Interesting Ideas in Evolution

A number of fascinating ideas that apply or extend Darwinian evolution by natural selection have been advanced within the scientific community. Many of these ideas have not been considered "mainstream" and accordingly are not included in general discussions of evolution; however, these ideas are fascinating speculations that could lead to truly brilliant insights into the workings of the world. One of the most interesting of these ideas deals with the first replicators; another postulates that the planet is one self-regulating super-organism; still another addresses the possibility of natural selection among universes.

The First Replicators: A Dissenting View

Generally, replicating entities - and therefore life - are assumed to have been generated from simple organic chemicals in the "primeval soup". This is a process called abiogenesis. In an alternative theory, chemist Alexander Graham Cairns-Smith has speculated that the earliest replicators were not organic matter at all, but rather were self-replicating crystals that were later superseded by the rise of the far-more-efficient organic replicators. In this view, the first replicators were crystals of the type that exist in clay or mud along riverbanks; they transmitted their "genetic" information through the natural tendency of these types of molecules to fit together into a geometric pattern.

The fundamental characteristic of crystals as replicators must be hereditary variation, or inheritance. Fortunately, crystals in nature display this pattern: they may be perfectly aligned until a specific point is reached, in which a flaw has accumulated (these are quite common in natural crystals). This flaw has a tendency to percolate down the subsequent layers of crystal, setting up a rudimentary system of heredity. Furthermore, atoms of the crystal's substance may be more attracted to certain geometric patterns than they are to others. This sets up a kind of "differential reproduction" which then leads logically to a form of natural selection.

The hypothetical crystals described above may very well begin a basic process of cumulative selection. Certain crystals may have the property of altering streams or other water sources for their own "benefit", such as by increasing the likelihood of more of the same material being deposited in the same location. Crystals may also encourage the formation of "spores" by breaking easily into subsequent "generations" Those crystals that broke into generations most easily would be selected for; these generations would invariably contain mutations on occasion and would intensify the competition between rival variants.

In time, the crystals could evolve a sort of "phenotype" by altering other materials in their environment. These materials could be used to further the crystal's replication by inhibiting rival crystals from forming or promoting the parent crystal's reproduction. Cairns-Smith's hypothesis is that these materials used by the crystals for self-replication later turned out to be even more efficient replicators in their own right. This process of replacement might repeat for several cycles, or the first products used by the crystals may have been the ancestors of modern replicators - i.e., RNA and eventually DNA.

Note: This description was generally based on an account of the same theory in Richard Dawkins' The Blind Watchmaker.

The Gaia Hypothesis

Scientist James Lovelock and Lynn Margulis jointly proposed a radical theory of the biosphere, differing widely with more conservative views. Their theory was called the Gaia hypothesis, and it posited that the earth in its entirety was capable of homeostasis, or self-regulation. According to this theory, the earth could be seen as a "super-organism" whose components (biological life) actively work to maintain a favorable abiotic environment.

There are many different variations on the basic Gaia hypothesis, ranging from weak to strong forms. The following is a list of the five main variations, all supported at one time or another by Lovelock, Margulis, or both.

• Influential Gaia: This is the weakest of the five formulations. It states that organisms have an influence over their non-biological environment, including factors such as temperature and atmospheric composition.
• Co-evolutionary Gaia: This version of the hypothesis states that organisms affect their non-biological environment, which in turn affects the organisms by determining which mutations will be adaptive.
• Homeostatic Gaia: This version is the one that is most frequently referred to as simply "the Gaia hypothesis". It asserts that organisms have a stabilizing effect on their environment through negative feedback loops.
• Teleological Gaia: This is one of the two strong versions of the Gaia hypothesis. It states that homeostatic regulation is not only the effect but also the purpose of the biosphere as a whole.
• Optimizing Gaia: This variation states that the planet's ecosystem as a whole works to manipulate the environment to its own benefit, even at the expense of some individual organisms.
• Other Forms and Extrapolations: In addition to these five main forms, there are many other variations on the Gaia hypothesis. Most of these involve connecting this very holistic, ecologically-inspired idea with ancient pagan or new age views of "the Earth Goddess" or "Mother Nature". However, these extrapolations are not scientific statements like the original hypothesis.

In general, it is agreed that the two strongest forms of Gaia (teleological and optimizing) are not true scientific theories and cannot be tested. Optimizing Gaia can be ruled out by simple appeal to normal Darwinian processes - no organism is going to participate in a consortium to regulate the environment "for the good of the ecosystem as a whole". Obviously, if an organism's survival and reproduction are served best by, say, manufacturing a substance that is poisonous to other species, then that organism will go ahead and produce its poison. This theory is quite simply illogical from an evolutionary perspective. Teleological Gaia, on the other hand, imputes a purpose to the biosphere, which is also clearly not in the realm of science. Even Lovelock agreed that these strong versions cannot work.

Of the remaining variations, the weakest two (influential and co-evolutionary) seem to be statements of the obvious. There is nothing in these assertions that goes beyond what would normally be expected as an emergent product of a set of systems undergoing evolution by natural selection.

Homeostatic Gaia is the only theory left, and it too is not a true scientific theory as formulated. It must be refined to a point where it can be tested and subjected to verification or falsification. Even reformulated, however, the theory would probably not state anything new; feedback loops can arise as properties of interacting systems (such as that between plants taking in CO₂ and releasing O₂, and animals doing the opposite). A feedback loop's existence in one or even many cases does not prove that it is inevitably the result of life on a planet.

In summary, the Gaia hypothesis is an intriguing notion, likely to have been largely inspired by modern views such as holism and planetary ecology. However, when it is "watered down" enough to make an actual, testable assertion, it no longer says anything new or unique that goes beyond what one might expect from a Darwinian perspective.

The Evolution of Universes by Natural Selection

An intriguing application of Darwinian reasoning outside of biology comes from cosmologist Lee Smolin. Seeking an explanation for the physical constants of the universe, Smolin speculated that universes themselves have undergone a form of natural selection and can in fact be considered replicators.

Smolin's idea was that universes "reproduce" by forming black holes, which some theorists (for example, Stephen Hawking) believe could spawn new universes connected to the parent by a wormhole. Smolin's hypothesis hinges on the speculation that, when a new universe is spawned, its properties can vary slightly from those of the parent, thus providing a source of mutations.

According to Smolin, the first, primordial universes were "phoenix universes" that expanded, collapsed, and then re-expanded with slightly different properties. The first repetitions of this process probably produced no black holes, since their properties were not suited for this function. However, after a number of iterations, a universe arose that was capable of producing a black hole or two. Thus, before it collapsed and re-formed, it spawned one or two new universes to begin the process again. These universes, having properties similar to but not the same as the parent, could have undergone more phoenix-like regenerations before producing another universe capable of making more black holes. These would then be more likely to produce additional black holes before collapsing, and the progeny would therefore be capable of producing even more black holes, etc. Before long, a form of "differential reproduction" would take place, and natural selection would, of course, select for those most capable of reproducing. Eventually, the vast majority of universes would be near the pinnacle of reproductive efficiency and would produce many black holes, as ours does.

If one grants this natural selection of universes, then an examination of the properties required for black holes neatly explains the apparent paradox of the physical constants of the universe. If these constants have been varying through time due to the process of forming a new universe, then they will have become optimized for producing black holes, obviously. If the properties required for life are strongly correlated with those required for black holes, then the paradox is resolved. Our universe looks optimized for life, but in reality it is optimized for a correlated phenomenon - the production of black holes.

Some of the properties required for black holes are:

• Rapid enough expansion after the Big Bang to allow for a transparent universe with stable atoms.
• Stable enough subatomic particles to allow for stable atoms.
• Subatomic forces that are neither so strong they do not allow nuclei to split, nor so weak they do not hold nuclei together.
• A gravitational force that is neither so strong that it halts the Big Bang or attracts all matter into a lump, not so weak that it can hardly hold any matter together.

All these properties (and many, many more) are required for the successful formation of stars, from which black holes are formed due to physical processes. Incidentally, these are also many of the same properties that are required for life as we understand it to originate! Though Smolin's theory currently suffers from a lack of physical or theoretical evidence, it explains too much to be put aside as a mere curiosity. This unique hypothesis will await verification or falsification by advances in theoretical or experimental physics.

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Looking Further: Links and References

The following links and references are useful in studying the origins of replicators, the Gaia hypothesis, and the theory of universe evolution.

• The Origin of Replicators: The Crystal Theory
  • Books
    • Seven Clues to the Origin of Life: A Scientific Detective Story by Alexander Graham Cairns-Smith
    • The Blind Watchmaker by Richard Dawkins
    • Darwin's Dangerous Idea: Evolution and the Meanings of Life by Daniel C. Dennett (brief discussion)
  • Websites
    • The Quest for a Chemical Origin of Life
• The Gaia Hypothesis
  • Books
    • Slanted Truths: Essays on Gaia, Symbiosis, and Evolution by Lynn Margulis
    • Symbiotic Planet: A New Look at Evolution by Lynn Margulis
  • Websites
    • A Goddess of the Earth? The Debate over the Gaia Hypothesis
    • An Overview of the Gaia Hypothesis
• Evolution of the Universe
  • Books
    • The Life of the Cosmos by Lee Smolin
    • Black Holes and Baby Universes by Stephen Hawking (discusses origins of new universes)
    • Darwin's Dangerous Idea: Evolution and the Meanings of Life by Daniel C. Dennett (brief discussion)

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