book reviews discovered just such a polymorphism on chromosome 4, which is linked to Hunting- Past masters ton’s disease, after screening with only three probes. That this led to the identification of the genetic disease locus made linkage analy- Artist’s impression of two resting sis seem relatively easy and highly effective. Styracosaurus albertensis, taken from But the hunt for mood genes has so far The Horned Dinosaurs: A Natural proved to be a dismal failure. Claims made History by Peter Dodson, which is now for linkages to the X chromosome and chro- out in paperback from Princeton mosomes 11 and 18, based on studies of University Press at $19.95, £15.95. A 8 Amish, Israeli and Costa Rican pedigrees “comprehensive” and “even-handed” respectively, have not been substantiated. work, wrote Angela Milner in a review Frustrated, Barondes turns to Alzheimer’s of the original hardback edition disease, susceptibility to which is increased (Nature 384, 426; 1996). by the presence of the apolipoprotein A4 genotype, to reassure us that gene linkage can be useful in studying mental disorders. Because the linkage approach has failed to identify mood genes, the peremptory dismissal of the candidate gene approach is puzzling. However, this and other inconsis- wiped out by the second wave, consisting of their biotas allows him to tell with authority tencies do not detract from the overall our ancestors, armed with tooth and buckler. a much broader story of their role in importance of Mood Genes as an interim Behind the ‘news’ story is the publication . No doubt some academics’ eye- account of an exciting gene hunt, written in of Mark McMenamin’s The Garden of Edi- brows will be raised by the intrusion of per- comfortable and in parts racy prose by an acara, a popular account of his interpreta- sonal belief but, as much as anything else, authority in the field. The evidence for the tion of the problematic soft-bodied organ- this book is an account of an intellectual genetic transmission of mood disorders is isms called the Ediacarans. He has based his journey and not an academic paper. His incontrovertible, so the hunt must go on. ideas on those of the German palaeontolo- authorial voice is a complex mix of omni- George Fink is in the MRC Brain Metabolism gist Dolf Seilacher, who coined the term Ven- scient narrator and guide/teacher, at times Unit, Department of Pharmacology, University dobionta to describe what he sees as the curi- demanding or dismissive but always enor- of Edinburgh, 1 George Square, Edinburgh ously alien nature of these fossils as neither mously informative and questioning. EH8 9JZ, UK. nor plants. Accordingly, the Edi- Conway Morris has the advantage that acarans were a failed evolutionary experi- the fossils are now better ment and were unceremoniously hustled off defined than the Ediacarans, with plentiful, the stage of life by the advent of the more biologically based data and a good under- Animal anomalies familiar Cambrian biota of arthropods and standing of the taphonomy (post mortem The Garden of Ediacara: Discovering ‘shelly’ molluscs. Ediacarans have been processes of burial and fossilization) of the the First Complex Life found around the world, mainly in late Pre- animals, both essential prerequisites for by Mark A. S. McMenamin cambrian marine sediments dating from 600 interpreting the fossil record. This has not Columbia University Press: 1998. Pp. 284. million to 544 million years ago, but they are always been so: as little as 20 years ago there $29.95, £23.95 now known to have survived into Cambrian were considerable misconceptions about The Crucible of Creation: The and possibly younger deposits. some of the weird and wonderful creatures Burgess Shale and the Rise of It is a hard task to inform a non-specialist of the Burgess Shale, such as Animals reader about the Ediacarans with their and Hallucigenia. by Simon Conway Morris unusual mode of preservation in sandstones. When published his Oxford University Press: 1998. Pp. 242. The task is made even more difficult because Wonderful Life in 1989, he claimed that so £18.99, $30 there is now an intellectual free-for-all on the many of the forms of life present at that time Douglas Palmer Ediacarans, unconstrained by much in the were wiped out by extinctions that, if the way of data. Ediacarans have variously been tape of life were replayed, there would have Writing for a wide readership about obscure ascribed to lichens, protozoans, cnidarians, been a very different set of survivors. Fur- and extinct organisms without common annelids and arthropods. thermore, chance would mitigate against names or modern analogues is peculiarly dif- McMenamin is at his best when he has a humans being among them. Conway Morris ficult. Nevertheless, the discovery of such good story to tell, such as his 1995 discovery argues against Gould’s historical contin- fossils, especially when they are the remains of Cyclomedusa fossils from late Precambri- gency, claiming that “it does not have such a of some of the earliest complex multicellular an sediments 600 million years old in north- meaningful effect on the totality of life” and organisms, is so important that it warrants ern Mexico. A traditional tale, it has a “a different message can be read from the any serious attempt to tell their story. At least sequence of trial and tribulation for the nar- Burgess Shale”. a book provides the scope to go beyond the rator ‘hero’ in his quest for the ‘holy grail’. Part of this argument extends back to the constraints of the media soundbite. But too often his narrative approach as jour- Ediacarans. Conway Morris makes a strong The pitfalls of gross generalization and nalist, observer and confidant is not as satis- claim for at least one biological contact misrepresentation are only too well known. fying as that adopted by Simon Conway between the Ediacaran Charniodiscus and Recently, the main morning news pro- Morris in The Crucible of Creation. Thaumaptilon, a sea-pen from the Burgess. gramme on British radio raised the question Conway Morris is concerned mainly with Perhaps the difficulties will be resolved only of whether ‘intelligent’ life, as it was put, had exploring the nature of the Burgess Shale if other Ediacarans are found in a similar evolved twice in the distant past. Further- organisms of middle Cambrian age, around mode of preservation to the Burgess. more, it was claimed that the first wave of 520 million years old. But his wide-ranging Douglas Palmer is at 31 Mawson Road, ‘innocent and peaceful, sentient beings’ was experience of other Cambrian deposits and Cambridge CB1 2DZ, UK.

536 NATURE | VOL 393 | 11 JUNE 1998 Nature © Macmillan Publishers Ltd 1998