In many cases, bodies of holy people have been mummified and preserved without apparent outside intervention. While believers point to holiness, many others point to rare natural conditions where the body desiccates, often in an extremely dry or seal environment. While there's no rot, often these bodies darken and become gaunt--all the pretty ones on display have been covered with wax or a similar substance to make them more appealing (there's a great Buddhist monk who's mummified in the position he died in....but his followers put incongruous sunglasses on him because obviously his eyes weren't preseved). Similar processes (not the wax part or sunglasses part, the lack of decay part) seem to have occurred in others to not particular holy people: bog bodies, Andean mummies, Tarim mummies, Mummies of Guanajuato, Maronite mummies, Mummies of Venzone, etc.

Most famously there's the incorruptibility of Eastern Orthodox and Catholic Saints (and Beati) (the best set of pictures is here, if you're curious). The next most well established tradition is that of so-called Buddhist mummies, called in Japan Sokushinbutsu.

In general, these claims appear less common in other traditions for rather obvious reason: Judaism and Islam require very quick burial. Zoroastrianism see bodies as polluting to both the earth and fire and uses "sky-burial". Hinduism generally recommends cremation. Buddhism and Christian are more flexible with what happens to a body after directly death, which may allow for more time to detect this sacred incorruptibility. Once one saint/bodhisattva is established as incorruptible, the trope of course spreads.

There are some claims of incorruptibility in other traditions as well: apparently, not all Hindu saints are cremated, and, for instance, Yogananda, who was buried 20 days after he died, apparently had an incorruptible corpse (the mortuary director who later embalmed him claimed as such, that "No indication of mold was visible on his skin, and no visible drying up took place in the bodily tissues [in the first twenty days after death]. This state of perfect preservation of a body is, so far as we know from mortuary annals, an unparalleled one."). I found a strange Muslim website that claimed all "true Muslims" are bodily incorruptible, though this does not appear to be a widespread belief.

The symbolic associations behind this belief are obvious: first, one of religion's major claims is an ability to triumph over death in this world, and provide some sort of transcendent existence. Therefore, the lack of corruption and rot shows evidence of this transcendence. Second, incorruptibility is evidence of the dead's absolute purity in life continuing beyond the mortal coil. But where does this belief first arise? I'm having trouble thinking of clear cases of incorruptibility in earlier traditions.

This obviously pushes us towards the illusory category of "dying and rising gods", which comes out of James Frazer's Edwardian The Golden Bough (many of these figures weren't gods, but other supernatural beings, folk heroes, etc). J. Z. Smith convincingly argues that this was a Christian conflation of two distinct types: gods that die (but do not come back to life) and gods that disappear and come back (but do not die). I believe the full version of Smith's essay is now online. Even in these cases, however, we don't really see accounts of natural bodily incorruptibility as far as I can tell.

When does this idea appear in Christianity and Buddhism? When does it appear in other traditions, if at all? Are there a pre-Christian/Buddhist traditions that match this format, of holy lives leading to incorruptible corpses?