Darwin's Legacy
| Organization for the Advancement of Interdisciplinary Learning |
The intellectual heritage passed down to us from Charles Darwin, although static in its
foundations, continues to be a dynamic force for academic and scientific exploration. Darwin
(1809-1882) was a Victorian gentleman educated as a minister who famously pursued an
occupation as a self educated naturalist. His theories have been elaborated on generously
without being modified to any large degree despite the fact that it has been nearly 150 years
since his first book, On the Origin of Species, was published. This book and subsequent works
by Darwin have provided the platform for a number of new fields of biological science. Like
any theorist in the sciences, Darwin was forced to make dozens of explicit and implicit
suppositions while writing. Time has revealed that the majority of the assumptions that his
theories relied on have proven to be correct. Conclusions that he reached, mostly through
thought-experiment and inductive logic, have caused revolutions in scientific and philosophical
thought, permitted humanity to find its place in nature, and both shaken and shaped our
deepest religious convictions. Although Darwin was able to achieve success in his lifetime,
there were still some questions he was never able to answer; some findings he was never able
to explain. Through advancements in technology, paired with the continued research of
scientists, much of what Darwin saw as the “unexplained” has been able to come to light.
Darwin was one of the first, educated, natural historians to see the world with his own eyes.
His trip around the world on the H.M.S. Beagle was truly formative for him and gave him a
cosmopolitan perspective on biology that few scientists of his time had. A close friend and
mentor advised that he spend his idle time during the voyage reading and recommended several
great books. Darwin read each of these suggested books on the boat, and later spoke about the
influence that they had on him (McCain, p. 97). The first book was Charles Lyell’s Principles of
Geology. This opus suggested that the earth is slowly but constantly changing, and that the
geological changes proceeded no faster or slower in the past than they do in modern times.
This idea, that geological changes happen too slowly to appreciate in a year- or even in a
lifetime- resonated with Darwin to a very large degree. Second, Thomas Malthus’ Essay on the
Principles of Population, and its arguments related to population surpluses, limited resources and
the competition to survive, greatly affected Darwin and allowed him to see much further than
the naturalists that came before him. Malthus’ essay was primarily concerned with economics,
there actually wasn’t a sentence about biology, but Darwin derived his first postulate of natural
selection from its wisdom (Futuyama, p. 85). This underscores the importance of
interdisciplinary thought in his work, and interestingly, the interdisciplinary approach continues
to be the one taken by present day evolutionary biologists.
A number of theorists proposed evolutionary theories before Darwin did. Individuals like
Georges-Louis Buffon, Jean Baptiste Lamarck and Charles’ own grandfather Erasmus Darwin
wrote about the interrelatedness of all living organisms and set precedence for the Darwinian
revolution. The capacity for evolutionary change in animal populations is a concept that can
actually be traced back to Greek philosophy but we credit Darwin because he was able to
logically delineate how this change occurs in the natural world, a rational concept that proved
elusive for all those that came before him.
In the 19th century it was largely thought that “acquired” traits, characteristics brought about
through use or disuse, could be heritable. Lamarck based his theory of evolution, one that
preceded Darwin’s, on this faulty premise. Although Darwin didn’t disagree with
“aquireability” of traits, he didn’t see acquired traits as the source of variation that natural
selection acted on, he thought that it acted on variation in particulate inheritance. He couldn’t
say where this variation stemmed from, though. Interestingly, Lamarckism was refuted and
ridiculed in the 20th Century, but it has been, more or less, exhumed in the last few decades.
Recent heritability studies have proven that a small degree of genetic traits can be acquired,
and then passed on to offspring, and this fascinating, new branch off of genetics is now called
“phenotypic plasticity.”
Darwin knew that science was not hospitable to speculation and that he was dealing with a
volatile, religiously offensive issue, so he delayed publication in order to elaborate, gather
more evidence and develop the best possible case (Rennie, p. 83). He waited a full 20 years,
after first outlining the theory, to publish. He was actually pushed to do so after receiving a
manuscript written by a contemporary, Alfred Russel Wallace, which was entitled On the
Tendency of Varieties to Depart Indefinitely from the Original Type. They both presented their
essays to the Linnean Society of London on July 1, 1858. On November 24, 1859, Darwin
published and released the famous, On the Origin of Species by Means of Natural Selection
(Zimmer, p. 145). If given the luxury of hindsight, Darwin may not have delayed publication for
so long, due to the fact that today it looks as if the vindication of his writings was inevitable.
Darwin asserted that natural selection can be explained through a series of four postulates, each
a logical step in the process: 1) Animals produce more young than are realistically viable. 2)
Traits that an animal exhibits are heritable. 3) The environment will favor the animals with
certain traits over others. 4) Animals with “adaptive” traits will survive to procreate, and
achieve greater reproductive success, causing them to parent subsequent generations. These
four postulates persist to date, completely unchanged, attesting to Darwin’s farsightedness and
prescience (Appleman, p. 183).
Biologists and evolutionary scholars continue to be astonished, not only by the number of
original hypotheses proposed by Darwin, but also by their accuracy. For instance, Darwin
explained: as adaptations arise by natural selection “the ultimate result is that each creature
tends to become more and more improved in relation to its condition.” But lowly organisms
continue to persist because “natural selection, or the survival of the fittest, does not necessarily
include progressive development; it only takes advantage of such variations that arise and are
beneficial to each creature under its complex relations to life.” Here he addressed what has
become one of the most misunderstood facets of evolution. Many people learning about
evolution tacitly assume that it is a “progressive” process. He foresaw this mistake and was
very careful to address it. Today, writings from junior high texts to peer reviewed articles try
to point out and rectify this common misconception (Hayden, p. 46).
Many scientists embraced Darwinism early on, however, it evoked strong protests from both
scientific and ecclesiastical circles. For instance, Louis Agassiz enthusiastically countered
Darwin, declaring that individual animals fall into discrete groups, without intermediary forms
and that each group was unique due to the fact that it was created by God independently. He
based much of his argument on the idea that birds were an example of this fact; that many
groups have clearly defined boundaries, ones which separate them from other groups in terms
of skeletal structure, behavior, appearance and position in the fossil record. Amazingly, just a
few years later, in 1868, the fossil, Archaeopteryx, a perfect example of an intermediate
between birds and reptiles rendered Agassiz’s point moot (Hull, p.192).
Since the time of its publication, hundreds of seemingly rational objections to Darwin’s Origins
have been overturned by new findings, discoveries and experiments supporting nearly
everything Darwin had to say about natural history. Today his theory of natural selection, or as
he called it early on, “transmutation of species,” has been reconciled with many other fields of
biology including: anthropology, cellular biology, ecology, ethology, genetics, microbiology,
paleontology and dozens of others. In fact, Darwinian evolution has spawned a large number of
subdisciplines that could have hardly existed without it: Darwinian Medicine, Evolutionary
Psychology, Exobiology, Molecular Taxonomy, Phylogeny, Sociobiology and Systematics, just to
name a few.
Darwinian evolution hasn’t always enjoyed such influence and success. It actually took a
backseat to genetics in the early part of the 20th century. This was partly due to the fact that
so many advances were being made in genetics as Gregor Mendel’s “laws of inheritance” were
being rediscovered, and partly because Darwin could not join his ideas with what was then
known about heritability. In fact, he couldn’t even explain where these variations in traits
were coming from. Darwin, along with others of his time, assumed that “particles of
inheritance” were passed through sperm and eggs, but it took the first half of the 1900’s for
scientists to begin to understand evolution in the language and phenomena of genetics, and vice
versa. This detailed reconciliation between the two disciplines, which happened decades after
Darwin’s death, came to be known as NeoDarwinism.
Darwin correctly assumed that “particles of inheritance” could determine how an organism will
develop and what it will look like but he had no idea how they might accomplish this. Today
we know that these particles that Darwin theorized about are contained in all cells and are
passed from cell to cell every time a cellular division takes place. The particles are what we
now know as DNA, “long linear molecules, or polymers that contain genes” (Campbell, p. 457).
Genes are recipes for proteins, and are “used by the cell as a template to mass produce proteins
which themselves perform chemical functions, and guide development” (Ridley, p. 26). DNA is
actually composed of small molecular subunits, called nucleotides, made of a few dozen atoms
each. As of the year 2000, we know that there are around 3 billion nucleotides and close to
33,000 genes in the human genome.
We have come a long way in describing the molecular basis of life and we have even uncovered
the evasive source of variation that Darwin’s theories once precariously stood upon. Before a
cell can divide it must copy the full nucleotide sequence that it holds so that both “daughter”
cells can carry the entire complement. During this copying process, mistakes are sometimes
made, and these errors are the source of gene pool variation that Darwin must have spent many
hours contemplating. About “1 mistake is made for every 10,000 nucleotides copied” and this
equates to (excluding the many mistakes which will be repaired) about 100 mutations per
generation (Ridley, p.141). These mutations create the variability in character that natural
selection picks and chooses from to guide each species off on different trajectories. Darwin
reasoned that somehow new types of heritable particles must find their way into the gene pool,
but because the technology of his time was far less advanced than ours today, he could never
have known that this was accomplished through mutations (Mayr, p. 80).
Examining the issues that Darwin faced, considering the answers that he didn’t live to hear, and
analyzing the new discoveries in evolutionary science is a fascinating area for many historians
and scientists today. Even in present time, evolution is a cause of discomfort and contention,
mostly in the U.S., but it is widely accepted by educated people around the world and has
helped us to makes sense of what we are, where we came from and how we are interrelated
with other animals. The significance of the intellectual “inheritance” that we received from
Darwin has been summarized well by Russian biologist Theodosius Dobzhansky: “nothing in
biology makes sense except in the light of evolution (Dobzhansky, p. 443).”
Works Cited
Appleman, Philip. Darwin: A Norton Critical Edition. Norton and Company: New York, 1970.
Campbell, Neil and Jane Reece. Biology. Benjamin Cummings: San Francisco, 2002.
Dobzhansky, Theodosius. “Biology, Molecular and Organismic." American Zoologist. 4
(1964): 443-452.
Futuyama, Douglas, J. The Growth of Evolutionary Science. Pantheon Books: Cambridge,
UK 1982.
Hayden, Thomas. “A Theory Evolves.” U.S. News and World Report. 133.4 (2002): 42- 50.
Hull, D.L. Darwin and His Critics. Harvard University Press: Cambridge, MA 1973.
Mayr, Ernst. “Darwin’s Influence on Modern Thought”. Scientific American. 283.2 (2000): 79-
83.
McCain, John and Marshall Salter. Character is Destiny. Random House: New York, 2005.
Rennie, John. “15 Answers to Creationist Nonsense”. Scientific American. 287.1 (2002): 78-
85.
Ridley, Matt. Genome. Harper Collins: New York, 1999.
Zimmer, Carl. Evolution: The Triumph of an Idea. Harper Collins: New York, 2001.