Many of you have expressed an interest in the process of Ava’s facial reconstruction, so Hew Morrison has kindly been working hard the last few days to put together a clear explanation to help us understand how he created the two-dimensional reconstruction.
Hew Morrison is a graduate of the MSc course in Forensic Art run by the University of Dundee. He graduated in 2014 and has been continuing to work as a forensic artist since then.
The surviving cranium is very delicate and is, of course, completely irreplaceable. The method of creating a three dimensional reconstruction can be very intrusive as the skull has to be cast in order to make a plaster copy. This process can be strenuous and we wanted to avoid causing any damage to the skull. It is possible to create a three-dimensional reconstruction using laser scanning equipment and three-dimensional reconstruction software, but without access to this expensive equipment Hew decided to carry out a reconstruction using the two-dimensional method.
The initial stage of the process was to carry out an assessment of the cranium to confirm the age, sex and ancestry of the skull. Hew determined (as have other specialists) that the skull was likely of an female individual in early adulthood, likely within their late teens to early twenties, based on the wear on the teeth and the suture lines of the skull.
Next, the skull was placed in what is known as the ‘Frankfort Horizontal Plane’ – a position which simulates the normal and natural resting position of the human head. The skull was then photographed at a distance of six feet so as to avoid lens distortion. A scale ruler was placed beside the skull so that it could be digitally scaled up to life size and measurements could be taken.
Part of the zygomatic (cheek) bone on the left side of the face was slightly damaged or eroded. To reconstruct the missing segment a vertical line was drawn down the centre of the skull and closely spaced horizontal planes were extended from this centreline to the right (complete) zygomatic bone. The planes on the right side of the skull were then mirrored from the centreline on the opposite side to recreate the incomplete left zygomatic bone as it would have appeared in life.
In order to recreate the missing mandible (lower jaw) of the skull, Hew applied a method from the 1962 book ‘The Human Skeleton in Forensic Medicine’ which was pioneered by the American Anthropologist Walter M. Krogman. Using this method, Hew was able to reconstruct a rough outline of the jaw and position it in the correct place and to the right size in correlate with the cranium.
Next measurements were taken at the widest points of the nasal aperture and a formula was used to calculate the width of the nose. Although some have come loose over time most of the teeth have survived, including some from the top and bottom jaw. By measuring the enamel of the teeth, the size of the lips could be calculated. The position of the corners of the mouth sits between the canines and the first premolars.
Reconstruction showing markers, eye size and location, tissue depths, jaw reconstruction and left zygomatic (cheek) bone reconstruction – Hew Morrison ©
In order to recreate the depth between the bone and skin, modern tissue depths that represent the average European Caucasian female within the age range identified was applied to the skull. The size of the human eye is 24 mm in diameter (coincidentally the same size as a U.S Quarter). So, the eyes were drawn digitally and placed in the appropriate place in each of the orbits (the eye sockets) to correlate with the anatomy and shape of each orbit. Lastly, the individual facial muscles were digitally drawn and added to the skull in the correct positions to relate to the muscle attachment markings present on the skull.
Digitally drawn facial muscles added to the skull in the correct positions in relation to the muscle attachment markings – Hew Morrison ©
Hew holds a very large database of high-resolution stock images of human faces, with a particularly diverse range of Caucasian individuals. To add skin to finalise the reconstruction, facial features from several individuals which matched were selected, as well as an appropriate face shape. Once the appropriate features were selected they were adjusted and tweaked to match with the anatomy of the skull. All of these features were built in separate layers but at this final stage they were blended and morphed together (a bit like a jigsaw puzzle) to create the finished product.
In terms of hair style, Hew selected what was thought to be a best fit for someone living in the Bronze Age: nothing too descriptive or modern looking. Clothing was not added as there is not enough surviving evidence to suggest exactly how people dressed at this time.
The hair colour and eye colour were chosen based on the modern population of this area: brown hair and blue eyes were a highly plausible possibility for this individual. However it is possible that this individual had blonde, red, or dark hair or had brown, hazel or green eyes. We hope that the results from the current ancient DNA analysis being carried out by the Natural History Museum in London might tell us more about eye and hair colour.