search on one of the sentences from his post and got 114 hits. I went to a few pages and it looks as though he sometimes modifies the intro paragraph, but otherwise it’s pretty much the same.

    It’s too bad he won’t bother to do a thorough examination of the evidence himself.

  5. says

    Heidi and Thought Shaman,

    I noticed that too. Heidi, do you think it is done manually on a case by case basis? That seems like an awful lot of work to no effect since no one will take seriously anyone who keeps repeating himself?

  6. says

    It’s probably automatede. I don’t know precisely how that works but he could have a program set up to post a certain chunk of text anywhere certain keywords are found. In spot checking my search results I saw that there were some differences in the intro paragraphs, so the program may choose version A, B or C based on the keyword combination.

    Then again I only found 114 posts, so he could have done that manually by just devoting a few hours per night. He obviously doesn’t need to read the entries to comment upon them. If he feels this strongly about it, that might seem worthwhile. But given that multiple posts are made to the same blog, it seems more machine-like.

    Either way, it hardly seems effective. How can he hope to convert us heathens if he won’t engage in dialogue?

  7. says

    Thank you for the link to my blog entry, Heidi; every time I see something by “James” it is a little different, so I think there’s a standard script that he copies/pastes and tweaks a bit here or there (in this case to mention Lyell).

    Anyway, I’ve been trying to read through the works of Hutton, William “Strata” Smith, Lyell, Steno, Buckland, etc. and it really is fascinating stuff. During much of Darwin’s life, studying nature was perfectly acceptable for a clergyman in training because it was supposed to reflect the works of god. Indeed, it was an interesting time in history when science and theology started to break away from each other, and lots of otherwise brilliant scientists bent over backwards to try and preserve the Bible while still telling of their discoveries (and just as a note to an above comment, Steno didn’t recant his thoughts on the age of the earth; he just became interested in religion instead, just as he had switched from anatomy to geology beforehand).

    Anyway, there is one book that is largely forgotten, but still available here and there; “Medals of Creation” by Gideon Mantell (the man who discovered/named the dinosaur Iguanodon). His view was that fossils were “medals” that god minted to mark each creation period, but as we now know his view never really caught on. Likewise, Gosse’s “Omphalos” is an interesting read if you can handle his purple prose; his view was the the world was created with the illusion of great age.

    I should probably stop before I turn this into a post in and of itself, but thanks again for the link and keep up the good work.

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