Forensic Anthropology – An Overview

The research I’m doing for my doctoral thesis falls under Forensic Anthropology, which means I specialise in the analysis of the human skeleton and I apply this in a legal context. The human skeleton can tell us a lot, but more often than not skeletal evidence leaves us with many unanswered questions.

Forensic anthropology is a science of last resort.  In an ideal forensic world, evidence is plentiful, victims are easily identifiable, and crimes investigated as soon as possible. Never do any of these things happen in forensic anthropology.  We are called in when the death occurred so long ago that the body has decomposed and traditional methods of identification no longer work. And because we’re a science of last resort, we operate with a certain level of uncertainty. We can measure things such as biological sex, age at death, past trauma, certain types of diseases, stature, but all of these within broad boundaries. We very rarely use skeletal remains to try and identify race anymore, as there just isn’t enough evidence that those methods actually work.

When we look at a pelvis to determine biological sex, for example, we rank on a spectrum how female or how male certain parts appear.  This spectrum is Very Male, Somewhat Male, Indeterminate, Somewhat Female, Very Female. Notice how we do not say “definitely female or definitely male.” So here is a human pelvis:

biology-forum-pelvis

We can look at the sub-pubic angle, shown at the base of each pelvis, for an indication of sex. When it’s narrow (left) we would label this Very Male, and when it’s wide (right) we would label it Very Female.

Looking at age can be even more vague! When we’re dealing with children we can be specific to within a couple of years, but past 25 it all goes downhill and we start giving age ranges in decades.  To further compound the work of the forensic anthropologist, most research that has been done to establish these methods of analysis has been done in population specific studies.  Now this can be great if you’re looking at a specific population that has been researched already, but in an increasingly globalised world much of this research is obsolete from a practical point of view.

Something more helpful in a forensic investigation would be using knowledge of past trauma or an illness which we can see in the skeleton. Like a broken arm or cancer. But this raises issues for anyone studying poor victims who have no medical or dental records to work from. And this is critical as it creates a socioeconomic disparity within the discipline. After the Indian Ocean Tsunami of 2004, victims with dental records were positively identified at a significantly higher rate, as dental analysis was the primary method of identification. But the majority of local victims did not have any dental records. One year later, 1252 European individuals were successfully identified with dental records compared to only 21 Thai victims. In these cases, we can ask surviving relatives for what’s called ante mortem evidence—that is evidence from before death including stories, testimonies, medical histories.

Usually at this point people ask about DNA evidence. It’s totally possible to do DNA analysis but it comes with its own set of problems. First, you need to have willing living participants to compare the DNA to and outreach to survivors can be limited, it’s expensive, and the DNA really doesn’t hold up too well over time. You need to have very specific samples from the skeleton and sometimes those just aren’t available because of the decomposition process, or because remains have been moved by perpetrators and are found incomplete. It also raises certain ethical questions. A forensic anthropologist at a conference over the summer gave a presentation about how DNA testing had revealed infidelity during investigations of mass graves in Iraq. Our first and foremost obligation is to the safety and wellbeing of our research participants, and as you can imagine this caused serious problems for them.

I work in mass grave contexts, specifically post genocide.  If that weren’t grim enough, there’s a whole other set of problems specific to mass graves.  In forensic anthropology, we usually look for something call Minimum Number of Individuals (MNI).  Notice how we don’t look for Actual or Estimated Number of Individuals. There are 206 bones in the adult human body, so we need to assume that if we find 206 bones in a grave that it’s one person not 206.  Sometimes the best we can do is put the pieces from the grave together until we get as many nearly complete skeletons as possible, and this means that we will inevitably miss individuals.   And in the case of genocide, often people are targeted for being from a specific genetic group or region, or because they look like they’re from that genetic group or region.  And those physical similarities can make identification of specific individuals that much more difficult.

For more information about the methodologies used by forensic anthropologists, keep your eye out for upcoming blog posts. But as always, feel free to ask any questions you may have in the mean time!

 

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