the use of small samples for research (seeChapter 4 and p. 228) and probably standsout because of the recent media attention toPaleoindians. The chapters on demographyare focused more on classic research inpaleodemography and population historythan on more recent work, and there is nodiscussion of mtDNA mismatch and inter-match distributions, which could provideevidence to support the notion of a demicexpansion of early populations in the Ameri-cas.

Overall, The Origins of Native Americans:Evidence from Anthropological Genetics pro-vides an extremely useful and insightful

examination of Native American biology.The volume will certainly be of interest tothose outside the field of anthropologicalgenetics and should serve as a referencework for those in the field. The breadth ofthis work and Crawford’s ability to useNative American biology to illustrate impor-tant evolutionary concepts make this anexcellent addition to the bookshelves of thoseworking with past or present populations ofthe Americas.

JOSEPH F. POWELL

Department of AnthropologyUniversity of New MexicoAlbuquerque, New Mexico

PHENOTYPIC EVOLUTION: A REACTION NORM

PERSPECTIVE. By Carl D. Schlichting andMassimo Pigliucci. Sunderland, MA:Sinauer. 1998. 387 pp. ISBN 0-87893-799-4. $38.95 (paper).

This is a very good book on a timely topic.Biological anthropologists wanting a mod-ern understanding of the role of genes inphenotypic variation and evolution wouldbenefit from reading it. This is especiallyimportant because in human genetics weare in an age of strong expectations ofsimple determinative relationships betweengenotypes and phenotypes. These are drivenby various motives, of glory and of gain, aspowerful new methods raise hopes for both.Excess genetic determinism has the poten-tial academic consequence of the acceptanceof oversimplified if not highly unrealistictheories and assertions about complex traits(like behavior traits). There are also practi-cal consequences, in the form of the fundingdevoted to biomedical genetics that inevita-bly drains funds from other avenues of re-search.

The evolutionary or modern synthesis wasa proclamation of the middle of this centurythat defined biology as essentially a matterof genetic information, evolution as changein allele frequencies, and population genet-ics as the formal theoretical support for

biology. In subsequent decades this wasextended to a further genetic determinismby the dogma that the genome is the codebook for life and that the flow of biologicalinformation is from genotype to phenotypevia the one-gene one-one protein model.Virtually all biological anthropologists whowere seriously trained in evolutionary prin-ciples beyond the hand-waving level wereindoctrinated by the modern synthesis (andthe problem could even be worse amonghand-wavers). Indeed, until recently it wasdifficult to find texts or even much mainlinematerial that was not based on this tacitformalization of biology.

However, the world does not have to followtheories proclaimed in an at least partlypolitical coup d’etat. A proper understandingof biology requires an accurate understand-ing of the genetic basis of interesting pheno-types. Thanks to advances in genetic technol-ogy, several areas of biology are making acomeback after having been banished by themodern synthesis as unimportant, unscien-tific, or irrelevant. This book presents amore modern view than we can usually findin the journals or most textbooks. Anthro-pologists whose major interest is in complextraits, such as the skeleton, behavior, orgrowth patterns, will find in this book muchof value. Genes are placed in context as butone of the factors, acting in many ways, by

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which phenotypic variation in the biospherearises.

The authors first review the history ofideas about complex traits. They note thecomplex pathways between genotype andphenotype and stress the modern researchthat reveals complexities of interactionamong genes and between genes and envi-ronment. Aspects of evolution that are notpurely gradualistic and in which complexadaptations can arise rapidly are discussed.Improved understanding has come as theresult of a genetic renaissance in develop-mental biology and in the use of newlyavailable genetic sequence data in compara-tive phylogenetic studies.

The authors present a theoretical basis fora norm-of-reaction, phenotypic plasticityview of biological phenotypes. A norm-of-reaction perspective considers the variationin a trait that can arise in genetically identi-cal individuals developing or living in differ-ent environments. The authors provide evi-dence to argue that the developmental normof reaction is itself an object of selection,that there are flexible mechanisms at manystages for regulatory reactions to variedconditions, and that the complexity of theinteracting factors leads to the emergentproperty that is the phenotype.

The authors review basic theoretical per-spectives on the evolution of complex traits,from experimental biology as well as quanti-tative genetics, and then outline theoreticalways to express ideas about reaction normsand phenotypic plasticity. A series of chap-ters deals in turn with various aspects ofphenotypic variation. These include a treat-ment of allometry (essentially correlatedvariation among traits) and variation occur-ring during ontogeny (development), includ-ing concepts such as heterochrony, by whicheven small variation in the timing of eventscan yield substantial phenotypic variation.

Nonetheless, the amount of variationwithin and even between species is effec-tively constrained, and this requires explana-tion. For example, a trait, like the shape andsize of an egg, can be described mathemati-cally in terms of a few parameters. Thatformalism describes a large, multidimen-sional morphological space; however, we find

that only a fraction of that space is or hasever been occupied by real creatures. Theauthors identify a number of constrainingfactors and processes and consider theirrelative importance. These include the inher-itance of a genetic patrimony that cannot beflexed beyond some limits without untowardpleiotropic effects, the legacy of millions ofyears of prior evolution.

One problem in the evolution of complex,especially quantitative traits that are pro-duced by the effects and interactions ofmany different genes and other processes isto understand how the components and theirinteractions can evolve. The authors ana-lyze this problem with a device that appearsin several places in the book, a diagram ofcorrelations of varying strength among thecomponents that contribute to a trait ororganism. Such a visual device schematizesthe limitations placed on any one of thecomponents. Strong empirical correlationsreflect constrained variation between twocomponents, whereas weaker ones allowmore variation (whatever the causes of thecorrelations). This is but one of many heuris-tic, schematic, or otherwise clever graphicdevices used by the authors to give a clearpicture of complex issues.

The authors consider norm-of-reaction ef-fects that are due not to primary DNAsequence directly but to the way the genomeis packaged, processed, and modified at dif-ferent life stages. Some common developmen-tal model systems are discussed in this light.Multiple ways of embryological develop-ment, the specification of cell fate in earlydevelopment, and other topics are included.The role of gene expression switching bytranscription factors like members of thehomeobox gene family is considered alongwith other epigenetic factors in variation.Epigenesis is a general term referring tothose things that are not due to the primarycoding sequences of genes themselves. Assuch, epigenesis is widespread, perhaps ubiq-uitous, and we are probably just beginningto get an inkling of the diversity of itsactions and effects.

The final substantive chapter in this bookconsiders the evolution of reaction normsduring development, putting many of the

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concepts previously considered into a uni-fied context. The book ends with a typicalsumming-up chapter.

It is difficult to provide a good sense of thisbook in a short review. The authors writewell on timely subjects, control a broadwealth of knowledge, and raise examplesranging from the molecular to the morpho-logical, animal to plant. The introductionalone will put many things in modern biol-ogy into clearer perspective, while the de-tailed middle chapters provide specific ex-amples and some technical details. This isan advocacy book and in a sense too special-ized for a standard course, but it would be anexcellent choice for a graduate or upper levelundergraduate seminar. Examples, illustra-

tions, graphs, figures, and text explanationsare compelling and keep the reader’s inter-est. Examples range from natural to theoreti-cal, experimental, and simulated. The tech-nical detail is kept to a manageable level,but the intellectual level is not compro-mised. The authors are persuasive propo-nents of their viewpoint, which, while notnovel to them, is very well articulated and towhich, as contributors to the area them-selves, they bring a fresh, modern, knowl-edgeable force.

KENNETH M. WEISS

Department of AnthropologyPennsylvania State UniversityUniversity Park, Pennsylvania

BOOK RECEIVED

Lynnerup N (1998) The Greenland Norse: ABiological-Anthropological Study. Copen-hagen, Denmark: Danish Polar Center.149 pp. 225.00 DDK (paper).

146 BOOK REVIEWS