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Charles Darwin and the Theory of Evolution

What is the theory of Evolution, what did Charles Darwin actually contribute to science and what makes this topic so interesting to the scientist and non-scientist alike? This short article is the answer to these questions according to the webmaster.

This year, 2009, marks the one hundred fiftieth anniversary of the publication of On the Origin of Species by Charles Darwin in 1859. Before this, Naturalists had theorized about evolution for centuries, but their ideas were often un-testable, wrong or failed to lead to anything new. It is often thought that Darwin’s great insight was the description of a simple mechanism –natural selection- that made evolution possible. A more important insight is that given a non-random changing environment and organisms in that environment whose reproductive success depends on inherited traits –evolution is inevitable.

Charles Robert Darwin (12 February 1809 – 19 April 1882) was an English naturalist who realised and presented compelling evidence that all species of life have evolved over time from common ancestors, through the process he called natural selection. The fact that evolution occurs became accepted by the scientific community and much of the general public in his lifetime, while his theory of natural selection came to be widely seen as the primary explanation of the process of evolution in the 1930s, and now forms the basis of modern evolutionary theory. In modified form, Darwin’s scientific discovery is the unifying theory of the life sciences, explaining the diversity of life.

Darwin , at the end of On the Origin of Species:

“ There is grandeur in this view of life,
with its several powers,
having been originally breathed into a few forms or into one;
and that, whilst this planet has gone cycling on according to the fixed law of gravity,
from so simple a beginning
endless forms most beautiful and most wonderful
have been, and are being, evolved.”

In 1831, Charles Darwin, a 6 foot tall, young (22 years old) medical school drop-out was invited to voyage on the “Beagle” by the captain of the ship. Darwin had no official position, he was merely invited to keep the captain company and act as the unofficial naturalist. His experience on that voyage set him on his life’s work.

What is the Theory of Evolution?

To begin with, there is an important distinction between the fact of evolution and theories proposed to explain causes and mechanisms of evolution.

The fact of evolution is defined as the genealogical connection among all living organisms, based on their descent from a common ancestor. This fact is based on evidence. First is the direct evidence of human observation and manipulation over hundreds of years in developing improved crops and domesticated animals -showing the small scale changes over relatively brief periods of time. Our observations include familiar cases like the pigmentation changes in moth wings as an adaptation to a soot covered industrial city, there are the changes in beak shape of Darwin's famous finches from the Galapagos islands, where changes in available food sources and climate lead to biological adaptations and we even have the relatively recent observations of the rise of antibiotic resistant bacteria -we should have seen that coming!

Do these small scale changes accumulate over geological time to become substantial changes that create whole new species and different forms? If so, then we expect to find transitional stages of these alterations in the fossil record. In fact, paleontologists have discovered numerous examples of sequences of intermediate forms joining ancestors in a long time line to very different descendants.

Finally, as evidence of the fact of evolution, I’ll mention the presence, in all organisms, of holdovers from their ancestral states. These are found as imperfections and quirks that only make sense if we recognize them as holdovers, useless remnants of formerly functional structures, such as leg bones in whales or snakes and see "THIS OLD BODY Evolutionary hand-me-downs inherited from fish and tadpoles have left us with hernias, hiccups and other maladies "• • • BY NEIL H. SHUBIN in Scientific American, January 2009.

On the molecular level we have genetic holdovers as well. All modern life forms carry genes that show their relationships to other life forms. Some of these genes have no function in the present organism. Darwin's theory of Evolution by Natural Selection, spelled out in his 1859 book On the Origin of Species is a simple explanation that is now one of two of the overall guiding theories of biology. The other being simply stated: biological systems conform to the laws of physics and chemistry. This theory of evolution by natural selection tells us that life on earth has diversified autonomously and has no goal or purpose. Living organisms are the way they are due to the long time given to random mutations sorted out by natural selection. In this view, change is inevitable while the actual specific changes are due to chance. In other words, if we went back and started over -we'd get a whole new collection of species -and quite probably, we wouldn't be one of them.

Just because the process has no goal or purpose does not mean we don't. As a matter of fact many scientists have chosen research in biology as their purpose. Since Darwin's time, we have discovered many of the mechanisms involved in the process of inheritance and found that these do indeed lend themselves to this operation of random mutations that are sorted out by natural selection. Natural selection is the name given to the obvious process in which organisms that, by chance, have some advantage in reproductive success will have more descendents in future generations. -By that criteria, I'm personally disadvantaged having only three children. But then evolution does not necassarily find advantage with the same traits we would personally choose.

This video is FANTASTIC- The most entertaining documentary you'll see on the topic of evolution and how it and the theory have changed our world!

What did Charles Darwin Contribute to Science?

Darwin's simple insight, that natural, physical processes could account for the diversity we see in the forms of life, has given science one of it's greatest tools. In Darwin's time, the mechanism for producing variation was not known. Since then, we have discovered the molecular basis for genetic transmission and that variation. Darwin’s scientific discovery, his insight, forms the foundation of modern biology by providing a unifying logical explanation for the diversity of life. Built on this foundation is the modern understanding of how today's living organisms have come to be, all from a common ancestor.

The natural, physical process in question is quite easy to describe. If a population contains members with variability in some feature, and that feature is inheritable then future generations will consist of more offspring of the members with the variety of that feature that contributed to producing more offspring. Multiply this by the many possible features and the eons of time and we get the world we have now.

With this theory we can trace the migrations of human populations, anticipate diseases and disease processes and understand the variety of forms we see in the natural world. Nothing in nature makes sense unless we consider the natural process of selection acting on ancestral life to give us the living forms of today.

One Long Argument

His 1859 book On the Origin of Species introduced the concept of natural selection as the driver of evolution by common descent giving us the modern scientific explanation of diversification in nature. Darwin had discussed these ideas with other naturalists during the span of more than 20 years between his voyage on the beagle and the publication of On the Origin of Species by Means of Natural Selection, Or the Preservation of Favored Races in the Struggle for Life. The first edition was published in 1859 as a letter from Alfred Russel Wallace presented an essay which described the same ideas thus prompting immediate joint publication of both of their theories.

This was Darwin's "one long argument", as he put it, in which he laid out in intricate detail, though cautious terms, the case for evolution by the process of natural selection. Click Here to Download The_origin_of_species.pdf now!

Three More Works

The Voyage of The Beagle

Or rather the 1845 book: Journal of Researches into the Natural History and Geology of the Countries Visited During the Voyage of H.M.S. Beagle Round the World. Intellectually the most important travel log of all time. This covers Darwin's observations during the 1831-1836 voyage. This book made Darwin's reputation as a naturalist by becoming what we would call today a best-seller. His attention to detail introduced this thinker to the world.

The Descent of Man

Victorian society was assaulted by Darwin's suggestion that man descended from "some pre-existing form" in his book The Descent of Man and Selection in Relation to Sex published in 1871. The fact that the evidence implied we shared a common ancestor with the great apes was nearly intolerable. In this work he presents a great deal of evidence all pointing to the origin of the human species from some lower form. Evidence includes the similarity of embryonic development among humans and other animals, homologues in the anatomy of humans and other primates and vestiges of structures in humans that suggest an animal ancestry.

The one thing lacking in this publication is any reference to fossils related to the human family tree. Such fossils were finally available only after publication. (Note: Neandertal fossils were discovered Engis, Belgium (1829) and in Gibralter (1848) and in 1856 near Düsseldorf we claim the original find, but these are not discussed in The Descent of Man. )

The Expression of the Emotions in Man and Animal

From the time of Homer and the on to the classical Greeks, emotions have been well described in literature. The emotions were once thought to distinguish us from the animals -and our moral sentiments needed to be explained as a consequence of evolution by natural selection before Darwin could imagine his work was finished. This was really the last argument against the descent of humans from some lower form and the topic did need to be addressed. In this work published in 1872 Darwin treated emotions and their manner of expression as products of evolution. He did this in painstaking detail in an empirical approach. His explanation considered our emotions as communications in a complex social setting and then looked at evidence in the development of emotions and their expression in children, the derangement of emotions in the insane and the consistency of emotional expression in cultures throughout the world.

How Scientists Use Darwin's Work Today

Progress is being made directly related to the theory of evolution every day. This progress is usually in the form of filling in details of the mechanisms involved in the rise of variation (mechanisms of genetic variation completely unknown in the time of Darwin, since the discovery of how the DNA molecule can carry genetic information wasn't made until the twentieth century). Sometimes it is in the form of novel discoveries of mechanisms bringing about variation -completely new research areas. And often it is in the form of elucidating the mechanisms of natural selection -what are the forces of selection, how do they act. Of course, there are also new discoveries of fossils that invariably bolster the fact of evolution.

My personal favorites in new research involve the elucidation of pressures of natural selection that gave rise to us. Such research includes the understanding of how social interaction selects for brain structures and processes that give us our behavior as social animals. It also shows how the need to be efficient with our use of energy in neurological processes while still getting what we need to survive and procreate leads to the way our mind works. For example, the fact that we cannot compute everything we need to know fast enough to deal with the world around us leads to automatic responses. Illusions come from a need to have mental models of the world around us, because we do not have infinite energy to process all of the possible sensory data available in the world. We create mental models of the past, present and future -including mental models of pasts & presents that did not and do not exist as well as a wide array of futures, because we can use these models to understand those around us as well as plan for the future. This line of thinking can even explain why we get stuck in a mode of thinking that does not fit the facts and find great difficulty in undoing this ingrained thought process. In other words, the theory of evolution can help us understand some of our cognitive weaknesses with the promise ways to overcome them.

Controversy Regarding Darwin's Theories

Darwin continually emphasized the difference between his two great and separate accomplishments: establishing the fact of evolution, and proposing a theory--natural selection--to explain the mechanism of evolution. - Stephen J. Gould, " Evolution as Fact and Theory"; Discover, May 1981. As soon as Origin of Species was published, there were attacks on both the fact and the theory, but the public concept has never quite kept these two separate. Today, most scientists, accept the theory and the fact as operational basics for understanding biology, however there are attacks directed against teaching both to young biology students. There are also publications with the purpose of throwing doubt on evolutionary theory and convincing the public that scientists themselves disagree about evolution. The reality is that scientists do not contend about the fact of evolution on any real scale, and usually only disagree on the particulars of theory as expressed in this quote:

Let me try to make crystal clear what is established beyond reasonable doubt, and what needs further study, about evolution. Evolution as a process that has always gone on in the history of the earth can be doubted only by those who are ignorant of the evidence or are resistant to evidence, owing to emotional blocks or to plain bigotry. By contrast, the mechanisms that bring evolution about certainly need study and clarification. There are no alternatives to evolution as history that can withstand critical examination. Yet we are constantly learning new and important facts about evolutionary mechanisms. - Theodosius Dobzhansky "Nothing in Biology Makes Sense Except in the Light of Evolution", American Biology Teacher vol. 35 (March 1973)

Mainly, these attacks are a reaction to what the theory of evolution can do to our emotional concept of ourselves. If we allow the fact that we share ancestors with apes and fish and worms to darken our world view -and our world view does make a difference in how we conduct our lives- then we may not want to accept the reality we face. But, most people who accept the fact and theory of evolution do not see a need to lose our moral values or sense of self worth simply because we share an ancestory with the other life forms on this planet. There are those that argue that our life goals become more grand if we see them as chosen by or serving a supernatural power, but others are quite certain that choosing our own purposes and seeing the world as it is presented to us by scientific knowledge is just as grand and even more fulfilling.

Thomas Huxley, 1825-1895

Huxley was born to something less than a gentleman's life. Having no money for an education he became a doctor's apprentice at age 13 and at age 16 he had followed the doctor to London and began training as a surgeon. Huxley was barely getting by on scholarships and loans, mostly from in-laws and he accumulated a considerable debt. To pay the debt he joined the crew of the H.M.S. Rattlesnake bound for New Guinea. He served as the ships surgeon. Four years later in 1850 he returned to London preceded by his reputation as a scientist due to the papers published from his letters. He was elected to the Royal Society at age 26 without even holding a degree.

Eventually, Huxley became well enough known through his work writing columns and reviews. He also became an adversary to the English biologist Richard Owen. Owen was working on a sort of "Divine Evolution" theory in which God made new species always referring to his archetypes for their basic design. Huxely openly mocked this approach. Huxley did not accept any form of evolution at all, preferring a static world to be discovered.

He changed his mind when Darwin invited Huxley out to the country for a weekend in 1856. Darwin explained his version of evolution based on purely physical processes and showed how it could account for the patterns in nature without supernatural intervention. Soon Huxley was persuaded and over time became known as Darwin's Bulldog for his passionately championing the Origin of Species

Sir Richard Owen, 1804-1892

Owen met Darwin only three weeks after the return of the Beagle at a dinner party at the home of Charles Lyell, the great geologist. Owen and Darwin got along well and Owen spent some time examining some of Darwin's specimens for him. Owen had spent some time worrying about the speculations of Geoffroy Saint-Hilaire who showed that animals have many unexpected similarities, and studied the development of embryos noting the similarities at various developmental stages. Owen was working on a way to explain the variety and similarity in nature, but keeping the hand of God in the work. For Darwin, Owen worked on fossil bones collected in South America. He showed the extinct giant creatures were rodents and sloths, and that they were related to current species in the same locality, rather than being relatives of similarly sized creatures in Africa, as Darwin had originally thought. This was one of the many influences which led Darwin to later formulate his own ideas on the concept of natural selection.

Owen had spent some time worrying about the speculations of Geoffroy Saint-Hilaire who showed that animals have many unexpected similarities, and studied the development of embryos noting the similarities at various developmental stages. Owen was working on a way to explain the variety and similarity in nature, but keeping the hand of God in the work. Later, Owen became an opponent of Darwin's Origin of Species. He agreed with Darwin that evolution occurred, but thought it was more complex than outlined in Darwin's Origin.

In 1840s Owen came to a remarkable conclusion: Species arise as the result of some sort of evolutionary process of which there was a total of six possible mechanisms: parthenogenesis, prolonged development, premature birth, congenital malformations, Lamarckian atrophy, Lamarckian hypertrophy and transmutation. He considered transmutation the least likely. Owen was criticised for remarks in his Nature of the Limbs in 1849, at the end of which he had suggested that humans ultimately evolved from fish as the result of natural laws. He was criticized in the Manchester Spectator for denying species like humans were created by God.

Owen's arguments against Darwin's work were primarily against the transmutation of man from an ape like ancestor -though he said that he had long believed that "existing influences" were responsible for the "ordained" birth of species. In long talks with Darwin, Owen said that the book offered the best explanation "ever published of the manner of formation of species", although he still had the gravest doubts that transmutation would bestialize man. It appears that Darwin had assured Owen that he was looking at everything as resulting from designed laws, which Owen interpreted as showing a shared belief in "Creative Power". Things heated up however as Huxley and Owen argued, Huxley claiming common ancestory with gorillas while Owen could not accept that idea. It may also be that Owen saw a disturbing trend, what we notice now as a misuse of Darwin's theory, for example Marx's claim that Darwin's theory provided a basis in natural science for the historical class struggle. Such a trend would put one off on a theory if it were not recognised as a terrible misuse.


"Today, nearly all biologists acknowledge that evolution is a fact. The term theory is no longer appropriate except when referring to the various models that attempt to explain how life evolves... it is important to understand that the current questions about how life evolves in no way implies any disagreement over the fact of evolution."

- Neil A. Campbell, Biology 2nd ed., 1990, Benjamin/Cummings, p. 434

Those that oppose the the theory of evolution generally do so based on religious reasons. In this case, they usually deny the fact of evolution as well as the various mechanisms proposed to account for it. There are some however that do accept the demonstrable mechanisms but still deny the concept of whole new species, especially ours, deriving from quite different ancestral species.

There are those that see Darwinism as dangerous -since, in their mind, "Only if God had directly created mankind in His image could there be any basis for morality." Darwin began the address to this objection in his work The Expression of the Emotions in Man and Animal and today the answer to this objection continues with work such as Michael Shermer's The Science of Good & Evil.

Some have presented objections to applying evolution to humans with the claim that Darwin's mechanism for evolution can never explain our free will. We now have work such as that presented in Read Montague's Why Choose this Book showing a clear mechanism for the evolution of our subjective consciousness and what we experience as free will by the operation of natural selection on the processes of the nervous system in an environment of scarce resources. So, the mind we enjoy now may owe a great deal to the fact that energy is not free!

Some claim that evolution does not need to be taught in science classes. How organisms function, how they are classified, and how they interact with one another, do not depend on evolution. But, biology without evolution is natural history and simple physiology. We should learn both natural history and physiology, but "evolution is the unifying idea that ties it all together, allowing one not only to know the facts but to understand them and to know where the facts come from."

Present Arguments

Early oppostion to Darwin's theory consisted of the claim that believing his theory was immoral. There are still those today that express this oppinion. However, this approach does not explain the evidence in favor of Darwinism, and suffers from the image of being religiously motivated -and people do not all agree on religious ideas. The favored approach today in opposing Darwin's theories is to claim that creation can be considered a viable scientific theory to account for the rise of life.

Today there are essentially two schools of thought in "creationist science": The young earth school and the old earth school. Young earthers simply deny the validity of any scientific method that yields unacceptable timelines in opposition to a strict reading and acceptance of the bible. This leaves the explanation of everything in geology to the flood event in the bible -most geologists do not agree that the flood can exlpain the observations. All other sciences, such as radio-isotope dating are assumed flawed due to unknown factors. Old earthers accept the nearly 5 billion year old earth but claim that God created man in quite recent times. As you would expect, these shcools each find fault with the other.

All progress in biological sciences today with regard to understanding evolution comes from elucidating previously unknown or little appreciated mechanisms involved in the process, mostly as described by Darwin. Real opposition comes only from those that believe we must accept "revealed" knowledge which is in opposition to the theory, which explains why many people associate acceptance of Darwin's theory with atheism. Admittedly, atheisim is much more prevelant among scientists of all types and biologists in particular, however the fact that there are those that practice religion while still working as scientists accepting of the theory of evolution suggests that you do not have to be an atheist to either accept, work with or understand the theory of evolution.

'In October 1838, that is, fifteen months after I had begun my systematic enquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The result of this would be the formation of new species. Here, then, I had at last got a theory by which to work' Charles Darwin, Autobiography 1876

From So Simple a Beginning The four great works of Charles Darwin, in their entirety and in the original editions. Each is edited by and introduced by Edward O. Wilson. If you want to understand Darwin, there is no better way than to read his own, rather accessible, words.

"Evolution , the Triumph of an Idea" by Carl Zimmer is a beautifully illustrated, well written, entertaining introduction to evolution. It covers the concept from the time of Charles Darwin to modern times, describing what is known and what is not understood. This is fun reading!

The Ancestor's Tale is a wonderous pilgrimage to the dawn of evolution. In this book, Richard Dawkins gives a clear picture of the our relationship to all the creatures on earth. By a trip back through time, we meet our common ancestors with so many wonderful creatures. The breadth of this work is stunning. You will meet creatures you've never heard of and see much of the evidence for their relationship to all of the other life. This is a trip you'll never forget -be sure to mark the pages, because you will want to come back again and again.

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