Organic organisms (plants) use solar energy to convert it into
chemical energy, turning nutrients into substances that make up their
bodies. Not only herbivores, but also the energy obtained by
carnivores by eating their prey goes back to the solar energy obtained
by plants. To simplify the ecosystem on Earth, all living things are
considered to be competing for the space they occupy in order to
obtain a limited amount of energy (solar energy) and substances as
nutrients.
Tierra mimics this basic mechanism of the global ecosystem. There are
two of the most important resources in a computer.
One is the speed of the CPU (Central Processing Unit), and the faster
it is, the more information processing can be done in a short time.
This corresponds to the fact that the more energy you get, the more
chemical reactions you can make, and you can do many life activities
such as building your own body and leaving offspring.
The other is memory space (RAM), where programs executed by computers
and data for them are placed in RAM. Larger and more complex programs
require more memory space. This is just like the larger organisms need
a larger space and the substances that make up the body.
In the world of Tierra, each creature (called a digital creature) is
considered an independent program. Those programs (digital creatures)
must have the ability to replicate themselves as a basic function.
Their purpose is to keep increasing the same program as themselves in
memory space. There are multiple digital creatures at the same time,
but in a general computer system, there is usually only one CPU. The
Tierra system in turn allocates CPU usage time to each organism.
Organisms that gain more CPU time will have a greater advantage in
survival competition.
He said that the creatures of the Tierra world are programs, but they
are written in their own machine language. Machine language is a
language that allows you to operate a computer directly. According to
Tom Ray, machine language is more like an amino acid that can be
chemically active rather than a nucleic acid because it can directly
manipulate bits, bytes, CPU registers and instruction pointers. In
Tierra, organisms can be explained by the analogy of organisms in the
RNA world. This is because the organisms in the RNA world carry
genetic information and carry out metabolic activities.
The part of RAM memory where digital creatures live is called soup in
Tierra. The genomes of digital organisms are composed of one machine
language. They contain code for self-replication. Tom Ray wrote the
code for an ancestral species composed of 80 machine languages ??as
the first organism.
