Biology Reference
In-Depth Information
FIGURE 2.1
The concept of 'neighbours' in the Game of Life. A cell in the location marked '*' is surrounded by
eight locations, marked in blue, each of which might contain a cell.
starting configuration at a location a little displaced from the starting position. Gliders can
therefore move across the playing area forever unless they meet a boundary or collide
with other cells (
Figure 2.3
). Patterns have even been found that eject streams of gliders,
one after the other
d
such patterns are called 'glider guns'.
The Game of Life is obviously not meant to be a literal simulation of any particular living
system. Nobody, not even in 1970 when the game was invented, thought that cells really
behaved according to such simple rules. The game does, however, share two important char-
acteristics with most morphogenetic processes in real biology. The first is that the operation of
the 'rules' is strictly local and requires no knowledge of the state of the system as a whole;
each cell senses only the conditions in its immediate neighbourhood. Biological molecules
are affected only by the other molecules with which they make contact and the rules that
govern them are therefore local to the nanometre scale. It is therefore encouraging to see
that strictly local rules can generate rich behaviour even in artificial systems that are simple
enough to understand completely. The second characteristic is that all cells are equal
d
in the
Game of Life there is no hierarchy and no one cell is in command over the others. This, again,
is similar to real life; in many systems described in this topic, no one cell takes command.
Even in the exceptions, once one drops down to a molecular level, there comes a point
that all agents of a given type (for example, molecules of myosin light chain) must be consid-
ered as equal in principle so that any special nature of any one molecule emerges from the
behaviour of the system as a whole, rather than an in-built privilege. It is precisely because
it shares these characteristics with real biology that the game is such a useful illustration of
