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May 29th 2020

Human Preservation Brings History to Life

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Human preservation techniques such as mummification leave evidence of what life was like hundreds or even thousands of years ago. Forensic scientists can use this evidence to recreate faces and even voices from the past. By physically reconstructing ancient figures, experts help the public connect with history on a deeper level.

“Forensic facial reconstruction is an extremely effective means of communicating skeletal data and human stories in history to the public,” explains Karin Bruwelheide, a skeletal biologist at the Smithsonian Institution’s Museum of Natural History.

Giving a Voice to the Past

In January 2020, a team of scientists from the United Kingdom announced that they resurrected a mummy’s voice. While they were only able to produce a single sound, it’s the first time anyone has been able to hear the sound of someone’s voice from three millennia ago in Ancient Egypt. To do this, the researchers used the same medical device that can scan your body for tumors to scan the body of an ancient Egyptian priest named Nesyamun. They published their findings in the journal Scientific Reports.

When he was alive more than 3,000 years ago, Nesyamun’s voice was an important part of his duties as a priest, which involved speaking and singing various rituals. The inscriptions on his coffin, in hieroglyphs, describe his wish to be able to speak after his death. In some ways, the researchers fulfilled this wish by recreating his voice.

Modern 3D scanning techniques can replicate artifacts or other evidence without even touching it. Timothy D. Christ, an international forensic engineering and reconstruction expert describes forensic reconstruction as reverse-engineering the past. Whether it involves recreating a car accident for an insurance claim, building a model of a crime scene for an investigation, or reconstructing a historical figure’s face, the trick is to study the evidence without disturbing it.

Forensic engineers can survey a scene with a scanner that measures the angles that the laser’s light particles bounce back.

“The accuracy of all the measurements is really precise because it figures all that out with an algorithm,” Christ says. “The level of detail and precision that you have is pretty remarkable. Twenty years ago that didn’t exist. We were still doing things with a tape measure.”

Now, forensic engineers use a combination of laser scanning tools, animation software and 3D printers to recreate the past. Similar techniques can be used for scanning historical figures.

Christ says, “With the technology available there is a huge opportunity to really take history to a whole new level.”

How They Do It

Forensic reconstruction involves a collaboration between scientists, 3D technicians, model makers, artists, historians and community groups.

In the case of the mummy’s voice, the body had been displayed at Leeds City Museum in England for nearly two centuries. It was first unwrapped in 1824 when a team of three surgeons and a chemist carefully investigated it. Over time, scientists have continued to study the body using more advanced techniques, like an X-ray examination in 1931 and early CT scanning techniques in the 1990s. Now they were able to use a modern CT scanning machine, plus medical imaging software and a 3D printer to recreate Nesyamun’s vocal tract.

The researchers removed the body from its coffin and placed it on a multi-detector CT scanner.

While conventional X-rays can reveal a two-dimensional image that’s useful for looking at bones, CT (short for computed tomography) scans contain more detailed information. According to the National Institutes of Health, when a patient gets a CT scan, a narrow beam of X-rays rotates around the body, producing signals that are processed by a computer to generate cross-sectional images of the body. The computer can then stack these image “slices” together to create a 3D image that shows the patient’s skeleton, organs and tissues. While CT scans are typically used to look for some kind of abnormality in a live patient, the same technique was used on the mummy to create a 3D model of its vocal tract without damaging it.

After the scans were complete, medical imaging software developed a digital model for the mummy’s vocal tract. Bruwelheide, who works on similar forensic reconstruction projects for the Smithsonian Institute, explains that the files are then translated into digital 3D images, using an algorithm that selects portions of the CT image based on the image’s grayscale.

Bruwelheide says, “Each slice must be checked for selection accuracy, cleaned, and smoothed. The final result is a ‘layer cake’ of colored images that can then be rendered out as a dimensionally accurate 3D object.”

The CT images confirmed that the structure of Nesyamun’s larynx and throat remained preserved for three millennia, due to the elaborate mummification process. The researchers attached the replica of the mummy’s vocal organ to an artificial larynx to synthesis speech. The artificial mummy voice uttered a sound similar to the vowel sounds in the words “bed” and “bad,” with researchers noting that Nesyamun’s vocal tract is smaller than the anatomy of contemporary adult men.

If this whole thing seems a bit far-fetched, consider the fact that the same researchers have previously proven their method. They’ve made 3D-printed models of living men’s vocal tracts and compared the synthesized sound to their real voices.

“We’ve done extensive work on 3D vocal tracts,” researcher David Howard told IEEE Spectrum. “I can recreate my vocal tract and then you can hear it next to me and tell me if it’s similar or not, and the answer is: It is. We are using that fact to transpose this back 3,000 years and say we have something like Nesyamun would have sounded.”

Recreating Yesterday’s Faces

Human preservation techniques such as cryogenics, embalming, and mummification are often steeped in spiritual beliefs. Many of the rituals involved in preparing bodies for the afterlife do in fact protect the person’s legacy for centuries or even millennia. Nesyamun isn’t the only historical figure whose body has been brought into the modern world. Facial reconstruction is a popular way for museums to help the public connect with the past.

“Facial reconstructions can not only show us what individuals from the past may have looked like, but they can communicate the distant and sometimes harsh history of the past to a broader audience that otherwise might not have listened,” Bruwelheide says.

At the Smithsonian’s Natural History Museum, for example, forensic facial reconstruction techniques were used to re-create likenesses of early colonists from their skeletal remains, and busts and full-body reconstructions of ancient hominids from fossil remains were included in the permanent exhibition of the Hall of Human Origins. StudioEIS, the New York firm of artists that creates many figures for Smithsonian also recently built the likenesses of Frederick Douglass and Harriet Tubman for the Annapolis State House Trust, to name just a few.

How They Do It

Historians can use a combination of bone analysis, genetics research, digital modeling, 3D printing, historic research and a bit of artistic license to recreate famous faces. Take England’s King Richard III, for example. He was killed in the Battle of Bosworth in 1485 and his skeleton was found buried beneath a parking lot in 2012, according to CNN. While all skulls may look alike to the general public, professionals can analyze the skull to find clues about the person’s appearance.

Even small differences in skull shape can alter the relationship between the underlying architecture of the skull and the hard (cartilage) and soft (muscle, fat, skin) tissues of the face, according to Bruwelheide. Bones contain details about age, sex and ancestry. Plus, any anomalies, such as a broken and healed nose, give additional detail. Therefore, a skull provides plenty of information for a scientist to figure out the main details of an individual’s appearance.

Beyond skeletal examinations, genetic tests can also track ancestral origins and confirm the sex of remains, even if the person’s remains weren’t protected with any human preservation techniques. DNA tests revealed sharper details about the king’s appearance, such as the fact that he likely had blonde hair and blue eyes. Museum Crush notes that a facial reconstruction expert spent four hours reworking King Richard III’s bust to make it more accurate.

After the baseline has been established through bone scans (and sometimes genetic testing), the next phase of facial reconstruction involves creating the bust. The goal is to align the factual details about the person’s anatomy with historical knowledge about the time and place where they lived.

The team considers “craniofacial morphology,” plus subjective features such as hair, skin color, facial expression and possible head coverings, says Bruwelheide. They even deliberate the gaze and position of the head because these details can change the viewers’ perception of the figure.

Next, a forensic sculptor builds the face, based on guidance from anthropologists who suggest details about age, ancestry, body build and any distinctive features of the skull. With this information, the sculptor places tissue depth markers at designated landmarks on the 3D-printed skull. Then they use strips of clay to fill in the areas between these markers to gradually build the head, face and neck.

The team consults with each other throughout the whole process, especially when it’s time for the finishing details like hair style, eye color and the skin’s color and texture.

Bruwelheide notes that there’s a fine line between making the figure just realistic enough. She explains, “A figure devoid of color can appear ghostly. In contrast, the addition of realistic colors can make a form too lifelike, allowing little room for personal interpretation on the part of the viewer. The tonal painting lends realism without being fully resolved. Color is suggested with enough realism that the figure is humanized.”

Check out Northrop Grumman career opportunities to see how you can participate in this fascinating time of discovery in science, technology, and engineering.

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