The wolf in your living room

For an animal that has such important sociological and ecological roles, it is perhaps surprising that there have been few attempts to synthesise all the available information on the many facets of the evolution and behaviour of the domestic dog. This book fulfils that need and as such is both welcome and long overdue.

By any standards, dogs are extraordinary animals. It appears that the dog was the first species to be domesticated by humankind and, of all domestic animals, it is the one most profoundly altered through selective breeding. No other group in the animal kingdom has achieved such a diversity of forms in so short of time, with the majority of the 400 or so breeds having been created since the late 19th century. Yet despite all this morphological diversity, there is less difference between the mitochondrial DNA of domestic dogs, wolves (their wild progenitors) and coyotes than there is between the various ethnic groups of human beings. In genetic terms at least, domestic dogs really are the wolf in your living room.

We still do not know why Paleolithic hunter-gatherers chose to tame wolves. The process started at least 12,000 years ago, possibly at one or a number of points in Eurasia. Whatever the origins, however, semi-domesticated wolves were to be found worldwide by about 8000 years ago, and this rapid spread suggests they were highly valued by early societies, and widely traded. During the early stages of domestication, the aim of selective breeding appears to have been to produce a docile and manageable temperament. Although wolves can be tamed, they are over-reactive and difficult to control. Yet selecting for this one feature also led to the acquisition of many other features, rapidly producing an animal that looked very different from a wolf. The morphological changes that had been produced in turn also had an impact on the animal's behaviour. In particular, the acquisition of such dog-like features as shaggy coats, drooping ears and curly tails meant dogs no longer rely to the same extent as wolves on visual signals to communicate and instead make greater use of sounds and smells.

One of the other consequences of this early selective breeding for temperament was that the aboriginal dogs retained the behavioural flexibility of juveniles. This was of great benefit because these animals then provided the ideal opportunity to develop breeds with novel and unusual patterns of behaviour, and most of today's breeds are associated with performing particular tasks or behaviours. Recently, however, this trend has been reversed; selection for breed characteristics has had a damaging influence on both temperament and behaviour, often the very behaviour patterns for which the breed was first developed.

Although this long association has meant that dogs have had a large impact on human society, particularly as working and companion animals, the relationship between dogs and humankind is complex. Dogs can be "man's best friend" or a social outcast - a pariah - and at least five million pet dogs are discarded and destroyed each year in the United States alone. Dogs are also the most frequent animal victims of cruelty and abuse. Dogs spread diseases such as toxocariasis, and feral dogs have a high nuisance value and are potentially dangerous; dog bites are frequent and some dog attacks even result in human fatalities. While it would appear that feral dogs generally have limited ecological impact, on islands they can cause significant losses of vulnerable species of wildlife. Elsewhere, feral dogs can pose a conservation problem by interbreeding with wolves.

This book has contributions from 21 authors. While this ensures a great diversity of information and views, there is also a lack of consistency. Overall, however, it is an admirable and wide-ranging compilation.

Stephen Harris is professor of environmental sciences, University of Bristol.