Keywords provenance research - radiology - anthropology - legal medicine - archeology - post-mortem
computed tomography
Introduction
The study of people, their origins, their environment and their lives – both healthy
and sick – has been the focus of numerous scientific disciplines for centuries. Especially
in the late 19th and early 20th centuries, collections were created to help record people’s phylogenetic development
and their existence in different “races” and to provide specimens of “disappearing
indigenous peoples” in the form of human remains and associated cultural objects.
Only recently has attention been devoted to researching the circumstances under which
these collections were acquired, i.e., were they acquired legally or by exploiting
injustice. The current focus in research projects is primarily on human remains of
non-European origin, which can be found not only in ethnological collections, but
also in a large number of “medical” collections, such as the collection at the Institute
of Anatomy, Rostock University Medical Center. Here, between 2020 and 2022, a project
was funded by the German Lost Art Foundation in order to conduct specific research
of the origin, acquisition history, and origins of individuals of non-European origin
in the collection. None of these individuals consented to body donation, as is customary
today [1 ]
[2 ]
[3 ]. Considering the period in which the collection was created, however, this is not
surprising. It should be noted that during that period countries such as Great Britain,
France, the Netherlands, and Germany fought over areas of the world that they could
include in their national territory as power territories. It was the time of colonialism.
In 1914, the German colonies together formed the third largest colonial empire in
terms of area after the British and French. It included parts of today’s People’s
Republic of China, Burundi, Rwanda, Tanzania, Namibia, Cameroon, Gabon, Republic of
Congo, Central African Republic, Chad, Nigeria, Togo, Ghana, Papua New Guinea, and
several islands in the Western Pacific and Micronesia. With the end of World War I,
German colonial rule ended.
The populations living in the colonies were subjugated and often brutally exploited
in order to produce goods for the colonial power. These populations were considered
extremely interesting for the newly emancipating scientific disciplines of the European
powers, such as ethnography, anthropology, anatomy, anthropology, and others. Through
merchants, naval doctors, and others, graves were looted, skulls were bought from
locals, or people were purposely killed in order to acquire interesting “specimens”
for their collections. In one case, a letter is preserved in the Institute of Anatomy
in Rostock which describes grave looting and thus indicates the origin of two of the
40 non-European skulls. In a few other cases, at least the consignors are named in
the preserved transcript of the inventory book. Most of them were ship doctors who
were directly connected to Rostock and even to the Institute of Anatomy in one way
or another [4 ]. However, the circumstances of the acquisition remain unclear here. All other individuals
came to Rostock via routes that are completely undetermined so far. It was, therefore,
important that this project was carried out in an interdisciplinary manner. In addition
to historical research into consignors, people, and old collection documentation,
an anthropologist examined skulls that no longer had any preserved soft tissue. She
was supported by forensic pathologists from the Rostock University Medical Center
[5 ]
[6 ].
However, special “fluoroscopy methods” were required for human remains in which soft
tissue was still preserved and which “masked” bone features, e.g., the heads with
skin and hair of people from pre-Hispanic Peru, the “Chilean mummy”, and a New Zealander
as well as a bandage-wrapped Egyptian mummy head. Some of the results of the radiological
examinations are presented below.
Materials and Methods
The collection of non-European human remains at the Institute of Anatomy at the Rostock
University Medical Center currently includes 40 skulls (China, Polynesia, Central
and South America, Namibia, Egypt, New Zealand), 14 plaster casts, 6 Egyptian mummy
heads, and 1 full-body mummy from Chile. In addition to collecting individual data
such as age, gender, and presumed pathologies, possible causes of death and, most
importantly, the origin of each individual were to be determined. An anthropologist
initially determined gender and age at the time of death, collected craniometric measurements
and dental status, and recorded individual abnormalities and cultural transformations
[7 ]. Detailed questions arose about individual skulls with post-traumatic changes, which
were then examined by forensic pathologists. Since anthropology is classically dedicated
to the study of skeletal material, radiology was consulted to study bandaged and mummified
human remains and also to clarify detailed questions, such as the treatment of the
dead and the effects of violence. At the Institute for Diagnostic and Interventional
Radiology, Pediatric and Neuroradiology at the Rostock University Medical Center,
the human remains of nine skulls and the full-body mummy were examined using the “Revolution”
computed tomography scanner from GE Healthcare (256 × 0.625 mm) ([Table 1 ]). To evaluate the image data, reconstructions in axial, sagittal, and transverse
planes as well as illustrative 3D models were created using volume rendering technology.
Table 1 List of human remains examined by CT with inventory number and origin.
Computed tomography
Origin
Skull Cd 1
Egypt
Skull Cd 2
Egypt
Skull Cd 3
Egypt
Skull Cd 4
Egypt
Skull Cd 5
Egypt
Skull Cd 6
Egypt
Skull Cd 7
Egypt
Skull Cd 8
Egypt
Skull Cd 10
Egypt
Skull Cd 11
Egypt
Skull Cd 12
Egypt
Skull Cf 22
New Zealand
Skull Cf 23
New Zealand
Mummy mod. b 9
Chile
At the Institute for ImplantTechnology Rostock, seven non-European skulls were scanned
using a micro-CT/X-ray microscope (Bruker SkyScan1273) and 3D data sets were created
for further analysis ([Table 2 ]). An isotropic resolution (voxel size) of approx. 52 µm could be achieved, which
exceeds the resolution of a clinical CT scanner by three times and thus allows analysis
of even the finest intracranial features and intraosseous structures. In micro-CT,
the sample is usually rotated up to 360° in defined steps while the X-ray source and
detector do not move.
Table 2 List of human remains examined by micro-CT with inventory number and origin.
Micro-CT
Origin
Skull Cd 20
Namibia or South Africa
Skull Cd 24
Namibia or South Africa
Skull Cd 35
Namibia
Skull Ce 27
Ancient Peru
Skull Cf 1
Java
Skull Cf 12
Yap
Skull Cb 28
Rostock, Germany
Acquisition of images of the entire skull was made possible by adding several individual
scans together. Depending on the condition of the sample (e.g., bone density, presence
of soft tissue), individual scans lasted 2 to 15 hours (with single image exposures
of 575 ms) and thus, depending on the sample dimensions, total scan times of 6 to
40 hours were necessary.
Similar to clinical CT examinations, the captured individual images are converted
into a voxel-based 3D volume using the appropriate device software, which can be further
processed or exported as an image series. With specialized software it is possible,
in addition to the overall representation as a volume model, to segment individual
tissue components and intraosseous structures manually or using AI algorithms and
to reconstruct them as surface or volume models [8 ]
[9 ]
[10 ].
Results
In all Egyptian heads, the stages of the ancient Egyptian mummification process were
visible. In particular, the destruction of the walls of the paranasal sinuses ([Fig. 1 ]a) and the floor of the anterior cranial fossa was visible ([Fig. 1 ]b). This artificial access to the brain was created by the embalmers in ancient Egypt
in order to remove the brain through the nose for successful mummification. One CT
scan showed a straw-shaped object in a mummy head (Cd 6), lying between the sphenoid
sinus and the cranial cavity. Presumably, it had been used as a tool and got stuck
there during the mummification process ([Fig. 2 ]).
Fig. 1 Removal of the brain was part of the mummification process. CT is able to visualize
the destruction of the skull base occurring as a result of the removal of the brain
through the nose. a Axial CT of the skull showing destruction of the posterior wall of the sphenoid sinus
(arrow). b Sagittal CT of the skull showing destruction of the rhinobase (arrow).
Fig. 2 Sagittal CT of the skull shows a tubular foreign body that may have been inserted
to remove brain tissue and got stuck in the base of the skull (arrow).
After removing all water-containing organs such as the brain and those from the abdominal
cavity, the body was dried, covered with bitumen, and then wrapped with the bandage
wrap, as is typical for Egyptian mummies. It was believed that the dead person would
then be granted eternal rest as an intact body for life after death. Centuries later,
in the time of grave robbers and Europeans traveling to Egypt, the belief in life
after death was still known, as was the curse of the mummy, supposedly killing anyone
who disturbed that peace. Grave robbers tried to protect themselves out of fear of
these “still living” individuals and their power over those living in this world.
They did this through what 21st -century researchers initially thought was a “post-mortem defect”: a hole hacked into
the skull. The grave robbers believed that this hole allowed the spirit of the dead
to escape. The corpse would thus be “empty” and inanimate so that no curse could harm
the living ([Fig. 3 ]).
Fig. 3 Axial CT of skull Cd 8 shows the remains of a bees’ nest (arrow) and a hole (star)
carved into the skull by grave robbers to allow the mummy’s spirit to escape.
A head (Cd 8) indicated the place of its storage after its removal from the grave
by a “subtenant”. After extensive interdisciplinary discussions as to whether this
was a postmortem or intravital finding act, a partially calcified foreign body on
the inside of the skull turned out to be a bees’ nest. Remains of straw which trickled
into the skull through the hole made by the grave robbers, indicated that the head
had presumably been wrapped in straw after it was taken from the grave and that a
bee had found shelter in it and built a nest ([Fig. 3 ]).
In the search for postmortem moving of the human body after its removal from the grave
and until entering the collection of the Institute of Anatomy, evidence was also found
in the head (CD 2) of another Egyptian mummy. In the area of the middle ear of this
skull, an asymmetrical configuration of the auditory ossicles was found. The 3D reconstructions
showed bilateral incomplete ossicles in the middle ear ([Fig. 4 ]a). The hammer was missing on the right and the incus and stapes on the left. Upon
closer inspection of the CT data, the “lost” ossicles were found in the cavities between
the bones, skin, and mummy bandages, while the intact incus on the left was clearly
visible ([Fig. 4 ]b). This finding is not uncommon in Egyptian mummies [11 ] and is related to the drying process, which destroyed the structures of the connective
tissue between the ossicles and the tympanic membrane. This resulted in the loss of
the connection between the ossicles which then dropped out and came to lie, largely
loose, in the middle ear. When the mummies were removed from their resting place and
moved, vibrations might have occurred that caused the ossicles to fall out of the
external auditory canal. However, the bandages, the “mummy wrap”, prevented them from
being completely lost. Due to the high density of the ossicles, they can also be easily
recognized by X-ray-based imaging in locations other than the middle ear. Occasionally
they are found in the Eustachian tube.
Fig. 4 During mummification, the drying process led to a loss of connective tissue between
the ossicles, allowing them to dislocate, e.g. during transport. In the paraaxial
CT examination of skull Cd 2, the incus and the stapes on the left cannot be depicted
(a , arrow). The incus was dislocated between the calotte and the skin during improper
transportation (b , arrow).
The two Maori heads in the collection of the Institute of Anatomy in Rostock (Cf 22
and Cf 23), a mummified head and a skull, were also examined using CT. In particular,
heads such as the former were popular “souvenirs” from New Zealand in the late 19th and early 20th centuries. The question now was whether the Maori skull was once a mummified head
which was macerated due to a lack of fluoroscopic methods at the time it entered the
collection, or whether it came from a burial context and was defleshed in the natural
decomposition process. The CT scan did not show any morphological differences in the
bone substance of the two heads, nor did it reveal any changes in the bone structure
that may have occurred during the mummification process of the head with preserved
soft tissue, e.g., like heat exposure (sphere fractures/tabula externa avulsions)
or the use of caustic chemicals.
The micro-computed tomography scans carried out at the Institute for ImplantTechnology
in Rostock were used in particular to analyze traces of injury, with the high-resolution
scans making it possible to obtain better information about a possible healing status
and to clarify whether detected injuries had occurred a long time ago and had or had
not healed, or if they were the cause of death or at least related to it. This was
the case for one skull (Cd 20), which shows an almost oval or triangular, funnel-shaped,
tapering defect (approx. 6 × 4 mm) on the right temporal bone, from which several
radial fractures and fissures extending in the surrounding bones were detectable ([Fig. 5 ]a and 5b). Micro-CT analysis showed that the causative object hit the bone from the
outside of the skull but did not penetrate the bone itself. On the inside of the skull,
broken bone fragments were visible, which still showed partial continuity with the
bone surface (hinge fracture) ([Fig. 5 ]c and 5d). There were no signs of bone healing. Anthropological experience led to
the interpretation of a perimortem injury (i.e., occurred around the time of death)
which, due to its defect characteristics [12 ]
[13 ], was most likely caused by the penetration of a projectile [14 ], but did not cause a brain injury due to the shallow penetration depth and was,
therefore, not immediately nor necessarily fatal. However, the lack of healing tendencies
might also suggest that other causes associated with this injury could have ultimately
led to the individual’s death.
Fig. 5 Skull Cd 20 shows a triangular defect/impression fracture on the right temporal bone
(a , arrow), with several small fissures/fractures extending from its center and outer
edge into the temporal bone (b , arrows) photos: Ute Brinker. In the axial (c , arrow) and sagittal (d , arrow) planes of micro-CT, it can be seen that the impinging object has not completely
penetrated the skull bone. The tabula externa, diploe, and tabula interna are imprinted.
Parts of the internal tabula have been blasted off. Fractures that completely penetrate
the bone are clearly recognizable. There are no signs of bone healing.
For skulls with preserved soft tissue, (micro-)CT was used to estimate the individual’s
age at the time of death based on tooth development [15 ]
[16 ]. On the CT scan of Cd 20, the complete closure of the roots of the two third molars
was detectable, one of which is in eruption ([Fig. 6 ]a) and the other in occlusion ([Fig. 6 ]b) which indicates an age at the time of death of approx. 18–20 years [17 ].
Fig. 6 The age at death can be determined on the basis of tooth development with the aid
of (micro-)CT. The micro-CT examination of the maxilla of skull Cd20 shows in sagittal
plane complete root closure of both third molars in eruption (a , arrow) and occlusion (b , arrow). The age at death could be narrowed down to 18–20 years.
Another method for determining the age of at the time of death beyond adolescence
is the analysis of the ectocranial suture closure – with CT helping in cases where
soft tissue or bandages mask bone structures. According to Herrmann’s scheme, the
suture frontalis and the suture lambdoidea were divided into three sections and the
suture sagittalis into four sections [18 ]. Based on the ossification stage of the respective sections, the individual’s approximate
age at the time of death can be derived ([Fig. 7 ]) ([Fig. 8 ]a and b). Furthermore, sex determination was carried out using anatomical landmarks
such as the shapes of the orbit, the jaw, the forehead, and bony protuberances of
the skull [19 ]. The assessment of the dental status was a standard part of the diagnosis in this
research. Here, the consequences of a diet of hard grains could be clearly seen in
the wear and tear of tooth structure and defects in the Egyptian skulls. Consecutively,
small osteolyses were found at the tooth root tips as an indication of past apical
periodontitis. [20 ]
[21 ].
Fig. 7 Scheme for determining the age of death based on the ectocranial suture closure according
to Herrmann.
Fig. 8 Axial CT of a skull with completely ossified sagittal sutura in a senile individual
(a , arrow) and partial occlusion of the sagittal sutura in a 30–50 year old individual
(b , arrow).
Conclusion and Perspective
Conclusion and Perspective
Provenance research attempts, firstly, to detect all possible information on the individual
whose human remains are in a collection, i.e., his/her origin and circumstances of
life and death, and, secondly, investigates the acquisition history.
Exposure to direct colonial-era injustice such as the use of violence to kill the
individual to be able to incorporate his/her remains into the collection could not
be found for any of the individuals examined in this provenance research project.
Most remains showed remnants of sand and natural decomposition, which indicates extraction
from graves.
However, through interdisciplinary collaboration, individual fates could be determined,
thus providing information about the circumstances of the life and death of individuals,
even if these took place before the colonial period. The context of injustice lies
primarily in grave robbing in the early 19th century and the inclusion of these human remains in collections such as in Rostock.
The future of the collection, as in other collections with human remains worldwide,
remains a “matter of negotiation” for the Institute of Anatomy at the Rostock University
Medical Center. The aim is to establish a dialogue with the descendants of the communities
of origin and with representatives of victim groups.
However, Egypt has not yet reclaimed any human remains from its pharaonic era. Things
look different in the efforts with New Zealand. In general, the Federal Republic of
Germany is always trying to find descendants or representatives of communities of
origin worldwide in order to start a dialogue about the future handling of collections
that were created in the colonial period. Some countries and groups have already achieved
the return of the bones of their ancestors several times in this process, especially
the indigenous peoples of North America and descendants in New Zealand, Australia,
and Namibia, whose bones are or were present in the Rostock collection. Repatriation
to the Maori/Moriori descendants in New Zealand has not yet taken place. However,
this could happen for both Maori heads, as repatriation to New Zealand is the current
standard procedure in Germany.
In general, noninvasive methods are to be preferred in provenance research in order
not to violate the dignity of the dead and, on the other hand, to respect the wishes
of the communities of origin regarding how to deal with their dead. Corresponding
noninvasive visualization and “dissection options” are now used in many places and
thus offer specialists the opportunity to examine the human remains without having
to treat them again or examine them directly.
In the future, three-dimensional reconstruction techniques may provide a solution
for further management after an initial CT scan. Basically, there are currently two
main procedures. The rather simple surface rendering, in which a contour of the body
is defined using the density value and then displayed in three dimensions. In contrast,
with volume rendering, with the individual density of a pixel determining its representation,
all structures can be displayed transparently and in different colors at the same
time. With this procedure it is possible to selectively display the different structures
of the CT-scanned body and thus to systematically dissect the person virtually. The
layer thickness determines the quality or realism of the 3D reconstruction. Optimal
results are achieved with an isotropic voxel resolution of a maximum of 1 mm³.
In addition to viewing the 3D objects obtained in this way on a screen, it is possible
to create a so-called holographic projection. The basic principle was first presented
in 1862 at a theater performance in London by John Henry Pepper. To achieve this,
an individual was attired as a ghost and positioned beneath the stage, concealed from
the audience’s view. Through the utilization of a sizable, segmented, semi-transparent,
and slanted mirror, this individual’s image was projected onto the stage. The mirror
reflected a portion of the incident light while allowing the remainder to pass through.
Consequently, spectators perceived the 3D object in the room behind the mirror, akin
to a ghost appearing to float freely in space.
In addition to the stage construction involving a large dividing mirror or dividing
film, which is still used today, there are also 3- and 4-sided pyramid constructions
in various sizes, ranging from 6 inches up to an edge length of 2 meters, enabling
life-size representation as a hologram. For each side, a projection coming from a
vertical direction can be viewed horizontally across the sloping glass surface. The
size of the holographic object is freely scalable and depends on the geometry of the
projection surface and the pyramid used [22 ]
[23 ].
VR/AR glasses have already been successfully utilized for direct interaction. The
3D data is manipulated using joysticks or simply by finger and body movements. When
operating online, these systems also enable direct and limitless interactive work
by different people or work groups on a dataset without needing the original. The
future lies in the virtual realm, both for researchers and museum visitors.
