Evolution
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Biological Information New Perspectives Investigates “Information Theory & Biology”
A Series on Biological Information: New Perspectives
Article 2: On the Origin of the Controversy Over Biological Information: New Perspectives
Article 3: Censorship Loses: Never Forget the Story of Biological Information: New Perspectives
This Article: Biological Information New Perspectives Investigates “Information Theory & Biology”
Article 8: Douglas Axe and Ann Gauger Argue that Design Best Explains New Biological Information
The new scientific volume Biological Information: New Perspectives covers many topics related to the origin of information. The first main section of the book investigates “Information Theory & Biology.” In the Introduction to that section, Robert Marks reviews various ways of defining information and explains that the particular type of information used by life is best characterized as demonstrating the quality called “specified complexity.”
What Makes a Search Successful?
One noteworthy paper in that section is by William Dembski, Winston Ewert, and Robert Marks, “A General Theory of Information Cost Incurred by Successful Search.” It provides a general explanation of their methodology for measuring “active information,” or the amount of information that is added to a random search to aid in finding a search target. This foundational paper is theoretical, aiming to establish mathematically that without active information being added, a search can perform, on average, no better than a random search:
When a search with probability q of success displaces a baseline search with probability p of success where q > p, conservation of information states that raising the probability of successful search by a factor of q / p (>1) incurs an information cost of at least log(q / p). Conservation of information shows that information, like money, obeys strict accounting principles.
In other words, a “natural” search — one that operates blindly — cannot, on average, find the target any faster than a random search working without active information. To increase the probability of finding the target, “active information” must be added. This “conservation” of information operates in a law-like fashion that would prevent unguided mechanisms, like Darwinian processes, from improving the search. This is the essence of Dembski’s “No Free Lunch” theorem. As Marks explains in the introduction, a search can be simplified “only by access to some source of information.” That source, of course, requires intelligence.
This methodology can then be applied to real-world situations, as it allows them to measure the extent to which computerized simulations of evolution are generating new information, or simply using information introduced by the programmer, not generated by the program.
Ewert, Dembski, and Marks have a second paper in the volume titled “Tierra: The Character of Adaptation” where they apply the sort of methodology developed in their first paper. This study looks at Tierra, one of the earliest computerized simulations of evolution, developed by Thomas Ray in 1989. According to the Tierra website:
Life on Earth is the product of evolution by natural selection operating in the medium of carbon chemistry. However, in theory, the process of evolution is neither limited to occurring on the Earth, nor in carbon chemistry. Just as it may occur on other planets, it may also operate in other media, such as the medium of digital computation. And just as evolution on other planets is not a model of life on Earth, nor is natural evolution in the digital medium.
The Tierra C source code creates a virtual computer and its Darwinian operating system, whose architecture has been designed in such a way that the executable machine codes are evolvable. This means that the machine code can be mutated (by flipping bits at random) or recombined (by swapping segments of code between algorithms), and the resulting code remains functional enough of the time for natural (or presumably artificial) selection to be able to improve the code over time.
According to Ray, Tierra is capable of modeling the evolution of complexity, as supposedly occurred in events like the Cambrian explosion:
While the origin of life is generally recognized as an event of the first order, there is another event in the history of life that is less well known but of comparable significance: the origin of biological diversity and macroscopic multicellular life during the Cambrian explosion 600 million years ago. This event involved a riotous diversification of life forms. Dozens of phyla appeared suddenly, many existing only fleetingly, as diverse and sometimes bizarre ways of life were explored in a relative ecological void. (internal citations omitted)
As Ewert, Dembski, and Marks explain, in Ray’s mind “once evolution (whether biological or artificial) has produced a Cambrian explosion, the rest of evolution should proceed easily.” They observe, however, that after 20+ years of people using Tierra, the widely agreed conclusion “is that Tierra did not produce a Cambrian explosion or open-ended evolution.” They observe that “Tierran evolution can be characterized as an initial period of high activity producing a number of novel adaptations followed by barren stasis,” and thus ask why Tierra stopped producing new features. They explain:
A closer look at Tierran evolution reveals an important characteristic of the adaptations. Tierra started with a designed ancestor to seed the population. In other words, it presupposed something like an origin of life and was concerned with the development of complexity after that point. The ancestor provides initial information to Tierra. Adaptations primarily consist of rearranging or removing that information. Open-ended evolution requires adaptations which increase information. However, such adaptations are rare in Tierra. Tierra’s informational trajectory is reversed from what evolution requires. It is dominated by loss and rearrangement with only minimal new information instead of being dominated by the production of new information with minimal cases of removal or rearrangement of information. Long term evolutionary progress is dependent on the generation of new information.
So does Tierra actually produce new information? Ewert, Dembski, and Marks studied the workings of Tierra in detail and found:
In a majority of the cases we see that evolution proceeded by deleting instructions. There are some new instructions inserted, but these are much smaller than the changes in other areas. As a result, we can clearly see that Tierran evolution is dominated by information-reducing mutations. … The interesting behaviors produced by Tierra are created mostly by rearranging the information seeded into the simulation by its designer.
Thus, they found that Tierra was in a sense front-loaded — or intelligently designed — to stably evolve:
Tierra also derives some information from the environment in which it runs. Ray was concerned about the brittleness of machine code, and accordingly made specific design decisions. Additionally, the original instruction set was created by choosing exactly the instructions which were used in the ancestor. This results in the Tierra instruction set being specifically tuned to the problem it faces. This work has not attempted to investigate the implications of these decisions, but it is our opinion that the Tierran evolution is substantially assisted through them.
Nonetheless, they observe, “The author of Tierra sought to create a digital Cambrian explosion whereby the power of the evolutionary process was unleashed. It is agreed that Tierra did not succeed in accomplishing this feat. Rather, the evolutionary activity within Tierra dies after only a transitory period. No Cambrian explosion occurs.”