Optics Does That? With Dr. Ashleigh Haruda, Zooarchaeologist.

Dr. Ashleigh Haruda is a zooarchaeologist.

Dr. Ashleigh Haruda

She examines animal bones found at archaeological sites to investigate the relationship between animals and ancient human societies. These bones reveal information about ancient societies including diet, trade, migration, and market forces. For her doctoral research, she studied pastoralists living in the Central Asian steppe in the Late and Final Bronze Age (1500-800 B.C.E.). These were people who did not practice agriculture, but lived off of their animals, including sheep. “Primarily these people are experiencing their world and their landscape through their animals,” said Haruda. “So, if they fail to move their animals in the right way, or they fail to understand how the weather is going to be that year, they could all die because there was no safety net for them.”

By measuring the bones of sheep found in the steppe from the Final Bronze Age, she was able to determine that these pastoralists did not migrate extensively or trade animals with their neighbors. This was because the morphology of the sheep bones she examined was very distinct from microregion to microregion; if regular migration or frequent trade occurred between these regions, the sheep would have interbred, homogenizing away such distinctions.

Haruda did her PhD research on sheep astragali, which are traditionally used as
game pieces in Kazakhstan. When she saw these huge sculptures depicting 
the game pieces in Almaty, Kazakhstan, she had to snap a pic!

Haruda is currently the project leader of “Sus 100” at the Natural Science Collections of Martin Luther University Halle-Wittenberg in Germany. The project is focused on the effects of selective breeding on domestic animals, and how quickly human influences become detectable in an animal’s genetics and skeletal structure. “We have historic pig skeletons from 100 years ago that were raised at the University…and then we are pulling pigs out of the food chain right now and comparing the genetics and the morphometrics of those skeletons,” said Haruda.

The results of that comparison will help to determine a rate of change that can be used to make assessments of time scales on much older bones found at archaeological sites. Check out the video below—in German!—for more detail on the project.

In her research, Haruda uses a digital measurement technique called Geometric Morphometrics, or GMM. GMM is the analysis of shape using Cartesian geometric coordinates to represent the landmarks, curves, and surfaces of objects. Archaeologists use it to generate 3D digital models of the bones they study. Compared to traditional linear measurements made with calipers, GMM allows for a greater interrogation of shape.

One of the largest sources of variation in bones is size, which can be affected by things like animal sex and nutrition level. Scaling of digital models allows researchers to control for size to make more direct comparisons between bones. “Which means,” Haruda added, “we can start to measure variation and covariation among those landmarks, so we can ask a lot more from our data set, and we can interrogate it different ways, statistically.”

Haruda washes animal bones at the archaeological site of Botai in Kazakhstan.

And GMM is enabled by optics! The first scanner that Haruda used to take such measurements was a NextEngine scanner, a device that uses laser scanning and a turntable to create 3D models of objects. Currently, she uses an Artec Eva, which is a hand-held scanning device that can be moved around the object for measurement. Instead of a laser, the Eva uses a flashbulb to generate “structured light,” or a pattern such as a grid, that is projected onto the object and measured by two cameras. The distortion of the projected lines and the offset of the cameras allows for triangulation of points on the object to generate a digital 3D model.

Haruda's "lab" set-up in Kazakhstan: a Next Engine Laser Scanner,
laptop, and calipers. 

GMM is not yet common in zooarchaeology, but is used more extensively in osteoarchaeology, the archaeological study of human bones. One issue facing the adoption of this technology is cost; another is complexity. In its current form, GMM requires a researcher to write their own code in a language like R or Python to do analysis, which only adds to the very long list of skills zooarchaeologists already need to possess. “We need a really good background knowledge of biology, anatomy, and physiology but also archaeological skills such as how to lay out a grid with a GPS, how to define soil color and type, and identify basic pottery styles and metals, plus we have to know about our historical contexts,” said Haruda.

But as the technology matures, it is becoming less expensive and more user friendly, and Haruda notes that in general the adoption of new technology is occurring rapidly in the field of zooarchaeology. GMM and digitization of data are also a great benefit in a field where bones must often be destructively sampled for DNA or other measurements.

Photogrammetry setup with a turntable at Haruda's current job.

Haruda also described a technique that she is learning called photogrammetry, which uses photographs (instead of scans) to generate measurements of an object. Photogrammetry has existed almost since the beginning of photography, but with modern processors and software, thousands of photographs can be integrated to generate high-detail 3D models of objects. This technique also moves complexity away from the measurement device and into the realm of postprocessing, giving it the potential to be more cost effective for archaeologists working in the field.

So now you know. Zooarchaeology: optics does that.

Guest Blogger: Christina C. C. Willis is an SPIE Board Member, laser scientist, and writer living in Washington, DC. Find out more about her on LinkedIn.

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Optics Does That is looking for more stories! Do you, or does someone you know, have an interesting or unusual application of optics that you use at work or elsewhere? Then please send us an email and tell us about it! emilyp@spie.org.