(C) The Field Museum
(C) The Field Museum

Tooth Decay May Have Turned Tsavo Lions into Man-Eaters

(C) The Field Museum
(C) The Field Museum

Looking for good motivation to brush and floss? Mammal experts say the infamous lions that killed dozens of rail workers in Kenya in 1898 may have been driven by dental disease. They published a report on the unfortunate beasts in the journal Scientific Reports.

There were only two of them, but the damage they did was both extensive and terrifying. “I could plainly hear them crunching the bones,” Lieutenant Colonel John Patterson wrote in his diary, “and the sound of their dreadful purring filled the air and rang in my ears afterwards.”

Patterson with one of the Tsavo lions. Image Credit: The Field Museum

Patterson eventually killed the lions, and their remains were preserved for scientific study. Today, the two skulls are kept in the collection of Chicago’s Field Museum so scientists can study them.

The Field Museum

Historians have long believed that the lions turned to human prey out of desperation when a famine eliminated their usual sources of food. If this was the case, the lions would have relished every last bite of every animal they killed, including the bones.

But when Field Museum researchers examined the Tsavo skulls, they began to suspect that the lieutenant’s “very vivid recollection” may have been at least slightly exaggerated, as the lions had clearly not been crunching anything. The microscopic signs of wear and tear that accompany regular hard use were nowhere to be found in the lions’ jaws.

They did, however, find evidence of dental problems. One lion had broken a canine tooth several years earlier, was missing three incisors, and had a periapical abscess, or pus pooled around the root of a tooth. The other had a fractured upper left carnassial (the equivalent of a molar) and exposed pulp (tissue at the center of a tooth).

Bruce Patterson (no relation) is the museum’s curator of mammals. He and his colleagues think the Kenyan lions’ suspiciously smooth teeth and dental injuries could have played a role in their attacks on humans. These types of injuries aren't uncommon, and they can be painful.

“Lions normally use their jaws to grab prey like zebras and wildebeests and suffocate them,” he said in a statement. If you’ve got a mouthful of hurt, you’re not going to leap face-first at a kicking wildebeest. “Humans are so much easier to catch,” Patterson said.

“We humans like to think we’re at the top of the food chain, but the moment we step off our paved streets, these other animals are really on top.”

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How Bats Protect Rare Books at This Portuguese Library
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Visit the Joanina Library at the University of Coimbra in Portugal at night and you might think the building has a bat problem. It's true that common pipistrelle bats live there, occupying the space behind the bookshelves by day and swooping beneath the arched ceilings and in and out of windows once the sun goes down, but they're not a problem. As Smithsonian reports, the bats play a vital role in preserving the institution's manuscripts, so librarians are in no hurry to get rid of them.

The bats that live in the library don't damage the books and, because they're nocturnal, they usually don't bother the human guests. The much bigger danger to the collection is the insect population. Many bug species are known to gnaw on paper, which could be disastrous for the library's rare items that date from before the 19th century. The bats act as a natural form of pest control: At night, they feast on the insects that would otherwise feast on library books.

The Joanina Library is famous for being one of the most architecturally stunning libraries on earth. It was constructed before 1725, but when exactly the bats arrived is unknown. Librarians can say for sure they've been flapping around the halls since at least the 1800s.

Though bats have no reason to go after the materials, there is one threat they pose to the interior: falling feces. Librarians protect against this by covering their 18th-century tables with fabric made from animal skin at night and cleaning the floors of guano every morning.

[h/t Smithsonian]

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Honey Bees Can Understand the Concept of Zero
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The concept of zero—less than one, nothing, nada—is deceptively complex. The first placeholder zero dates back to around 300 BCE, and the notion didn’t make its way to Western Europe until the 12th century. It takes children until preschool to wrap their brains around the concept. But scientists in Australia recently discovered a new animal capable of understanding zero: the honey bee. According to Vox, a new study finds that the insects can be taught the concept of nothing.

A few other animals can understand zero, according to current research. Dolphins, parrots, and monkeys can all understand the difference between something and nothing, but honey bees are the first insects proven to be able to do it.

The new study, published in the journal Science, finds that honey bees can rank quantities based on “greater than” and “less than,” and can understand that nothing is less than one.

Left: A photo of a bee choosing between images with black dots on them. Right: an illustration of a bee choosing the image with fewer dots
© Scarlett Howard & Aurore Avarguès-Weber

The researchers trained bees to identify images in the lab that showed the fewest number of elements (in this case, dots). If they chose the image with the fewest circles from a set, they received sweetened water, whereas if they chose another image, they received bitter quinine.

Once the insects got that concept down, the researchers introduced another challenge: The bees had to choose between a blank image and one with dots on it. More than 60 percent of the time, the insects were successfully able to extrapolate that if they needed to choose the fewest dots between an image with a few dots and an image with no dots at all, no dots was the correct answer. They could grasp the concept that nothing can still be a numerical quantity.

It’s not entirely surprising that bees are capable of such feats of intelligence. We already know that they can count, teach each other skills, communicate via the “waggle dance,” and think abstractly. This is just more evidence that bees are strikingly intelligent creatures, despite the fact that their insect brains look nothing like our own.

Considering how far apart bees and primates are on the evolutionary tree, and how different their brains are from ours—they have fewer than 1 million neurons, while we have about 86 billion—this finding raises a lot of new questions about the neural basis of understanding numbers, and will no doubt lead to further research on how the brain processes concepts like zero.

[h/t Vox]

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