Blending art and science
Forensic scientists and others conduct facial approximation for two quite distinct but related purposes: to identify the recently dead so that they can be reunited with their kin, and to give the people of today a glimpse of our forebears as they might have appeared in life. Either way, facial approximation is a closely integrated blending of science and art, the result of a fruitful collaboration between scientists and sculptors.
In the NOVA film "Mystery of the First Americans," for example, sculptor Thomas McClelland and I produced Kennewick Man's image, while artist Sharon Long and anthropologist Douglas Owsley created the approximations of the Spirit Cave mummy. The best known facial-approximation team is led by Richard Neave of the University of Manchester, England, who, with John Prag, co-authored the book Making Faces: Using Forensic and Archeological Evidence (Texas A&M University Press, 1997). Neave's team includes not only a medical artist and archeologist, but also specialists in medicine, dentistry, and genetics.
Such teams fashion approximations either sculpturally or by computer. Sculptural methods such as those documented in the NOVA film allow the artist a freer hand than computer techniques. Specialists using the sculptural approach belong to two schools, which I will call the Gerasimov and American schools. (The Gerasimov method was developed by the late Russian paleontologist Mikhail Gerasimov.)
Making a face
Both schools follow similar basic protocols. Practitioners begin with a skull or, in the case of ancient specimens, a model of a skull, and, at standard locations on its surface, place a set of pegs cut according to average tissue thicknesses. These thicknesses vary according to the ancestry and health of the individual and differ for males and females; people of emaciated, average, or obese condition; and Europeans (or white Americans), Africans (African Americans), or Asians (Japanese). (Experts have not yet developed measurements of average tissue thicknesses for other peoples.) The artist chooses these thicknesses according to information the anthropologist provides based on clues gleaned from the skeleton and any associated clothing and/or preserved soft tissue.
Evidence for severe injuries suggested that the man lived many of his 40-plus years in frequent if not chronic pain.
With the markers in place, the artist centers the eyes in the sockets and roughs out the size of the nose and mouth. The sculptor determines the profile of the nose by one of two means. One approach, used primarily by the American school, estimates the projection of the nose at three times the length of a bony spur located beneath the nasal opening in the skull. The width of the nostril wings is a set distance from the lateral edges of the nasal openings, six millimeters for Europeans and Asians and eight millimeters for Africans.
The Gerasimov school, as practiced by Neave's team, creates the outline of the nose by extending one line from the bridge of the nose and a second line from the floor of the nasal opening, and then rounding their point of intersection to make the tip of the nose. They estimate nose width as 1.67 times the width of the nasal opening. The width of the mouth is either the distance between the inner edges of the irises in the eyes or the distance between the lateral edges of the canine teeth—measurements that are typically very close to the same.
The American school
The schools differ most in how they place tissue on the face. The American school relies heavily on the skill of the artist and less on the underlying structure of the skull. The artist first connects tissue-thickness markers with walls of clay pressed against the skull, tapering each bar so that its height is even with the markers at both ends. This creates an open, grid-like pattern. The artist then fills the spaces between the grid lines with clay, and a mannequin-like face begins to take shape. Finally, the artist uses personal experience and input from the scientific members of the team to humanize the face and decide what eye-form and lip characteristics the person should have. In the hands of a skilled artist such as Sharon Long, this approach has proven highly effective, particularly as an aid to identification of the recently dead.
Part of the method's effectiveness in the forensic realm lies in the nonspecific appearance that it produces. When the police broadcast faces approximated in this manner, they are likely to stimulate a large number of responses from people missing friends or loved ones. From this large pool of possible identities, the authorities have a good chance of determining the actual identity of the deceased. If the face looked like only one particular individual, the police might get fewer calls and may never identify the subject.
The Gerasimov school
The Gerasimov method aims to produce a very specific image, one as close to that of the deceased as possible. Practitioners of this school, who tend to have an extensive background in osteology and anatomy, begin by closely studying the bones of the face and observing asymmetries in bone structure and variations in the development of muscle markings. These are clues to the personal characteristics of the dead. Heavily used muscles, for example, leave prominent spurs or ridges in facial bone and show what expressions the person most often held.
Facial approximations are not literal portraits of the dead. No means yet exist for doing that.
Next, after placing the tissue thickness markers, the Gerasimov-style artist fashions 18 major muscles from clay and places them on the face according to their standard thickness in human beings. These include the oval sphincters that surround the mouth and eyes, the massive muscles that close the jaws, and the delicate muscles that manipulate the corners of the mouth and wrinkle the brows and nose. Once these are in place, the face begins to take on a human look, albeit a macabre one. Using the muscles now as a secondary superstructure, the artist lays a thin clay "skin" over the face to the height of the tissue markers, taking into account the topography created by the musculature. The resultant face is immediately quite life-like and gives the artist less latitude in crafting the finished face.
As with the American school, the sculptor ages and lines the face following advice from the team's scientific members, taking cues from the asymmetries and markings noted in the initial inspection of the skull. In the case of Kennewick Man, evidence for severe injuries suggested that the man lived many of his 40-plus years in frequent if not chronic pain. Prominent muscle markings above the chin and beneath the eye sockets confirmed this, revealing a face held in an expression of determined endurance. For this reason, our approximation of Kennewick Man, which we created in about three days using the Gerasimov method, shows the weariness of a middle-aged man in perpetual discomfort.
Face to face with the dead
Like the American method, the Gerasimov approach has proved useful for forensic identification, but its best application is for approximating the appearance of the long dead. Forensic anthropologists ordinarily rely on this method for recreations of our earlier hominid ancestors. Well-known examples include the Homo erectus created by museum artist John Gurche of the Denver Museum of Natural History and the Neanderthal approximation crafted by Gary Sawyer, a preparator at the American Museum of Natural History. Because we have no artistic standards for how these hominids looked, approximators must produce them with as much scientific rigor as possible.
As well founded in science as they may be, facial approximations, as their name suggests, are not literal portraits of the dead. No means yet exist for doing that. Nevertheless, approximations constitute the only way we have of gazing at our early ancestors and thereby seeing them as vital beings like ourselves.