Anthropological research suggests that the study of dental microwear may go a long way to helping scientists reconstruct the diets of extinct mammals, including our early hominid ancestors
Using high resolution surface mapping techniques, Philip Walker and Ed Hagen of the Department of Anthropology at the University of California at Santa Barbara (UCSB) are attempting to develop a new topographical approach to dental microwear analysis.
Recent anthropological research suggests that the study of dental microwear, the pits and scratches formed on a tooth surface through use, may go a long way to helping scientists reconstruct the diets of extinct mammals, including our early hominid ancestors.
Dental microwear features range in size from submicron to about one millimetre.
To collect data on such small features, Dr Walker's lab has been using a surface profilometer and an interference microscope, which are both interfaced to PCs.
The interference microscope works on the principle that when two light waves are brought together, they interact.
In practice the microscope splits a light beam, with one beam reflecting off the specimen and the other directed at a reference mirror.
When the beams are recombined, the number of degrees they are out of phase can be translated into a highly accurate map of the surface's microtopography.
The research team has found enormous benefit in using the interference microscope over previous methods.
Instead of laboriously digitising individual microwear features by hand, they can now measure the surface topography directly.
In less than a minute their scanning equipment can record the x, y and z coordinates of more than 300,000 surface points.
Typical data files range from less than 100K to over a megabyte, depending on the region examined and the scanning resolution, and are imported directly into Dadisp.
With Dadisp, Walker and Hagen can view and analyse up to a dozen different surface scans in parallel using a variety of filters, spectral analyses and data integration.
Thus, they can easily examine the statistically significant differences and similarities in dental microwear among individuals.
Using artificially abraded model surfaces, Dr Walker and colleagues have already been able to demonstrate that certain aspects of microwear feature size distributions correlate highly with important dietary variables.
Once their surface analysis technique has been thoroughly worked out with model surfaces, Dr Walker plans to apply it to microwear on the teeth of early hominids and related animals found in the same region.
His ultimate goal is to provide a sounder scientific basis for describing the diets of our earliest ancestors.
To Dr Walker's research team, it is becoming clear that simple analogies between the microwear patterns on the teeth of living animals of known diet and those of extinct animals with similar microwear patterns can lead to serious errors in reconstructing the diets of extinct species.
The amounts and types of grit in an animal's diet determine the nature and extent of dental microwear.
Differences in local geology, soil formation, drought and volcanic eruption history can all affect the quantity and quality of ambient grit in an animal's diet.
So rather than analyse a single individual out of its environmental context, the UCSB group plans to investigate dental microwear from the entire collection of animal bones found in a specific region.
With the sheer amount of data that needs to be viewed and compared, Dadisp should play a significant role in this ongoing research.
Dadisp is supplied and supported in the UK and Ireland by Adept Scientific.
