Our own mortality both fascinates and repels us.

On 1 April 2008, the Guardian published a series of black and white photographic portraits of people in hospices taken just before - and just after - their death. Within hours, the photos and link were forwarded to millions across the globe through blogs and social networks. The speed with which these photos - a preview of Wellcome Collection exhibition 'Life Before Death' - went 'viral' shows both our global fascination with death, and how rarely we deliberately confront it before we have to.

The exhibition's photographer Walter Schels and his partner, Beate Lakotta, describe death as a modern taboo. Both say they have overcome their fear of the dead, and of being dead, through the experience of photographing, talking to and touching the dying and dead. It was also brought home to them how important it was to start living now - since many of the dying they spoke to felt their lives were only just beginning at the time death came to interrupt them.

'Life Before Death' is a modern example of Memento Mori (Latin for 'remember you must die'), which have been produced by all cultures across the globe and throughout the ages to remind people of their mortality - and the need to live each day fully and well. These were usually artistic creations such as statues, architecture, engravings, drawings, paintings or mottos, such as 'time flies', which often appear on clock faces.

One response by many cultures to the inevitability of death has been the notion of an afterlife - an idyllic place in eternity that can be reached by living a 'good' life on this earth, according to the spiritual principles of the prevailing culture. A sheet from the Egyptian Book of the Dead, for example, shows the judgment ceremony before Osiris, god of the Underworld. The heart of the deceased is weighed against a 'feather of truth' to determine whether the soul will be devoured by a crocodile or enter the Happy Fields. In Buddhism, death is not seen as something to be feared or avoided. Hell doesn't exist in the afterlife - only in this world. Only once we escape the Wheel of Life (the impermanence of this world) by reaching enlightenment through spiritual practice, will we permanently escape the remorseless cycle of rebirth and enter Nirvana.

Many cultures have depicted the transition from life to death as a journey, often across a river, during which the deceased must overcome difficult challenges and slay or appease various monsters to arrive in eternity. Some cultures, including the Egyptians and the Chimu of Peru, buried their dead along with pottery vessels containing food and drink - either to sustain the dead person on their journey to the other world, or to serve as offerings to the gods once they arrived.

Cultures that mummified their dead, also believed that preservation of their physical bodies was essential for them to be able to persist in the afterlife. As a result many developed extraordinarily advanced preservation techniques. The Egyptians, for example, removed many internal organs to prevent the body from rapidly decomposing many of the internal organs, including the lungs, stomach and intestines. These were then placed in different jars in the tomb close to the body.