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Bones Got Bite (Pt. 1)

UF's C.A. Pound Human Identification Lab found bite marks on human bones — made by sharks?

Although the fear of sharks has persisted for centuries and shows no sign of cessation, a great white is the least of Floridians’ risks in the water. Now, UF forensic anthropologists and the Florida Museum’s shark expert have joined forces to use sharks’ behavior to help forensic scientists determine cause of death for those who perish at sea. A paper published in the Journal of Forensic Sciences in May 2017 analyzes six cases in which human remains were recovered from the oceans around Florida.

The Pound Lab is located on the UF campus; forensic anthropology has been at UF for more than 45 years.
Doctoral candidates in the Department of Anthropology staff the Lab.
The Pound Lab does casework for medical examiners, law enforcement agencies, and attorneys.

As on the hit series Bones (but with more realistic timelines and equipment), forensic anthropologists apply their robust understanding of human anatomy and physiology to determine cause of death and help law enforcement investigate crimes. In this study, the team hopes to contribute to the scientific body of knowledge about scavenging behavior. Identifying geographic areas in which scavenging occurs and the shark species that do it can help forensic scientists trace the movement of a body in the ocean.

forensic anthropology 101

A Brief History. Forensic science emerged during the Song dynasty in 13th-century China, when Song Ci wrote Xi Yuan Lu (Washing Away of Wrongs). Many of his described methods, including tracking insect activity to determine time of death and inspecting the head and chest to identify areas of impact, are now a part of contemporary forensics.

Many Bones About It. In older films and TV shows of the 20th century, murder victims often are euphemistically said to have been identified by "dental records." In both archaeology and forensic anthropology, the teeth actually do provide a lot of information on the deceased's age, diet, geographic location, and behavior, despite the absence of all or some flesh.

If death or trauma resulted from something that hit the bone, forensic anthropologists will find it. Many people assume that bones, which we know to far outlast the flesh, are somewhat impervious, but both sharp and blunt object strikes and crushing leave marks on the bone. Moreover, forensic anthropologists can tell if a bone has healed from previous trauma, while bone marks incurred after death have no such healing.

Human Nature. The overall discipline of anthropology is the study of humans, plain and simple. At varying levels of inquiry, each of its subfields study human behavior, culture, physiology, and evolution. Forensic anthropologists are no different. For example, involuntary defensive moves or postures can affect the trajectory of wounds and the ultimate position of remains.

Animal Insights. Anthropologists already collaborate with zoologists, botanists, entomologists, and other natural scientists, and when you prefix those with "forensic," the same is true. Forensic entomology, or insect analysis, is especially important when remains are found in the wild. The recent Pound Lab–Florida Museum study represents a fruitful collaboration between forensic anthropologists and ichthyologists, both of whom also work with marine biologists and ecologists to produce a body of knowledge that's crucial to the forensic investigation of adrift bodies.


"bones" — myths and facts

While Bones is more realistic than many of its fellow procedural shows, it distorts or exaggerates some things for dramatic effect. (Bones is based on a series of novels by Kathy Reichs, who is indeed a forensic anthropologist.)

DNA tests are fast and easy. Although DNA profiling — the examination of a small set of genetic markers that are likely to differ among individuals — is a remarkably reliable means of confirming identity, it is not a speedy process (6 months, not 60 minutes), and in court, positive matches may or may not lead to conviction. However, perhaps in an effort to be more realistic, Bones doesn't use DNA profiling as much as real-world forensic anthropologists would.

Ethnicity and sex are easily seen in skeletons. This is true to an extent; there tend to be noticeable differences between male and female pelvises, and both ethnicity (more precisely called ancestry) and sex entail slight differences in the shape and orientation of eye sockets, nasal cavities, and jaws. However, forensic anthropologists can only make a best guess, especially if the remains are those of a child or adolescent.

Forensic anthropologists solve murders. They can help, but that's not their job description. In fact, while forensic anthropologists' findings are increasingly invaluable to law enforcement, it's investigators' jobs to solve the case, and scientific evidence has a lesser role in court than many contemporary juries expect. Moreover, forensic anthropologists focus on analyzing skeletons and the environmental effects on decomposition; they do not supplant medical examiners, who are usually forensic pathologists and are responsible for running "tox screens" and other crime-show favorites. Also, forensic anthropologists are called upon for mass-grave and disaster excavations— time-consuming and politically sensitive projects — while medical examiners work in conjunction with local governments to name cause of death on an individual basis.

further reading

Learn more about... forensic anthropologists defeat murderers who think they destroyed evidence with fire forensic anthropologists can guess at age and sex forensic anthropologists tackle a set of remains

Disclaimer: these images are for demonstrative purposes only and do not reflect or illustrate the present study.

What made this hole in the skull? Forensic anthropologists analyze size, shape, and force to get clues.
Shark teeth come in a surprising variety of shapes, and therefore leave differently shaped marks behind.

Skeleton secrets

To begin to determine identity of — and what happened to— the victim, forensic anthropologists construct a biological profile:

Sex and Age. Sex is easy to determine in adult skeletons, although beyond that, it can be difficult to determine age. For young skeletons, age is relatively easy to determine, but sex is not.

Ancestry. As discussed above, skull features offers some insights in the probable race or ethnicity of the victim.

Stature. If they have only parts of a skeleton (which is usually the case), forensic anthropologists can extrapolate from measurements of the bones they have to determine the approximate height of the victim, which is useful for identification.

Finally, forensic anthropologists may need to add trauma to the profile. As mentioned above, anything that leaves marks on the bone can help forensic anthropologists reconstruct what happen to the victim. Marks are classified as perimortem ("before death") or postmortem ("after death"). If those marks appear to be tooth marks, this determine very quickly becomes very important to the investigators.

In the Pound Lab–Florida Museum study, researchers identified six sets of remains that had potentially been in the jaws of sharks. Questions emerged: Were the victims alive when they were bitten? How and where were they bitten? Was it a man-eating shark or a confused one more interested in fish? Collaboration between ichthyologists familiar with shark behavior, geographic range, and physical characteristics, and anthropologists who can see stories in bones, is crucial to answering these questions.

types of shark attacks

Learn more or hover over the photos for more information.

Hit and run attacks are usually cases of mistaken identity and can be carried out by any species, but in FL, it' usually the blacktip shark.
Bump-and-bite attacks happen when sharks try to assess whether something is threat or food. Bull sharks are often aggressive in this way.
Sneak attacks are true predation and often happen in deeper waters. These are the most deadly, and a great white often is implicated.

Many sharks are actually opportunistic feeders, not the vicious behemoths shown in horror movies, and so most human injuries or deaths occur from one or two bites as the shark assesses a potential threat or mistakes a human for its usual prey of fish and turtles. The three species most likely to harm humans — the bull, tiger, and great white shark — happen to occupy shallow waters where humans are likely to swim or fish. However, there are still only a handful of shark attacks per year in the U.S., and an average of one fatality every two years. You’re much more likely to be killed at sea by almost anything besides sharks. According to the U.S. Coast Guard, there are at least 4,000 recreational boating accidents, resulting in more than 600 deaths, every year. Drowning is the leading cause of death in those accidents. Swimmers are much more likely to encounter dangers such as algal blooms and jellyfish, both of which can have debilitating or fatal effects, than sharks.

So why are people so afraid of sharks? Subscribe to our page and check back tomorrow for a brief history lesson and a pop culture review, followed by more intriguing findings by the pound lab.

Footnote: Story written and content curated by Rachel Wayne. This is part two in a three-part series about the intersections among the studies of humans, sharks, and their relationship.