Brain size and the evolution of mind

Brain size and the evolution of mind

books connections of the pallium of a pleurodele salamander; the other describes how neuronal birthdates in various parts of the brain of a lizard wer...

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books connections of the pallium of a pleurodele salamander; the other describes how neuronal birthdates in various parts of the brain of a lizard were analysed using tritiated thymidine. Only three chapters involve broad comparisons of brains of different species: most summarize the literature or present new data concerning a specific brain region of a particular species. Although the chapters represent a reasonable cross section of the types of techniques currently applied in neuroanatomical research on nonmammalian vertebrates, the book will be of interest primarily to specialists in the field. Perhaps the most disappointing feature of the chapters comprising this book is that they do reflect the current state of comparative neuroanatomy; that is, the presentation of more and more anatomical detail outside a

biological context. The brains of

Jerison's thesis is based on his concept of mind: '1 identify mind by Harry Jerison, The American with knowing reality' (p. 4). What Museum of Natural History, 1991. is meant by 'knowing' is ex£10.00 (x + 99 pages) (No ISBN plained in the book. The thesis number, but can be ordered from the also requires that equal volumes American Museum of Natural of brain tissue in different species History, Central Park West at 79th be substantially uniform in their Street, New York, NY 10024, USA) organization. This notion is supThe title of this book will seem ported by unpublished data of disturbing if you have spent a Jerison and Almut Schiiz, which good part of your life searching demonstrate uniformity in the for the secrets of what the brain size of callosal axons in mice does (i.e. the forming of a par- and rhesus monkeys, in spite of ticular 'representation' of its en- the large difference in brain size vironment that is the most appro- between the two species. This priate for reproduction and sur- is a puzzling finding that will vival), as if such functions were undoubtedly stimulate more to be found in the cellular and research. subcellular organization of neural Jerison then takes you through circuits. fascinating worlds and epochs. You may disagree with the Perhaps some 175 million years author that from brain size alone ago early mammal-like reptiles nothing can be inferred about the successfully occupied crepuscular mindJ Furthermore, Jerison does and nocturnal niches, possibly benot discuss real brains, but rather cause they could very effectively missing brains - stony (fossil) integrate information from difbrains at best - and the inscru- ferent sensory sources into cotable minds of our ancestors. It is herent representations of the for these reasons that you will 'world'. More recently, some two pick up this book, which is based million years ago or less, Homo on a lecture supported by the sapiens may have started using American Museum of Natural language rather than scents as a History, and will probably be un- way of labelling his environment. able to put it down until you read On both occasions, brain size through the last sentence. increased disproportionately to

body size. Mind emerged first, possibly in early mammals; then, with language, consciousness of the self. From this kind of book you do not expect new data, but stimulating ideas. If you care about the brain, humanity or life, you will not be disappointed. You will also find precious references, concepts that border on philosophy and, above all, the refreshing feeling that while we restlessly hunt for new data much can still be done with what is available. And that can be a lot of fun.

Books in Brief The Forebrain in Nonmarnmals edited by Walter K. Schwerdtfeger and Peter Germroth, Springer-Verlag, 1990. DM 138.00 (viii + 223 pages) ISBN 3 540 52087 2

This book is based on presentations given at a satellite symposium entitled 'Comparative Aspects of the Structure and Development of the Forebrain in Lower Vertebrates' held in conjunction with the meeting of the European Neuroscience Association in 1988. The volume comprises 17 chapters, which deal primarily with the cellular organization and connections of various portions of the telencephalon in fishes, amphibians, reptiles and birds. Only two of the chapters deal with development: one compares the larval and adult

Brain Size and the Evolution of Mind

TINS, Vol. 14, No. 12, 1991

vertebrates are dissected with ever-increasing technical sophistication - as if they were machines being dismantled - but few evolutionary hypotheses ever appear to be tested. There is no question that there exists a staggering amount of variation in the forebrains of nonmammalian vertebrates, and there is little doubt that this variation is the result of half a billion years of evolution. However, in the contributions to this volume, as is too often the case, there is no stated purpose for many of the individual studies, no focus on an important biological question, and none of the sense of excitement that presently permeates many other comparative disciplines. R. Glenn Northcutt Dept of Neurosciences, 0201, University of California,SanDiego,LaJol/a, CA92093, USA.

Giorgio M. Innocenti Institut d'Anatornie, 9 rue du Bugnon, 1005 Lausanne,Switzerland.

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