Books
of Humanities, Education, and Social
Sciences at Örebro University, in
Sweden. She is an environmental
sociologist studying knowledge
production and the relations between
knowledge producers, with a specific
focus on biodiversity issues. Her most
recent publication is “The monarch
butterfly through time and space: The
social construction of an icon”
(http://io.aibs.org/gust).
doi:10.1093/biosci/biv145
CAN A PLANT REALLY THINK?
Plant Behaviour and Intelligence.
Anthony Trewavas. Oxford University
Press, 2014. 304 pp., illus. $90.20
(ISBN: 0199539545).
S
ome of the most commonly used
words in our vocabulary are
the most difficult to define. Take for
example the word life or the word
intelligence. We use these and many
other words glibly, often without
reflecting thoughtfully on the many
deep layers of meaning a certain word
contains. This applies no less to how
words are used in the sciences than
to how they are used in everyday
discourse. Many scientists have tried
to define life, and many have tried to
define intelligence. But it is fair to say
that no definition for either has met
with general approval or even reluctant acceptance.
In his book Plant Behaviour and
Intelligence, the renowned plant
physiologist Anthony Trewavas takes
up the huge challenge of convincing
the reader that plants such as an oak
tree or a stalk of corn manifest intelligence—or, at the very least, some
form of consciousness. This challenge necessitates telling the reader
what he means when using the word
intelligence, and, as is often the case
with words that convey complex
notions, this presents a challenge
in its own right. Trewavas offers us
a practical if perhaps idiosyncratic
definition: “My view of intelligence,
outlined later, is that it reflects a
capacity to solve problems, particularly those that deal with survival.”
Note that this technically is not a
definition, owing to the phrase “it
reflects a capacity,” which appears
to suggest that the capacity to solve
problems is an emergent property of
intelligence rather than what intelligence is exactly. The reader must
read considerably further to find out
what “outlined later” means. Here, we
learn that “intelligence is quite simply the capacity for problem solving.”
We now have a formal definition
and also learn that “all organisms
act intelligently within their environment.” With this definition in hand,
Trewavas makes the cogent observation that the concept of intelligence is
typically and incorrectly confined to
organisms with a brain but should be
extended to all forms of life, including the bacteria. In a curious train
of thought, we see that Trewavas
not only defines intelligence but also
(at least to some extent) life.
Some may well reject this line
of reasoning for philosophical
­reasons. Others may point out that a
­computer has the capacity for problem solving. Indeed, so does a slide
rule. Nevertheless, I think an important point would be lost in dismissing the central thesis of this book.
I believe that the main purpose of
Plant Behaviour and Intelligence is
1192 BioScience • December 2015 / Vol. 65 No. 12
to dispel the naïve and erroneous
view that plants are static chemical
factories encased within an unmoving
sarcophagus of cell walls rather than
the dynamically reactive living entities
that they really are. I have been teaching plant biology for nearly 40 years,
and I have faced this prejudice every
year from those students who were
trained to have a zoological perspective when dealing with the general
subject of biology. This is perhaps
not surprising. Examine almost every
major introductory biology textbook,
and you will find plants described in
ways that emphasize the chemistry of
photosynthesis and water transport
on one hand and the coevolution of
insects adapting to the shape, size,
color, and fragrance of flowers on the
other. The biology of behavior is generally dealt with by using animals as
exemplars. However, leaves turn to the
light while roots burrow and search
for water and minerals. Can anyone
look at a vine climbing the side of a
building and not see a search pattern
that is both economical and successful? Indeed, sadly, many can.
In his book, Trewavas draws upon
erudition and his many years of experience as an experimentalist to change
our perspective about plants. He
begins by tracing the history of the
study of plant behavior and expounds
thoughtfully on plant responses
to external and internal stimuli.
Because of this, Plant Behaviour and
Intelligence becomes a fascinating
read. Starting with the experiments
of Charles and Francis Darwin, both
of whom were superb botanists, we
are led through a series of chapters
dealing with the evolutionary origins
of photosynthesis and multicellularity; the various guises of plant behavior in response to light, gravity, and
touch; and topics such as the nature of
cognition, instinct, reflexes, and intelligence itself. In sum, Plant Behaviour
and Intelligence is a carefully crafted
philosophical discourse on plant life,
one that will undoubtedly tread on
some cherished and long-held prejudices about plants—and one that
might change the opinions of some
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about the living substance that makes
up over 90 percent of all visible living
matter.
Although I did not agree with all I
that read, I found this book to be an
easy read, probably because I have
been teaching plant biology for many
years. But I also believe that Plant
Behaviour and Intelligence can be easily approached by anyone with an
interest in plants or biology in general,
because Trewavas writes clearly and
well. For this reason, I recommend
this book to the general public, as
well as to students. You may not agree
with everything you read in it, but
you most certainly come away thinking about the meanings of life and
intelligence.
KARL J. NIKLAS
Karl J. Niklas is the Liberty Hyde
Bailey Professor of Plant Biology in
the Plant Biology Section of the School
of Integrative Plant Science at Cornell
University, in Ithaca, New York.
doi:10.1093/biosci/biv146
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December 2015 / Vol. 65 No. 12 • BioScience 1193