History [of biological
complexity]
The origins of biological complexity
have been debated since antiquity. For a long time it
was assumed that the magnitude of the complexity was so
great that it could never have arisen from any ordinary
natural process, and therefore must have been inserted
from outside through some kind of divine plan. However,
with the publication of Charles
Darwin's Origin of Species in 1859 it became
clear that there were natural processes that could in
fact shape features of biological organisms. There was
no specific argument for why natural selection should
lead to the development of complexity, although Darwin
appears to have believed that this would emerge somewhat
like a principle in physics. In the century or so after
the publication of Origin of Species many
detailed aspects of natural selection were elucidated,
but the increasing use of traditional mathematical
methods largely precluded serious analysis of
complexity. Continuing controversy about contradictions
with religious accounts of creation caused most
scientists to be adamant in assuming that every aspect
of biological systems must be shaped purely by natural
selection. And by the 1980s natural selection had become
firmly enshrined as a force of practically unbounded
power, assumed--though without specific
evidence--to be capable of solving almost
any problem and producing almost any degree of
complexity.
My own work on cellular automata in
the early 1980s showed that great complexity could be
generated just from simple programs, without any process
like natural selection. But although I and others
believed that my results should be relevant to
biological systems there was still a pervasive belief
that the level of complexity seen in biology must
somehow be uniquely associated with natural selection.
In the late 1980s the study of artificial life caused
several detailed computer simulations of natural
selection to be done, and these simulations reproduced
various known features of biological evolution. But from
looking at such simulations, as well as from my own
experiments done from 1980 onwards, I increasingly came
to believe that almost any complexity being generated
had its origin in phenomena similar to those I had seen
in cellular automata--and had essentially
nothing to do with natural selection.
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