Does evolution follow the scientific method? If so, how?

[johnnesteixeira]

I am a supporter of evolution, and I often see creationists claiming that evolution is not scientific because it fails to meet the requirements of the scientific method.

 

They claim that any scientific idea must be testable, observable, repeatable and falsifiable, and this is true.

I know that direct observation is not always possible in science, but I want to know, how do scientists test evolution (changes that create new species)? How is it observable?

 

I am not referring to natural selection, like bacteria resistance or changes within the same species, I am referring to those changes above a species level, which create new ones. How do scientists test and confirm speciation? How is speciation a repeatable idea?

 

I am not doubting evolution, it's just because these claims have made me feel consufed.

 

Creationists often claim that there are no transitional fossils in the fossil record. Is it true? I would like tests that confirm speciation (creation of new species) by geographic isolation.

 

I thank for replies!

[Strange]

The objection is rather simplistic. However, there are cases where speciation has been directly observed. For example: http://www.talkorigins.org/faqs/faq-speciation.html (this includes some examples due to isolation)

 

 

Creationists often claim that there are no transitional fossils in the fossil record. Is it true?

 

The claim is meaningless. Transitional between what? I would say that there are only transitional forms.

[CharonY]

First a correction, evolution is not the formation of new species, that is speciation and a specific subset of evolution. Now evolution is trivially observed as a shift in gene frequencies within populations over time. Now the term species is fuzzy and is used slightly differently under different conditions. For example, in bacteria the concept of reproductive isolation does not make much sense, rather a species is essentially defined as having less than 70% genome hybridization or about more than 97% sequence divergence in their 16srRNA. Again, this is something that can even be created artificially (e.g. curing genomes, mutate ribosomal genes etc.)

 

Now if we move toward complex organisms and use reproductive isolation, there are numerous examples of that, too. Polyploidy is commonly observed in plants. But also many other mechanisms have been observed. One particularly interesting example is the use of sexual deception for pollination, where the plant mimicks the sex-pheromone of the pollinator species. Thus, plants that attract slightly different pollinators cannot cross-pollinate each other and get isolate (that can happen in conjunction with hybridization).

 

Numerous Drosophila speciations have been reported, including a study in the 70s where changes in courtship behavior resulted in reproductive isolation and changes in mating behavior and resulting isolation were also reported for fish and mice, IIRC. There are certainly many more examples out there that are either directly observed or can be traced back using genetic methods.

 

With regards to fossils, every species is transitional so I am not sure how that question makes sense.

Edited October 7, 2014 by CharonY

[delboy]

How is it observable?

 

 

The fossil record is one of the best observations. A species that exists now, but didn't exist 10 million years ago proves speciation.

 

 

Creationists often claim that there are no transitional fossils in the fossil record. Is it true?

 

There are so many 'transitional' fossils in the human evolution line that no one can agree on which are the same species and which are different. Which is the way it should be really, because evolution is a gradual process - there are no sudden jumps from one species to another.

[Phi for All]

I am a supporter of evolution, and I often see creationists claiming that evolution is not scientific because it fails to meet the requirements of the scientific method.

 

They claim that any scientific idea must be testable, observable, repeatable and falsifiable, and this is true.

I know that direct observation is not always possible in science, but I want to know, how do scientists test evolution (changes that create new species)? How is it observable?

 

At the risk of sounding like a broken record to other members, I'll repeat that the best "short answer" evidence I've ever seen for speciation (which is crucial when talking with creationists since they tend to know very little actual science) is the presence of the recurrent laryngeal nerve in vertebrates. Forget evolving from apes, with the laryngeal nerve you can go all the way back to our fish ancestors.

 

With a single piece of evidence, you can show speciation, as well as how our design is far from intelligent. If I were designing a car, and the battery is six inches away from the horn, why would I use a wire 7 times longer than needed and loop it around the motor?

 

[Mitch Bass]

Perhaps the best place to examine for the best evidence of evolution is the same place that inspired darwin. The Galapagos islands ended up in a location far enough from any other land mass that land animals were isolated. darwin noticed the existence of ANIMALS THat were unlike that existed elsewhere because of the specialization of features these animals had which were essential for survival on one of the most remote places in all the world.

 

I have heard that a developing human fetus goes through transformations that is inclusive of less complex forms of life. I seem to remember being told that at some point a developing fetus has gills for a short period. does this sound familiar to anyone else?

[Strange]

I have heard that a developing human fetus goes through transformations that is inclusive of less complex forms of life. I seem to remember being told that at some point a developing fetus has gills for a short period. does this sound familiar to anyone else?

 

That is a bit of a myth. Especially the "gills" thing. This might not be the right thread to discuss it in (it could just cause more confusion). I would suggest starting a thread if you wan to discuss it more...

[Arete]

First off, I think a couple of definitions are required.

 

1. Biological evolution: At its most basic sense, evolution is the change in allele frequency, in a population, over time. This phenomenon has been directly observed countless times, in virtually (likely every, but I'll avoid absolute claims for now) population that has ever been looked at. Through scientific investigation we understand, to a large extent, that mutations in the DNA/RNA genome of organisms are heritable, and largely responsible for the physical changes observed in populations over time (i.e. mutation causes observed changes in allele frequency) . We also know that particular environmental conditions and circumstances favor the propagation of particular genotypes (i.e. selection influences observed changes in allele frequency)

 

So the basic underpinnings of biological evolution - that mutations cause variation in a population, and that the environment causes shifts in the population over generations through time, are well documented through a multitude of independent lines of scientific investigation. Denying biological evolution is rather impossible - akin to claiming that the Earth is flat.

 

2. The theory of evolution: The theory of evolution postulates that all of the organismal diversity of Earth occurs due to biological evolution. While this obviously cannot be directly observed due to the time scale involved, like many other scientific theories which occur over long time scales (e.g. plate tectonics, the formation of fossil fuels, most of geology and astrophysics, etc.) we can make predictions about what present day organisms will be like, if organimsal diversification did arise through biological evolution.

 

Examples of biological fields which make predictions in accordance with the theory of evolution include (but are not limited to): comparative genomics, phylogenetics, biogeography, morphology, molecular ecology, population genetics, experimental evolution, paleontology, and many others.

 

The establishment and continual testing and refinement of the theory of evolution DOES follow the scientific method - any claim to the contrary is simply false. Additionally, any claim that the theory of evolution is based on unsupported speculation is, at best, supremely ignorant of the vast number of supporting observations which are in accordance with predictions made using the theory of evolution, and finally, if direct observation is required for a scientific theory to be somehow "valid" then vast swathes of science (geology, atomic science, astrophysics, etc) are also invalid - which doesn't make very much sense.

[Mauricio Porte]

Creationists often claim that there are no transitional fossils in the fossil record. Is it true? I would like tests that confirm speciation (creation of new species) by geographic isolation.

 

Think about this: Before there were no "transitional fossils" in human evolution.

 

So Lucy (Australopithecus Afarensis) was discovered. Now creationists say ok well now we have two missing links, one between Lucy and apes, another between Lucy and humans.

So Turkana Boy was discovered (Homo Ergaster). Now creationists say well now we have three missing links, one between Lucy and apes, another between Lucy and Turkana Boy, and lastly, one between Turkana Boy and Humans.

The list goes on and on: of course there are transitional fossils in human evolution, but more importantly all fossils are transitional between one species and another, no species has ever given birth to another species, changes happen gradually and incrementally over time and it is only when you look at the broad scope of time that you can observe the changes.

 

In order to find all "transitional fossils" in human evolution we would have to dig up all of the hominids ever born in a specific descendant line, which is preposterous, since take into account that one could dig up a fossil and identify it as a species that formed part of our evolution, but that doesn't mean that that particual homind actually is part of our descendant line. He is most likely to share common ancestors but not common descendants.

[Robittybob1]

 

Think about this: Before there were no "transitional fossils" in human evolution.

 

So Lucy (Australopithecus Afarensis) was discovered. Now creationists say ok well now we have two missing links, one between Lucy and apes, another between Lucy and humans.

So Turkana Boy was discovered (Homo Ergaster). Now creationists say well now we have three missing links, one between Lucy and apes, another between Lucy and Turkana Boy, and lastly, one between Turkana Boy and Humans.

The list goes on and on: of course there are transitional fossils in human evolution, but more importantly all fossils are transitional between one species and another, no species has ever given birth to another species, changes happen gradually and incrementally over time and it is only when you look at the broad scope of time that you can observe the changes.

 

In order to find all "transitional fossils" in human evolution we would have to dig up all of the hominids ever born in a specific descendant line, which is preposterous, since take into account that one could dig up a fossil and identify it as a species that formed part of our evolution, but that doesn't mean that that particular hominid actually is part of our descendant line. He is most likely to share common ancestors but not common descendants.

I think that was one of the best answers I've ever read. Thanks.

[OrionzRevenge]

https://www.youtube.com/results?search_query=pbs+evolution+on+trail

Judgment Day: Intelligent Design On Trial (creationism vs evolution) NOVA-PBS (1:51:26)

This is a great source for ammunition and clarity.

Edited October 22, 2014 by OrionzRevenge

[starlarvae]

The original post was about scientific method in evoutionary biology, so you can approach it like this:

 

Based on observations, propose a hypothesis: If circumstance A is in effect, then outcome B will be observed.

Then you watch to see if it happens. For example, If there's differential reproductive success among the members of a local population of some species, then the traits characteristic of the more successful reproducers will tend to proliferate in the next generation, and the traits characteristic of the less successful reproducers will tend to be under-represented in the next generation. If observations of the next generation agree with the prediction, then the hypothesis gains strength.

 

The problem comes in with trying to pin down the CAUSAL mechanism responsible for differential reproductive success in the first place. The mechanism of natural selection is inadequate, because it is just an alternative term for "differential reproductive success." It just puts a label on what is observed, while pretending to explain why that observation obtains and not some other. And this confusion between observation and explanation is a foundational weakness in the theory of evolution, as it has come to us.

[Strange]

 

The problem comes in with trying to pin down the CAUSAL mechanism responsible for differential reproductive success in the first place.

The mechanism of natural selection is inadequate, because it is just an alternative term for "differential reproductive success." It just puts a label on what is observed, while pretending to explain why that observation obtains and not some other. And this confusion between observation and explanation is a foundational weakness in the theory of evolution, as it has come to us.

 

Not really. In many (most?) cases we can see what the factor(s) determining success are; i.e. what is being selected for or against. And, of course, in laboratory studies the selection can be controlled.

 

So I fail to see any evidence for the "weakness" you claim.

[starlarvae]

Can you elaborate? If we observe differential reproductive success, how do we determine what caused it? How do we see which factors cause differences in reproductive success?

[Myuncle]

I am a supporter of evolution, and I often see creationists claiming that evolution is not scientific because it fails to meet the requirements of the scientific method.

 

They claim that any scientific idea must be testable, observable, repeatable and falsifiable, and this is true.

I know that direct observation is not always possible in science, but I want to know, how do scientists test evolution (changes that create new species)? How is it observable?

 

I am not referring to natural selection, like bacteria resistance or changes within the same species, I am referring to those changes above a species level, which create new ones. How do scientists test and confirm speciation? How is speciation a repeatable idea?

 

I am not doubting evolution, it's just because these claims have made me feel consufed.

 

Creationists often claim that there are no transitional fossils in the fossil record. Is it true? I would like tests that confirm speciation (creation of new species) by geographic isolation.

 

I thank for replies!

 

It's difficult to convince a creationist, the first obstacle for them, is to accept the existence of genetic mutations. Try to show them these google images, and see their objections, these are animals, not bacteria:

 

https://www.google.co.uk/search?q=new+animal+species+discovered&biw=800&bih=471&source=lnms&tbm=isch&sa=X&ei=G6BOVM_HBbGv7AaO4YHYAg&ved=0CAkQ_AUoAg

 

Try to ask them, how long will these new species survive? Centuries? Millions of years? Are they going to lead to new species, are they just going to be transitional? You need millions of years to answer these questions. And if they are going to be transitional, which fossil trace are they going to leave? You have to be very lucky to find bones of transitional species, just like you have to be extremely lucky to find a dinosaur, mammoth, or hominid skeleton. But you just need a single dinosaur skeleton to prove the existence of many dinosaurs. Bones decay, otherwise, we would walk on a huge pile of bones left from the animals that lived in the past.

For a creationist is difficult to understand this, but it's not impossible, you can try. Same thing is for continental drift, 50 years ago it was an hypothesis rejected even by most geologists. Today is universally accepted as true. Our planet is cooling down, any proof? Yes, volcanoes. Try to ask a creationist how long is going to take for a volcano to become inactive, and see how it goes...

Edited October 27, 2014 by Myuncle

[imatfaal]

!

Moderator Note

 

Large branch of posts that were completely off-topic split to Speculations

 

http://www.scienceforums.net/topic/86276-split-from-evolution-morphology-and-exobiology/.

 

Le Repteux

Your branch was clearly a hijack of an existing topic. Do not do this. Do not respond to this moderation within the thread.

 

[overtone]

One of the scientific arguments for speciation via evolutionary change is the success of predictions made accordingly.

 

Using that theory, we can predict genetic similarity between animals that look much different, and genetic disparity between animals that look much the same, based on their taxonomic relationship.

 

And our predictions check out.

 

Making successful predictions of observations not yet made, especially counterintuitive and unlikely ones, is one of the best arguments for a theory.

 

 

 

Can you elaborate? If we observe differential reproductive success, how do we determine what caused it?

Depends - lots of things, including random chance, can cause differential reproductive success.

 

Darwinian evolutionary theory does not specify particular causes for differential reproductive success. Anything will do, and quite a few very different things have done at one time or another - from slightly lighter colored bark to rocks falling out of the sky.

Edited November 7, 2014 by overtone

[overtone]

Which makes me wonder what justifies the notion of natural selection.

Can somebody provide a clear definition of natural selection?

Darwinian evolution is a fundamental theory, like (but actually deeper than) Newton's Laws of Motion. The term "natural selection" is analogous to the term "force" in Newton's Laws (Newton didn't say "natural force", even in English, although just as with Darwinian "selection" he had essentially borrowed a term of human agency as a metaphor, because others had established the metaphor already and it was taken for granted). It's a label for anything that behaves as required - not only the three or four fundamental forces of modern physics, these days, but such different logical levels of "force" as air pressure or heat expansion or elasticity.

 

You appear to be asking for an exhaustive or exclusive set of mechanisms able to perform selection on variations among entities undergoing Darwinian evolution. I suggest unasking that, and reconsidering your approach.

Edited November 14, 2014 by overtone

[Dekan]

I think the term "Natural Selection" is not good. It tends to causes confusion. Because of the word "Selection".

This is a noun derived from the verb to "select". And the primary meaning of "select" is:

 

"Carefully choose as being the best or most suitable". At least, that's the Concise Oxford English Dictionary definition of the word.

 

Obviously, we shouldn't attach a superstitious value to dictionary definitions!

But such definitions, do show how words are generally interpreted. These interpretations can guide, or lead, our thoughts.

 

Thus, our thoughts tend to be lead, by the word "Selection" - towards this idea: That there's some kind of "choosing" going on. Which seems to imply a conscious entity, to do the "choosing". Hence, God?

 

Would it be scientifically better, if the term " Natural Selection", were replaced by a more neutral term. Such as "Natural Result". Or "Natural Outcome"?

[Strange]

 

That there's some kind of "choosing" going on.

 

There is.

 

 

Which seems to imply a conscious entity, to do the "choosing".

 

No, that is why it is called natural selection: selected by nature.

 

 

Would it be scientifically better, if the term " Natural Selection", were replaced by a more neutral term. Such as "Natural Result". Or "Natural Outcome"?

 

No, because that completely misses the point: favourable traits are selected.

[Dekan]

Could you clarify that Strange, because it seems to me, that favourable traits aren't "selected" or "chosen" - they just "happen". And if the trait "happens" to cause an organism to produce more offspring, then the organisms that possess this trait, reproduce more. So they get more common. It's just simple maths.

 

What's this "Nature" thing that's selecting them?

[Ophiolite]

Favourable traits happen, by chance, through mutation.¹

 

They are then selected for, by Nature.

 

Nature is a short hand term for all the relevant environmental factors.

 

 

1. Or because they happen to already be present in the gene pool when the environment changes in a way to convert them from neutral, or unfavourable, to favourable.

Edited November 14, 2014 by Ophiolite

[Strange]

 

And if the trait "happens" to cause an organism to produce more offspring, then the organisms that possess this trait, reproduce more. So they get more common.

 

Yes, the traits that allow them to have more offspring are selected (by the fact they have more offspring). Without that selection process, all you have is a population with a variety of traits. Without the selection process, there is no evolution.

 

"Differential reproductive success" is arguably more accurate but just not as snappy for a lay audience. (There is another thread with people complaining about scientific elitism making concepts too hard to understand.)

[Dekan]

Thanks Ophiolite. I think, what's wrong here - as I already said - is this word "selection". It implies conscious choice.

[overtone]

What makes the traits favorable, other than their being selected?

They are not "made favorable" by being selected, but identified as likely to have been favorable by noticing they were selected. The work of tracing their advantage in specific cases, if any, is done by evolutionary biologists.

 

It's possible that neutral, even unfavorable, traits could be selected by chance or fixed by the QWERTY effect - marsupial reproduction in mammals living in Australia, say, or the wrong side optic nerve connection in the human eyeball.

 

 

 

 

The finches descended from a common ancestral population on the mainland. Members of that population would have varied phenotypically. When the birds went to the islands, they just ended up wherever they found suitable accommodations, as far as edible food and whatever else they found to be agreeable.

None of that agrees with the evidence. There is no common population of any bird that exhibits within-population speciation like that, and certainly no such common population of finches in nearest South America. Darwin did not even know what kind of birds they were, or that they were related - they are that different from the mainland populations and often from each other. There is no evidence of a very large colonizing population with lots of variation, and there is evidence of a small colonizing population of closely related individuals.

 

and so forth.

Edited November 14, 2014 by overtone