Interview with Tom Ray
by Second Part To Hell

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	  ************        Interview with Tom Ray        ***********
	  ************     by Second Part To Hell/[rRlf]    ***********
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  0) About Tom Ray

  1) About Tierra

  2) The Interview

  0) About Tom Ray

     Dr. Thomas S. Ray is a professor of Zoology at the University of Oklahoma,
     with an adjunct appointment as Professor of Computer Science. He received his
     Masters and Doctorate in Biology from Harvard University, specializing in plant
       Tom Ray is a well-known scientist in the field of artificial life and
     evolution. In The 1990s he has developed "Tierra" and "Virtual Life".
     Beside of that, he has also been deeply involved in rain forest conservation
     in Costa Rica.

     His homepage:

  1) About Tierra

     Tierra is a computer simulation developed in the early 1990s in which computer
     programs compete for central processor unit (CPU) time and access to main memory.
     The computer programs in Tierra are evolvable and can mutate, self-replicate and
     recombine. Tierra is a frequently cited example of an artificial life model;
     in the metaphor of the Tierra, the evolvable computer programs can be considered
     as digital organisms which compete for energy (CPU time) and resources (main memory).

     ( and at Tom Ray's homepage)

  2) The Interview

   1.) Why have you started to do researching in such an unusual topic 
       as "artificial life"?

   I feel that I answered this question in my essay:
   Ray, T. S. 1993. How I created life in a virtual universe.

   2.) After you have introduced Tierra@Home, which has terrifically
       increased the size and speed of Tierra, have there been any
       significant successes (social behaviour, increase of complexity,

   Although I have released the source code for the network version of
   Tierra, I have never fostered a Tierra@Home project.  The reason is
   that I am not convinced that running a really large network would
   produce the desired result, a virtual Cambrian explosion.

  3.) In the real world there are hundreds or thousands of chemical
      reactions, which are equally to computer functions in Tierra. But
      the amount of functions in Tierra is limited in comparison to
      Operation Systems or BIOS functions. Would be a more complex system
      more suitable for evolution?

   I don't think your analogy is appropriate:

      chemical reactions = functions in Tierra

   I think I might equate chemical reactions the actions of algorithms,
   or code fragments, of which there are a limitless number.

   4.) Soon in Tierra parasites have been formed, later cells with
       immunity, which has been a highly interesting development. What has
       been the most impressive development in Tierra in your opinion?

   I think the ecological/evolutionary dynamic was the most impressive
   result in Tierra.

   5.) Sexuality is a very successful way of recombining the genomes 
       of creatures in biology. Is this system also successful in 
       artificial evolution?

   Yes.  I don't use it much in Tierra, but it is used a lot in genetic
   algorithms and genetic programming.

   6.) In some of your publications you mentioned the phrase "Cambrian
       explosion" in computers. In the history of life this happened more
       than 1 billion years after the development of first forms of life.
       In addition, earth had more resources than networks like Tierra -
       even more than the whole worldwide network. Is there still a reason
       for believing that this will happen in computers much faster?

   The Cambrian explosion happened when organisms were prepared to explore
   the diversity of the multi-cellular developmental process.  It took
   about three billion years to reach that point.  However, in an artificial
   system, we can attempt to engineer the conditions from which that
   exploration is possible.

   7.) What has prepared biological organisms for that important step 
       of evolution?

   Some say that it was necessary for the concentration of oxygen in the
   atmosphere to reach a level high enough to support large multicellular
   organisms.  But I also think that it had to await the evolution of a
   flexible genetic system for directing the developmental process, such
   that mutations in the developmental controls could produce changes in
   body plan.

   8.) How do you want to engineer this condition in an artificial system?

   The network Tierra experiment was not about scale, it was about engineering
   a system poised on the threshold of a digital Cambrian.  This is discussed
   in papers such as:

   Ray, T. S. 1998. Selecting Naturally for Differentiation: preliminary 
   evolutionary results. Complexity, 3(5): 25-33. John Wiley & Sons, Inc.

   Ray, T. S. and Joseph Hart. 1998 Evolution of Differentiated 
   Multi-threaded Digital Organisms. In: Artificial Life VI proceedings, 
   C. Adami, R. K. Belew, H. Kitano, and C. E. Taylor [eds.], 295-304. 
   The MIT Press, Cambridge.

   The multicellular starting organisms in network Tierra were differentiated
   at the most primitive level: two cell types.  The object of the experiment
   was to observe an increase in the number of cell types.

   9.) You have compared today's software with biological cells, and
       wrote that even our most complex software (such as operation
       systems including multi-threading) are just Protozoa (single-celled
       organism). What could be the "Cambrian explosion" in computers and
       what do you expect from it?

   I discuss this in a paper that I think you have read:
   I point out that we probably can not imagine what such digital organisms
   might be like.

   10.) Are there conditions, which influence the speed of evolution in 
        a positive ways  in biological and artificial systems?

   In biological systems, adaptive radiations occur when species invade
   ecological voids (such as the colonization of a newly formed archipelago,
   e.g. Galapagos) or when they evolve new morphological novelties (such as
   multicellularity, e.g. Cambrian explosion; or jointed appendages, e.g.
   diversification of insects).  Artificial systems unfortunately are orders of
   magnitude simpler that biological systems that exhibit adaptive radiations.
   Many studies in genetic algorithms or evolutionary computation compare
   rates of evolution under different conditions.  But this is all trivial
   compared to what happens in biological systems.

   11.) The whole theory of evolution relies on randomness. New let's 
        change the view: Is there also a way of mutation, where artificial 
        creatures try to improve their own code by calculate a 
        best-case-scene, and what is your opinion about that?

   This kind of reverse engineering is not practical for a variety of reasons.
   Organisms don't have any means of forseeing what kinds of changes are
   needed for adaptation.  Also, if it were known what kind of adaptation is
   needed, it is generally not possible to know what kind of mutations would
   generate such an adaptation.  We don't have a general understanding of
   the mapping from genotype to phenotype.

   12.) In 1986 Fred Cohen wrote in "Computer Viruses - Theory and
        Experiments" about the possibility of accidental development of
        artificial life due to software bugs. Could this thought come true
        in our modern world, which is "dominated" by computers?

   David Ackley gave a fascinating lecture about "real" AL several years
   ago, in which he claimed that all the critters living on the net (viruses,
   worms, etc) are in fact artificial life.  This is one view, but see my
   answer to the next question.

   13.) Several sources count computer viruses as first artificial
        life. What is your opinion about that statement and what do you
        think about harmless computer viruses, which have just been created
        for the purpose of existing?

   This question forces us to take a position on defining life.  Computer
   viruses, worms, etc exhibit self-replication, an important quality of life.
   However, I consider evolution to be both the defining property and the
   creative process of life.  Evolution is the missing element in the kind
   of "real" AL that Ackley talks about.

   14.) What do you consider as "computer virus"?

   I think this is adequately answered here:

   15.) How would you describe a program with self-replication- and 
        evolution-capability? Computer virus or artificial life?

   I think if it both self-replicates and evolves, we can consider it to
   be artificial life.

   16.) Beside of self-replication and evolution, what else do you 
        consider as conditions of life?

   I think self-replication and evolution are what matters, but many people
   will produce a long list of characters, including such things as metabolism
   and repair.

   17.) Metabolism is biochemical process mainly for getting energy and 
        for anabolism - both is not needed for an artificial organism. What 
        else could "artificial metabolism" be?

   We can only make analogies between organic and digital life.  These analogies
   may or may not be meaningful.  A digital analog of metabolism might just be
   the processing of instructions and manipulation of data.

   18.) In Tierra, phenotype and genotype of the creatures are the 
        same. What could be the phenotype of an artificial creature, if we 
        do not count simulated "earth-like" systems as Karl Sims' "Virtual 

   I think it is a mistake to see the phenotype and genotype as the same in
   Tierra.  The genotype is the bit sequence or instruction sequence of the
   genome.  The phenotype is what happens when those instructions are executed.

   19.) In John Conway's "Game of Life" 2-dimensional "pixel-creatures" 
        behave as they would life. What do you think about this 
        mathematical simulation - do you consider its creatures as alive?

   I enjoyed playing with it as a kid, when it was published in Scientific
   American.  Today I don't find it very compelling.  The entities don't have
   a genetic representations, thus there is really no heredity, so there can
   not be a basis for evolution, and there is no evolution in the biological
   sense.  I don't consider them to be alive.

   20.) In "The Universe in a Nutshell" Stephen Hawking explains that 
        (biological) life is just possible at universe with more then 2 
        dimensions. What do you think about that idea, and is there 
        something equal to dimensions in the computer?

   This may be true in the context of the material universe.  However, I don't
   consider it to be true in the digital universe, where dimensionality has
   quite different qualities.  I discussed dimensionality here:

   By the way, I urge you to read the zen paper:

   It may be my best paper.

   21.) Are you interested in any other artificial life or 
        evolution projects?

   I like Karl Sims evolved virtual creatures very much, and I created a version
   of it that runs on the PC:

   22.) What do you expect about artificial life and about Tierra in future?

   Open ended evolution, and large evolutionary increases in complexity
   remain challenges in AL.  I don't know what the prospects are of
   overcoming these challenges.

   23.) What are your current researches, and what are your future 
        plans about that topic?

   I am currently working in the area of psychopharmacology, trying to understand
   the chemical architecture of the mind.

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                                                    Second Part To Hell/[rRlf]
                                                    written in June 2006

                                                    ...surrealistic viruswriter...
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