The role of natural selection is highly debated within the scientific
Some see it as a primary creative force at all levels of evolutionary
change, others see it as having only a stabilizing role.
Some see evolution as more mutation-driven than selection-driven. Random
mutation and genetic drift in small isolated populations has been given
different weights by different workers. The role of mutation and random
assortment of apparently nonfunctional and repeated codes in DNA is a
significant unresolved issue. The relative roles of different types of
genes (structural vs regulatory) and gene complexes is debated. How easy
is it to modify regulatory genes while maintaining viability of the
The role of the external environment in directly influencing genetic change
has been revived. Some recent work suggests the possibility of the
alteration of an organism's genome in response to environmental stresses.
Related to this is that some genes subject to selection are known to
actually promote mutation. This opens up a "neo-Lamarkian" (my term) view
The question of contingency has also emerged as a major pint of debate.
How "open" is evolution? To what extent are the possible evolutionary
solutions limited? Some workers see the inherent properties of matter set
such that the emergence of creatures fundamentally similar to ourselves was
a near certainty.
The developing science of complexity theory is beginning to have an
influence in evolutionary theorizing. I will leave it to others to
elucidate these contributions.
Keith B. Miller
Department of Geology
Kansas State University
Manhattan, KS 66506