All,
In which we are told that the study of the oxygen isotope content of the Kennewick fellow’s teeth may help us figure out where he came from and what he ate along the way. Let’s hope that they’ll not determine that he came directly from Solutré!
Also worth keeping an eye for is what will be reported “later this month at the annual meeting of the American Academy of Forensic Scientists in Seattle.”
Researcher seeks secrets of Kennewick Man
BY SUSANNE RUST
Milwaukee Journal Sentinel -- Monday, Feb. 06, 2006
Ground to the bone, the teeth of the famous fossil skeleton, Kennewick Man, look as if they've spent a lifetime gnashing rocks.
But it's from these worn choppers that Thomas Stafford Jr., a research fellow in the department of geology at the University of Wisconsin-Madison and president of Stafford Research Laboratories in Boulder, Colo., plans to learn about the origins, movement and lifestyle of this highly controversial, 9,000-year-old North American.
[Snipped, the summary of the whole Kennewick story/controversy]
And last summer, for the first time, archaeologists, anthropologists, paleontologists, geologists and chemists began investigating this enigmatic American, attempting to answer questions that have been nagging them for nearly a decade: Was Kennewick Man an aberration? A loner who wandered into the New World on his own? Or does he represent an early migration of people who subsequently died out or were killed? Or is Kennewick Man an ancestor of the native tribes we recognize today?
To help answer some of these questions, Stafford has begun examining Kennewick Man's teeth. He's working with John Valley, a University of Wisconsin geologist, to decipher the secrets hidden in the worn enamel of this enigmatic fossil.
From the fossil's tooth enamel, they'll learn where Kennewick Man lived as a child, the kinds of food he ate, from where and whence he traveled, and when he died.
Although enamel is an extremely hard substance, it's actually more like a sponge in terms of its record-keeping - soaking up and recording the events of an individual's early life.
For example, on a lark, Valley decided to geochemically demonstrate the birthplaces of his children by examining the oxygen isotope ratios in their baby teeth: One was born in Texas, the other in Wisconsin.
"There was a significant difference" in the ratios of the two isotopes of oxygen in their teeth, he said.
It's analyses like these that Stafford and Valley will use to determine several aspects - geography, migration and diet - of Kennewick Man's life.
For starters, Stafford is going to try and figure out when Kennewick Man died. While most experts agree his death was likely 8,000 or 9,000 years ago, the five different dates collected so far have varied by as much as 3,000 years.
"That's unacceptable variation," Stafford said.
To settle the issue, Stafford will use radiocarbon gleaned from Kennewick Man's teeth to give a definitive answer.
Indeed, Stafford is considered a pioneer - and expert - at using carbon to date teeth and bones, said Margaret Schoeninger, an anthropologist at the University of California, San Diego.
Therefore, his dates are pretty much considered gold.
But Stafford's hoping that Kennewick Man's teeth can tell him more than when he died. He's working with Valley try to figure out what kind of climate Kennewick Man was born in.
They will analyze the ratio of a heavy form of oxygen (Oxygen 18) to a lighter form (Oxygen 16) stored within them.
Normal elemental oxygen is made up of eight protons and eight neutrons, hence, oxygen 16. But every once in awhile, an oxygen atom will appear with nine or 10 neutrons along with its suite of eight protons, making oxygen isotopes 17 and 18.
These different isotopes are found in predictable ratios - reflecting the source from which they were extracted, or in the case of carbon, from the period of time they were deposited.
Stafford and Valley are interested in oxygen because water - local springs, lakes and rivers - contains isotope signatures that are particular to geographic regions. These signatures become embedded in the enamel of a person's teeth. And because enamel is laid down early in life - depending on the tooth, it can accumulate anywhere between birth and adolescence - researchers can gain information about the birthplace of an individual, and possibly whether he or she migrated or moved as a child.
Therefore, Kennewick Man's teeth "should tell us about the temperature," of his environment "and the source of water this individual was ingesting," said Valley, as well as whether he grew up in a lower or higher latitude, close to the sea or far inland, high on a mountain or deep in a valley.
In other words, they should be able to say whether Kennewick Man was a Kennewick native, or not.
That's a key question. Was Kennewick Man an anomaly in this region? Did he grow up elsewhere and trek across the Bering Land Bridge to present-day Washington state? Or was he born there - representing an, until now, unrecognized population?
"We don't really know what happened," in terms of the populating of North America, said Stafford. "It's possible there were several waves of migrants moving into the continent."
Some, like those in Kennewick Man's population, may have died out. They may have been killed. Or they may have interbred with other groups who were already here or yet to come.
In their research, Valley and Stafford will be using an 11-ton machine called an ion microprobe to separate the oxygen isotopes.
James Burton, an archaeo-chemist at the University of Wisconsin who was not involved in the study, laughed when asked if this was an appropriate tool for such an analysis. "Yes," he said, though it's so powerful, it's "like using dynamite to crack open walnuts."
In general, performing isotopic analyses requires a substantial amount of material. But the CAMECA 1280, as the ion microprobe is called, reduces the sample size by a factor of a million.
"You're talking about a sample smaller than the unaided eye can see," said Valley, which means little, if any damage will be inflicted on the skeleton's worn teeth.
The researchers embed the flake into a mold of gold - a coin-sized chip they place inside the microprobe - which they place inside the probe.
The machine fires a narrow beam of ions - 10,000 volts of cesium - onto the sample, essentially blasting a small number of atoms off its surface. A double-focusing mass-spectrometer and secondary ion mass spectrometer then measure the charge and mass of the atomic masses, revealing the isotopic ratio in question.
Burton said researchers will need to make sure they are comparing Kennewick Man's oxygen ratios with the ratios of the Columbia River region of 8,000 years ago, not today, because the climate has likely changed. Valley said they will compare Kennewick Man's ratios to those of mammals from that time and place.
Stafford also will be looking at other isotopes, including nitrogen and carbon (Carbon 12 and Carbon 13) to see what kinds of foods Kennewick Man ate. These isotopes, which are also stored in the teeth, can tell Stafford whether Kennewick Man was a fish-eater, big-game hunter or a man with broader tastes. They'll also provide Stafford with a glimpse of the man's produce preferences: legumes, grasses, seeds or leaves.
The tricky part, at least for the nitrogen analyses, is that Stafford will need enough collagen - a protein found in bone and teeth - to run them. As bones fossilize and mineralize, the collagen often disappears.
But if he can find enough, he can run those informative tests, as well as others that may tell him and his colleagues even more about Kennewick Man.
If there is collagen, then there's DNA, opening the door to genetic analyses and information.
Stafford, who was not part of the original team of scientists who fought to study Kennewick Man, said that all of his work has been done in conjunction with the core group of researchers, including Doug Owsley at the Smithsonian Institute; James Chatters, the archaeologist who first excavated Kennewick Man; Vance Holliday, an archaeologist at the University of Arizona; and others.
The team will be presenting some of its preliminary discoveries later this month at the annual meeting of the American Academy of Forensic Scientists in Seattle.
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Jacques Cinq-Mars
