The Oxford Companion to the Body

eds Colin Blakemore and Sheila Jennett

753pp, Oxford, £39.50

Babies are born without an idea in their heads, but with an innate talent for looking at faces. Studies show that babies spend a lot of their waking hours in the parental arms, studying noses, chins and eyes. At just a few weeks, a baby will start to copy the parent's expression. At three months they will take the lead in the silent dialogue, smiling, scowling, turning away.

We talk of a speaking likeness, a nose for gossip, bedroom eyes, a noble brow, a sulky mouth. Language begins with the face, an architecture of 14 bones and 32 teeth supporting a fabric of muscle and skin, which shapes both outlook and identity. At four weeks, the foetus has a forehead protrusion and an incipient mouth, but the face goes on changing dimension well into adolescence. Then, notoriously, it succumbs to time and the assaults of the environment.

Yet humans have an astonishing ability to spot a once-known face from a random selection, or identify an adult friend from a 40-year-old school photo. Faces conceal, but more often reveal: doctors use the word "facies" to describe the general appearance of a patient, and can look for a number of congenital conditions and even infectious diseases - Down's syndrome, measles, syphilis, polio, chronic alcoholism and so on - in the face on the other side of the consulting room. The capacity to read the message in a pair of eyes or the tilt of a mouth is acutely developed. Victorian phrenologists began looking there for the stigmata of criminality. Is the face what Corneille called a "smooth imposter"? Or was Schopenhauer on to something when he said that, as a rule, a man's face was "the monogram of all his thoughts and aspirations"?

Much of this comes from one entry in this marvellous book, between a piece on eye movements and equally gripping little essays on facial expression, faeces, fainting, Fallopian tubes and farting. Most are heady cocktails of serious science and eye-popping anecdote. (Sample: "A vet in Holland was smoking a cigarette while working on a cow. It farted and after the subsequent explosion the barn burned to the ground.")

This is a book edited and written almost entirely by scientists, but it serves equally as an anatomy of human ideas, a physiology of human endeavour, a companion to human culture. It begins with abdomen and abortion and ends with zombie and zygote, and the entries themselves are inclusive: it is one step from the appearance of hominid bipedalism millions of years ago on the plains of Africa to the ritual in Palestine of washing a guest's feet, the foot as a measure of distance, and the Chinese practice of foot binding.

This is that rare thing, an encyclopaedia you want to go on reading. Some entries are terse and functional, but most celebrate the intimacy between physiology and achievement. Hygeia was the goddess of healthy living and hygiene has a powerful role in the battle against disease; but it didn't take 20th-century savants long to get to less healthy ideas of racial hygiene, or start worrying about sexual hygiene. Here you go straight from sexual hygiene to hymen, with the additional information that the Virgin Mary's unbroken hymen was likened by medieval thinkers to "a pane of glass that the sun passed through without piercing". The stuff that follows on hyperbaric chambers is almost as gripping, and there are entries on physical actions such as gasp and gaze so neatly put as to provoke a deep, near maximal inspiration through an open mouth, followed by a wide-eyed stare.

It would be wrong to call this a work of genius, having read the appropriate entry (degenerationist psychiatrists in the 19th century believed that geniuses were either short of stature, or had a propensity to gout). This is the book in which to look up the word genome, only to be immediately beckoned and beguiled by entries on gestures, ghosts and giants. This giant endeavour should be very high on everyone's wish list: a dictionary of life and death, to be placed on the shelves next to the Shorter Oxford, probably to be consulted as often.