Darwinian Evolution - Theory & Fact

Charles Darwin's Evolutionary Mechanism of Natural Selection

Dec 23, 2007
Tami Port

: Avian Evolution: Archaeopteryx fossil - Originator unknown. Source hmnh org

"It is important to understand that the current questions about how life evolves in no way imply any disagreement over the fact of evolution." - Neil A. Campbell

Those who still dispute evolution often use the argument that it is “just a theory.” Stating that, as theory, scientists cannot even agree if it occurs.

This is an argument of those with little understanding of what evolution actually is. Evolution occurs. It is observable not only in the geologic record, but also in the world around us. Evolution means change, and populations of organisms certainly change over time. So where does the confusion lie regarding evolutionary theory?

Is Evolution ‘Just’ a Theory?

Non-biologists discussing the “theory of evolution” typically confuse two different aspects to evolutionary theory:

1. Does evolution occur?

2. How does evolution occur (i.e. what is the mechanism)?

Does Evolution Occur?

The first is a question of whether modern organisms evolved from ancestral organisms and are continuing to change over time. Biologists consider the existence of biological evolution to be a fact. It can be demonstrated today and the historical evidence for its occurrence in the past is overwhelming.

How Does Evolution Occur?

Beyond the fact that organisms do change over time, there is the question of how, or the mechanism change. Regarding this question, biologists are still discussing and debating the details of 'how,' and there are several theories regarding the mechanism of evolution.

Evolution as Fact & Theory

The late Stephen J. Gould, one of the great thinkers regarding evolution, explained the confusion as such: “…Facts and theories are different things…Facts are the world's data. Theories are structures of ideas that explain and interpret facts. 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.”

How Does Evolution Work?

Evolution can be defined as inheritable change in a population that ultimately results from the interaction of individuals with their environment. And its action over very large stretches of time explains the origin of new species, occasionally the elimination of existing species and ultimately the vast diversity of the biological world.

Today’s species are related to each other through common decent (ancestors that they share) and are products of evolution over billions of years.

Key concepts of evolution:

Any change must be inheritable (able to be passed on to the next generation).

These changes are regulated by natural selection.

Natural Selection

Natural selection is the theorized mechanism of evolution, the process in nature by which only the organisms that are best adapted to their environment tend to survive and transmit their genetic characteristics to the next generation. Individuals less well adapted to their environment tend to be eliminated.

More Information on Evolution

See the Science education website Science Prof Online for more information on evolution and natural selection or L. Moran's article Evolution is a Fact and a Theory or the Suite101 articles Darwin, Evolution & Natural Selection, Natural & Artificial Selection or Pre-Darwinian Evolutionary Theory.

Sources

Moran, L. (1993) Evolution is a Fact and a Theory.

Gould, S. J. (1981) Evolution as Fact and Theory. Discover, May issue.

Campbell, N.A. (1990) Biology 2nd ed., Benjamin Cummings, p. 434.

Tami Port, MS, creator of SciencProfOnline.com, Tami Port

Tami Port - After completing a bachelor's degree in biology and master's degree in psychology, I continued to pursue my love of learning by collecting ...

Comments

Oct 8, 2009 5:50 AM

Guest :

Darwin is an idiot. Are you trying to tell me that a monkey and a cucumber are cousins? Right, and what about the evolution of the horse? they removed it from the school books, why? Species don't evolve from other species, there has NEVER been a transitional fossil of ANY species from one to another, even from CRO-MAGNON MAN to HOMOSAPIEN. And don't believe this "facts are the worlds data" crap unless you can prove it yourself, otherwise your going on someone else's PERCEPTION of the world's data. --- "Listen to everything, believe nothing, unless you can prove it.":William Cooper...Thanks for your time :)

May 11, 2010 6:57 AM

Guest :

Tell me any other way we were made...and dont say anything unless u can prove it!!!!! =@

May 18, 2010 4:10 AM

Guest :

Actually species do evolve from other species.... how about do some reading other than the bible, try researching allopatric speciation, the geographic seperation of a single species leading to the formation of new species! If you want to see evolution proved just look at Geochelone elephantopus, through natural selection each islands tortoise has a very different shell morphology and is dependant on the location of the vegitation, the higher the food, the higher the shell has to be to reach meaning the animals with short necks and low shells would die and therefore not pass on genes. These islands subspecies are derived from a common ancestor G. elephantopus and with time will go on to be their own species thus meaning they have evolved. And as for your fossil theory... There has only been 1 to 10% of all living species catalogued through fossils because not all have been preserved. The only way your going to disprove evolution through fossils is if you somehow manage to find a pre- Devonian mamal skeleton.. good luck with that.

Aug 2, 2010 2:54 AM

Guest :

There is only one explanation for the diverse life on this planet that has living examples, fossils, DNA evidence etc to back it up, ..........it's called Evolution. There is even man-made Evolution, just look at all the different breeds of dogs or varieties of orchids, the facts are there for all to see.

Jan 13, 2011 1:04 PM

Guest :

Darwin has never been idiot, you are. You need to read more about it, than to make those stupid guesses.

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