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David DeHetre via Flickr Creative Commons // CC BY-NC 2.0
David DeHetre via Flickr Creative Commons // CC BY-NC 2.0

Research Suggests Horses Can Read Human Expressions

David DeHetre via Flickr Creative Commons // CC BY-NC 2.0
David DeHetre via Flickr Creative Commons // CC BY-NC 2.0

Everybody loves a good interspecies friendship story. But do the animals in those relationships actually know how their friends are feeling? Some of them might. A new study published in Biology Letters suggests that horses can read different emotions on human faces. 

Researchers rounded up 28 horses from stables in Surrey and Sussex in the UK. The horses were shown photos of men they'd never seen before while researchers monitored their heart rates and behavior.  

Happy pictures didn’t provoke much of a response in the horses, but when the men in the pictures looked angry, the horses’ heart rates increased. They also turned their heads to view those pictures with their left eye—an action associated with increased attention. Previous studies have shown that many animals use their left eyes to look at things that are scary or alarming. This is likely because input from the left eye is sent to the brain’s right hemisphere, a region associated with processing threats. 

Dogs, too, have been shown to look at angry human faces with their left eyes; and dogs, too, have had close relationships with humans for thousands of years. Is it any wonder they learned to read us?

"It's interesting to note that the horses had a strong reaction to the negative expressions but less so to the positive,” study co-author Amy Smith said in a press release. "This may be because it is particularly important for animals to recognize threats in their environment. In this context, recognizing angry faces may act as a warning system, allowing horses to anticipate negative human behavior such as rough handling." 

The study marks the first time human expressions have been shown to affect another animal’s heart rate. Co-author Karen McComb has a few theories on how this interaction evolved. “There are several possible explanations for our findings,” she said in the press release. “Horses may have adapted an ancestral ability for reading emotional cues in other horses to respond appropriately to human facial expressions during their co-evolution. Alternatively, individual horses may have learned to interpret human expressions during their own lifetime.”

Part of what makes this finding so unusual, McComb added, is the fact that a horse’s facial structure and expressions are so different from a human’s. Smith agreed: "What's really interesting about this research is that it shows that horses have the ability to read emotions across the species barrier. We have known for a long time that horses are a socially sophisticated species but this is the first time we have seen that they can distinguish between positive and negative human facial expressions."

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Animals
Pigeons Are Secretly Brilliant Birds That Understand Space and Time, Study Finds
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Of all the birds in the world, the pigeon draws the most ire. Despite their reputation as brainless “rats with wings,” though, they’re actually pretty brilliant (and beautiful) animals. A new study adds more evidence that the family of birds known as pigeons are some of the smartest birds around, as Quartz alerts us.

In addition to being able to distinguish English vocabulary from nonsense words, spot cancer, and tell a Monet from a Picasso, pigeons can understand abstract concepts like space and time, according to the new study published in Current Biology. Their brains just do it in a slightly different way than humans’ do.

Researchers at the University of Iowa set up an experiment where they showed pigeons a computer screen featuring a static horizontal line. The birds were supposed to evaluate the length of the line (either 6 centimeters or 24 centimeters) or the amount of time they saw it (either 2 or 8 seconds). The birds perceived "the longer lines to have longer duration, and lines longer in duration to also be longer in length," according to a press release. This suggests that the concepts are processed in the same region of the brain—as they are in the brains of humans and other primates.

But that abstract thinking doesn’t occur in the same way in bird brains as it does in ours. In humans, perceiving space and time is linked to a region of the brain called the parietal cortex, which the pigeon brains lack entirely. So their brains have to have some other way of processing the concepts.

The study didn’t determine how, exactly, pigeons achieve this cognitive feat, but it’s clear that some other aspect of the central nervous system must be controlling it. That also opens up the possibility that other non-mammal animals can perceive space and time, too, expanding how we think of other animals’ cognitive capabilities.

[h/t Quartz]

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Squirrels Are Probably More Organized Than You, Study Finds
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Despite having a brain that's slightly bigger than the size of a peanut M&M, squirrels have a fascinating, razor-sharp instinct when it comes to survival. They know that acorns that are high in fat and sprout late are perfect for long-term storage, so they salvage them for winter and eat the less nutritionally dense white-oak acorns right away. They also tend to remember where they put their acorn stash rather than relying solely on smell. Like nature's perfect stunt performer, they can even fall out of trees in a way that minimizes physical damage. Now, researchers at the University of California, Berkeley have unveiled a newly discovered part of a squirrel's hoarding strategy, Atlas Obscura reports.

The researchers tracked 45 wild fox squirrels on the UC-Berkeley campus for nearly two years. They made available to the squirrels four different types of nuts—walnuts, pecans, almonds, and hazelnuts. Sometimes the animals were given a single type of nut, and other times the nuts were mixed. Either way, the squirrels promptly sorted and stored their food according to type—walnuts went in one hiding place, almonds in another, and so on.

This type of behavior is known as "chunking" and makes it easier to retrieve data in memory. In doing this, a squirrel won't have to visit several different places looking for pecans: They know just where the main supply is. Squirrels can stockpile up to 10,000 nuts a year, so it's essential for them to know which type of nut is where.

The study, published in Royal Society Open Science, also indicated that squirrels seem to understand nuts have weight, choosing to carry heavier acquisitions to a different location than lighter nuts.

Squirrels being squirrels, they were happy to be gifted an assortment of nuts during the experiment, but there was one wrinkle: Rather than stash them away, sometimes they'd just eat them on the spot.

[h/t Atlas Obscura]

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