Is it human?
It's not uncommon for a hiker to find a bone in the woods. Sometimes it’s clearly from an animal, a minute mouse skull or perhaps a fragment of turtle shell. Other times, however, the origins are more unsettling: the bone may be large or perhaps unsettlingly familiar. In these cases, questions about its source may creep into mind since the words “a hiker’s chance discovery” are all too well known by Americans today. Bones of this nature are often presented to police departments for identification, but the police do not always have the necessary expertise to make a definitive identification. Instead, they might refer bones to a local coroner, medical doctor or osteologist for a more exacting opinion.
That said, there are relatively few species of animal in the Eastern United States with skeletal elements large enough to be confused with those of an adult human. Of these, many are either uncommon or have limited ranges, such as elk, moose or harbor seals. In the east, only two frequently encountered wild mammals are of sufficient size to be confused with humans: white-tailed deer and black bears. Black bears in particular are notorious among anatomists for the similarity of some of their skeletal elements with those of humans. Below is an image of a severed bear foot that was sent to my mentor at Penn State, Dr. George Milner. The construction worker who found it was deeply disturbed, thinking it to be the foot of a murdered child. 
Similarly, a bear’s front paws can also look frightfully human. The image below was taken from my thesis, a photographic guide that deals with the problems of identification. At first glance, the picture seems to be that of a human hand. Closer examination reveals some differences though. For example, when observed more closely, the paw seems to have five fingers and a thumb. This “thumb” is actually an elongated wrist bone however, and not a digit.
In America today, we tend to think of graveyards as permanent: once someone is buried, that’s where they’re going to stay. This really wasn’t the case even in the relatively recent past. Especially in urban areas were burial space was at a premium, a grave wasn’t a final resting place, so much as a convenient location to let a body rot. Afterwards the bones would be disinterred and moved to a more permanent area such as a charnel house or ossuary, which are structures devoted to this task. Ranging from modest to immense, these can contain either unsorted bones from newly excavated graves or intricate, carefully stacked piles. Below is an example of exhumed skulls I saw at a church in Poznan, Poland. The second image is one I took at a larger, more orderly ossuary I visited in Sedlec in the Czech Republic.
In other cases, new graves would simply be cut into the ground on top of older ones. I took the image below at a medieval burial site in Poland that I helped to excavate. In it, you can clearly see how a child’s grave was dug into a preexisting adult grave. In the process, the rest of the remains were simply cast aside, and the few remaining adult bones in the picture were all that were found.
The knob of bone on the front of this skull is a button osteoma. These are small, benign tumors that, though rare, are most commonly found on the frontal or parietal bones of the skull (the forehead or sides). Though small ones can be the size of a pin head and are rarely visible through the skin, larger ones such as this one would cause a distinctive bump that would have been plainly visible in life. As such, they tend to be useful in a forensic context for identifying remains.
Interestingly, this individual had another anomaly as well. The apparent fractured line running up the center of the forehead is actually called a metopic suture. It’s unusual because, though present in children, it usually disappears early in childhood, leaving a smooth expanse of bone. Retaining one through adulthood is rare, though harmless. On the other hand, if this suture closes too early in life the frontal bone will be unable to grow properly, resulting in a deformation called trigonocephaly, so named because the sufferer’s head will have a triangular appearance when viewed from above. Fortunately, this can be corrected surgically if it’s noticed soon enough.
I've heard of trepanation. What is it?
Trepanation is an intriguing procedure that has been practiced for several thousand years. Basically, trepanation is the process of removing part of the skull for a variety of real or imagined benefits. The procedure, or variants of it, is still done today, but no, doctors aren’t drilling into the skull to release evil spirits. Dubbed a craniotomy or craniectomy depending on whether or not the removed bone is replaced, the intent is to reduce pressure on the brain for people who have experienced severe head trauma. Modern trepanation isn’t as uncommon as you’d think.
Of course, there are those who claim that trepanation also has all manner of spiritual benefits. Tales of increased energy, improved creativity or permanent highs, have convinced some people to undertake trepanation in their own homes using drills or carpentry equipment. In a fascinating, if gory, article, a body modification affectionado named Bryan Henderson explains his experiences with the procedure.
http://www.bmezine.com/news/people/A10101/trepan/
As much as I hate to even have to say this, please don’t try to open your skull at home. Henderson himself admits that any positive changes he experienced were short-lived and mostly due to wishful thinking. The stupidity of drilling holes in your head for unrealized benefits really can’t be understated.
That said, as I mentioned earlier, trepanation has been practiced around the world for millenia. Some of the best documented cases come from the Andes Mountains where, at some archaeological sites, skulls have been found that are riddled with holes. What’s particularly intriguing is that the survival rate seems to have been fairly high for operations. You can tell by looking at signs of healing that some individuals lived for longer periods than one would expect. This is especially surprising considering that the openings were made by sawing or scraping into the skull with stone tools. These unusual survival rates are still not meant to be an endorsement. Please don’t cut your skull!
In archaeology, however, not all holes in skulls are trepanations. In any society with warfare, there will likely be a number of head injuries that look like intentional trepanations that are more likely to simply be battle wounds. In the pictures below for example, the hole in the upper individual’s skull is probably the result of a glancing sword blow. This can be inferred from the large number of skulls from the same area that look like the one shown in the second image. The massive piece of bone missing from the face was obviously not intentional..jpg)
I found this weird, lumpy bone in the woods. Did the animal have cancer?
Possible, but doubtful. It’s much more likely that it stems from one of two causes. First, little woodland creatures generally lead harsher lives than we do. If an animal breaks a leg, it’s not as if it has many medical options: it gets better on its own, or it dies. Healed fractures, especially bad ones, can look rather freakishly malformed and even cause normally separate bones to fuse together in a mass of bony tissue. Of course this sort of situation is not just limited to animals. On a trip to the Czech Republic, I visited the crypt of a church filled with remains of generations of parishioners (though that’s a story unto itself!). Among them was this:
You can see that many of the separate bones of the wrist and palm have fused together forming a solid mass. Presumably, the poor fellow had a crushing hand injury at some point that, upon healing, fused into the immobile, paddle-like appendage seen here. Bad for him, but instructive for us.
Alternately, a malformed bone could be the result of an infection, referred to broadly as osteomyelitis. Again, this is a nasty sort of thing and can affect the bone and surrounding tissue. Osteomyelitis can also accompany bad fractures. Here’s an example from an opossum:
Although it may be difficult to believe, these two bones are both femurs (thigh bones) from the same animal. The upper one has what would normally be considered a bad case of osteomyelitis, especially on the right half were the heavily pitted surface would have joined the knee. The lower one, on the other hand, looks obliterated.
So yes, probably not cancer, but almost undoubtedly the result of animal misery. If you feel bad at this point, you can always make a donation to local animal shelters or wildlife rescue services that deal with this sort of thing.
