This page contains excerpts from web-pages by Craig Rusbult, Ph.D.
The Science of a "Chemical Evolution" Origin of Life (short, medium, long,
plus other views)
• The Second Law of Thermodynamics and "Chemical Evolution" for the Origin of Life
• METHODOLOGICAL Questions about "Origin of Life" Science and Intelligent Design
• PHILOSOPHICAL Questions about "Origin of Life" Science and Methodological Naturalism
• a LINKS-PAGE (written by me as editor trying to describe a wide range of views accurately, not as
an author arguing for my own views) about The Origin of Life: Abiogenesis by Chemical Evolution?
The Science of Chemical Evolution (short version)
In an attempt to explain the origin of life, scientists propose a two-stage process of natural chemical evolution:
1) formation of organic molecules, which combine to make larger biomolecules;
2) self-organization of these molecules into a living organism.
For each stage, scientists are learning that what is required for life seems to be much greater than what is possible by natural process. This huge difference has motivated scientists to creatively construct new theories for reducing requirements and enhancing possibilities, but none of these ideas has progressed from speculation to plausibility.
The simplest "living system" we can imagine, involving hundreds of components interacting in an organized way to achieve energy production and self-replication, would be extremely difficult to assemble by undirected natural process. And all of this self-organization would have to occur before natural selection (which depends on self-replication) was available.
Basically, the Second Law of Thermodynamics is just a description of probability, ... stating that during any reaction the entropy of the universe will increase. ...
The everyday analogies used by some young-earth creationists — like "a tidy room becoming messy" due to increasing entropy — are not used in scientific applications of the Second Law, because entropy is about energy distributions and associated probabilities, not macroscopic disorder, and our psychological intuitions about "entropy as disorder" are often wrong. ...
Living organisms in the earth's biosystem are maintained in their unusual state (having high chemical potential energy, with low constraint-entropy and normal temperature-entropy) by using external energy from the sun, with solar energy first being directly consumed by plants, which convert it into chemical potential energy that can be consumed by animals. In both plants and animals, coordinated biological systems produce the mechanisms of life — operating in control systems, coupled reactions, and in many other ways — that are necessary to make these unusual things happen.
Now we'll look at "problems
to solve" in a formation of life by Chemical Evolution:
1) an evolutionary mechanism [mutation-and-selection] would not exist before life began,
2) and neither would the coordinated biological systems that make unusual things happen,
3) including the formation of specific biomolecules that are needed to make the systems;
4) some chemical reactions that seem important for life are energetically unfavorable.
you read the comments below, think about how each of the four problems involves
"chicken and egg" relationship, if life is necessary to produce what is necessary for life.
1) The origin of life requires a minimal complexity that may exceed what can be produced by natural process, and until a system can accurately reproduce itself (until it's alive?) the neo-Darwinian evolutionary mechanisms cannot help a system (or a population of systems) move toward the minimal complexity that is required for life.
2) A wide variety of biological processes, ...
Thaxton & Bradley "conclude
that, given the availability of energy and an appropriate coupling mechanism,
the maintenance of a living system far from equilibrium presents no thermodynamic
problems." But they recognize the important difference
between maintenance and origin: "While the maintenance of
living systems is easily rationalized in terms of thermodynamics, the origin of
such living systems is quite another matter."
During biological evolution after life is established, the basic life-allowing mechanisms already exist, which allows life to continue with inheritance-replication that is adequate (but not perfect) through many generations, and during these generations the mechanisms can increase in variety and complexity through a neo-Darwinian "ratcheting process" that includes, but is not limited to, mutation and selection. But even though an evolutionary increase in biological complexity is compatible with the Second Law, scientists should still ask "What types of complexity can be produced, in what amounts, and how quickly?"
In chemical evolution the basic mechanisms do not exist (thus life cannot exist) so the mechanisms must be produced (so life can exist). For a variety of reasons, producing life seems much more difficult than maintaining life and increasing its diversity & complexity.
Typically, young-earth creationists
use the Second Law of Thermodynamics to criticize ALL evolution, even though
arguments against two types (astronomical and biological) don't seem valid.
Defenders of evolution correctly claim that an external source of energy can allow a decrease of entropy within an open system during any type of evolution. But appeals to an inflow of energy don't address the important difference between chemical evolution and biological evolution, between producing a coupling mechanism (in the first generation of life) and then maintaining it (through succeeding generations). Even though most thermo-based arguments are wrong, the questions in this page are scientifically interesting and currently unanswered.
Should scientists consider all possibilities? All current theories for a natural chemical evolution from nonlife to life seem implausible, because what is necessary (for life) seems greater than what is possible (by undirected natural process). Is it rational for scientists to consider the possibility that carbon-based life on earth did not originate by undirected natural process, but was the result of design-directed action? The certainty of "proof" is impossible because we can never propose and test all possibilities for non-design. But could we develop a logically justified confidence that our search has been thorough yet futile, and no promising possibilities remain unexplored?
What are the possibilities? Perhaps a feature, such as the first life, was produced by undirected natural process that: • did occur even though it was extremely improbable (so we should reject it as a scientifically plausible explanation), or • would be improbable in a universe but was highly probable because we live in a multiverse; or did occur and was reasonably probable and can be described in a naturalistic theory that • is currently known (even if this theory currently seems inadequate) or • will be known in the future, or • will never be known because the natural process was too complex or unfamiliar for us to pro pose. Or maybe the feature was produced by design-directed action, by: • natural design and construction, or • supernatural design and creation. Should scientists ignore the last two possibilities? .....
What might happen in the future of science? We can try to predict improvements in current theories and inventions of new theories, by using current knowledge (*) plus creative thinking (to imagine what could be) and critical thinking (to predict what is probable in reality, not just possible in our imaginations) so we can avoid the extremes of insisting that "nothing new will happen" or "anything could happen." .....
If the current evidence-and-logic is not
conclusive, maybe saying "no conclusion" is the best conclusion. Instead
of thinking it's necessary to "declare a winner," can we just say "we're
not sure at this time" and continue searching, with a humble open-minded
attitude, in our efforts to learn more?
Should we ask the question? Imagine a "super science" constructed by trillions of super-intelligent space aliens who have studied biochemistry for billions of years, have explored the universe searching for life and environments for producing it, but have not yet constructed a plausible theory for a natural origin of life. Even in this situation a denial of design would be possible, but would it be rational?
Compared with this imaginary super-science, in the near future the actual state of human knowledge will remain much less advanced. For awhile, scientists will continue to disagree about the plausibility of design, but this is healthy for science when it stimulates thinking and discussions between advocates for different points of view. Proof is impossible in science, and it can be difficult to confidently answer the question, "Was design-action involved in producing this feature?" Although it should be easier to decide, "Should we ask the question?", there are also vigorous arguments about this, as you'll see in Sections 7C and 7D.
For judging the depth of commitment to naturalism — an assumption that everything in the history of nature happened by natural process — the origin of life makes a fascinating test-case. To see why, let's compare three characteristics of chemical evolution and biological evolution.
• Scientific Support? Current theories about chemical evolution seem highly implausible, so the scientific support is very weak. But support is much stronger (*) for biological evolution, for a neo-Darwinian development of biocomplexity and biodiversity. * the scientific support is stronger, but is usually overestimated due to a shifting of support [that is described in the full page]
• Unifying Function? Most scientists and educators think biological evolution — but not chemical evolution — plays an important unifying role in biology.
• Worldview Function? Both types of evolution are necessary for a worldview of naturalism, for a universe with a natural total evolution (astronomical, chemical, and biological), with only normal-appearing natural process throughout the entire history of nature.
Worldview Asymmetry: If a natural origin of life (of any type, anywhere in the universe) is impossible, this would be devastating for the worldview of an atheist, deist, or rigid agnostic. But either way — with or without a natural origin of life — is fine for Christians, including me, as explained in my FAQ for Creation, Evolution, and Intelligent Design (conclusion of 5B, plus 5C) and No Proof for the Existence and Activities of God? Why isn't God more obvious?
When we look at the origin of
life, interesting questions arise from an interesting combination, because
• is not supported by a logical evaluation of evidence,
• and is not important for unifying biological science,
• but is essential for a "no miracles" naturalism.
This is an opportunity for scientific humility about naturalism. Is the response a humble acknowledgment that maybe life did not begin by natural process, so maybe naturalism is wrong? No, instead there are confident statements (by individuals and organizations, in textbooks and websites) claiming that chemical evolution definitely did produce life, even though we don't yet know the details of how this happened.
For example, here are scientists — who
are speaking "in the
name of science" for a prestigious organization — making a claim
that is confident but is not scientifically justifiable:
Although a natural origin of life by chemical evolution seems implausible, the National Academy of Sciences confidently asserts (in Science and Creationism, 1999) that "For those who are studying the origin of life, the question is no longer whether life could have originated by chemical processes involving nonbiological components. The question instead has become which of many pathways might have been followed to produce the first cells." This confidence in the power of natural process doesn't seem consistent with the scientific evidence, so why does the NAS make the claim? Maybe they are influenced by an assumption, which is not based on science, that everything in the history of nature happened due to natural causes.
As explained briefly above, my links-page about Origin of Life: Abiogenesis by Chemical Evolution? — which contains overview-summaries of the main ideas, plus links to pages where you can explore these ideas in more depth — is written by me as an editor (for the "Whole-Person Education" part of the website of the American Scientific Affiliation) and my goal as editor is to describe a wide range of views accurately. By contrast, in the four pages above (about science, thermodynamics, methodology, philosophy) I'm writing as an author, and my goal is to describe my own views and persuasively argue for them.
I'll let you, as a reader, evaluate what I've written and then decide how neutral I've been as an editor (I recognize that I'm not totally unbiased, but I have tried to be fair when writing my descriptions, and in linking to the best pages I could find by advocates of each view) and how persuasive I've been as an author.
Here are excerpts from the introduction in the links-page:
How did life begin? What was the origin of the first carbon-based life on earth?
Scientists are proposing various theories for a natural origin of life by a process of abiogenesis (a non-biological production of life) that can be viewed as a chemical evolution from non-life to life. ..... [snip] .....
Before looking at web-pages with proposals (and criticisms, as in claims for Intelligent Design) for various scientific theories about a natural origin of life, let's get a "big picture overview" of some problems and possible solutions: .....
This website for Whole-Person Education has TWO KINDS OF LINKS:
an ITALICIZED LINK keeps you inside a page, moving you to another part of it, and
a NON-ITALICIZED LINK opens another page. Both keep everything inside this window,
so your browser's BACK-button will always take you back to where you were.
They are listed above and are
described throughout this page.
this page is
all pages copyright © by Craig Rusbult, all rights reserved