Hold two teeth in your hand, one from a Neanderthal and one from an early human. On the surface of the not-so-pearly whites, you’ll see no obvious distinctions.
But Stanford paleoanthropologist David DeGusta, PhD, believes that comparing their internal structures might help answer one of anthropology’s big questions: just how closely related are Neanderthals — the primates that disappeared 30,000 years ago — to modern-day humans?From Stanford University:
Scientists create high-tech images of ancient teeth to compare Neanderthals with humans
Hold two teeth in your hand, one from a Neanderthal and one from an early human. On the surface of the not-so-pearly whites, you’ll see no obvious distinctions.
But Stanford paleoanthropologist David DeGusta, PhD, believes that comparing their internal structures might help answer one of anthropology’s big questions: just how closely related are Neanderthals — the primates that disappeared 30,000 years ago — to modern-day humans?
This month, DeGusta, assistant professor of anthropology, and other scientists will get the best view yet of the insides of Neanderthal teeth. Instead of chiseling away at them, he’ll explore them virtually, using some of the highest resolution images of teeth ever obtained.
The project involves not only DeGusta but also School of Medicine researchers, other imaging experts and scientists from the Smithsonian Institution, which provided the Neanderthal teeth and bones. The National Institutes of Health has helped to finance the effort with an $860,000 grant.
The moment of truth came a few weeks ago when a Smithsonian anthropologist arrived at the medical school with a box of Neanderthal remains — two teeth, a vertebra and a wrist bone — from the Smithsonian’s collection. Since then, the team has spent hours creating high resolution X-ray images of the bones and teeth that will provide a plethora of data for scientists around the world to analyze.
The project grew from a chance encounter. Last year DeGusta was going to the anatomy lab to pick up some bones when a fire drill forced him to wait outside. The lab manager then introduced him to endodontist Paul Brown, DDS, saying, ”Here’s a dentist who’s interested in human evolution.”
Brown, a researcher at the medical school’s National Biocomputation Center, turned out to be a paleoanthropologist’s goldmine. He had just recently finished creating an interactive database that provides complete 3D virtual models of 400 teeth from modern-day humans — information that could be useful in anthropological assessments of ancient teeth. (Brown developed the ”Tooth Atlas” CD, which went on the market last year, with two colleagues: Eric Herbranson, DDS, who is partners with Brown in an educational software company for dentists and doctors, and Kevin Montgomery, PhD, the biocomputation center’s technical director.)
Although few, if any, paleoanthropologists know of the atlas, DeGusta believes it will prove very useful to him and others in the field. Modern bones and teeth are as vital to anthropological study as are old ones, he explained. ”If we see, for example, an anatomical difference between two different fossil teeth or bones, does it mean they were different species or is it just natural variation within one species?” The tooth atlas offers an overview of the variation in modern-day human teeth, he added, making it ”a yardstick” for gauging how fossil findings compare to each other and to us.
What made the meeting with Brown even more of a stroke of good fortune for DeGusta was that the dentist had just begun negotiating with the Smithsonian Institution for access to its collection of rare Neanderthal teeth and skeletal remains so that he could make images of them. Brown and DeGusta joined forces.
The Neanderthal has posed a challenge to scientists since the discovery of its bones in the Neander valley in Germany in 1856. For years, scientists have debated the evolutionary connection between Homo sapiens and this short, stocky primate with the long, sloping forehead. Lately, evidence has been mounting, reviewed most recently in last week’s issue of Nature, that the two are separate species that never interbred, despite coexisting for about 10,000 years in Europe.
Brown, DeGusta and their colleagues hope that the new data will offer another avenue for clarifying the similarities and differences between Neanderthal and Homo sapiens.
The images that the project is developing will be even sharper than those used for Brown’s tooth atlas. While the atlas images reveal details as small as 30 microns, the scans planned for the Neanderthal skeletal pieces are supposed to show details all the way down to 10 microns. They are being made at the Lawrence Berkeley National Laboratory’s brand-new synchrotron, one of the world’s brightest sources of X-rays that can be used for CT scans. Once the data are collected, computer engineer Montgomery is slated to transform them into interactive 3D visuals using software he developed. The data will be available online for free.
Scientists have already made plans to scrutinize the images. For instance, Amy Ladd, MD, professor of orthopedic surgery, wants to study mineralization patterns within the Neanderthal wrist bone. That might reveal how much the thumb and fingers were used for precision work. ”Anytime there’s mineralization,” she said, ”you have a fingerprint of function.”
DeGusta plans to measure the internal structures he finds in the tooth images — for instance, the thickness of the enamel covering — and compare them with modern human teeth. ”We don’t know what we’re going to find,” he said. ”We just have to look.”
In the meantime, Brown has started thinking about the next project. A Smithsonian official has told him and his colleagues that they’re welcome to make images of other items in the institution’s collection. ”We’re going to propose a grant between the Smithsonian and Stanford,” he said, ”to create a database of high-resolution skull images.”’