The Biological Profile

So a briefing on the Biological Profile: This is the term that FAs use to cover the four parts peer-established to help identify a person based on their skeleton, and their skeleton only. Age, Sex, Ancestry, and Stature. My biggest challenge..explaining this to middleschoolers.

First, I started with determining the sex, so in this case it’s a biological sex, not a self identified gender. The choices are male or female. And I agree with using these two “sexes” at this point in time because when you identify yourself on your license or birth certificate (etc) you have to choose male or female. This is one of the most conservative things I will say, but I’m sure I’ll counter it shortly. In the classroom, I explained that in general males bones are larger than female bones, point #1. Then I held up  the skull and showed some features that indicate the skull was male, drastically male; thick, large (even protruding) eyebrow ridges, a large jaw, overall large size of the cranium, and  the distinct, heavy muscle markers on the occipital region of the skull (the back that anchors neck muscles). They got it. Nice!

Second, I roll with Ancestry, since we’re on the skull. The face is the hot spot for indicators that suggest ancestry. I could get all sociological about the differences between race, ancestry, ethnicity, and nationality…but not now. FAs use the terms ancestry and race interchangeably because it depends on what the association you’re working for calls it. What also varies across associations is the group terminology: either White or Caucasian, Black or African, or Asian or Mongoloid. In the classroom I explained that these three are the ones that we have the most information on so we try to group people according to the facial (or skeletal) features into those groups. Some people might have a combination of groups, which is called admixture, and it’s difficult to determine; however, we know that it’s a person of mixed ancestry (like millions of people around the world, especially in this melting pot). How can I tell this is a White guy? Well the shape of his skull, the lack of prognathism, the shape of the eye orbits, the teeth, the nasal aperature, and so on.

Third, moving onto Age equals not easy. I explained that a baby human has wayyy more bones than an adult human (206). By scientists sharing and recording their findings about when (# of years after birth) bones fuse together, they can develop charts, methods, and reference tools. The methods can then be used by other scientists and students. They not  only apply these methods using visual assessment but then you add statistics to it to prove how accurate the method is. You know, like everybody’s teeth fall out around a certain age, it’s like a trend. I started with the skull and pointed out where the cranial sutures are located and that they have no space in between the bones, they’re “closed”. That means this guy is older than someone who has cranial bones that are not fused together, “partially closed” or “open” (I know, high tech words). I compared it to stitching the bones together, because that’s what it looks like, or when you tear a cotton ball, all those fibers stretching out. Next, I said the teeth were fully grown in and there were wisdom teeth present, indicating adult over 18. Then I talked about the pelvis, very laymently. But what I thought really helped was when I said that your arm bone starts in three pieces and then they grow to meet each other and fuse together forming one full arm bone by the time you’re an adult. I guess the general population declares an adult to be 18 or older. Another major indicator that an individual was 18 at the time of death is spheno-occipital synchrondosis. Basically, it’s when your sphenoid and occipital bones fuse at the base of your skull, near where the spinal cord enters your skull.

Stature was kind of an easy one to explain, but a database? not so much. So measuring stature is taking some instruments like an osteometric board, a sliding caliper, a spreading caliper, and/or a tape measurer and measuring out the bones. Ok, easy we can estimate how tall the person was if we have the whole skeleton. Well not entirely because you have to account for the muscles, fat, and other stuff in between your bones. So, what we do is enter this stuff in database, called FORDISC. FORDISC can spit out an estimated height based on these measurements it calculates into statistics. This is more accurate than simply measuring all the bones then adding up the totals to get a height.. not realistic. I didn’t have anything to physically show them for this one.

FORDISC also helps with estimating sex and ancestry based on measurements. A posterior probability and likelihood ratio are spit out after you enter in the measurements. It’s basically telling you what the skeleton is most likely to be. Although, you can only compare your measurements to those in the database. So, still not totally sound but it gives you a good base. Then combine it with your visual assessment and you should be able to put some pieces together to find characteristics of the missing person.

So, the students definitely liked it and so did I. I think they learned something too. One boy asked me “Could you tell someone who is from Cape Verde”? It was difficult to answer. In short, I said yes. I mean, probably not me personally on my own because I don’t know if I’ve ever seen bones from that population before but he doesn’t have to know that. Real FAs can.

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