Information Technology Reference
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exhibits many characteristics of evolution and variation, as well as all sorts of
behaviors similar to life on earth. In the beginning, there is only a simple ancestor
“living being” in Tierra model. After the computation of 5,260,000 commands,
366 kinds of digital living beings in different sizes appear in Tierra model. After
2,560 million commands, 1180 kinds of different digital living beings appear.
Among these living beings, some live in the bodies of other digital living beings,
and some are immune to the parasites. Tierra also generates the punctuated
equilibrium phenomenon, in which the social organization even appears. In a
word, nearly all the characteristics in the process of natural evolving, and all kinds
of functional and behavioral organizations similar to the life on earth, will appear
in Tierra. The homepage of Tierra is http://www.his.atr.jp/~ray/tierra/index.html.
The most exciting achievement of Tierra is proving that the machine codes
can evolve. This means that machine codes can have variation or reorganization,
and the generated codes keep enough functions in order to change at times
through the natural selection. In addition, the natural environment also evolves
with the evolving of organisms. This is one of the basic factors of promoting the
evolution of biological species and complexity on the earth.
Another achievement of Tierra is adding a digital multi-cellular analog into
Tierra. Thomas S. Ray thought that it was the natural analogy of parallel
computation, as well as the characteristic of increasing the variety of evolution.
The characteristics in multi-cellular Tierra model include:
(1) The cellular organism originates in the single-cellular form, and develops into
the multi-cellular form through a binary cell division process;
(2) Each cell of an individual has the same genetic materials, because all of them
come from one initial cell;
(3) There are potential differences among sufficiently developed cells, so that
they can represent different parts of the genome.
However, the multi-cellular evolution has increased the quantity of cells, but
not the number of cell types.
In order to cause the growth of cell types in the evolving multi-cellular digital
organisms, Tierra runs on the distributed computer network. Thomas S. Ray
utilizes a new observation tool called Beagle to observe and control the running
Tierra in the network. The digital life designed by Thomas S. Ray, takes numbers
as carriers to explore various phenomena, laws and emergence behavior of
complex systems in the evolving process.
