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First Signals: The evolution of multicellular development by John Tyler
Bonner, Princeton University Press, $49.50, ISBN 0691070385

INSIGHTFUL aphorisms have been a distinctive feature of John Tyler Bonner鈥檚
writing ever since his first book, Morphogenesis. Half a century later,
it鈥檚 a delight to find him still in fine form with observations such as: 鈥淎 tree
is an embryo all its life鈥攊t does not stop developing in the manner of an
animal embryo turning into a static adult.鈥� Or there鈥檚 the wry phrase: 鈥淯nlike
so many advances in evolution, sex does not seem to have been required for the
invention of multicellularity.鈥�

Bonner鈥檚 purpose in First Signals is to examine the origins of
multicellular life not only from the fashionable perspective of molecular
biology but also from those of mathematical modelling and traditional
observation. He does so by exploring shifts in developmental biology through his
career鈥攆ollowing his initial amazement that animal and plant development
were studied in mutual isolation.

While Bonner neglects few components of the biosphere, his longest chapter
focuses solely on cellular slime moulds. It demonstrates vividly how all three
approaches are essential for a convincing understanding of how multicellular
life arose. In particular, Bonner re-emphasises Alan Turing鈥檚 belief, now
unpopular among molecular biologists, that emerging patterns in living organisms
can usefully be described by reaction-diffusion equations. That advocacy may
prove to be the book鈥檚 lasting value.