Moonlight has helped solve the mystery of Egypt’s sacred baboons

Spectral analysis has shown that the silvery fur of hamadryas baboons and the light plumage of sacred ibises reflect light in a manner similar to that of the moon. Researchers suggest that it is precisely this shared characteristic that may have led to these two completely different animals being regarded as earthly incarnations of a single deity.

The study has been published in the journal *Time and Mind*.

Why was Thoth depicted as two different animals?

Most ancient Egyptian gods were associated primarily with a single species of animal. However, Thoth was an exception.

He was depicted as a man with the head of a sacred ibis, as well as in the form of a hamadryas baboon — a large baboon with silvery fur.

Thoth was regarded as the patron of knowledge, writing, arithmetic and magic. He was also closely associated with the Moon, which helped the ancient Egyptians measure time and compile a calendar.

The ibis’s connection to the Moon was relatively easy to explain. Its long, curved beak resembles a crescent Moon, whilst its black-and-white plumage is associated with the alternation of light and darkness.

But why the Egyptians accorded the baboon the same sacred status remained a mystery for a long time.

Scientists compared the animals’ fur to moonlight

Researchers from the Universities of St Andrews and Dartmouth decided to investigate whether the answer might lie in the animals’ colouring.

To do this, they used spectroscopy — a method that allows scientists to determine which wavelengths of light are reflected by a surface.

This approach helps to avoid subjective descriptions such as ‘silvery’ or ‘moonlight-like’. Colour perception depends not only on lighting, but also on cultural context and the characteristics of human vision.

Measurements showed that the spectral characteristics of the sacred ibis’s light plumage and the hamadryas baboon’s fur are virtually indistinguishable from those of moonlight.

According to the authors, it was precisely this ‘lunar’ colouration that may have linked the two animals in the religious beliefs of the ancient Egyptians.

Why did the Egyptians choose these particular species?

The ancient Egyptians were familiar with several species of ibis, but it was the sacred ibis, with its bright white plumage, that they associated with Thoth.

They were also familiar with various primates, including several species of baboons and monkeys. Yet it was the silver-backed hamadryas baboon that became the divine embodiment of Thoth.

These animals differ greatly in body structure, behaviour and way of life. What they have in common is their distinctive light colouring, which, under certain lighting conditions, can resemble the moon’s glow.

Researchers believe that this shared characteristic may have played an important role in the selection of animals to represent Thoth.

Why the ancient Egyptians revered baboons

The attitude of the people of Ancient Egypt towards baboons was unusual for African cultures.

These primates can destroy crops and come into conflict with humans over food. Consequently, in many societies they were traditionally regarded as pests or dangerous animals.

The Egyptians, on the other hand, not only revered baboons but also associated them with one of the most important gods in their pantheon. The animals were kept at temples, mummified and sacrificed as part of religious rituals.

The authors of the study suggest that the hamadryas baboons’ unusual colouring may have helped to forge this exceptional symbolic connection.

Has the hypothesis regarding the moon-coloured ibis been proven?

Spectral similarity does not prove that the ancient Egyptians chose the ibis and the baboon solely because of their colouring.

Researchers cannot directly ascertain what motives guided people thousands of years ago. Religious symbolism usually arises from a combination of an animal’s appearance, behaviour, habitat, mythology and ritual traditions.

The authors therefore propose a new scientific hypothesis rather than a definitive solution to the mystery.

Nevertheless, spectral analysis shows that the connection between both animals and moonlight is not limited to subjective visual impressions.

Why this is important

The study demonstrates how methods from the natural sciences can be used to investigate ancient religions and symbols.

Spectroscopy made it possible to examine the physical properties of the animals’ colouration and then compare these with archaeological, linguistic and historical data.

Such an interdisciplinary approach offers the opportunity to cautiously gain an understanding of how the ancient Egyptians perceived the world around them and transformed the natural characteristics of animals into religious imagery.

Source

Study: Moonlight and the apotheosis of sacred baboons.

Authors: Nathaniel J. Dominy et al.

Journal: *Time and Mind*.

Year of publication: 2026.