Thursday, August 9, 2007

Charles Darwin (1809-1882)

Sierra Club


It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change.


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Charles Robert Darwin (February 12, 1809 - April 19, 1882), British Naturalist. Charles Darwin developed the first theory of a naturalistic mechanism for evolution, that of natural selection, it explains the diversification of life through a lengthy process of change by adaptation. He was born in Shrewsbury, England, the fifth of six children of Robert and Susannah Darwin (nee Wedgwood), and the grandson of Erasmus Darwin, and of Josiah Wedgwood. After finishing school, Darwin studied medicine in Edinburgh in 1825. His dislike for dissection and the brutality of surgery at the time led him to leave the medical school in 1827. Whilst there, however, he was influenced by the Lamarckian Robert Edmund Grant. His father, concerned by his son's apparent academic failure, and fearing that he would become a "ne'er do well", enrolled him at Cambridge to read Theology, with the hopes of Charles eventually becoming a parson. While at Cambridge, he came under the intellectual influence of scientific minds such as William Whewell and John Stevens Henslow which (combined with his interest in collecting beetles, which was encouraged by his cousin, William Darwin Fox) resulted in him pursuing natural history. Darwin planned to visit Madeira with some class-mates upon graduation in 1831. These plans, however, fell through and after Darwin finished his studies, Henslow recommended him for the position of gentleman's companion to Robert Fitzroy, the captain of HMS Beagle, which was departing on a five-year expedition to chart the coastline of South America. Prior to departure, Darwin spent a few weeks with the geologist Adam Sedgwick mapping strata in Wales. It must be noted that (aside from a few lectures that he endured in Edinburgh) this was Darwin's sole exposure to formal geological study.

Darwin's work during the expedition allowed him to study both the geological properties of continents and isles and a multitude of living organisms and fossils. During his voyage, he visited the Cape Verde Archipelago, the Falkland Islands, the South American coast, the Galapagos Islands and Australia, collecting considerable quantities of specimens. After returning from the voyage in 1836, Darwin analyzed the specimens he collected, and noticed similarities between fossils and living species within the same geographic area. In particular, he noticed that every island had its own kind of tortoises and birds that were all slightly different in appearance, favored food etc., but otherwise quite similar. This observation was especially apparent among the specimens collected on the Galapagos Islands. He developed the theory that, for example, all the different turtles had originated from a single turtle species, and had adopted to life on the different islands in different ways.

Based on these thoughts, he formulated his thoughts about the changes and developments of species in his Notebook on the Transmutation of Species, which was in accordance with Lyell's Principles of Geology and Thomas Malthus' Essay on the Principle of Population, which stated that the size of a population is limited by the food resources available. In 1842, Darwin formulated a short "Pencil Sketch" of his theory and by 1844 had written a 240 page "Essay" which provides an expanded version of his early ideas on natural selection. Between 1844 and 1858, when he would prevent his theory to the Linnean Society of London, Darwin would modify his theory in a number of ways. Darwin married his cousin Emma Wedgwood in 1839. After living for a number of years in London, the couple eventually moved to Downe House, in Downe, Kent (which is now open to public visits, south of Orpington). Darwin and his wife had ten children, three of whom died early. Between 1839 and 1843, Darwin's Zoology of the Voyage of H.M.S. Beagle was published in five volumes. On July 1, 1858, Darwin's paper about The Origin of Species by Means of Natural Selection was read to the Linnean Society in London, on the same day as a paper from Alfred Russel Wallace, who had developed a similar theory independently.

Darwin's book On the Origin of Species by Means of Natural Selection was published one year later, and was of sufficient interest to have the publisher's stocks completely sold to bookstores on the first day. In his later books The Variation of Animals and Plants Under Domestication (1868), The Descent of Man, and Selection in Relation to Sex (1871) and The Expression of Emotions in Animals and Man (1872), Darwin expanded on many topics introduced in Origin of Species.

In spite of some criticism, the value of Darwin's work was appreciated throughout the scientific community. He became a member of the Royal Society of London in 1839 and of the French Academy of Science (l'Académie des Sciences) in 1878. Darwin died in Downe, Kent, England, on April 19, 1882 and was buried in Westminster Abbey. Darwin was given particular recognition in 2000 when his image appeared on the Bank of England ten pound note, replacing Charles Dickens. Reportedly his impressive and supposedly hard to forge beard was a contributing factor in this choice.

Before Darwin

Before the nineteenth century, the accepted theory for the extinction of species was called Catastrophism, which stated that species went extinct due to catastrophes that were often followed by the formation of new species ex nihilo (out of nothing). The extinct species can then be found as fossils. The new species were considered unchangeable. This theory was in accordance with the story of the Flood in the Bible. In the early nineteenth century, several new theories started to compete with Catastrophism. One of the most important ones was developed by Jean-Baptiste Lamarck (1744-1829). He observed that every new generation inherits the traits of its ancestors. He suggested that traits or organs become enhanced with repeated use and weakened or removed by disuse in each individual, who will pass these improvements or losses directly to their offspring. In 1830, the British geologist Sir Charles Lyell disproved the Catastrophism Theory, but held on to the theory of species staying unchanged during time. Lyell founded uniformitarianism, a theory stating that the surface of earth changed slowly through eons by constant forces.

The Structure of Darwin's Theory

Darwin's theory of evolution states that all individuals of a population are different from each other. Some of them are adapted better for their actual environment than the others and have therefore better chances to survive and procreate. That way, their genetic properties are given to the following generations, becoming dominant among the population throughout time (Fig. 2). This gradual and continuous process results in the evolution of species. The four key points of his theory were : Evolution does occur; Evolutionary change is usually gradual, requiring thousands to millions of years; The primary mechanism for evolution is natural selection; All species alive today originated from a single life form through a branching process called specialization.

The Response to Darwin's Theory

After the publication of Darwin's book, evolution as the means of natural selection was widely discussed, particularly by the religious and the scientific communities. Though Darwin was supported by some scientists (e.g., T.H. Huxley), others hesitated to accept the theory due to the unexplained ability of individuals to pass their special abilities to their offspring. The last point remained a mystery until the existence of genes was discovered. In 1874, the theologian Charles Hodge accused Darwin of denying the existence of God by defining humans to be a result of a natural process rather than a creation designed by God. Even today, many Christian and other religious fundamentalists continue to fight the Darwinian theory of evolution. Darwin's theory is now backed up by the comparison of DNA from different organisms which shows the closeness of their relationship.

Contrary to popular opinion, Darwin did not "discover" evolution as it was accepted by many since the beginning of the 1800's. Instead, he provided the first really coherent theory of how evolution occurs (via the mechanism of natural selection). Other important aspects of Darwin's overall theory were: common descent, sexual selection, gradualism, and pangenesis. It is important to remember that Darwin's version of natural selection was different from that presented by Wallace in that he held that natural selection was continuously operating, whereas Wallace argued that selection only occurred when the environment changed. [This article is licensed under the GNU Free Documentation License and uses material adapted in whole or in part from the Wikipedia article on Charles Darwin.]

Darwin as a Classical Thinker
Russell McNeil, PhD (Copyright 2005)
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Archaeopteryx lithographica is regarded as one of the most important fossils ever discovered. This isn't because of any uniquely transitional nature, since many transitional forms exist, but due to the fact that Archaeopteryx is such a good example of evolution. The skeleton is essentially reptilian, with close affinities to theropod dinosaurs, with teeth, a long bony tail, abdominal ribs and three digits on each hand - characters absent in birds. However, the specimens also show certain bird characters such as a furcula (wishbone) and a retroverted pubis (characters also shared with some dinosaurs) and a opposable hallux (big toe) for perching. Along with these other avian characters, the most spectacular feature is the distinct impression of feathers around the forelimbs and tail, feathers almost exactly like those of modern birds.

Archaeopteryx  lithographica
Archaeopteryx lithographica

The original 150 million year old Archaeopteryx fossil was uncovered in 1860 sprawling within a split block of limestone in a Bavarian quarry in Germany. This discovery occurred a year after Darwin's publication of The Origins of Species, and only weeks after a famous Evolution versus Creation debate in Oxford where Bishop Wilberforce is alleged to have asked a defender of Evolution whether he thought he was descended from the ape on his grandmother's side or his grandfather's side. The memory of this debate was still fresh in everyone's minds, as was the fact that a major issue causing some consternation that came up in the debate related to the lack of fossil evidence for intermediate forms. The discovery of the Archaeopteryx on the heals of this debate seemed to fill an important gap, supplying to the delight of evolutionists, a fossil form intermediate between reptiles and birds. Despite rumblings from German experts at the time that this new fossil was a forgery, the then Director of the British Museum, Richard Owen, commissioned its purchase..

Artist's Drawing of Archaeopteryx
Artist's Drawing of Archaeopteryx

The authenticity of Archaeopteryx, or more specifically the authenticity of the feather impressions, was questioned in more recent times in 1985 by a group which included, Fred Hoyle (an astronomer), N. Wickramasinghe (mathematician), L. Spetner (physicist), and Dr. R. Watkins (medical doctor). The issue was explored in a series of four articles published in the British Journal of Photography (Hoyle et al. 1985; Watkins et al. 1985a, 1985b, 1985c).

Fred Hoyle is one of the world's foremost astronomers--the parent of the quasar--he predicted them before they were seen. Chandra Wickramasinghe is one of Britain's foremost astronomers and an international authority on interstellar material.

The claims made by Hoyle and Wickramasinghe were opposed by the British Museum of Natural History and refutations of the original claims were published in the literature. As far as I am aware, Hoyle and Wickramasinghe never reversed or withdrew their claim after these refutations.

What's the point?

Well, more recently (1990) Ian Taylor (1990), a creationist, this time, has revived the old forgery claim citing new evidence based mainly on "unexplained" differences between early engravings, historical photographs, and the modern appearance. However, the evidence presented by Taylor has been soundly discredited.

Taylor's research was nevertheless published in the Journal of the Institute of Creation Research,. This is an the official organ of an organization dedicated to fostering what they refer to as creation science. But mainstream science generally regards creation science as an anti-intellectual activity - primarily because the assertions or hypotheses of creation science are not falsifiable - and falsifiability is the generally accepted criterion for any scientific theory. As a consequence Creation science by definition is considered pseudo-science and thus anti-intellectual.

Now, I am not making any particular claim about Archaeopteryx. I don't know if the thing is a fake or not. The scientist in me hopes it is genuine--good reptilian birds are hard to find. But the journalist in me--I covered this as a science story when it came out in 1985-- was amused then by a respectible British scientific establishment getting egg in its face. My point is that legitimate criticisms of evolutionary theory (Taylor's is not legitimate--Hoyle's was) are in danger of being tarred by the brush of this anti-intellectual charge. Therefore, anyone offering a critique of evolution must be prepared to take some heat - if only because any opposition to any of the theoretical underpinnings of evolutionary theory is suspect. Therefore any radical thinking that hits too close to the core of Evolution theory is always in danger of being dismissed as anti-intellectual. The safe course is to stay out of the kitchen. The very presence of creationist pseudoscience effectively dampens any novel thinking about evolution.

My faith in the fact of evolution does not hang on the authenticity of a bird in a British Museum. In human terms I've never in the least felt diminished by the connectivity and unity of Nature contained in the Idea of Evolution. That I am linked to, part of, connected with, and related to everything in the biosphere makes me feel allied to nature - not alienated! For me it is the old idea of design--the notion that we are somehow unique and special--that makes me feel alienated from nature.

Evolution as an idea is a wonderful gift -- Darwin's logic has affected an important intellectual transformation. Darwin may indeed have moved us away from design and moved us into the realm of chance--and that seems scary to some people--but he in a very real sense Darwin also moved us together--by drawing a tether through all we call life. And for many people that is far more uplifting and enervating than the idea of design--at least the old classic idea of design, including the biblical notion of special creation. That takes takes away, but hands us back something better: a special unity with nature.

In showing us how we are one, Darwin in a sense may have saved us all from extinction--a consequence of the responsibility Darwin's logic introduces into the intellectual life.

I've said two things so far. First: taking issue with Darwin is intellectually risky. Two: Darwin's contribution is intellectually magnificent.

That said I want to take issue with Darwin, specifically with the concept of natural selection. As I understand it, the critical steps around the mechanism of Natural Selection as presented by Darwin in Origen of Species are listed below:

1. All species follow from the struggle for life.

2. Natural Selection [is] the preservation of individual differences and variations, and the destruction of those that are injurious.

3. We see nothing of these slow changes in progress, until the hand of time has marked the lapse of ages, and then so imperfect is our view of long-past geological ages, that we see only that the forms of life are now different from what they formerly were.

4. Natural Selection will generally act very slowly, only on a few individuals of the same region.

5. Varieties are species in the process of formation...incipient species

6. Natural Selection acts exclusively by the preservation and accumulation of variations.

7. The species of large genera present a strong analogy with varieties.

Here is where my question arises. What is this analogy above?

What did Darwin have in mind when he talked about varieties? Did he think about varieties as we might, or was his thinking formed by a conception of variation determined by a different mindset?

For example, did he imagine that the range of possible varieties as large (yet finite) or essentially unlimited (i.e. infinite)?

This is a useful question. Another way of asking the question is this: how many unique potential reproductive outcomes is possible from the sexual pairing of two individuals?

I suspect Darwin would affirm that those possibilities were unlimited.

This means that the Darwinian framework was guided by a non-discreet and effectively analog thought pattern.

So what? What difference does it really make if the number of outcomes from a sexual pairing is finite (because of genetics) or infinite (because the range of variations is a smoothly changing blend of possibilities contributed from both parents.) In the analog case (Darwin's mindset) we would see a smoothly changing normal distribution for any characteristic or trait. In the non-analog case the distribution would still be normal, but the distribution curve would be made by joining the points from a histogram of a large but limited number of possibilities.

An analogy here might be the range of discreet colors available on a digital computer (64,000 or more - but finite) vs. the infinite number of colours produced by mixing of tinted paints.

Now, speciation is really no problem in the Darwinian process and analog mindset: It is simply a matter of time. Competition, environment, struggle and so on push the envelope in any direction and towards whatever configuration is profitable for survival.

But speciation may be more of a problem for the digital scheme because there are prohibitions built into this model. Some variations are prohibited. The envelope is pushable but there are limits as to how far the envelope can be pushed because by definition the possibilities are limited.

What does this mean? It means that to account for speciation in the discreet scheme we need to invoke a mechanism, a process, which allows us to break the rules that hold a discreetly determined model so rigidly in place. What is prohibited must be somehow no longer prohibited.

Well, rules are broken in the real world--things like mutations allow for the variations that a digital scheme would disallow. Darwin himself alludes to other processes, processes other than Natural Selection that might assist Natural Selection--although Natural Selection might be the main process.

What am I getting at? Darwin uses analog thinking to explain a process is inherently quantized or discreet.

Well, rules are broken in the real world--things like mutations allow for the variations that a digital scheme would disallow. Darwin himself alludes to other processes, processes other than Natural Selection that might assist Natural Selection--although Natural Selection might be the main process.

What am I getting at? Darwin uses analog thinking to explain a process is inherently quantized or discreet.

What difference would this make?

I don't know that we really know the full implications of this. In the world of physics there are significantly different world views associated with the classical and quantum world picture. Classical (analog) theories do marvelously well, but fall to pieces when they are used to describe very small things and very big things. Newton's achievements are not diminished by quantum theory--quantum theory explains things Newton's theory could not touch--mainly because it was oblivious to the nature of the small.

Darwin too would be oblivious to the small because he was unaware of its nature.

Darwin's ideas as they come to us here are necessarily limited by the state of knowledge in 1859.

I could say much the same thing of Newton. No one faults Newton today for not having discovered the true nature of physical mechanics two hundred years before Darwin.

I will argue that Darwin -- confined as he was by an essentially classical mind set -- is in part open only to only those possibilities that a classical mind set might allow. The great fallacy of classical models is their failure to accurately describe nature in the small and nature in the large. All early classical thinkers attempted to do that by extrapolating from what is well described to what is not. I see this as similar to what Darwin is attempting to do with speciation. He tries to extrapolate from the observables of macroevolution to the details of microevolution.

What this opens up in my mind is a line of Enquiry directed towards a deeper understanding of how nature works. We do this by taking a second look as Darwin's exquisite reasoning with new questions: questions which -- if Darwin had asked them -- might have augmented, modified, or radically opened up new channels or ways in which speciations might occur.

One possibility might be to explore the idea of life cycle. Individuals are born. They grow old. They die. That phenomenon is independent of natural selection. Some process is at work during the life cycle -- a biological clock -- that ticks on independently of individual action. That process seems to be dictated by biology and not circumstance. There is plenty of data about to support the conclusion that every biological entity on earth is subject to the process. If this biological timing process is so ubiquitous in the individual, is it irrational to suppose that the process may not manifest -- in an analogous fashion (to borrow from Darwin) -- at the level of the species -- as an independent and inexorable cofactor? Species emerge, they mature, they go into decline, they die. Natural selection might intervene to end this inexorable process independently but perhaps a species life cycle (if there is one) is nonetheless unstoppable?

I see advantages and disadvantages in offering an idea like this. The advantage is that if we take the analogy seriously -- then during the life cycle of a species there would be little change seen during the life cycle of a species. There might be lots of variation due to Natural Selection, but no great structural change in the species as a whole (with the possible exception of a decline in species fecundity as is the case in the individual fecundity with increasing age). If the biological life cycle for a species was 30 million years then the fossil record might show little major change over that sort of time frame. Another advantage is that a mechanism like this could account for the so-called poverty of intermediates Darwin is concerned about.

Perhaps we could modify the analogy by invoking the (caterpillar to butterfly) metamorphosis analogy. Species do not die at the end of their life cycle, they transform into other organisms. Is some sort of mild metamorphosis at work at the level of the species?

I think that Darwin could have drawn on other possibilities as well. One possibility he might explore had he been aware of genetics is the notion of threshold response. The idea of critical threshold is mirrored also in nature in other ways: critical mass, black holes, escape velocity, tree lines on mountain sides. etc.

I've picked 1) life cycle, 2) metamorphosis, and 3) threshold as analogy alternatives available essentially only to a mindset schooled in the discreet and limited nature of the biological variation of traits. These and perhaps a much broader range of possibilities would not be available to a classically formed modality of thought - and Darwin's thinking was so formed. Darwin did not and could not explore possibilities still hidden from the human mind.

My suspicion is that in exploring these possibilities now, we may be able to understand more fully what Darwin was attempting to do and hoping to explain--including such things as the paucity of intermediate species in the fossil record.

Not to challenge Darwin does great disservice to the Enquiry. I'd say the same of Newton.

Unfortunately in the intellectual climate surrounding the discussion of Darwin today -- challenging Darwin is interpreted as support for Creationism--an anti-intellectual thesis. It's a poor environment in which to push the envelope. Better to concentrate on other problems. I don't know if that's healthy with the golden age of biotechnology on the threshold of radically altering our world.

Books from Alibris: Charles Darwin

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