Defending the Cavewoman and Other Tales of Evolutionary Neurology

  • Harold L. Klawans
W W Norton, $24.95,224 pp, 2000 ISBN: 0-393-04831-4 | ISBN: 0-393-04831-4

The use of neurological case histories to explore aspects of mind–brain function has a long tradition, with the most well-known contemporary exponent being the neurologist and author Oliver Sacks. It was a pleasure, therefore, to review a book in this genre written by the late Harold Klawans, who was a working clinical neurologist. Klawans' stated aim is to give a neurologist's account of human evolution through the recounting and interpretation of a number of clinical vignettes. Many of the tales and their interpretation make interesting reading for a clinical neurologist, although whether they can be really used to say much about human evolution is debatable.

The book consists of a preface and 13 chapters, and is divided broadly into two parts: the first, the ‘ascent of cognitive function’; and the second, ‘the brain's soft spots’. Readers may find the style of the book a little folksy, yet it is always easy to read. Most chapters begin with an introduction to the patient and his or her neurological problem. In the first section, there are interesting accounts of patients with disorders of language and movement. Although it was not stated, one assumes that the names of Klawans' patients and those of at least some his medical colleagues have been changed to avoid embarrassment or worse. The importance of these cases for the cerebral localization of function, human development and evolution is discussed.

Among other patients discussed, Klawans describes a patient with epileptic aphasia (Landau-Klefner syndrome) treated successfully with neuro-surgery (Morrell's procedure); a conductor who retained his musical gifts despite a severe stroke causing hemiplegia and global aphasia; the effects of acquired dyslexia in a professor of English; as well as the effects of psychosocial deprivation on language development. The second section of the book departs from classical neurology and neuropsychology and encompasses some diseases that are of interest now to geneticists and molecular biologists as well as neurologists. In particular, there are interesting yet tragic descriptions of a family with Huntingdon chorea and a patient with Creutzfeldt-Jakob disease.

The strongest aspects of the book are the humane and vivid descriptions of Klawans' patients, their conditions, and the ways in which their lives were affected. There are many references to art, music and literature; famous names of the arts and science crop up regularly throughout the text. For example, did the great science fiction writer Kurt Vonnegut in his 1963 description of “ice-nine,” as a substance that converts all that it touches into its own ice-like crystalline structure, anticipate Stanley Prusiner's prion?

The uniting theme of evolutionary neurology is somewhat harder to follow, and at times the concept is rather stretched. Klawans has several main points. First, aspects of our brain function have been selected for and certain anomalies may be best understood by appeal to Darwinian principals. One might reasonably ask whether there are any aspects of the human condition that cannot be ‘understood’ retrospectively in this way. A further point is that learning and the brain plasticity it requires underpin cultural and social changes that, in turn, affect the processes of natural selection.

Some of the examples given provide rather tenuous support for the involvement of natural selection in shaping human disease. For example, it is argued that wildebeests don't get Parkinson disease because the slower baby wildebeests with ‘less robust’ (that is, vulnerable) basal ganglia are eaten by lions before reaching reproductive maturity, and the parkinsonian tendency is therefore selected out. I am not a veterinary surgeon, but is it not possible that wildebeest do slow as they age beyond their reproductive prime, and that their ‘Parkinson disease’ is ‘diagnosed’ at this point by the lions? Are there remnants of our ancestors in our nervous system? Klawans explains to a patient with a syndrome of painful foot and moving toe that it has occurred because of an abnormality of circuits in her vestigal (or ‘dinosaur’) ‘spinal brain’. Maybe clinical governance has taken its toll, but I suspect most clinicians—even those with a paelentological bent—would shy away from using examples from Jurassic Park to enlighten patients about their condition.

What of the cavewoman in the title? Klawans credits her first with bringing language into the lives of our ancestors through her prolonged nurturing of the child. And around 200,000 years ago, by surviving a bottleneck in human evolution, she has managed to pass on to us small yet vital amounts of her mitochondrial DNA and, finally, her slim hips and the resulting cephalo–pelvic disproportion prevented successful interbreeding with the bigger, tougher, larger-headed, and therefore larger-brained, Neanderthal. We have much to thank her for—well maybe.

Are these tales of evolutionary neurology? That I think depends on one's understanding of evolution. Using ‘evolution’ to link together the clinical themes, however, does work and the framework it provides leads to stimulating writing. Mostly these are tales of neurology patients and very interesting and well told they are. Neurologists, neuroscientists, students and interested general physicians will find this a book that entertains and stimulates their enthusiasm for wider aspects of the subject.