An object lies on a bed, inside a round CT scanner. It is illuminated with blue and purple lights.

The ‘digital autopsies’ revealing secrets of animal mummies

There is a belief, held still today, that the path to a happier life lies in regularly contemplating death. For example, in Bhutanese Monks (considered by many to be the happiest people on earth), think about their own demise a minimum of five times a day. While there is no way to know whether the ancient Egyptians were an ecstatically happy people, they too considered death throughout their lives and spent a great deal of time preparing for the thereafter. They invested heavily in the building of tombs, funerary objects, charms and talismans in the hope that these would see them safe and prosperous in the afterlife.

Mummification too played a large part in these preparations, as it was believed that the body must be preserved in order to protect the journey of the soul into the underworld. However, it was not only humans that underwent mummification, but animals. You might expect that they would be pets or domestic animals, prepared this way to accompany their owners on the journey to the other side, but this was actually quite rare. In fact, the majority of mummified animals discovered are known as ‘votive mummies’ or offerings, bred in the temples, killed, mummified and sold to visitors, who used them to beg favour of the gods.

It was believed that the divine powers could manifest themselves in animal form – a crocodile, for example, or a snake, could be a powerful protective force. As wild dogs were frequently seen on desert plateaus near tombs, dogs were thought to invoke Anubis, the jackal god, and protect the deceased. About 30 kilometres south of what we know as Cairo, a maze of underground catacombs, temples and shrines was discovered and nicknamed ‘the necropolis of the sacred animals’. It was filled with the mummified remains of ibises, baboons, falcons, cats and dogs.

A dark-haired woman wearing a blue scarf and medical gloves places a small mummified animal onto a cushion, in front of a CT scanner.
Dr Lara Weiss of the National Museum of Antiquities, RMO, gently places a mummified ibis onto a cushion in readiness for its scan.

The Rijksmuseum van Oudheden (The Dutch National Museum of Antiquities, RMO) in Leiden has one of the most important collections of the ancient Egyptian culture worldwide, including several intact animal mummies. With great foresight, the first director of the museum took the wise decision to preserve the mummies, not giving in to the temptation to discover what lay within. He understood that unwrapping the 2000-year-old creatures would destroy them forever. So, the animals sat waiting until the technology became available to allow their closer examination. First, by X-ray in 1896, then radiographs in the 1960s. In the years since, imaging technology has developed exponentially, and the mummies have undergone many CT scans, but it was only in February 2020 that scientists at Canon Medical Systems Europe in Zoetermeer, the Netherlands, were able to combine state-of-the-art CT with the power of deep learning to the examination of the animals.

Computer scientist Berend Stoel, physicist Irene Hernández-Girón of Leiden University Medical Centre, and Leiden University biologists Michael Richardson and Merijn de Bakker conducted ‘digital autopsies’, using the latest Canon Medical Systems Aquilion ONE / PRISM Edition CT system, together with their proprietary AI reconstruction technology ‘AiCE’ (short for ‘Advanced intelligent Clear-IQ Engine). Because the mummies had already undergone X-rays and other scans, the team didn’t anticipate any real surprises, but they discovered a resolution that truly exceeded all expectations. The scans were so clear, they showed structures within the mummies that had never been seen before. Using an advanced ‘Global Illumination’ visualisation software from VitreaTM , they were able to create incredible 3D models of the animals. This extraordinary tool allowed the team to ‘virtually’ remove layer after layer of their mummification until only the bare remains were visible. The images can then also be ‘suspended’ in space on screen, so the mummies can be rotated.

The scans show in astonishing detail the structure of each animal, even throwing up a couple of surprises where the animal believed to be mummified was actually something else entirely. They tell a story of the complexity of mummification and the way in which the wrapping was ‘sculpted’ around broken forms that in no way resembled the beautiful objects they became. There are even questions raised around ‘fakery’, where a mummy sold for the purposes of worship is not what it purported to be. In the case of the crocodile, one might wonder how one goes about the mummification of such a creature. The circumstances around these mummies are enough to make the imagination run wild, but the evidence shown in this extraordinary set of scans is clear documentation of a an endlessly fascinating civilisation and time in human history.

A CT Scan of a mummified falcon. On the left are the bones, labelled. On the right is the original mummified presentation of the animal.

This falcon mummy (Leiden inv. no. F 1982/12.10) is a great example of the kind of detail achieved with the Aquilion ONE / PRISM Edition CT system and AiCE. In an earlier publication, scholars were uncertain if the mummy was a falcon or a sparrowhawk. This has now kindly been confirmed by

Hanneke Meijer of the University of Bergen in Norway, who kindly assisted with the analysis of this specimen. This mummy has limbs, but is missing most of its bones, including its head. However, in Egyptian religion, one part of the body could symbolise the whole, an understanding we now term ‘pars pro toto’, Latin for 'a part (taken) for the whole’.

A CT scan of a mummified dog head. On the left, the skull, on the right, the original mummified presentation.

This mummified dog head (Leiden inv. no. AMM 16m) shows how revealing CT scanning can be. It was purchased by the museum as an animal of unknown type in 1828, and long thought to be an ibis mummy, until a previous scan revealed it was actually the head of a dog. It was highly unusual for the head to be mummified separately, which raised the question of whether it was deliberately made to look like an ibis.

A CT scan of a mummified crocodile. On the left, the adult skull, on the right, the original mummified presentation of an entire juvenile crocodile.

This crocodile mummy (Leiden inv. no. AMM 16h) was artfully wrapped and designed with incredible attention to detail. However, inside is not a juvenile crocodile, as expected, but simply a skull – without lower jaw – of an adult crocodile. It appears to have been attached to a stick extending through the whole mummy.

This article is kindly abstracted from Canon Medical Systems Europe VISIONS magazine #35.

Written by Dr Lara Weiss, Curator of Egyptian Collections, Rijksmuseum van Oudheden