Science Panama , Panamá, Thursday, July 14 of 2016, 20:23

A Bioarchaeologist Reads History from Bones

Nicole Smith-Guzmán holds up a small lower jawbone and says it belonged to a seven-year old child who grew up on a sugary, corn-based diet

STRI/DICYT Nicole Smith-Guzmán holds up a small lower jawbone and says it belonged to a seven-year old child who grew up on a sugary, corn-based diet. Although the child died over 1,500 years ago, she can determine its age to within six months based on the number and size of milk versus permanent teeth. She points out several signs of dental disease—a tooth cavity, an abscess in the jawbone, a gap from a fallen milk tooth with the bone healed over before the permanent tooth could grow out. On another person’s jaw, impacted teeth suggest that the jawbone never grew to its full potential because it only chewed on soft, mushy food. On yet another set of teeth, she points out ancient tartar, which may hold plant remains and even traces of mouth bacteria.


“Non-specialists sometimes mistakenly brush these teeth,” she says, which erases valuable data. Smith-Guzmán is the kind of specialist for whom details like skeletal and dental abnormalities matter. She excavates, identifies and curates ancient human skeletal remains, but also does comparative medical analysis on the specimens to determine signs of health and disease. As a bioarchaeologist, her expertise ranges from anatomy and disease pathology to biological anthropology and archaeology.


A postdoctoral fellow at the Smithsonian Tropical Research Institute (STRI), Smith-Guzmán splits her time between two main projects. One of these is to bring the assorted skeletal remains stored at STRI’s Naos Island Laboratory up to international curation standards. Some of the remains were originally found in looters’ pits, stripped of the cultural context of their original burial sites. Others were donated to the laboratory and include multiple people’s remains mixed up in the same storage boxes. About 400 skeletons come from excavations conducted in the nineties, led by senior STRI staff scientist Richard Cooke at the Cerro Juan Díaz archaeological site—the jawbones Smith-Guzmán is currently cataloguing are part of a mass tomb that held eighteen people.


Smith-Guzmán’s other project dives into a more specific research question. She holds up a skull she reassembled from fragments, pointing out an unusual flatness on the back of the head, a sign of artificial cranial modification. She is curious about whether this kind of body modification signified a person’s status or occupation in early Panamanian society, and whether it was widely practiced by people in the region, or isolated to certain communities. To answer these questions means putting together a jigsaw puzzle not just of a single broken skull or the jumbled remains of many comingled bodies, but comparing skeletons from different geographical sites and points in time—work that is made harder because the acidic soils of the Tropics literally erase history by dissolving bones and other organic material.


“At old sites, there’s often nothing left of human remains,” says Smith-Guzmán, and at some younger sites, “The bones can be the consistency of butter, making them nearly impossible to remove from the ground.”


Despite such challenges, the rewards of studying human bones range from once-in-a-lifetime events like finding a bone tumor, to observing population-wide features like the effect of sugar-rich diet on tooth quality, or the prevalence of bacterial diseases like syphilis or yaws, which leave signature effects on bones that take years of practice to identify. “Our field of study is constantly becoming more refined, with new technologies and clinical discoveries,” says Smith-Guzmán. “It’s a lifelong learning process.”