Wednesday, 12 November 2008

How proxy is a proxy? - Part I

As I've mentioned in a blog a couple of months ago, Piggy hide and seek, I've recently been looking into the idea of using shallow water marine geophysical techniques in helping Law Enforcement Agencies conduct underwater body searches. Going through the frantic research process involved with writing any kind of research proposal, a particularly interesting thought occurred to me, namely:

How accurate are taphonomic experiments where non-human, proxy cadavers are used?

In certain states of the USA it is possible to use human cadavers when people have donated their body to science, or their body remains unclaimed. This has enabled researchers at the University of Tennessee's Anthropological Research Centre, in Knoxville, to setup their 'Body Farm', where human cadavers are placed in a variety of environmental conditions and their decay monitored over a period of days, weeks, months, and sometimes years. As a result of the ground-breaking research conducted at Tennessee, other body farms have now sprung up in Western Carolina University and Texas State University, although on considerably smaller scales.

The work undertaken by these institutions has been truly astonishing, advancing forensic entomology immensely. Without this work there must be thousands, perhaps hundreds of thousands, of homicides the world over that would never have been solved. However, outside of these specific locations, the vast majority of people trying to undertake research in this, or related, fields have to rely of using proxy cadavers, normally domestic pigs. This leads to the question of how accurately a pig cadaver can imitate a human one? Taphonomically they have been shown to be very, very similar; their skin is close enough to ours for use in skin grafts for burns victims, whilst, also being omnivores, they have much the same gut bacteria, leading to a decomposition progression that very closely mimics our own.

This is all well and good for taphonomic and forensic entomology studies of beetle or fly larvae colonization, etc, but for our purposes, where we want to image the acoustic properties of the cadavers, can we truly say the same?

This is something I'm, hopefully, going to explore in the next few blogs by discussing the physics behind the variety of acoustic profilers that can be used. In this way, it should be possible to see where the potential differences between the different cadavers could result in different observations.


pacalaga said...

See? This is why I love the internet. The fact that someone out there wants to know about acoustic properties of cadavers is so cool, and random, and still useful...
Are there studies on acoustic principles of live humans vs. live pigs? (I'm no scientist, but I'm deeply entertained and fascinated by your whole idea.)

Mark said...

Thanks! Glad to hear that someone finds my random thoughts interesting.

Sadly there are no studies, or none that I'm aware of, that have compared the acoustic return from pigs and humans. If they were, it would be something from the 50s/60s. With all the issues surrounding whale and dolphin beachings that have dominated the press recently, there is a lot of concern regarding the dissorientating and, potentially, harmful effects of sound waves. Animal rights campaigners would probably ear your arms off just for thinking about it! :)