Pharaoh-era bees found naturally mummified on the Southwest Coast of Portugal

X-ray micro-computed tomography of a 3000-years-old bee found inside its brood cell.

About 2975 years ago, Pharaoh Siamun reigned in Lower Egypt; in China the Zhou Dynasty flourished; in the territory that is now Portugal, the tribes were heading towards the end of the Bronze Age. On the southwest coast, on what is now Odemira, something strange and rare had just happened: hundreds of bees died inside their cocoons and were preserved in the finest anatomical detail.

A new study published in the international journal Papers in Paleontology from the Palaeontological Association reports on the discovery of hundreds of mummified bees inside their cocoons, in a new paleontological site discovered on the southwest coast of Portugal. This fossilization method is extremely rare and normally the skeleton of these insects is quickly decomposed, as it has a chitinous composition, which is an organic compound. “The degree of preservation of these bees is so exceptional that we were able to identify not only anatomical details that determine the type of bee, but also their sex and even the supply of monofloral pollen left by the mother when she built the cocoon” stresses Carlos Neto de Carvalho, the paleontologist who coordinated the project. This project is the result of an Ibero-Italian cooperation that brought together researchers from IDL – University of Lisbon, DISTAV – University of Genova, MARE – University of Coimbra, the Polytechnic Institute of Tomar, the Portuguese Center for Geo-History and Pre-History, the Center for Research in Theoretical Physics Abdus Salam, and from the universities of Siena, Venice and Seville. Carlos Neto de Carvalho, scientific coordinator of Naturtejo UNESCO Global Geopark and collaborating researcher at Instituto D. Luiz, says that the project identified four paleontological sites with a high density of fossils of bee cocoons, reaching thousands in a meter squared. These sites were found between Vila Nova de Milfontes and Odeceixe, on the coast of Odemira, a municipality that gave strong support to the execution of this scientific study, sponsoring dating by carbon 14.

“With a fossil record of 100 million years of nests and hives attributed to the bee family, the truth is that the associated fossilization of its user is practically non-existent” reinforces the Italian paleontologist Andrea Baucon, one of the co-authors of the present work. These cocoons produced almost 3000 years ago preserve, like a sarcophagus, the young adults of the Eucera bee that never met the chance of seeing the light of day. This is one of the approximately 700 species of bees that currently exist in mainland Portugal. The newly discovered paleontological site shows the interior of the cocoons coated with an intricate thread produced by the mother and composed of an organic polymer. Inside, it was possible to find under the electronic microscope what’s left of the monofloral pollen left by the mother as provision, with which the larva would have fed in the first times of life. The use of microcomputed tomography allowed to have a perfect and three-dimensional image of the naturally mummified bees inside sealed cocoons.

Bees have more than twenty thousand existing species worldwide and are important pollinators, whose populations have suffered a significant decrease due to human activities and which has been associated with climate change. Understanding the ecological reasons that led to the death and mummification of bee populations nearly three thousand years ago could help to understand and establish resilience strategies to climate change. In the case of the southwest coast of Portugal, the climatic period that was experienced almost three thousand years ago was marked, in general, by colder and wetter winters than the current ones. “A sharp decrease in the temperature at night at the end of winter or a prolonged flooding of the area already outside the rainy season could have led to the death, by cold or asphyxiation, of hundreds of these small bees, significantly depleting local populations”, reveals Carlos Neto de Carvalho.

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X-ray micro-computed tomography of a male bee (Eucera sp.) inside a sealed brood cell

The Southwest Coast of Portugal, where ancient bees were found inside their cells.

Interpretation of the studied palaeoecosystem

Reconstitution of the studied paleoecosystem

X-ray micro-computed tomography of a male Eucera sp. inside a sealed brood cell

Wing of a bee mummy.