Scientists studying a cave on a Caribbean island discovered something they didn’t expect: ancient bees are very different from the hive-dwelling insects we’re all too familiar with.
For the first time, paleontologists have discovered fossils of bees digging into the bones of other animals. These fossils, thousands of years old, are the end result of a macabre life cycle that involved ancient rats and giant owls. And they may teach us a few lessons about bees today, the researchers say.
“I think the most important result is to show how different bees’ behavior can be,” study researcher Lazaro Viñola Lopez told Gizmodo.
A “lucky” discovery.
Viñola Lopez was working as a doctoral student at the Florida Museum of Natural History when she helped excavate fossils inside a cave on the island of Hispaniola (the cave is the eastern part of the island, owned by the Dominican Republic). But he and his colleagues did not plan to find that out.
“The discovery was a stroke of luck. We were looking for monkeys, rats, lizards, and other vertebrates to do our work on the Quaternary extinction on islands associated with humans and climate change,” he said. “We didn’t want insects because they usually don’t save in that area.”
This cave, called Cueva de Mono, contained thousands of remains of hutia, rodents related to the guinea pig. This discovery was surprising enough, given how rarely hutia fossils are found in the area. But Viñola Lopez also noticed that one of the fossils, an example of hutia mandibles, had an unusual smoothness to it.
Viñola Lopez didn’t immediately delve into her chances, and there were bumps along the way. Based on his previous work on dinosaur fossils, he initially speculated that hutia fossils were used by wasps to build their nests, but the characteristics of these nests did not match what he found.
However, he eventually realized that these fossils were probably used by a different insect, an ancient type of bumble bee, called Osnidum almontei, who lived thousands of years ago. Thanks to a recent trip inside the cave to find more fossils, they also found evidence of these nests inside the core of hutia and the pulp cavity of a beaver tooth (sloths used to live on the Caribbean islands, but were largely exterminated by human activity).
The team’s findings were published Tuesday in the Proceedings of the Royal Society B Biological Sciences.
Unusual bees
Although we tend to think of bees as social insects that build elaborate nests in the open, Viñola Lopez notes that many bee species are solitary and use a variety of structures and nesting materials. But while these ancient bees seem to share much in common with their modern counterparts, they also differ in important and mysterious ways.
“The bees that make these traces are similar to other bees because they build a nest in the ground, but they are different from all other known species because they used to use the chambers of buried bones (as bases for their teeth),” he said. Another major difference is the arrangement of the caves for these fossils. There has been one other documented example of bees using burrows in their nests, according to the researchers, and that did not involve bees using the remains of another animal.
As best as they can tell, the cave was home to ancient owls who used it as a den to hunt hutia. Owls could take mice back home for dinner or sometimes just take them out of the food on the go; these remains later proved to be an attractive breeding ground for bees. And while much of the environment is unsuitable for these insects, the cave and others like it may have contained enough structured soil for the bees to rely on for their nests.
Besides learning more about bees, the group’s research also taught them to be more careful.
“It changed the way we look at and process fossils from these cave remains in the Dominican Republic.” Now we take extra care before we clean them to make sure we don’t destroy any other interesting behavior of ancient insects hiding in the dirt inside the fossils,” he said.
Ancient cave bees aren’t the only discovery researchers hope to make. They are already working to describe many other fossils found in the cave, which should include previously undescribed species of mammals, reptiles and birds.
