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Why write a book about shrews? The authors of Shrews, Chromosomes and Speciation, edited by Jeremy B. Searle, P. David Polly, and Jan Zima, make a convincing case that shrews have fascinating chromosomes and are an exciting system to study chromosomal divergence and speciation. The book focuses on the common shrew, Sorex araneus, and its 10 closest relatives (S. araneus group), each of which has a unique number and arrangement of chromosomes–known as a karyotype. This alone is a remarkable amount of chromosomal diversity, but the extent of chromosomal divergence within S. araneus is even more extraordinary, with 76 unique karyotypes defined as chromosomal races. As Searle et al. note (p. 456), this may not be the sort of diversity that every biologist gets excited about, but chromosomal variation reflects diversity at its most fundamental level—the packaging of the eukaryotic genome …