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Saturday, January 13, 2007

What Is Evolution?

Most non-scientists seem to be quite confused about precise definitions of biological evolution. Part of the confusion is because the word "evolution" has many different meanings, depending on the context. When we talk about biology we are thinking about biological evolution and that's the term I want to define here. What do biologists mean when they refer to biological evolution?

One of the most respected evolutionary biologists has recently defined biological evolution as follows:
Biological (or organic) evolution is change in the properties of populations of organisms or groups of such populations, over the course of generations. The development, or ontogeny, of an individual organism is not considered evolution: individual organisms do not evolve. The changes in populations that are considered evolutionary are those that are ‘heritable' 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 proportions of different forms of a gene within a population, such as the alleles that determine the different human blood types, to the alterations that led from the earliest organisms to dinosaurs, bees, snapdragons, and humans.
Douglas J. Futuyma (1998) Evolutionary Biology 3rd ed., Sinauer Associates Inc. Sunderland MA p.4
Note that biological evolution refers to populations and not to individuals. In other words, populations evolve but individuals do not. This is a very important point. It distinguishes biological evolution from other forms of evolution in science (e.g., stellar evolution). Another important point is that the changes must be genetic, or heritable—they must be passed on to the next generation. Evolution is the process by which this occurs and it is spread out over many generations. Thus, the short minimal definition of biological evolution is,
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, but it also conveys the essence of what evolution really is. When biologists say they have observed evolution, they mean that they have detected a change in the frequency of genetic variants (alleles) in a population. (Often the genetic change is inferred from phenotypic changes.) When biologists say that humans and chimps have evolved from a common ancestor, they mean there have been successive heritable changes in the two separated populations since they became isolated.

Unfortunately, outside of the scientific community, the common definitions of evolution are quite 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 that's supposed to be a dictionary of science. Not only does this definition exclude prokaryotes, protozoa, and fungi, but it specifically includes a term "gradual process" that 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 Europeans over the past several hundred years an example of evolution? Are the color changes in peppered moth populations examples of evolution? The definition of evolution in the Oxford Concise Science Dictionary is not a proper scientific definition of evolution.

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. The problem is that it's 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 they don't believe in evolution they cannot be referring to an acceptable scientific definition of biological evolution because that would be denying something that is easy to prove. It would be like saying they don't believe in gravity!

Anti-evolutionists often claim scientists are being dishonest when they talk about evolution. The anti-evolutionists believe that evolution is being misrepresented to the public. The real problem is that the public in general, and anti-evolutionists in particular, do not understand what evolution is all about. Their definition of evolution is very different from the common scientific definition and, as a consequence, they are unable to understand what evolutionary biology really means. Scientist are not trying to confuse the general public by using a rigorous definition of evolution. Quite the contrary, saying that evolution is simply "a process that results in heritable changes in a population spread over many generations" is a way of simplifying discussions about evolution.

Note that I have described the minimal scientific definition of biological evolution. Nobody believes that this is all there is to evolution. There are other processes, such as speciation for example, that are clearly important parts of the process of evolution. [Macroevolution]

Objections to the Minimal Definition

Some people, including some scientists, are uncomfortable with this minimal definition because they think it excludes some important parts of evolutionary biology. I'll try and discuss the various objections in a short while but first let me explain why we need a strict minimal definition in the first place.

I've already alluded to one of the classic questions that a proper definition can answer—the increased height of Europeans over the past five centuries. Armed with a good definition of biological evolution we can focus on one of the key requirements; namely, heritable change. It turns out that the increase in height is due to a better diet and not to genetic changes. Therefore, this is not evolution according to the scientific definition.

We can also ask whether the development of antibiotic resistance in bacteria is a valid example of biological evolution. In this case the answer is "yes" because a new antibiotic resistance allele has arisen by mutation and subsequently became fixed in the population. Anyone who wants to offer an alternative minimal definition of evolution will have to make sure that it will help answer questions such as these.

Sometimes it's convenient to refer to evolution as "descent with modification." This conveys a different impression of evolution than the minimal definition. Descent with modification refers to the long-term consequences of short-term changes within a population. It incorporates additional concepts such as speciation, which is an important part of macroevolution. Paleontologists are one group of scientists who aren't directly concerned with the minimal definition of evolution since they are mostly interested in the history of life. They have to deduce that evolution, in the sense of the minimal definition, has taken place from evidence of phenotypic change in the fossil record.

The bad thing about "descent with modification" is that it's not a very rigorous definition. It doesn't rule out modifications that are not genetic in origin and it doesn't rule out individuals evolving—as opposed to populations.

Many people are confused about the difference between a definition and an explanation. That's why we often see incorrect "definitions" that describe how natural selection works. This is wrong. In order to be useful, a definition has to enable us to distinguish examples of evolution from non-evolution but the definition should be neutral with respect to how evolution occurs. It should not distinguish, for example, between Lamarckian evolution and Darwinian evolution even though we know that one of these explanations is incorrect.

Attempts to define evolution in terms of natural selection are not only logically flawed but scientifically flawed as well. They exclude change due to random genetic drift when every evolutionary biologist agrees that drift is a mechanism of evolution.

Evolving Definitions

In 1997 a group of twenty scientists chaired by Douglas J. Futuyma issued a working draft of a "white paper" on Evolution, Science, and Society. The paper was written on behalf of eight scientific societies who wanted to make a statement about evolution. The initial draft defined evolution as,
Biological (or organic) evolution consists of change (modification) in the hereditary characteristics of groups of organisms over the course of generations. Such groups of organisms, termed populations or species, are formed by division of ancestral populations or species, and the descendant groups then change independently. Hence, in a long-term perspective, evolution is the descent, with modification, of different lineages from common ancestors.
This is a pretty good definition. It includes the minimal definition but adds the idea that long-term evolution is descent with modification. The initial draft definition was modified [final draft] so that on the current website it now reads,
Biological evolution consists of change in the hereditary characteristics of groups of organisms over the course of generations. From long-term perspective, evolution is the descent with modification of different lineages from common ancestors. From a short-term perspective, evolution is the ongoing adaptation of organisms to environmental challenges and changes.
This last sentence is really unfortunate. These twenty scientists have now agreed to a definition that specifically mentions the mechanism of adaptation. This is not how one should define evolution. One wonders whether they mean to exclude random genetic drift or whether they simply lost sight of their goal in trying to work out a compromise definition.

The Gene Centrist Objection

Ernst Mayr wrote an entire book on the subject of this little essay. One might expect some insight from one of the original founders of the Modern Synthesis but, unfortunately, we aren't going to get any help from Mayr. On page 157 he says,
Evolution in sexually reproducing organisms consists of genetic changes from generation to generation in populations, from the smallest local deme to the aggregate of interbreeding populations in a biological species.
Ernst Mayr (2001) What Evolution Is, Basic Books, New York p.157
This is good stuff. It restricts the changes to genetic changes and it clearly identifies the population as the unit that evolves. There's no mention of any particular mechanism. But—and you knew there was going to be a "but" didn't you?—good things never last. In his chapter on macroevolution Mayr describes the work of his colleagues Rensch and Simpson. These workers were able to study macroevolutionary events without referring to allele frequencies in a population. Mayr coments,
This approach was consistent with the modern definition of evolution as a change in adaptedness and diversity, rather than a change in gene frequencies, as suggested by the reductionists.
Ernst Mary (2001) What Evolution Is, Basic Books, New York p.189
Consistency is not one of the hallmarks of Ernst Mayr's writings. That's why he can propose two conflicting definitions in the same book, even a book that's devoted to the topic of defining biological evolution! Nevertheless, Mayr does highlight two different objections to the minimal definition that I am defending.

First, Mayr wants a definition that restricts evolution to the mechanism of adaptation. This is a lost battle. There may have been a time in the 20th century when a majority of biologists rejected random genetic drift and other non-adaptationist forms of evolution but that time is long gone. Mayr was one of the last hold-outs. Besides, as I mentioned above, it isn't appropriate to restrict the definition of evolution to a particular mechanism even if you strongly believe that it's the only possible mechanism. That's not how you define something.

Second, Mayr doesn't like reducing evolution to the level of the gene. This charge of reductionism is more interesting. In spite of the fact that Mayr was one of the founders of the Modern Synthesis, he never had much respect for genes and population genetics, or "bean-bag genetics" as he called it. He makes this point very strongly in the preface to his book.
... most treatments of evolution are written in a reductionist manner in which all evolutionary phenomena are reduced to the level of the gene. An attempt is then made to explain the higher-level evolutionary process by "upward" reasoning. This approach invariably fails. Evolution deals with phenotypes of individuals, with populations, with species; it is not a "change in gene frequencies." The two most important units in evolution are the individual, the principle object of selection, and the population, the stage of diversifying evolution.
Ernst Mary (2001) What Evolution Is, Basic Books, New York p.xiv
I happen to agree with some of those who criticize the extreme reductionist views of scientists like Richard Dawkins but in this case Mayr has it all wrong. When we define evolution as a change in the heritable characteristics of a population we are not reducing evolution to the level of the gene. We are merely stating that populations don't evolve unless they undergo genetic changes. This is not controversial in spite of Mayr's objection. He is confused about the difference between a definition of evolution and a proposed mechanism of change—as was obvious in his attempt to include adaptation. This is a remarkable error in a book called "What Evolution Is."

The Minimal Definition and Macroevolution

The minimal definition of evolution is not inconsistent with Hierarchical Theory and a focus on macroevolution as opposed to microevolution. This point is worth emphasizing since the minimal definition has often been criticized for excluding lots of evolution that takes place at higher levels. Stephen Jay Gould—no fan of reductionism and no stranger to hierarchical theory—addressed this problem in his last anthology.
The Darwinian principle of natural selection yields temporal change—"evolution" in the biological definition—by a twofold process of generating copious and undirected variation within a population, and then passing only a biased (selected) portion of this variation to the next generation. In this manner, the variation within a population at any moment can be converted into differences in mean values (such as average size or average braininess) among successive populations through time.
Gould, S.J. (2002) "What Does the Dreaded 'E' Word Mean Anyway?" in I HAVE LANDED Harmony Books, New York p. 246
The purpose of his essay was to point out the fundamental difference between this biological definition and the common vernacular meaning of the word "evolution." (I wish he hadn't used the word "selected" in his definition since it implies natural selection and Gould knows that there are other mechanisms.) Gould points out that other sciences, such as astronomy, use the word "evolution" in a very different sense—one that is actually closer to the original nineteenth century meaning. The vernacular meaning carries an implication of purpose and direction that is entirely absent from the biological definition of changes in the heritable characteristics of a population over time. This is why Darwin never used the dreaded "E" word.

Gould argues that an understanding of the true importance of the biological definition is absolutely essential to understanding why the general public is confused. He is especially concerned about emphasizing the lack of progress and direction in the definition of biological evolution. He advocates that scientists owe it to the general public to teach the biological definition.
I don't mention these differences to lament, or complain, or to criticize astronomical usage. After all, their concept of 'evolution' remains more faithful to etymology and the original English definition; whereas our Darwinian reconstruction has virtually reversed the original meaning. In this case, since neither side will or should give up its understanding of "evolution"—astronomers because they have retained an original and etymologically correct meaning, evolutionists because their redefinition expresses the very heart of their central and revolutionary concept of life's history—our best solution lies simply in exposing and understanding the legitimate differences, and in explaining the good reasons behind the disparity of use.

In this way, at least, we may avoid confusion and the special frustration generated when prolonged wrangles arise from mis-understandings about words, rather than genuine disputes about things and causes in nature. Evolutionary biologists must remain especially sensitive to this issue, because we still face considerable opposition, based on conventional hopes and fears, to our emphasis on an unpredictable history of life evolving in no inherently determined direction. Since astronomical 'evolution' upholds both contrary positions—predictability and directionality—evolutionary biologists need to emphasize their own distinctive meaning, especially since the general public feels much more comfortable with the astronomical sense—and will therefore impose this more congenial definition upon the history of life if we do not clearly explain the logic, the evidence, and the sheer fascination of our challenging conclusion.
(ibid p. 250-252)
I agree with Gould. That's why I think it's important to explain the real biological definition of evolution as a change in the heritable characteristics of a population over time. We can explain that this is a minimal definition, and that there's more to evolution than this, but we shouldn't back away from the real meaning of the term since it conveys some important messages. If we cave into pressure from the general public to make evolution into something they can understand, with all their biases, then we will have lost the battle before we even begin.

The amazing thing about the minimal definition of biological evolution is that it doesn't carry any baggage concerning the history of life or its future. As soon as we try to define evolution in terms of the historical record, we run into all kinds of problems because we confuse evolution as a process with evolution as a history of life. The scientific definition attempts to describe the minimum thing that might be called evolution. We know that the history of life is more complicated than this and we know that evolutionary theory encompasses other things such as the formation and extinction of populations. There is no conflict between the minimal definition of evolution as a change in the genetic composition of populations and macroevolution. Gould understands this.

[This is a slightly modified version of an essay that appears here. An earlier version is on the TalkOrigins Archive.]


Torbjörn Larsson said...

Third time could be the charm:

A good thing that it is easier to describe which processes guides life (and possibly things like evolutionary algorithms) than what life is.

Though I have taken "descent with modification" to be a description instead of a definition. Moreover, since I haven't seen an exact definition of descent I though that it covered all scales of evolution. So, what is "descent" if it isn't replication with inheritance?

Btw, I don't understand the obsession with astronomy using the term evolution, it is common in math and physics when systems evolve over time, deterministically or not. I don't think us laymen are generally confused over that evolution describes special systems that "evolves", but instead what the definition should be.

"In other words, populations evolve but individuals do not. This is a very important point. It distinguishes biological evolution from other forms of evolution in science (e.g., stellar evolution)."

But stellar populations evolve too, including inheriting materials from one generation to the next which makes the changes. (Though here they mess up, or not, by calling each generation a population.)

Considering GA's, does the definition need to exclude non-living things? The mechanisms to consider will be different, but it seems to be necessary to leave the mechanism part out. So why isn't it good to leave the application part out too?

Les Nyman said...

"Evolution is a process that results in heritable changes in a population spread over many generations."

This definition is better than some of the others cited because it does not specify an inheritance system. While the genetic inheritance system has a special and central role, it is not the only one.

Drake, AJ and BR Walker. 2004. The intergenerational effects of fetal programming. Journal of Endocrinology. 180:1-16.

Durham, WH. 1991. Coevolution: Genes, Culture, and Human Diversity. Stanford University Press.

Jablonka, E and MJ Lamb. 2005. Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life. MIT Press.

Laland, KN, J Odling-Smee, and MW Feldman. 2000. Niche Construction, Biological Evolution, and Cultural Change. Behavioral and Brain Sciences. 23:131-146.

Anonymous said...

A problem with the phrase "descent with modification" is that I think "modification" connotes that there is some design to it, such as an intelligent designer of some sort.

If astronomers and biologists have different ideas of "evolution," why didn't biologists use another word?

Torbjörn Larsson said...
This comment has been removed by the author.
Torbjörn Larsson said...


"I think "modification" connotes that there is some design to it"

I can't see that - a modification is simply a bounded change from a previous structure. As Larry has pointed out, it is important that the mechanism is taken out of the picture. The mechanism (and, I would argue, the application) should be decided by the theory.

"If astronomers and biologists have different ideas of "evolution," why didn't biologists use another word?"

Well, IMO "evolution" is simply a system's change of state over time. This is a common concept in math, physics, and probably chemistry. It covers evolution theory well.

But I agree that a specific term would have been nice. (Especially if Larry agrees that genetic algorithms, stars and possibly other systems may be covered by the minimal definition. Then "biological evolution" doesn't cut it.)

OTOH, at least astronomers and possibly other areas differ in handling the term "populations" too.

Anonymous said...

In the post you use the terms macroevolution and microevolution. Would you be so kind as to provide a short definition for these?

Looney said...

Well, I would just note that the definition of biological evolution proposed - a process that results in heritable changes in a population spread over many generations - would be accepted by even fanatical creationists. As such, it is unable to distinguish the beliefs of Darwinists and is worthless.

No, biological evolution is the belief that all of the technology of biology spontaneously generated through heritable changes over many generations. Furthermore, biological evolution demands that you believe (i.e. have faith) that all biological technology was the result of random processes to be a scientificly proven fact. Otherwise, you are doomed to scientific incompetence in any discipline.

Unknown said...

That... certainly is looney, Looney.

Yes, even a creationist would have to be crazy to deny this definition of evolution.

That's why we think creationists are crazy - because they seem to do so, insisting on using the word "evolution" even after the distinctions are explained, even if their only objection is common descent.

Looney said...

Michael, the distinctions of evolution were explained in the original post just as abortion is explained as pro-choice.

On the other hand, "evolution" and "change" are synonyms. There is no scientific working definition for "change". We observe change, and then we look through our repertoire of scientific principles to try to see which one(s) account for the change. Thus, it is impossible for a definition of "evolution" to have any scientific value, but it can have value to mislead.

Larry Moran said...

Andys asks,

In the post you use the terms macroevolution and microevolution. Would you be so kind as to provide a short definition for these?

That's too hard. The issues surrounding proper use of "microevolution" and "macroevolution" require a full essay. There it is [Macroevolution].

Larry Moran said...

Torbjörn Larsson asks,

Considering GA's, does the definition need to exclude non-living things?

Yes, the definition of biological evolution excludes non-living things. Genetic algorithms are very bad models of biological evolution.

Anonymous said...

Wow! Exactly how much of an individual's brain must be physically removed for them to descend to this level of irrationality? "Thus, it is impossible for a definition of "evolution" to have any scientific value, but it can have value to mislead."

Looney said...

Maybe this will help: Macro evolution = big change or difference. Micro evolutions = little change or difference. We don't need essays for the banal.

Anonymous said...

Looney, you said:

Maybe this will help: Macro evolution = big change or difference. Micro evolutions = little change or difference...

Is this right? I though that the standard creationist definitions for those terms were:-

"Microevolution" = evolution the evidence for which is so overwhelming that even the most closed-minded creationist cannot deny it occurs

"Macroevolution" = evolution the evidence for which creationists are able to dismiss by ignoring it.

Interestingly microevolution, that creationists claim to accept, is precisely the evolution that manifests in different skin-colour and appearance generally; so creationists accept the level of evolution acceptance of which, in other contexts, they argue leads to racism/Nazism/folk-dancing...

Looney said...

Robin, I don't read the Creationist literature. All I know is that "evolution" and "change" are synonyms. They are always observations and may help in classifying data. Invoking change, however, is never an explanation.

Torbjörn Larsson said...

"Otherwise, you are doomed to scientific incompetence in any discipline."

Evolutionary theory makes amply predictions, and many has been verified by observations. This follows the most basic definition of science as we know it; observe, predict and verify (or falsify).

So there is definitely no case of "faith" or "incompetence" here.

"Yes, the definition of biological evolution excludes non-living things."

That explains your intent, but I can't see that it answers my question. These are judgment calls, but it is bad to include mechanisms, why isn't it also bad to include applications? it would work anyway, and it is easier to make a weaker and general definition.

"Genetic algorithms are very bad models of biological evolution."

Yes, they are mainly models or technological applications. And they only (at least in the simpler codes) include mechanisms intentionally put there, while biological evolution is observed on behavior and predicted on mechanisms.

But again, why can't we say evolution in biology, evolution in software algorithms, evolution in star populations (clusters and galaxies, populations in the biological sense)? The article doesn't tell us this.

Has Gould an answer to this, or is it an underlying assumption that biological evolution must be uniquely enclosed?

Anonymous said...

Looney, you said:

Robin, I don't read the Creationist literature. All I know is that "evolution" and "change" are synonyms. They are always observations and may help in classifying data. Invoking change, however, is never an explanation.

You are intentionally equiovocating on the word "evolution". It has a particular meaning in biology that is rather more than just "change". Perhaps you should read the parent post to start with...

You also claim not to read Creationist literature, but in your previous comment told us what "fanatical creationists" would accept. Make your mind up...

Looney said...

"Evolutionary theory makes amply predictions, and many has been verified by observations."

Evolution theory can also explain the relationship of orcs to elves with the exact same methodology and the exact same scientific precision as anything else. Evolution is so pliable that it explains everything - and therefore explains nothing.

As my son said after taking a biology test, every answer is correct, as long as it refers to evolution.

Looney said...

"But again, why can't we say evolution in biology, evolution in software algorithms, evolution in star populations (clusters and galaxies, populations in the biological sense)? The article doesn't tell us this."

As noted, evolution = change and therefore evolution theory encompasses everything whether real or imaginary. As software algorithms are pure ID, but also involve evolution, we observe that evolution theory isn't in any way incompatible with ID. i.e. Even when evolution explains the relationship of apes to humans, it fails to preclude a creation event.

Torbjörn Larsson said...


"Evolution theory can also explain the relationship of orcs to elves with the exact same methodology and the exact same scientific precision as anything else."

No, I'm discussing quantifiable predictions, such as molecular clocks et cetera. Read some papers.

Anonymous said...

Anonymous said...

Larry, does evolution even have to be over many generations?

Consider a population struck by a pathogen that kills every single individual lacking a particular gene variant. In theory at least, that gene variant could go from being rare to ubiquitous in less than a single generation.

Surely that counts as evolution, too?

Anonymous said...

The Origin, Nature And Mechanism of Life's Evolution
Life Evolution Is A Fractal Of The Cosmos Evolution
(In Basic, Not AcademEnglish, Language)

A. Comment-reply, Jan 12th 2010, at

Quote : "the basic property of life as a system capable of undergoing Darwinian evolution began when genetic information was finally stored and transmitted such as occurs in nucleotide polymers (RNA and DNA)."

*** The basic property of life as a system capable of undergoing Darwinian evolution began at life's genesis, with the first replication of the first independent gene, not yet genomed not yet celled gene...initiated and maintained with direct sun energy. Connote this with sleep and with life's chirality.

Quote : "life (even primitive early-stage life) is restricted to be one which can undergo Darwinian evolution."

*** Life is life is life. Life is gene, and gene is gene is gene. There is no "primitive early-stage life" versus "evolved modern life". Complexity in life is what physics calls Broken Symmetry, which is what biology calls Evolution. And life's evolution is simply a cosmic mass evolution, life being just one of the many cosmic mass formats. And, like in cosmic mass evolutions, life's (Darwinian) evolution is based on and consists of the genes replicating with or without change, depending on whether its suggested-by-feed-back progeny's expression gains or does not gain more constrained energy. Plain and simple. All cosmic and life evolutions are initiated and proceed and accumulate in answer to this one single question. All evolutionary complexities, of all degrees of complexity, evolve and develop in response to and in the direction of this one single question.

B. "Should Evolutionary Theory Evolve?"
Some biologists are calling for a rethink of the rules of evolution.

Life evolution is a fractal of the cosmos evolution.

Dear Bob Grant, you can extend the list of evolution theorists and the descriptions of their theories, but IMO none of them will survive into the 22nd century. Just wait and see.

Life is just one of many forms of mass in the universe, ALL of which are forms of energy. Life's evolution is a fractal of the cosmos evolution. It is so plain and simple, therefore unbelievable in view of the immense verbiage mountains about it. The origin, nature and mechanism of life's evolution is the origin, nature and mechanism of the evolution of mass formats in the cosmos. So plain and simple that it hurts, it's embarassingly clear.

Glance at the Evolution Theory of the future. Brace yourself to a realization of its obviousness and simplicity. Start the search at the three brief notes, in basic English, below.

Dov Henis
(Comments From The 22nd Century)
Updated Life's Manifest May 2009
28Dec09 Implications Of E=Total[m(1 + D)]
Cosmic Evolution Simplified

Buy Propecia said...

without a doubt evolution is the key to survive to any condition to our environment, that's is how we can reach so far and now we predominate over the others species.

Annette said...

Thanks for clearing up the inconsistencies in definitions.

buy phentermine said...

the question I would ask here is "Do you believe in God?"

Unknown said...

What does God have to do with any of this? Why must we manufacture a debate that should not exist?

Michael Apostolides said...

Yes, the definition must include non-living things. Abiotic things do not have heritable genetic material. Stellar populations do 'evolve' but as was addressed in this blog post, this is a different definition. I encourage you to re-read the post, and to understand the differences between the different definitions of evolution discussed here.

Michael Apostolides said...

Stellar populations do not have generations, and do not have populations. You need to understand what the definition of 'generation' is and what 'population' is, which you do not. Generations apply only to biological populations because they have heritable material (DNA), while stellar systems do not. You need to re-read this article and understand the distinction between biological evolution and other types of evolution. There is a difference, and you do not understand it.

Jamie said...

Hi Larry,

I find it impossible to believe that human emotions could have evolved through the evolutionary process and have been hesitant to ask about it on this page because it seems any questioning of evolution puts one in either the Creatard or IDiot camp but I figured what the hell.

I haven't been able to find any what might be called "scientifically satisfying" resources or explanations on how chemical reactions or mutation could have lead to human emotions and I figure you and your people could point me in the right direction for explanations or experiments that could help out.


John Harshman said...

Jamie, I don't think anybody knows that. But we do know that other primates and other mammals, at least, have emotions. So why do you limit this to "human emotions"? It seems fairly clear that the more closely related a species is to us and the more similar their social relationships, the more similar their emotions tend to be. That may lead you to some idea of how evolution might proceed.

Mikkel Rumraket Rasmussen said...

One problem is you describe emotions as human, yet I'm pretty sure countless other organisms experience emotions too to varying degrees. Try very basic biological emotions like fear, anxiety, hunger, or even happiness. These are so obvious you can even recognize them in other animals, as any owner of a cat or dog will attest to. If you can understand why an emotional sense like feeling fear, hunger, or sexual desire would evolve, I don't see why it shouldn't also be the case that other emotions could evolve too.
In this respect it is interesting to consider that most if not all emotions seem to be related to behaviors that affect survival and reproduction, and which would have mattered for the propagation of our genes. We generally have stronger emotions towards our close genetic kin, and about things that are critical to our ability to cooperate to survive, and to reproduce.

Of course, we know certain drugs can induce particular emotions, so there does not seem to be any reason why if a chemical drug can cause certain emotional states, there can't also be a genetic basis for this capacity.

Perhaps your question is more fundamental, and has to do with the evolution of consciousness, rather than individual examples of conscious experience(such as particular emotions). But then the question is really not just a question for evolutionary biology, but for the relationship between physics and the mind. In that case there does not appear to be any explanation for why anything should be conscious which does not amount to a mere assertion. A sort of brute fact which is at bottom just assumed but not explained. Whether you think consciousness is a product of physics, or it is supernatural, either way you are left with it being unexplained why it should be the case that anything is conscious.

João said...

Any thoughts on this critic to the minimal definition?

Population geneticists use a different definition of evolution: a change in allele frequencies among generations. This meaning is quite different from the original; it now includes random as well as directional changes ..., but it does not require the origin of new forms. It is roughly equivalent to microevolution (subspecific evolution; macroevolution involves major trends, or trans-specific evolution...). Unfortunately, the use of the population genetics definition often results in an overemphasis on changes in allele frequencies and an underemphasis on (or no consideration of) the origin of the different alleles and their properties. Both are important in evolution.... An additional problem is that, for quantitative genetic traits, the frequencies of alleles at many contributing loci can change while the overall mean and variance of the trait remain roughly constant (Endler 1986: 7-8).