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Evolution: What We Know and What We Don’t

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September 20, 2013 Tags: History of Life

Today's video features Jeffrey Schloss. You can read more about what we believe here.

This entry was originally posted on February 17, 2010.

In this video conversation, Jeff Schloss discusses different meanings of the term “evolution” and observes that some of these are disputed and some are not. For example, genetic change over time is not even a theory; it is simply an observation—we see it. But whether that change over time has resulted in the diversity of species we see now—that is an interpretation of the facts. But, Schloss emphasizes, it is an interpretation that is accompanied by overwhelming scientific evidence—ranging from biogeographic evidence to the more recent discovery of genetic fossils. Further, he notes that this idea—that evolution results in the diversity of species—is firmly established and it is central to our understanding of how organisms work and how they are structured.

Then there is a theoretical aspect to evolution that is not fully settled even among scientists themselves. This meaning of evolution asks what the causes are that drive the evolutionary process. While the synthetic theory of evolution, which suggests that evolution results from the twin processes of mutation and natural selection, is the dominant theory, scientists are not fully in agreement with regard to the extent that other factors play a significant role in evolutionary change.

 

Commentary written by the BioLogos editorial team.


As Senior Scholar of BioLogos, Dr. Jeff Schloss provides writing, speaking, and scholarly research on topics that are central to the values and mission of BioLogos and represent BioLogos in dialogues with other Christian organizations. He holds a joint appointment at BioLogos and at Westmont College. Schloss holds the T. B. Walker Chair of Natural and Behavioral Sciences at Westmont College in Santa Barbara, California, and directs Westmont’s Center for Faith, Ethics, and the Life Sciences. Schloss, whose Ph.D. in ecology and evolutionary biology is from Washington University in St. Louis, Missouri, often speaks to pubic, church-related, and secular academic audiences on the intersection of evolutionary science and theology. Among his many academic publications are The Believing Primate: Scientific, Philosophical, and Theological Reflections on the Origin of Religion


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Paul Lucas - #82666

September 20th 2013

So close!  So close!  But misses in some subtle but important aspects.   

For example, genetic change over time is not even a theory; it is simply an observation—we see it.”

That’s also not the definition of evolution.  And it confuses the idea of theory and observation.  Is “the earth is round” a theory or observation?  Both.

Then there is a theoretical aspect to evolution that is not fully settled even among scientists themselves. This meaning of evolution asks what the causes are that drive the evolutionary process.”

That isn’t what is in dispute.  Instead the search is for all the different ways that can result in new species and the time frame that it happens.  What is called the “tempo and mode” of evolution.  

 While the synthetic theory of evolution, which suggests that evolution results from the twin processes of mutation and natural selection,”

Natural selection includes mutation.  They are not twin processes.  Natural selection is a 2 step process:

1. Variation
2. Selection

Mutations are one source of variation. In sexually reproducing organisms, a much larger source of variation is recombination. 

Darwin used the term “natural selection” to distinguish it from what human breeders were doing with plants and animals: artificial selection.  In artificial selection, the variations were there, but the human breeders were selecting those traits the humans wanted.  In natural selection, the selection happens in nature without the input of intelligence. 

The Modern Synthesis has been strawmanned as a process that means:
1. Only single nucleotide substitution mutations resulting in only small changes in form or function
2.  Happening very slowly  where one large population slowly changes over generations to another large population (phyletic gradualism).

But the Modern Synthesis never required those.  All it requires is that there was never a leap to a new species within a single generation.  So now people discuss how and when endosymbiosis was involved in evolution, whether most speciation happens by phyletic gradualism or allopatric speciation happening in small populations (punctuated equilibria), whether selection acts on individual genes, individual organisms, or occasionally on populations of organisms (group selection), whether all traits in all organisms are due to natural selection, how much a role does genetic drift play and when, how much of a role do small changes in developmental genes that result in large morphological changes (evo-devo), etc.    

And, of course, there are always the discussions about the specifics of individual evolutionary lineages. Did amphibians evolve from Acanthostega or from an earlier species?  Is Homo ergastor and Homo erectus the same species?  Which of them is our direct ancestor?  How much genetic material, if any, did we get from Neandertals?  

“Facts are the world’s data. Theories are structures of ideas that explain and interpret facts. Facts don’t go away when scientists debate rival theories to explain them. Einstein’s theory of gravitation replaced Newton’s in this century, but apples didn’t suspend themselves in midair, pending the outcome. And humans evolved from ape-like ancestors whether they did so by Darwin’s proposed mechanism or by some other yet to be discovered.” Gould defines a scientific fact as “confirmed to such a degree that it would be perverse to withold provisional assent.”

“Evolutionists have been clear about this distinction of fact and theory from the very beginning, if only because we have always acknowledged how far we are from completely understanding the mechanisms (theory) by which evolution (fact) occurred. 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.” SJ Gould, Science and Creationism, ed. by Ashley Montagu, 1984.

Notice “mechanisms”, not “driving force”.  That’s a very loaded and dangerous term to use here.


Eddie - #82668

September 21st 2013

Paul, you wrote:

“Natural selection includes mutation.  They are not twin processes.  Natural selection is a 2 step process:

“1. Variation
“2. Selection”

You’re of course free to define terms any way you like, and as long as the reader understands your meaning, discussion can proceed.  But I see little value in employing terms in a non-standard way.  “Natural selection includes mutation (or as you later write, variation)” is not standard usage.  That’s not how Darwin, Dobzhansky, Mayr, Gaylord Simpson, Gould, Dawkins, Margulis, Shapiro, and many other evolutionary biologists have defined “natural selection.”  Further, your proposed definition has a partial repetition of the thing to be defined (your “natural selection” is variation plus “selection”), which creates a certain lack of clarity; the old grade-school rule of not defining something in terms of itself is still useful.

Of course you are right that in the Modern Synthesis (by which I mean the “neo-Darwinism” of Mayr, Dobzhansky, Gaylord Simpson, etc.—the term “Modern Synthesis” was coined by their colleague Julian Huxley) there is a two-step process; that two-step process is called “evolution”—with variation (including “random mutation”) generating the novelty, and natural selection either accepting or rejecting the novelty.  If accepted, the novelty becomes over time “the new normal” upon which further novelties can be built; and the series of these novelties and acceptances, looked at in the broad sweep over time, is “evolution.”

I notice that you did not answer my earlier question about the religious orientation which you bring to the science-theology project of BioLogos.  That makes it hard to tell whether you are here to discuss science/theology issues, especially since most of your comments seem to be a vigorous defense of standard evolutionary theory and to have little to do with what BioLogos is about.  But maybe you are just warming up and your religious interests will become apparent in due course.  In that case, I look forward to hearing your perspective.

 


George Brooks - #83268

October 28th 2013

Wouldn’t it be good to have a Table that lists the various options for how God interacts with the Universe, which a Christian Evolutionist could review to see which matches his or her philosophical outlook best.  The options could be matched to pros and cons, and would make a gradient of some kind:  Guided Evolution?  Unguided Evolution?  Adding of a Soul or of a Moral Imperative?  There’s many more options.

This could advance the level of discussion.  Rather than disputing whether or not God and Evolution can exist in the same Bible we can discuss the ramifications of all the various ways God’s Biblical will is most feasibly expressed.  George B.


Paul Lucas - #83449

November 6th 2013

Eddie:  How I used natural selection is exactly how Darwin, Dobzhansky, Mayr, Gaylord Simpson, Gould, Dawkins, Margulis, Shapiro, and many other evolutionary biologists have defined “natural selection.”   As just 2 examples, see Ernst Mayr’s book What Evolution IS or Douglas Futuyma’s textbook Evolutionary Biology. 

But let’s go back to Darwin’s description of Natural Selection.  Look what I bolded:

“If, during the long course of ages and under varying conditions of life, organic beings vary at all in the several parts of their organization, and I think this cannot be disputed; if there be, owing to the high geometric powers of increase of each species, at some age, season, or year, a severe struggle for life, and this certainly cannot be disputed; then, considering the infinite complexity of the relations of all organic beings to each other and to their conditions of existence, causing an infinite diversity in structure, constitution, and habits, to be advantageous to them, I think it would be a most extraordinary fact if no variation ever had occurred useful to each beings welfare, in the same way as so many variations have occured useful to man. But if variations useful to any organic being do occur, assuredly individuals thus characterized will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance they will will tend to produce offspring similarly characterized. This principle of preservation, I have called, for the sake of brevity, Natural Selection.” [Origin, p 103 6th ed.]

In order to have “preservation”, you need variations to be preserved.  So, from Darwin on down, natural selection has indeed been a 2-step process.

“Evolution” involves more than natural selection. Populations change also due to genetic drift, gene flow, etc. 

As to my “religious orientation” (what a weird phrase), that is also a 2 parter.  Science is agnostic.  So, when speaking as a scientist, I am going to sound agnostic as I accurately represent science’s outlook.

On a personal level, I’m a Christian.  Many of my posts have discussed the theology inferences of creationism and the theological shortcomings and problems inherent in creationism and Biblical literalism.   


Paul Lucas - #83455

November 7th 2013

George:  You and I, as Christians who accept evolution, can have such a conversation about the various implications for Christianity of evolution.  I would suggest the book Finding Darwin’s God by Kenneth Miller for you to start.  Then Ian Barbour’s Religion and Science.  Barbour listed the 4 ways science and religion interact.

I will say, as a scientist, that all 3 of your listed ways are possible.  Nor are they mutually exclusive. God can let most evolution happen without any type of interaction (other than sustaining the process, of course) and guide a few lineages at specific points.  Then God can add a soul to whatever species (singular or plural) that He wishes.  Once again, people should actually read Darwin:

“He who believes in the advancement of man from some low organised form, will naturally ask how does this bear on the belief in the immortality of the soul. The barbarous races of man, as Sir J. Lubbock has shewn, possess no clear belief of this kind; but arguments derived from the primeval beliefs of savages are, as we have just seen, of little or no avail. Few persons feel any anxiety from the impossibility of determining at what precise period in the development of the individual, from the first trace of a minute germinal vesicle, man becomes an immortal being; and there is no greater cause for anxiety because the period cannot possibly be determined in the gradually ascending organic scale.” http://www.literature.org/authors/darwin-charles/the-descent-of-man/chapter-21.html  The Descent of Man

However, since a few people are absolutely convinced that evolution and “the Bible” cannot co-exist, it is very difficult to get to that level of discussion.  Of course, what those people are really saying is that God’s Creation and their interpretation of the Bible can’t coexist.  And they are correct.  The answer is to discard that interpretation of parts of the Bible. 


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