INTELLIGENT DEVELOPMENT 137into multicellular organisms beginning about 2.2 billion years ago. Mul-
ticellularity itself evolved as a way by which single cells could become
more adaptable to changing environments. It began as temporary ar-
rangements established during hard times. Even some bacteria and slime
molds occasionally form multicellular groups in response to extreme
conditions, such as nutrient depletion. In the slime mold Dictyostelium,
for example, it culminates in striking individual diff erences in cell form,
including functional specializations that could not have been foreseen
from reading DNA “instructions” in the single cells. Some cells form a
stalk to prop up others supporting a fruiting body, from which still others
produce and shed spores that emerge into new individuals when condi-
tions improve.
One quite instructive aspect of this early example of development is
how we get so much sudden variation from cells previously quite uniform
and having essentially the same genes. Th ere is no overall controller or
plan for the process—no recipe for specialization in each cell. It is a
dynamical, self- organized pro cess that emerges from interactions and
structural information shared among the individual cells. Th ere is no dis-
tinct executive or supervisory agent.
It was a foretaste of much more spectacular evolutionary possibilities.
Th e divisions of labor and mutual support in these fi rst pioneers imparted
adaptability to changing environments. Permanent multicellularity
eventually evolved. Rapid diversifi cation of species followed. It culminated
in the Cambrian Period about 550 million years ago, which founded all
the major branches (or phyla) of animal life we know today, with the ex-
ception of vertebrates (appearing a little later).
Th at diversifi cation of species itself changed the environment in an
ever- increasing spiral. As animals have been forced to inhabit those more
changeable parts of the environment, the living world has become in-
creasingly dynamic and multifaceted. With the evolution of increased
motility, for example, the environment increasingly became more about
interactions among animals themselves. Th is is a world in a diff er ent
league of changeability from the fl owing concentration gradients experi-
enced by the fi rst primitive organisms. It required development as itself a
major instrument of adaptation, oft en on a lifelong basis.
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