We are skeptical of the claims for the ability of random mutation and natural selection to account for the complexity of life. Careful examination of the evidence for Darwinian theory should be encouraged. (A Scientific dissent from Darwinism, signed by over 100 advanced degree scientists.)
A new era of biology began on November 24, 1859, the day Charles Darwin published On
The Origin of Species by Means of Natural Selection. Darwin’s book drew a cohesive picture of life by connecting the dots among what had once seemed a bewildering array of unrelated observations.
The Origin of Species focused biologists’ attention on the great diversity of organisms—their origins and relationships, their similarities and differences, the geographic distribution, and their adaptation to surrounding environments
.
Darwin made two major points in the Origin of Species. First, he presented evidence that the many species of organisms presently inhabiting the earth are descendants of ancestral species that were different from the modern species. Second, he proposed a mechanism for this evolutionary process, which he termed natural selection. The basic idea of natural selection is that a population can change over generations if individuals that possess certain heritable traits leave more offspring than other individuals. The result of natural selection is evolutionary adaptation, an accumulation of inherited characteristics that enhance organisms’ ability to survive and reproduce in specific environments. In modern terms, we can define evolution as [1]*a change over time the genetic composition of a population. Eventually, a population may accumulate enough change that it constitutes a new species—a new life form. Thus we can also use the term evolution on a grand scale to mean [2]*the gradual appearance of all of biological diversity, from the earliest microbes to the enormous variety of organisms alive today.
Evolution is such a fundamental concept that its study illuminates biology at every level from molecules to ecosystems, and it continues to transform medicine, agriculture, biotechnology, and conservation biology.
(AP Biology 7th edition, p 438)
What is Evolution?
Copyright © 1993-1997 by Laurence Moran
[Last Update: January 22, 1993]
Most non-scientists seem to be quite confused about precise definitions of biological evolution. Such confusion is due in large part to the inability of scientists to communicate effectively to the general public and also to confusion among scientists themselves about how to define such an important term. When discussing evolution it is important to distinguish between the existence of evolution and various theories about the mechanism of evolution. And when referring to the existence of evolution it is important to have a clear definition in mind. What exactly do biologists mean when they say that they have observed evolution or that humans and chimps have evolved from a common ancestor?
One of the most respected evolutionary biologists has defined biological evolution as follows:
"In the broadest sense, evolution is merely change, and so is all-pervasive; galaxies, languages, and political systems all evolve. Biological evolution ... is change in the properties of populations of organisms that transcend the lifetime of a single individual. The ontogeny of an individual is not considered evolution; individual organisms do not evolve. The changes in populations that are considered evolutionary are those that are inheritable via the genetic material from one generation to the next. Biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population (such as those determining blood types) to the successive alterations that led from the earliest protoorganism to snails, bees, giraffes, and dandelions."
- Douglas J. Futuyma in Evolutionary Biology, Sinauer Associates 1986
It is important to note that biological evolution refers to populations and not to individuals and that the changes must be passed on to the next generation. In practice this means that,
Evolution is a process that results in heritable changes in a population spread over many generations.
This is a good working scientific definition of evolution; one that can be used to distinguish between evolution and similar changes that are not evolution. Another common short definition of evolution can be found in many textbooks:
"In fact, evolution can be precisely defined as any change in the frequency of alleles within a gene pool from one generation to the next."
- Helena Curtis and N. Sue Barnes, Biology, 5th ed. 1989 Worth Publishers, p.974
One can quibble about the accuracy of such a definition (and we have often quibbled on these newsgroups) but it also conveys the essence of what evolution really is. When biologists say that they have observed evolution, they mean that they have detected a change in the frequency of genes in a population. (Often the genetic change is inferred from phenotypic changes that are heritable.) When biologists say that humans and chimps have evolved from a common ancestor they mean that there have been successive heritable changes in the two separated populations since they became isolated.
Unfortunately the common definitions of evolution outside of the scientific community are different. For example, in the Oxford Concise Science Dictionary we find the following definition:
"evolution: The gradual process by which the present diversity of plant and animal life arose from the earliest and most primitive organisms, which is believed to have been continuing for the past 3000 million years."
This is inexcusable for a dictionary of science. Not only does this definition exclude prokaryotes, protozoa, and fungi, but it specifically includes a term "gradual process" which should not be part of the definition. More importantly the definition seems to refer more to the history of evolution than to evolution itself. Using this definition it is possible to debate whether evolution is still occurring, but the definition provides no easy way of distinguishing evolution from other processes. For example, is the increase in height among Caucasians over the past several hundred years an example of evolution? Are the color changes in the peppered moth population examples of evolution? This is not a scientific definition.
Standard dictionaries are even worse.
"evolution: ...the doctrine according to which higher forms of life have gradually arisen out of lower.." - Chambers
"evolution: ...the development of a species, organism, or organ from its original or primitive state to its present or specialized state; phylogeny or ontogeny" - Webster's
These definitions are simply wrong. Unfortunately it is common for non-scientists to enter into a discussion about evolution with such a definition in mind. This often leads to fruitless debate since the experts are thinking about evolution from a different perspective. When someone claims that they don't believe in evolution they cannot be referring to an acceptable scientific definition of evolution because that would be denying something which is easy to demonstrate. It would be like saying that they don't believe in gravity!
Recently I read a statement from a creationist who claimed that scientists are being dishonest when they talk about evolution. This person believed that evolution was being misrepresented to the public. The real problem is that the public, and creationists, do not understand what evolution is all about. This person's definition of evolution was very different from the common scientific definition and as a consequence he was unable to understand what evolutionary biology really meant. This is the same person who claimed that one could not "believe" in evolution and still be religious! But once we realize that evolution is simply "a process that results in heritable changes in a population spread over many generations" it seems a little silly to pretend that this excludes religion!
Scientists such as myself must share the blame for the lack of public understanding of science. We need to work harder to convey the correct information. Sometimes we don't succeed very well but that does not mean that we are dishonest. On the other hand, the general public, and creationists in particular, need to also work a little harder in order to understand science. Reading a textbook would help.
--
In the preceeding discussion, Laurence Moran (as posted on Origins.net) seeks to clarify just what scientists mean by the term evolution. He points out specifically that populations (as opposed to individuals) evolve, and that gradualism should not be included in the definition. The only problem -- even after a number of clarifications, we are still treated to several ideas of what evolution might entail.
Take for example, the first sited definition provided by Douglas J. Futuyma
"In the broadest sense, evolution is merely change, and so is all-pervasive; galaxies, languages, and political systems all evolve. Biological evolution ... is change in the properties of populations of organisms that transcend the lifetime of a single individual. The ontogeny of an individual is not considered evolution; individual organisms do not evolve. The changes in populations that are considered evolutionary are those that are inheritable via the genetic material from one generation to the next. Biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population (such as those determining blood types) to the successive alterations that led from the earliest proto-organism to snails, bees, giraffes, and dandelions."
Within this sample are at least three ideas how the word “evolution” is used by thoughtful people.
1) Broad Brushstroke: i.e. Pervasive, systematic change, ranging from galaxies to politics.
2) Biological evolution: Change in the properties of populations over time
3) Applied Evolution: i.e., the successive changes which characterize the transformation of proto-organsims to the broad display of biological life we know today.
As the essay by Moran continues, the author hones in on the second meaning, and elevates it as the standard.
The only problem, with this limited definition, is that it does not address the central idea that is at the core of the origins debate.
Introductory thoughts
Evolution as a concept holds many meanings, henceforth, a poor word to use asking certain kinds of questions (or making certain statements). The question “Do you believe in evolution” --is specifically problematic because of the multi-hued nature of the word itself. A person might believe in evolution (given one meaning) and disbelieve in it given another. (The same problem holds for the statement “Evolution is a fact.”
For problematic definitions see
http://creationevolutiondesign.blogspot.com/2008/02/poe-111-no-standard-definition-of.html
The “ethos” of evolution may apply (and often is) to the larger question of the origin of the universe, but technically speaking “Evolution” is properly applied only to existing biological systems. Naturalism offers suggestions about the origin of the universe, or the origin of life, but evolution as formally understood, has nothing to say.
The Big Bang theory (whatever its merits, or lack thereof, should not be argued as part of the evolutionary debate.)
What is Evolution?
( ) However, this lack of a standard definition of "evolution" provides evolutionists with an enormous tactical advantage, in that the same word "evolution" can mean something as narrow as "dog-breeding" and as wide as "all living things are the accidental products of a purposeless universe" (Johnson, 1997, pp.44-45). "Evolution" therefore is a highly manipulable (sp?) term that enables the evolutionist to switch back and forth between those very different meanings of "evolution" and any meaning in between, during in the course of the same discussion (Johnson, 1995, p.74).
(Steven Jones/Blog) http://creationevolutiondesign.blogspot.com/2008/02/poe-111-no-standard-definition-of.html
This may be repete:
Addendum: Critique of Evolution:
Introductory thoughts
Evolution as a concept holds many meanings, henceforth, a poor word to use asking certain kinds of questions (or making certain statements). The question “Do you believe in evolution” --is specifically problematic because of the multi-hued nature of the word itself. A person might believe in evolution (given one meaning) and disbelieve in it given another. (The same problem holds for the statement “Evolution is a fact.”
For problematic definitions see
http://creationevolutiondesign.blogspot.com/2008/02/poe-111-no-standard-definition-of.html
The “ethos” of evolution may apply (and often is) to the larger question of the origin of the universe, but technically speaking “Evolution” is properly applied only to existing biological systems. Naturalism offers suggestions about the origin of the universe, or the origin of life, but evolution as formally understood, has nothing to say.
The Big Bang theory (whatever its merits, or lack thereof, should not be argued as part of the evolutionary debate.)
We are skeptical of the claims for the ability of random mutation and natural selection to account for the complexity of life. Careful examination of the evidence for Darwinian theory should be encouraged. (A Scientific dissent from Darwinism, signed by over 100 advanced degree scientists.)
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