Forensics, or forensic science, is always evolving to better aid in the apprehension of criminals. But what if a killer leaves his victim with no fingertips, DNA, or teeth? One way to determine the age of a victim is by examining the eyes.
Sounds bizarre, doesn’t it? The soulless eyes of a murder victim allow investigators to determine their age at the time of death. This process is called Radiocarbon Dating.
You’re probably familiar with how to tell the age of a tree by examining a split piece and counting the number of rings. Same basic idea when examining a victim’s eyes.
How is this possible?
Each of us, whether we realize it or not, have been exposed to naturally occurring levels of radiation. Most prominent in the 1960’s and 70’s, particles of radiation released into the atmosphere while testing nuclear weapons. Over the years—decades—these particles have fallen to trace proportions. But there still remains naturally occurring levels of carbon in the air. Different forms of carbon are ingested every day. Thus introducing the trace into our system. Actually, many carbon compounds are crucial to our way of life.
Radioactive particles and naturally occurring carbon settle in the crystallins of the eyes, and Radiocarbon Dating is the process of detecting this manifestation.
What are Crystallins?
Crystallins are microscopic proteins that bind together and collect on the lens of the eye. According to Explore Forensics, one of my favorite sites, crystallins got their name because of how they react under a microscope–like crystals, allowing light to pass through. From the time of conception (conception! Let that sink in) until age two, these crystallins form in and around the lens of the eyes. At which point the formation stops. When this happens trace elements of carbon permanently fuse in between the crystallins.
So when an investigator–usually a scientist or pathologist–conducts a Radiocarbon Dating examination s/he’s looking at the levels of the carbon fused with the crystallins. To calculate age, s/he subtracts the current levels of radioactive carbon in the eye from the naturally occurring levels of carbon in the atmosphere today. By comparing the levels of radiocarbon in the crystallins to the atmospheric levels s/he can determine the precise year of a victim’s birth.
Determining the Sex of a Skeleton
There are many differences between the two sexes, and the variation runs as deep as our skeleton. This is especially important for corpses in advance stages of decomposition. All that might remain is the skeleton, perhaps teeth, and possibly some hair. Even if the pathologist has teeth and hair to work with, that doesn’t mean enough material remains to ID the victim’s gender.
This is where the skeleton offers more information. The only exception would be that of a pre-adolescent, where sexual dimorphism is slight, making the task much more difficult.
The most common way to determine a skeleton’s gender is by bone size. Not the most accurate, but it’s a starting point. For the most part male bones are larger than female bones because of the additional muscle that increases on the male through adolescence and into adulthood.
Another good inclination of gender is the pelvic area.
The sub-pubic angle (or pubic angle) is the angle formed at pubic arch by the convergence of the inferior rami of the ischium (loop bone at the base) and pubis (top of loop) on either side. Generally, the sub-pubic angle of 50-60 degrees indicates a male. Whereas an angle of 70-90 degrees indicates a female. Women have wider hips to allow for childbirth.
There are also distinctive differences between the pubic arches in males and females. A woman’s pubic arch is wider than a male’s as is the pelvic inlet, to allow a baby’s head to pass through.
The pubic arch is also referred to as the ischiopubic arch.
Incidentally, this difference is noticed in all species, not only humans. Same with Radiocarbon Dating.
The area around the pelvic inlet (middle of the pelvic bone) is larger in females than in males. A female skeleton who has given birth naturally will be identifiable because this space widens during childbirth. Even though it contracts afterward, it never fully returns to its original size. In the picture above notice the heart-shaped space.
Other Body Clues
The acetabulum—the socket where the femur (thigh bone) meets the pelvis—is larger in males. Also, the head and skull have several characteristics indicative of one sex or the other.
- In males, the chin is squarer. Females tend to have a slightly more pointed chin.
- The forehead of males slant backward, where females have a slightly more rounded forehead.
- Males tend to have brow ridges, where females do not.
These differences and more tell the pathologist the gender of the deceased.
What Do Forensics and Skeletal Differences Have To Do With Crime Writing?
Everything! We can use the differences between male and female skeletons to add realism to our fiction. Let’s say a body is discovered in the blistering heat of the summer. The victim hasn’t been found for months, leaving only the skeleton. By showing our pathologist or Medical Examiner measuring the pelvic inlet, arches, and angles, we’ve essentially ensured our reader isn’t going anywhere.
Same holds true for the lab conducting a Radiocarbon Dating Test on the eyes of a murder victim. Adding forensic details is a lot of fun, too, for the writer and the reader. The trick is to disguise our research in a compelling storyline rather than dumping the information all at once.
One of the things readers comment most about in reviews for Marred are the forensics. Specifically, the blood spatter analysis scenes, where Niko Quintano, Grafton County Sheriff, teaches one of his deputies how to determine low, medium, and high velocity spatter.
I’ve spent countless hours studying forensic science. The field fascinates me. As such, in the coming year not only will I set specific days for posts but I’ll share several forensic techniques and advances. Writers can use the forensic details in their stories and readers should find the posts interesting as well. Win win.