Bones have gotten a bad rap in popular culture over the years. If they don’t represent death (hello, Grim Reaper), they portend a bad omen, something to be feared. When Simba strays from the pride lands, he stumbles into an elephant graveyard, full of bones. It is suddenly dark, misty. [You probably don’t need us to tell you the plot of “The Lion King.”] The same could be said in the movies “Pirates of the Caribbean,” “Lord of the Rings,” or “The Mummy.”
Not a movie-goer? If, on a walk in the woods, you come across a carcass, what is the first thing that comes to mind — life or death?
Yet for scientists like Sue Black, skeletons live on after us, often leaving a slough of clues about their previous owners.
Black is an England-based forensic anthropologist whose work involves assisting in criminal investigations to find out who people were when they were alive. The catch? Mrs. Black usually has access to a piece of the person. Maybe it’s an arm, a leg, a hand, or a finger. From this clue, Black tries to deduce at least four characteristics — say, gender, height, ancestry/complexion — to set investigators on a path towards identification.
Sometimes, Black does not have the luxury of a physical piece of skeleton. All she has is an image. Yet even in images, anatomy can be telling. “The pattern of superficial veins on the back of your right hand will be different to your left,” as will the pattern of skin creases across the knuckles of your fingers. Freckles, birthmarks, and moles are unique identifiers.
Black has worked with researchers to pair comparative anatomy with artificial intelligence. On a large scale, if you have, say, a database of photos of hands of mystery perpetrators, you can teach a computer how to recognize patterns. You can then harness new information, extrapolate unforeseen connections, establish new leads, etc.
The pairing has helped Black contribute to 30 life sentences, 400 years of prison sentences in child sexual assault cases. 82 percent of these cases resulted in a plea change — a testament to the fact that it is hard to argue against your own anatomy.
But how do you paint a picture when you don’t have a photo when time has erased distinguishing characteristics such as flesh, skin, or hair? You need a different kind of technology, something to the order of stable isotope analysis.
Stable isotopes are parts of elements that do not change over time and can be found in tissues (such as bone collagen) of long-dead remains. Since the structural protein that makes up bone collagen can only be made up of what an individual ingests, its analysis gives the scientist a sense of what the individual ate and how and where she or he lived. Similarly, the presence of oxygen isotopes in fossils can describe the climate in which the organism lived. And strontium, which makes its journey from bedrock, to soi,l to crop to, yes, human bone, can tell scientists about the geologic environs (and thus age) of the organism.
A recent study published in Science discusses the findings of such an analysis of fossilized remains located in a burial pit high up on the southwestern altiplano of Peru. On top of what would have been the thigh bone of one individual, diggers found an impressive tool kit, cutting blades, and projectile points. Carbon and Nitrogen isotopes present in teeth showed this individual had a healthy diet of animal meat and plants.
Further testing of the enamel revealed a version of a protein called amelogenin that only occurs in women. Not only was the hunter seemingly prolific; she was decidedly female. This shred of ossified evidence, 9,000 years old, certainly gives those who believe in traditional hunter-gatherer gender roles something to chew on.
Speaking of teeth, scientists in another study observed that all of the lower second premolars of six horse skeletons discovered in northwestern China showed significant signs of abrasion, a sign of “traumatic contact” possibly due to the tugging of a bit.
Then the scientists found pronounced grooves in the bones making up the horses’ noses. The altered bone structure suggests overdeveloped muscles, which can happen from a life of heavy work and heavy breathing.
Then they found excessive bone growth, fusion and fractures located, for the most part, towards the lower back. The lower back is where horses bear the brunt of riding.
All of these factors taken together account for the earliest known record of equestrianism in China, more than 2,300 years ago. The possibilities that horseback-riding opened up could help explain the rise of the Qin dynasty in third century B.C., as well as the beginnings of trade routes that would later turn into the Silk Road.
So, in closing, suppose that scientists unearth your skeleton in thousands of years. What kind of physical injuries did you suffer? Were you sedentary or mobile? Did you live a bucolic life in the south of France, or were you a lifelong New Yorker? What sort of pollution were you exposed to? Did you eat McDonalds, or grass-fed Wagyu beef from New Zealand?
After all, bones don’t lie.