Evolution By Natural Selection

[CosmicJoghurt]

Why is evolution a fact but gravity a law?

 

[Inferno]

Why is evolution a fact but gravity a law?

First of all, let us examine evolution as both fact and theory. To quote AronRa:

It is a fact that evolution happens; that biodiversity and complexity does increase, that both occur naturally only by evolutionary means.

It is a fact that alleles vary with increasing distinction in reproductive populations and that these are accelerated in genetically isolated groups.

It is a fact that natural selection, sexual selection, and genetic drift have all been proven to have predictable effect in guiding this variance.

It is a fact that significant beneficial mutations do occur and are inherited by descendant groups, and that multiple independent sets of biological markers exist to trace these lineages backwards over many generations.

It is a fact that birds are a subset of dinosaurs the same way humans are a subset of apes, primates, eutherian mammals, and vertebrate deuterostome animals.

It is a fact that the collective genome of all animals has been traced to its most basal form, and that those forms are also indicated by comparative morphology, physiology, and embryological development.

It is a fact that everything on earth has definite relatives either living nearby or evident in the fossil record.

It is a fact that the fossil record holds hundreds of definitely transitional species even according to it's strictest definition, and that both microevolution and macroevolution have been directly-observed.

Then of course, there are the laws inside the theory of evolution like Mayr's Law of Monophyly, Gould's Law of Evolutionary Economics, Darwin's Laws of Biodiversity, Dollo's Law (that might not be a law after all) and so on.

Laws are part of a theory, facts are part of a theory. Evolution is both a fact in the every day use of the word (in that it is true), it is a fact as shown above and it is also a theory.

Does that answer your question?

 

[Deleted member 619]

snip...

Just popped in to apologise for not getting back to this. I had typed most of a lengthy response, but then Mrs Slash closed the browser before I finished it, and I've been super busy since.

I will get back to it when I have a moment. For the moment, suffice it to say that I largely agree with much of what you've said, but I still stand by the BSC. I would simply say that care has to be taken in its application but, if care is applied, it's still extremely robust. It certainly doesn't face any problems from ring species.

Anyhoo, I'll get back to it ASAP.

 

[Inferno]

Just popped in to apologise for not getting back to this. I had typed most of a lengthy response, but then Mrs Slash closed the browser before I finished it, and I've been super busy since.

I will get back to it when I have a moment. For the moment, suffice it to say that I largely agree with much of what you've said, but I still stand by the BSC. I would simply say that care has to be taken in its application but, if care is applied, it's still extremely robust. It certainly doesn't face any problems from ring species.

Anyhoo, I'll get back to it ASAP.

No problem, but there's really no need. I misunderstood something you said in one of your first posts and absolutely agree, as long as we understand that there are limitations and problems with the BSC and can work around/with them, it is indeed a very robust definition.

 

[Dean]

CosmicJoghurt

Why is evolution a fact but gravity a law?

Let's start at the end.

Law (Science)

Web definitions (in this case from Wikipedia):

Laws of science
The laws of science are various established scientific laws, or physical laws as they are sometimes called, that are considered universal and invariable facts of the physical universe. Laws of science may, however, be disproved if new facts or evidence contradicts them. A "law" differs from hypotheses, theories, postulates, principles, etc., in that a law is an analytic statement, usually with an empirically determined constant. A theory may contain a set of laws, or a theory may be implied from an empirically determined law.

Theory:

the,·o,·ry/ˈTHÄ“É™rÄ“/
Noun:
A supposition or a system of ideas intended to explain something, esp. one based on general principles independent of the thing to be...: "Darwin's theory of evolution"
A set of principles on which the practice of an activity is based: "a theory of education"; "music theory".

(Source)

Most web definitions of the latter shown here ("theory") will tell you that a theory is a supposition or set of ideas, designed to explain observed facts, and in scientific terms it is the highest degree of accuracy one can attain, and theories do not become laws, but theories such as evolution can included and/or are encompassed by laws, which is why gravity is a law but evolution is not. Evolution pertains to laws, but it is not per se a law itself.

Forgive me if I mention something that's already been said, as I heard a mention of AronRa somewhere else in the thread, but I particularly like this video he did on evolutionary phylogeny. It hits the nail:


P.S.: Also see his Foundational Falsehoods of Creationism series ...

 

[Laurens]

This is a really good series of lectures for anyone interested:

 

[josh]

I'm really interested in this thread. I'm very interested in evolution, but I'm still learning the details. Lots of great information in here. I found the video Dean posted to be enlightening. At one point, he mentions that birds have lost their hands and can't get them back. I'm wondering, given the explanation slightly earlier in the video, if what he meant was that genetically there is no longer a mechanism for birds to ever have hands, or if there is some mutation possible that could give them hands and digits again, but that they new appendages would be something fundamentally different from hands. I understand the idea that they will never regrow their fingers and redevelop hands, but could they develop new handlike things?

 

[Deleted member 619]

Certainly they could. There is a principle at play known as 'Dollo's Law', which states, essentially, that evolution is not reversible. This is not to say that an organism can't evolve similar solutions to those possessed by ancestors, only that evolutionary pathways can't be reversed. The reason for this is that evolution is stochastic, which is to say that it depends on initial conditions plus one or more random variables. Individual mutations can be reversed, but full reversals of pathways are not possible.

It should be noted that Dollo's Law is a statistical law. What this means is that, while not actually prohibited by any physical law, the probabilistic resources are simply not available for wholesale reversals of evolutionary pathways. A good analogy for elucidation is quantum tunnelling; an individual particle can tunnel through barriers (it is this principle that the semiconductors that your computer relies on for operation, utilising principles first put into practice in Esaki diodes) with ease, as a product of quantum uncertainty. For large agglomerations of particles to do this, though, while not prohibited, is incredibly improbable. You could theoretically put your car in the garage at night and come out in the morning to find that it had tunnelled through the wall and is sitting in your garden. The probability of this actually happening, though, is such that it would be unlikely to happen in the entire life of the universe (and I don't just mean from the BB until now, but the whole span). Compared to Dollo's law, however, this is pretty probable. An exact reversal of an evolutionary pathway is orders of magnitude more improbable than your car appearing in your garden.

 

[Isotelus]

I'm really interested in this thread. I'm very interested in evolution, but I'm still learning the details. Lots of great information in here. I found the video Dean posted to be enlightening. At one point, he mentions that birds have lost their hands and can't get them back. I'm wondering, given the explanation slightly earlier in the video, if what he meant was that genetically there is no longer a mechanism for birds to ever have hands, or if there is some mutation possible that could give them hands and digits again, but that they new appendages would be something fundamentally different from hands. I understand the idea that they will never regrow their fingers and redevelop hands, but could they develop new handlike things?

Well, technically birds still have hands, they're just reduced and the remaining digits have fused. And no, they can't get their "theropodish" manus back. To answer your question on the re-development of hands: what hackenslash said.
For some interesting bird anatomy info, there's some debate as to whether or not the digits are I-III or II-IV. Personally, I prefer the I-III hypothesis, simply because there's more evidence for it. Also, there are several extant bird species that still grow claws on their digits, both in the juvenile and adult forms.

Digit I corresponds to the phalanges below J, Digit II to the middle phalanges, and so on.

 

[Laurens]

I was thinking that it would be cool/useful if we compiled a list of resources about evolution. I wouldn't want to clutter up this topic just with people posting links, but I thought I'd ask whether it is something people would be interested in contributing to?

I think it would be nice to have a list of resources to help in any debates one might have about evolution, or simply for people interested in learning more about it. Should I bother making such a topic or not?

 

[Inferno]

I was thinking that it would be cool/useful if we compiled a list of resources about evolution. I wouldn't want to clutter up this topic just with people posting links, but I thought I'd ask whether it is something people would be interested in contributing to?

I think it would be nice to have a list of resources to help in any debates one might have about evolution, or simply for people interested in learning more about it. Should I bother making such a topic or not?

What, you mean like this topic?

 

[Laurens]

I was thinking that it would be cool/useful if we compiled a list of resources about evolution. I wouldn't want to clutter up this topic just with people posting links, but I thought I'd ask whether it is something people would be interested in contributing to?

I think it would be nice to have a list of resources to help in any debates one might have about evolution, or simply for people interested in learning more about it. Should I bother making such a topic or not?

What, you mean like this topic?

Yeah, something like that, except more specifically about evolution.

 

[sturmgewehr]

Hi, I know this is slightly off topic but I didn't know where to ask so here I go.

Does anyone know what are the best books on Evolution there where you can learn how evolution happened and occurred, like tell me 3 of those books.

 

[devilsadvocate]

I recommend Ernst Mayr's "What Evolution Is", http://www.amazon.com/What-Evolution-Ernst-Mayr/dp/0465044255

"At once a spirited defense of Darwinian explanations of biology and an elegant primer on evolution for the general reader, What Evolution Is has several audiences in mind: those scientists and nonscientists who accept evolutionary thinking but do not know exactly how it works, and those who accept evolution but are not sure the Darwinian explanation is correct.With rare clarity, Mayr poses the questions at the heart of evolution-What is the evidence for evolution on earth? What is the origin and role of organic diversity?-and describes in refreshingly nontechnical language how the search for answers has over the years revealed solutions to the most challenging problems posed by evolutionary theory. In a provocative final section, Mayr considers how our improved understanding of evolution has affected the viewpoints and values of modern man."

 

[Inferno]

Hi, I know this is slightly off topic but I didn't know where to ask so here I go.

Does anyone know what are the best books on Evolution there where you can learn how evolution happened and occurred, like tell me 3 of those books.

That's really hard to say. Evolution is so wide a topic, it's extremely hard to give you three books that cover the whole range. However, the three most important popular books are, in my opinion, the following:
Why Evolution is True - by Jerry A. Coyne
Only a Theory - by Kenneth R. Miller
The Ancestors Tale - by Clinton Richard Dawkins

Why Evolution is True covers a wide range of evidence for evolution, including fossil evidence, atavisms, vestigial structures as well as genetic evidence. It's beautifully written and has a special place on my book shelf, if only because both Jerry Coyne and I can wiggle our ears. Read to understand.

Only a Theory examines Creationist/Intelligent Design claims and debunks them, all the while still explaining such fascinating things as the bacterial flagellum and Chromosome number two.

The Ancestors Tale explores our ancestors and shows how each of them has a story to tell about our evolution, about why we turned out the way we did.

There are other books, including The Blind Watchmaker, The greatest show on earth, The Making of the fittest, Endless forms most beautiful, Your inner Fish, etc. etc. All of them cover merely one sub-topic of evolution, but all of them are equally fascinating.

 

[CosmicJoghurt]

@Dean and the others who answered my question

Thank you for your kind answers

The only thing I've yet to understand is what exactly is the fundamental difference between a scientific fact and a scientific law. Both can be parts of a theory, but in what do they differ?


Cheers!

 

[sturmgewehr]

@ Inferno & @ devilsadvocate

Thank you very much guys

So you actually saying I can learn something from these books.

I see that The Ancestor's Tale has won The Royal Society Prizes for Science Books which is an annual award for the previous year's best general science writing and best science writing for children.

Is that book serious and based on Actual researches and finding ?

 

[Inferno]

Is that book serious and based on Actual researches and finding ?

Absolutely, yes!

The only thing I've yet to understand is what exactly is the fundamental difference between a scientific fact and a scientific law. Both can be parts of a theory, but in what do they differ?

A fact is defined as something observed, that happens without the shadow of a doubt. (Whether or not someone doubts it does not matter, by the way.) Fact is more or less synonymous with "observation".
-It is demonstrable that things that are heavier than air do indeed fall down if you let go of them.
-It is demonstrable that things weigh more on different planets.
-It is demonstrable that planets do rotate around the sun.
-It is demonstrable that planets that are further away go slower.
-It is demonstrable that ...

You get my drift?

A law is a statement that explains something. This law only applies to an extremely narrow field and as such isn't as encompassing as a theory. Law is more or less synonymous with "explanation of observation(s) X", whereas "theory" would roughly mean "explanations of all processes in this field."
-The above facts/observations are explained by Newton's law of universal gravitation and Kepler's laws of planetary motion.

Is that good enough?

 

[CosmicJoghurt]

Very well. I'm starting to like you. And your accent!

 

[Inferno]

Very well. I'm starting to like you. And your accent!

Thanks?