Charles Darwin And The Theory of Evolution

It is commonly thought today that the theory of evolution
originated with Darwin in the nineteenth century, however,
the idea that species mutate over time has been around for
a long time in one form or another. It was rejected by
most, because the proponents of evolution could not come up
with a satisfactory mechanism that would explain this
change. 
The most influential evolutionary theories prior to Darwin
were those of Lamarck and Geoffroy St. Hilaire, developed
between 1794 and 1830. Lamarck suggested that species
evolve through the use or disuse of particular organs. In
the classic example a giraffe that stretches its neck
slightly to reach higher leaves will gain in neck length,
and this small gain would be passed on to its offspring.
Geoffroy, on the other hand suggested that the change was
discontinuous, large in magnitude, and occurred at the
production of offspring. However, these theories of
evolution were based on a priori explanations that offered
no demonstrated mechanism.
 
Darwin's theory of evolution differs in that it is based on
three easily verified observations.
 
1. Individuals within a species vary from one another in
morphology, physiology, and behavior.
 2. Variation is in some part heritable so that variant
forms have offsprings that resemble them.
 3. Different variants leave different number of offspring. 

Darwin then proceeded to elaborate on the mechanism of
evolution by suggesting that in the universal struggle for
life, nature "selects" those individuals who are best
suited (fittest) for the struggle, and these individuals in
turn reproduce more than those who are less fit, thus
changing the composition of the population. In addition to
natural selection, Darwin also suggested that species also
evolve through the complementary process of sexual
selection. According to Darwin, in sexual selection, one
gender of a species develops a preference for individuals
of the other gender who possess certain features. The
individuals who possess these features will then have a
reproductive advantage over others, resulting in a greater
number of offsprings, and thus, again, a change in the
composition of the population. Therefore, it was Darwin who
made the theory of evolution feasible by providing the
mechanisms of natural and sexual selection.
 
Charles Darwin was born in England in 1809 to a wealthy and
respectable family. His grandfather, Erasamus Darwin, was a
noted botanical expert in his day who published two
important books, Zoonomia, and The Botanic Garden. In these
books, Erasamus speculated about various evolutionary ideas
that were dismissed as too radical (i.e., the nose of the
swine has become hard for the purpose of turning up the
soil in search of insects and roots). Darwin who in his
youth read his grandfather's books with admiration, later
commented that his grandfather "anticipated the views and
erroneous grounds of opinion" of Lamarck. Nevertheless,
Erasamus may have unconsciously influenced Darwin in
preparing the way for evolution by natural selection.
 
In 1818, at the age of 9, Darwin entered the Shrewsbury
school, which was run by Dr. Butler. Darwin later recalled
that "nothing could have been worse for the development of
my mind than Dr. Butler's school, as it was strictly
classical, nothing else being taught , except a little
ancient geography and history. The school as a means of
education to me was simply a blank". He was removed from
the school in 1825, and was sent to Edinburgh to study
medicine. There he studied for two years before deciding
that he didn't like medicine. But before he left Edinburgh,
he was introduced for the first time to the theories of
Lamarck. According to Darwin at the time he was not very
impressed with Lamarck's ideas. In 1828, at his father's
suggestion, Darwin entered Christ's College in Cambridge to
become a clergyman. To Darwin a good education meant
instruction in the methods and logic of thought. Therefore,
Just about the only thing he enjoyed studying there was
Paley's works on theology, because of their logic. For the
rest, however, he judged Cambridge to be just as much a
waste of time as Edinburgh and Shrewsbury.
 
Nevertheless, in his spare time at Cambridge, Darwin became
interested in various scientific endeavors, and became
acquainted with and influenced by the scientific ideas of
Henslow, Sedgwick, and Whewell (ironically Sedgwick later
became a bitter opponent of Darwin's theory). In addition,
during his last year at Cambridge Darwin read two books
which influenced him greatly, Herschel's Preliminary
Discourse on the Study of Natural Philosophy, and Von
Humboldt's Personal Narrative of Travels to the Equinoctial
Regions of the New Continent. Darwin later confessed that
these books inspired in him "a burning zeal to add even the
most humble contribution to the noble structure of Natural
Science".
 
In 1831 Darwin graduated from Cambridge, and as he was
pondering his future, he received a proposal to join a
scientific expedition that would survey the southern coast
of Tierra del Fuego. Darwin accepted the proposal, and
sailed from England aboard the famed Beagle on December,
27, 1831. His job was to collect and catalogue new species
so that they could be sent back for further research in
England. It is commonly thought that Darwin used the voyage
to test his theory of evolution, but this is highly
unlikely. At the time Darwin's interests were purely
geological as can be seen by his correspondence with his
sister. For instance, writing about the fossils which he
discovered he said, "All the interest which I individually
feel about these fossils is their connection with the
geology of the Pampas". Furthermore, Darwin himself
confessed that he could not have appreciated the
significance of his findings while on the voyage, because
he lacked the necessary training in dissection and drawing
as well as the knowledge of comparative anatomy. It was
only much later when Darwin returned from the voyage, and
when the fossils were identified by Owen, that Darwin began
to examine them as zoological, rather then geological,
phenomena.
 
The voyage turned out to be very productive for Darwin, who
upon his return in 1836 began to work on the conversion of
the diary, which he kept during the voyage, into a journal
suitable for publication. The Journal was first published
in 1839 under the title "Journal and Remarks", as Volume
III of the Narrative of the Surveying Voyages of H.M.S.
Adventures and Beagle. Enough people thought that Darwin's
work was sufficiently important to warrant a separate
publication, and in 1845 a second edition was published
under the name Journal of Research into the Natural History
and Geology of the Countries Visited during the Voyage of
H.M.S. Beagle Round the World (henceforth referred to as
the Journal). Darwin "Discovers" Evolution
 
It appears to be that only sometime in 1837 did Darwin
first start to entertain the idea of evolution seriously.
The proof for this lies in the notebook which he kept from
July 1837 to February 1838. In particular, the following
statement from the notebook provides valuable insight: "In
July opened first notebook on transmutation of species. Had
been greatly struck from about the previous March on
character of South American fossils, and species of
Galapagos Archipelago. These facts (especially latter),
origin of all my views". Therefore, it must have been at
this time that Darwin's ideas took this turn. Furthermore,
had the change occurred earlier, it would have shown up in
Darwin's writings in the Journal, which, more than half
completed by March, shows no trace of it. Overall, with the
notable exception of the idea of natural selection, most of
what Darwin later wrote in On the Origin of Species by
Means of Natural Selection, or the preservation of Favoured
Races in the Struggle for Life (henceforth referred to as
the Origin), was already sketched in that notebook. 

It is important to note that Darwin's thinking at this
point was still distinctly teleological in character. He
still believed that God had instituted the laws governing
reproduction to maintain species in a state of perfect
adaptation to their environment. Only after his full
appreciation of the struggle for existence did he come to
believe that a changed environment disturbs growth to
produce random variation.
 
Curiously, Darwin asserts that in originating his theory of
evolution he was trying to follow "Baconian principles",
that is collect facts before theorizing. Specifically, in
his autobiography he states "After my return to England it
appeared to me that by following the example of Lyell in
Geology, and by collecting all facts which bore in any way
on the variation of animals and plants under domestication
and nature, some light might perhaps be thrown on the whole
subject. My first notebook was opened in July 1837. I
worked on true Baconian principles, and without any theory
collected facts on a wholesale scale...". However, as his
notebooks of the time amply demonstrate, he was speculating
boldly from the very beginning in favor of evolution. In
addition, Darwin himself at other times admitted his
dislike for the "Baconian method". For instance in one of
his correspondences he wrote "How odd it is that any one
should not see that all observation must be for or against
some view if it is to be of any service". And elsewhere,
"No one could be a good observer unless he was an active
theorizer". Therefore, a more accurate description of his
method would be, "inventing a theory and seeing how many
classes of facts the theory could explain". Darwin
"Discovers" Natural Selection
 
During his early theorizing, Darwin was fixated upon the
"whys" of evolution. He contemplated such questions as "Why
is life short? Why does the individual die, and why do
species die? Why does nature put so high a premium on
generation? And why does generation have the twofold
character of perpetuation and variation?". It seems that
apart from the occasional reference to "adaptation", Darwin
,at that time, almost deliberately tried to avoid the
contemporary theories of the mechanics of evolution.
 
Notwithstanding, Darwin, sooner or later, had to confront
the question of "how" evolution occurred. Amusingly, he
happened to stumble upon the answer quite accidentally. In
his spare time Darwin enjoyed reading various books rather
aimlessly, for amusement. One of these books, which he read
in October 1838, happened to be Malthus' Essay on the
Principle of Population.
 
As Darwin himself later related, "Malthus' description of
the struggle for existence in human society immediately
suggested to him that under the competitive conditions of
animal and plant life, favorable variations would tend to
be preserved, and unfavorable ones destroyed, the result
being the formation of new species". By this chance
encounter than, Darwin's theory was provided with a
rationale, and the "how" of evolution came to supplement
the "why".
 
It is important to note, that even though the crux of
Darwin's theory was inspired by Malthus, Darwin diverged
from Malthus in a critical way. Darwin's debt to Malthus
lies in the borrowing of the concept of the "struggle for
existence". However, in general, what Malthus was concerned
about was not how the struggle for existence affected the
quality of the population (i.e., he did not suggest that in
the struggle for existence the strong survive and the weak
perish) but simply how it limited its numbers. Indeed,
Malthus' essay was written as a rebuttal to Godwin and
Condorcet, both of whom had argued that humans, under
conditions of equality, were capable of infinite progress
and perfection. In the essay Malthus advanced the
"principle of population" to refute that idea. Thus,
Malthus' principle argued that "human society could never
progress toward perfectibility because the population
inevitably tends to increase beyond the means of
subsistence and is kept within the bounds of its resources
only by misery, vice, and moral restraint".
 
Malthus' principle of population was based on the supposed
differences in reproduction rates between humans (who
because of their status as "top dog" in the animal kingdom
reproduced "geometrically") and animals and plants (who
could only increase "arithmetically", because they served
mankind as a means of sustenance). Darwin by contrast,
shifted the center of attention from humans to the animal
and plant kingdoms, because he was impressed by their
enormous natural fertility, which was kept in check only by
their own limited means of sustenance. By shifting his
perspective from mankind to animals and plants Darwin
revealed the basic fallacy of Malthus' argument. For if
humans increased geometrically, animals and plants must
also increase at the same rate, and perhaps even more,
because overall their natural rate of reproduction is
higher than that of mankind. Therefore, the struggle for
existence, which to Malthus meant that hardship and misery
were the defining features of human life, to Darwin meant
that every species was in constant change, because nature
favored the fittest through the process of natural
selection. 

Three and a half years passed after reading Malthus in
October 1838, before Darwin finally sat down to write his
ideas formally in May 1842. There are two main reasons for
this lengthy delay. First, throughout his life Darwin
suffered from ill-health , which began to get acute in
1837, and was particularly debilitating between 1838 and
1842. Second, during this time Darwin had more pressing
matters which occupied his mind. In particular he was
working on the book Coral Reefs, papers for the Geological
Society, and work connected with the Zoology of the voyage
of the Beagle.
 
After completing the initial first sketch of 35 pages, he
set out to write a larger and more thorough sketch in 1844
(by the time he was finished the sketch numbered 230
pages). However, Darwin still proceeded to write his ideas
on evolution at a "leisurely" pace, and not until 1856,
when urged by his colleague Lyell, did he start working on
his magnum opus, The Origin. By June 1858 Darwin had
completed about half of the book (on a scale three to four
times as large as when it was later published), when one
day a nasty surprise awaited him.
 
On June 18, Darwin received a manuscript from the English
naturalist, Wallace. In the manuscript Wallace described
the theory of natural selection, and asked Darwin to
comment on his ideas. Darwin thought that the only
honorable thing to do was to recommend the paper for
publication. Fortunately, for Darwin, Lyell suggested (and
Wallace and Darwin accepted) that both Wallace's paper and
extracts from Darwin's sketch of 1844 be published
simultaneously, thus establishing the rights of both to
priority. Interestingly, later on at the fiftieth
anniversary meeting of their joint publication, Wallace
made it clear that although the idea of natural selection
came to both of them independently, Darwin's contributions
outweighed his by twenty to one because Darwin had the
credit of twenty years of priority and work.
 
Finally, by 1859 Darwin finished writing the book, and on
November 24 the Origin was first published. The sales of
the book exceeded everyone's expectations (by 1876 16,000
copies were sold in England alone), and the book's impact
was felt almost immediately. In the mid nineteenth century
English society where science was a popular topic of
conversation, the book competed with such dinner party
topics as the Italian revolution. Even those who most
bitterly despised its content were quick to concede its
importance.
 
Within the scientific community the book was creating a new
paradigm that threatened to disrupt the existing
status-quo. The mood of the time is illustrated by August
Weismann who states: "Darwin's book fell like a bolt from
the blue; it was eagerly devoured, and while it excited in
the minds of the younger students delight and enthusiasm,
it aroused among the older naturalists anything from cool
aversion to violent opposition". The young saw in Darwin an
opportunity for a new and freer philosophical universe. For
instance, young biologists such as Karl Pearson, referring
to the beginning of time, were rejoiced when "that wretched
date BC 4004, was replaced by a long vista of millions of
years of development". However, the older more professional
scientists, objected to Darwin's ideas on religious
grounds. 

Before Darwin published the Origin, science and religion
existed in harmony. There was an understanding on the part
of religion that evolution was discredited by science. Now
that men of science were finally favorites of the church
(just two centuries ago scientists such as Galileo were
unfavorably perceived by the church), it seemed foolish to
give up this hard won peace for just another evolutionary
hypothesis.
 
Although Darwin discussed sexual selection in the Origin,
the majority of the book (and hence the primary importance)
was devoted to natural selection. However, sexual selection
played a far more important role in Darwin's The Descent of
Man, and Selection in Relation to Sex (henceforth referred
to as the Descent), which was published on February 24,
1871. In the Descent, sexual selection assumed an equal if
not greater than role for the origin of species. 

For Darwin sexual selection was not simply a subcategory of
natural selection, but rather an alternative or
complementary mechanism of evolution. In addition, sexual
selection, to a larger extent than natural selection,
shifts the focus of attention to one of the most
significant and least appreciated aspects of Darwin's
theory: "the location of the struggle for existence lies
primarily within species rather than between species". It
is therefore inaccurate, from this point on, to refer to
Darwin's theory as simply "evolution by natural selection"
(Darwin himself called the theory "the principle of
evolution").
 
The primary reason why Darwin "abandoned" natural selection
in favor of sexual selection was the fact that natural
selection could not properly explain either the evolution
of man from the animals or the differences between the
sexes and races. The problem is that natural selection
assumes that only beneficial changes get preserved in
future generations, whereas in reality "the races of man
differ from each other and from their nearest allies
amongst the animals , in certain characters which are of no
service to them in their ordinary habits of life". By
contrast, sexual selection does not have to be useful for
the purpose of adaptation to the environment, and it may
actually work against natural selection. Therefore, Darwin
now argued that any features which are not adaptive to the
individual, and thus could not have been acquired through
the process of natural selection, must have been acquired
through sexual selection.
 
When the Descent was published in 1871, it became an
immediate best-seller. The initial 2500 copies were sold
almost instantaneously, and an additional 5000 copies were
sold by the end of the year. The book was exceedingly
controversial at the time, dealing with perhaps the most
provocative evolutionary topic of all, the origin of man.
In the book Darwin suggested that man differed from animals
in degree and not kind, and than proceeded to conclude that
man descended from a "hairy, tailed quadruped, probably
arboreal in its habits". Surprisingly, the reaction to the
book was not as violent as one might have expected it to
be, from Darwin's previous experience with the Origin. For
instance, Hooker, who at that time found evolution
discussed everywhere relates the following: "I dined out
three times last weak, and at every table heard evolution
talked of as an accepted fact, and the descent of man with
calmness". However, the picture painted by Hooker is rather
deceptive, as the portrayed amiability was often a matter
of tone rather than of substance. People may not have been
outraged, but neither were they placated.
 
Most of the critics choose to ridicule Darwin's ideas
rather than attack them head on. For example, a typical
response, published in the Athenaeum, went along the lines
of: "No man will ever develop religion out of a dog or
Christianity out of a cat". Nevertheless, criticism was
mostly tempered with praise. A good example of this is
provided in the Edinburgh Review which carefully balanced
displeasure with tribute: "Mr. Darwin appears to us to be
not more remarkable for the acuteness and ingenuity of his
powers of observation of natural phenomena, than he is for
the want of logical power and sound reasoning on
philosophical questions".
 
Therefore, while despised by some and adored by others,
Darwin's ideas were quickly permeating into the fabric of
society.
 
Darwin left us a legacy which is greater than just the sum
of his scientific work. Not only did his theory of
evolution illuminate our past, but also the present and the
future were now possible to interpret in "Darwinian terms".
Probably more so than any other scientific theory, Darwin's
theory of evolution, lends itself to various social
interpretations known as "social Darwinism".
 
From the radical left to the radical right, Darwin's theory
has been adopted by such people as Marx and Hitler, each of
whom saw in it evidence for their own ideology. Alongside
the likes of Copernicus, Galileo, and Newton, Darwin has
rightly earned his place in history as one of the giants of
the scientific revolution. 
 
Bibliography
 
Bowler, Peter J. Charles Darwin the Man and His Influence.
Basil Blackwell Ltd. London, 1990
 
Himmelfarb, Gertrude. Darwin and the Darwinian Revolution.
Doubleaday & Company Inc. New York, 1959
 
Lewontin, R. C. Darwin and Mendel-the Materialist
Revolution. In: Neyman (ed.) The Heritage of Copernicus.
MIT Press. Cambridge, 1974.
 
Gertrude Himmelfarb. Darwin and the Darwinian Revolution.
Doubleaday & Company Inc. New York 1959. p. 168
 
Ibid. p. 33
 
Ibid. p. 43
 
Ibid. p. 53
 
Ibid. pp. 109-112
 
Ibid. p. 111
 
Ibid. p. 112
 
Ibid. p. 111
 
Ibid. p. 146
 
Ibid.
 
Ibid. p. 150
 
Peter J. Bowler. Charles Darwin the Man and His Influence.
Basil Blackwell Ltd. London, 1990 p. 79
 
Himmelfarb. Darwin and the Darwinian Revolution. p. 152 

Ibid. p. 154
 
Ibid. p. 155
 
Ibid. p. 157
 
Ibid. p.159
 
Ibid. p. 161
 
Ibid. pp. 189-190
 
Ibid. p. 280
 
Ibid. p. 282
 
Ibid. pp. 271-272
 
Ibid. pp. 299-300
 
Ibid. p. 346
 
Ibid. p. 342
 
Ibid. p. 336
 
Ibid. p. 337
 
Ibid. p. 338
 
Ibid. pp. 394-400