Replies

There are lots of variables here. Consider just a few possibilities: Shot, collapses to ground, dies, exposed to elements, starts decomposition. Same as above, but body falls into water--decomposition rate and type changes. Same as above, but becomes covered with water before or after decomposition begins (due to flooding)--decomposition again will be of a different pattern. Same as above, but scavengers (in or out of water) alter body and body parts. And so on.

Regardless, if the decomposition is advanced, especially if the remains are scattered, it can be difficult to tell human from animal, at least for non-anthropologists and non-pathologists (for example, hikers, park rangers, deputy sheriffs, news photographers). Dead cats have been mistaken for human babies, if all that is left are ribs and spine. Deer and cattle leg bones have been mistaken for human arm and leg bones. Bear paws have been mistaken for human hands and feet. And so on. Many times the skull and jawbone are absent--very easy for animals with canine teeth to drag those away from the body to a separate location to gnaw on them--so an easy way to tell human and adult vs. child is frequently gone.

So the remains found have to be removed back to a laboratory and more closely examined for clothing, collars/bracelets, tattoos, hair vs. fur, etc., and then the tissue removed from the bones (takes a few days, with scalpels and scissors followed by heat, agitation, and soapy detergent degreaser solutions on the bones to separate the soft tissues), and the numbers and types of bones examined (two femurs, one right and one left, of same size, so one individual present, for example). Animal bones have different shapes, thicknesses, and markings than human bones (leg bones, for example, usually do harder work and may carry more weight than humans--think big cow, for example--and will have deep grooves for their strong tendons at the knee joints, rather pulley-like, compared to human joints). And are diseases present, which can alter the bone appearances? And are any prostheses present, such as hip replacements, plates and screws, etc.? Note that even pets these days can get hip replacements and orthopedic plates on fracture repairs.

DNA, being a biological material, will likely be partly or severely degraded with the decomposition, and full DNA profiles can't be done, just mitochondrial DNA, which matches only a person's mother's female line. And that also requires knowing some idea of who the dead person is, so that relatives can be identified and tested for DNA for comparison--not that many databases around with lots of people's DNA or mitochondrial DNA already tested. And the results are matches with odds like 1 in 5,000 chance of being a random match, with mitochondrial, vs. 1 in 350,000,000 chance of being a random match with full DNA, so far less persuasive. And it takes days to weeks to get a result, after the referral lab begins the testing (which can take months to get around to starting).

So the dramatic scene on TV of a swab of a decomposed body in the woods immediately stuck into a test tube in the field and the answer coming out just as fast--species, sex, race, age, identify, how long dead--it's all garbage.