Like all other animals, humans are bound to die, but unlike other species we are aware of our own mortality. A funeral is the last of the rites of passage by which society marks our progress from birth to death. For at least 30,000 years, human beings have felt the need to dispose of their dead in some way, by burial or cremation, and this ritual always seems to have been connected with a belief in survival after death, either in an afterlife or through reincarnation. This is why, oddly enough, much of what we know about the lives of ancient civilisations derives from customs that they associated with death and the goods that they left in their graves, pyramids, tombs or burial mounds.

Funerary rites can usually be divided into two parts, sometimes reflecting a distinction between public mourning and private grief. Therefore, at the funeral of Pope John Paul II, the actual burial took place in the crypt of St Peter’s, attended by only a few of the Pope’s close associates. However, this was preceded by three days of public lying-in-state, then a ceremonial in the presence of the coffin placed on a carpet in front of the basilica.

This event was witnessed on the spot by an estimated two million people, including many heads of state, cardinals, priests and ordinary mourners, as well as by millions more watching on television.

In traditional societies, the two phases are even more clearly defined. The funerary rites of the Toraja people of Indonesia are so unusual that they have become a tourist attraction. The dead are kept in their houses for up to a year, or longer, then buried in rock tombs after an elaborate ceremony. Some religious believers, such as the Zoroastrians in Persia (Iran), would expose the body on platforms until it had been stripped of flesh by vultures, then bury the remaining bones. In certain Mediterranean societies the body is buried for a time, sometimes for years, then exhumed and the skeleton reburied in an ossuary.

Anthropologists sometimes describe the two parts of such funerals as the separation and incorporation phases, since they are designed, first, to remove the body from the realm of the living and, second, to settle it in the realm of the dead. One may see a parallel, for example, in the Church of England funeral service, where a thanksgiving for the life of the departed and a prayer for those who mourn (separation) are followed by prayers of penitence and prayers for readiness to live in the light of eternity (incorporation).

Death can be the source of many superstitions and taboos, particularly in the separation phase, when some societies believe that there is a danger of the spirit of the departed person returning to the realm of the living as a ghost. Customs that still exist in Christian and other Western societies, such as covering the face of the dead person, lighting candles, ringing bells, wailing and playing music, were originally connected with warding off evil spirits and protecting the living. The wearing of special mourning clothes (black costumes, veils) may have been an attempt to hide the identity of mourners from returning spirits. Legends about vampires and zombies derive from such superstitions about the undead.

The dead body is often considered a source of contamination, quite apart from the dangers of decaying flesh to the health of the living.

Zoroastrians are very much against cremation, for example, because they consider that fire is sacred and that it will be polluted by the dead body.

Taboos about death can extend to family members during the separation phase due to their association with the spiritual pollution of death. For the Cherokee Indians of America, the house and family of a dead person had to be ritually purified by a priest in elaborate ceremonies that would involve burying the dead person’s clothes and washing the relatives in a river. The Maori also wash after a burial to remove the death taboo from themselves.

Most societies have conventions about periods of mourning: how long it should be and how strict. The Catholic Church held a nine-day period of mourning for Pope John Paul II. In Russia, the dead person is commemorated with a wake on the day of the funeral, then again after nine days and after 40 days.

Orthodox Jews observe very precise rules for mourning. Close relatives tear their clothing on learning the news of a death. Burial takes place within a day or two and is followed by a meal of eggs (symbolic of life) and bread.

For the next seven days, the mourners stay at home and do nothing for comfort or pleasure: they sit on the floor or on low stools, do not shave, bathe or cut their hair. After this, the family observes 30 days of less severe mourning. Finally, children who have lost a parent are expected to avoid parties and entertainments for the next year, and every day for 11 of those months to recite the Kaddish, a prayer in honour of God.

This recitation can be seen as a means for the mourner to come through the separation phase as well as benefiting the incorporation of the deceased: it is a reminder of God’s wisdom for those whose grief may make them question their faith and a demonstration of the piety of a well-educated child which should make God look favourably on the lost parent.

A century ago, the French sociologist Emile Durkheim wrote: “Mourning is not the spontaneous expression of human emotion... It is a duty imposed by the group.” Durkheim was keen to emphasise the importance of sociological factors in human behaviour, and it is true that strict and elaborate rituals, such as those observed in Victorian times, tend to reinforce his view.

However, it may also be the case that ritual helps individuals to cope with grief, one of the least manageable of emotions. One way of diverting grief and affirming life is by eating and drinking, two activities widely associated with funerals. The final stage of a Toraja funeral involves singing, dancing and the sacrifice of many water buffalo, in contrast to the frugal egg and bread eaten after a Jewish funeral. Both, however, are means to celebrate the continuity of life. In Russia, graves may actually include a small table and stools. Walking round a Russian cemetery, you can sometimes see a glass of vodka still standing on the table, or friends drinking at the graveside.

Perhaps the most famous custom of this kind is the Irish wake. The wake is not a funeral feast but a preparation for the funeral that takes place around the dead body. Traditionally, the body is laid out, clocks are stopped and mirrors turned to the wall. The mood of a wake is solemn but not sombre. There is keening or wailing over the corpse, and eating and drinking - though the Catholic Church tries to discourage this - as neighbours, friends or even strangers call in to pay their respects. It is not considered improper to joke and laugh.

This savage union of grief and hilarity may be psychologically beneficial: it can be seen in the comic ballad, “Finnegan’s Wake”, which records the death of a builder, Tim Finnegan, and the riotous festivities that followed. A barrel of whiskey is placed at the dead man’s head and a barrel of porter at his feet. When both of these are overturned, drenching the body, Finnegan leaps up, crying: “Holy Jesus! D’you think I’m dead?” The chorus ends: “Lots of fun at Finnegan’s wake!” Behind the comedy, James Joyce saw the song as a resurrection myth and took it as the inspiration for his last novel.

In earlier times, food was also associated with the incorporation of the deceased into the afterlife. All round the world, prehistoric tomb burials are associated with objects that the dead person was supposed to need. In some cases - among the Incas, for instance - wives and slaves would be sacrificed to accompany an important person in death.

The passage to the afterlife is universally seen as a journey, for which the dead person has to be prepared. The Ancient Egyptian Book of the Dead is a collection of incantations, many designed for protection against the dangers of the world to come. These poetic texts, addressed to the deceased, also describe the rituals of purification carried out to prepare him or her for the realm of the dead: “You are pure! You are pure! The front of your body has been washed with spring water, your back has been purified with salts and freshened with incense, your whole body has been washed with the milk of the cow Hesat, with beer of the goddess Tenemit and with saltpetre; all the evil that was in you has been driven out... so that you may live and your soul prosper, and your body, embalmed and whole, be set for eternity.”

The living do what they can for those who precede them into death. In a country that generally has less solid convictions about the afterlife, the emphasis is on recalling the achievements and personality of the dead person, through obituaries, memorial services and other celebrations of the life lived. Especially when death has been accidental or arbitrary, survivors may set up inquiries or trusts in an attempt to reduce the likelihood of similar occurrences in the future, and to console themselves with the idea that the person’s death has served some purpose. All of us like to feel that we shall leave something behind, in the loving memories of friends, in what we have achieved and in our children. At the very least, we may reflect that our death is necessary to make way for continuing life. These may be small consolations, but they are a source of hope - and to sustain that, surely, is the underlying purpose of all funerary rites.