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Pig Carcasses Aren’t a Great Model for Studying Human Decay, Study Finds

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Like so many fields of science, forensics relies heavily on the use of animals as human stand-ins. But a new study calls the wisdom of that practice into question, since researchers have found drastically different decay patterns for the bodies of humans, pigs, and rabbits. The scientists recently presented their findings to the American Academy of Forensic Sciences.

Our bodies, like every organism on the planet, are in a constant state of decay. Our cells are in perpetual turnover, dying and being replaced. Once we die, that replacement stops, and other processes and actors take over. Bacteria and fungi flourish and spread, gradually breaking down our flesh. Bodies left out in the open attract invertebrate scavengers like maggots and beetles, and vertebrates like birds and raccoons turn up to take away what’s no longer needed.

The details of the process are both fascinating and important to understand, especially for the scientists who aid police in investigating deaths. But finding human bodies to study is pretty difficult (if you do it legally, anyway), and so researchers often look to the bodies of pigs and other non-human animals. 

But what’s true for a pig is not always true for a person. An interdisciplinary team of researchers at the University of Tennessee Forensic Anthropology Center (FAC) tracked the day-by-day breakdown of 15 human, 15 pig, and 15 rabbit bodies through spring, summer, and winter. (The FAC, more commonly known as the Body Farm, is one of the few places in the U.S. that provides researchers with access to decaying human bodies.)

They found great variation in the speed and manner in which species decayed. In spring, for example, human and pig bodies were fairly well-matched until about 25 days in, when the pig bodies started rapidly turning to skeletons. Rabbit bodies broke down slowly at first, then quite rapidly once the maggots set to work. One rabbit looked fine one day, but was partially reduced to a skeleton 24 hours later.

In summer, pigs decayed faster than people and rabbits, turning to skeletons within 12 days. In winter, for obvious reasons, the bodies were insect-free for the first 100 days, but had plenty of visits from larger scavengers. Those raccoons, opossums, birds, and skunks were far more interested in human bodies than those of rabbits or pigs.

“This strongly indicates a preference for the humans over the other species,” the authors report. They conclude that human decomposition is a lot less predictable than that of pigs, which is bad news for all those pig studies.

“This research provides guidance to lawyers and judges concerning the admissibility of testimony by anthropologists and entomologists,” said principal investigator and FAC director Dawnie Steadman in a press statement. “Now [they] may be asked in court which studies they used to base their estimate of postmortem interval, and if they are based on nonhuman studies, their testimony could be challenged.”

[h/t Forensic Magazine]

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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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