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Alastair Rae via Wikimedia Commons // CC BY-SA 2.0

Why Are Some Birds So Smart? Their Brains Are Neurally Dense

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Alastair Rae via Wikimedia Commons // CC BY-SA 2.0

Little by little, the well-established myth of the stupid bird is crumbling. Just a few months ago, researchers reported that some birds are as smart as apes. Now another team of scientists say that bird brains pack way more brain cells per square inch than those of primates and other mammals. They published their findings in the Proceedings of the National Academy of Sciences.

The brains of humans and apes include a structure called the neocortex, which houses some of our most sophisticated thought processes and mental tasks. Birds don’t have neocortices at all, and so for years, scientists assumed that meant they were unintelligent. As it turns out, we were just being self-centered. Birds don’t need neocortices; a similar structure called a pallium does their mental heavy lifting.

One bird stereotype is accurate: Compared to, say, a human or a chimpanzee, birds do have little brains. Yet “corvids and some parrots are capable of cognitive feats comparable to those of great apes,” the authors write. “How do birds achieve impressive cognitive prowess with walnut-sized brains?”

To find out, the researchers examined the brains of 28 different bird species, from tiny zebra finches to towering emus. They examined the birds’ brain tissue at a cellular level, measuring the number and distribution of neurons in each region. They compared the neural density to that found in the brains of mice, rats, primates, and artiodactyls (even-toed ungulates).

As it turns out, when it comes to brain cell density, birds have them all beat. The pallium was crammed wall-to-wall with brain cells. Parrot and songbird brains contained twice as many neurons as similar-sized primate brains, and two to four times as many neurons as those of rodents. Birds also dedicate way more brainpower to their pallia than we do to our neocortices. The pallium houses 33 to 55 percent of a songbird’s brain cells, and 46 to 61 percent of a parrot’s. By comparison, the human neocortex hosts only 19 percent of our brain cells.

Senior author Suzana Herculano-Houzel, a neuroscientist at Vanderbilt University, said in a press statement: “In designing brains, nature has two parameters it can play with: the size and number of neurons and the distribution of neurons across different brain centers, and in birds we find that nature has used both of them.”

These findings open a new pathway in understanding how brains evolve. Generally speaking, in order to advance, brains have had to get bigger, and bigger brains are linked to more cognitive capacity. But, Herculano-Houzel said, “bird brains show that there are other ways to add neurons: keep most neurons small and locally connected and only allow a small percentage to grow large enough to make the longer connections."

But no evolutionary advantage is truly free. Does a denser bird brain require more energy to run than ours, which are spacious by comparison? If so, where is that energy coming from?

“Something I love about science is that when you answer one question, it raises a number of new questions,” said Herculano-Houzel.

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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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10 Amazing Facts About Our Bond With Dogs
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They’ve been our companions for tens of thousands of years. They share our beds, follow us into the bathroom, and star in our holiday cards. The beautiful friendship between Homo sapiens and Canis lupus familiaris has had some surprising effects on both species—read on to learn more about the ways we’ve helped each other along the way.


Living with furry friends, especially dogs, has been shown to decrease babies’ and kids’ risk for asthma, allergies, and other immune conditions. Some studies have found that the benefits can begin as early as the womb. Scientists aren’t completely sure why this happens; it may be that bacteria on the dogs’ bodies can help give our immune systems a boost during a crucial moment in our development.


Keeping your phone loaded with pictures of your pet may pay off in the long run. In one 2012 experiment, people who looked at pictures of puppies scored higher on tasks that required their close attention. Photos of older dogs were less effective; the researchers say it might be that baby animals inspire a specific type of positive emotion and mental activation.


Dogs are social animals; that’s part of the reason we were able to tame them in the first place. And once we take them in, they really start to care what we think. Experiments with dogs and their owners have shown that when given the choice between snacks and praise, most prefer being told what good dogs they are.


Sharing your life with a drooling, adoring furry friend is good for your attitude and your stress levels. Spending time with dogs can ease tension and stress. Studies have found that this is especially true in high-stress situations like crises, natural disasters, and the office.


Reduced stress is its own reward, but it can also have long-term health benefits, including lower blood pressure, lowered heart rate, and a decreased risk of heart disease. This works even in little doses: just petting a dog for a few minutes sends feel-good chemicals to the brain and can soothe a frazzled nervous system.


All those millennia together have made a real impression on dogs’ brains. One 2016 study found that dogs could read and respond to the emotions on human faces, even in photographs. This is especially cool when you consider the major differences in body language between our two species. Dogs don’t smile, but they still know what our grin means when they see it.


There’s nothing like an “I’ve-got-to-pee-RIGHT-NOW” bark to get you up and out the door. For obvious reasons, dog owners get more casual exercise than other people. This, in turn, can also lower stress levels and improve heart health.


Spoken language, like body language, differs drastically between our two species, but that hasn’t stopped dogs from trying to figure ours out. A series of Hungarian experiments using MRI scanners found that dogs’ brains responded to human voices speaking both positive words and with positive tone. This was true even when the positive words were spoken in a neutral tone (“good boy”) and the positive tone was applied to a neutral phrase (“however!!!”). They get us.


The good news for dogs is that domestication has given them a steady source of food, shelter, and companionship. The bad news is that all this cushy living has dulled their edges somewhat. Compared to the wolves from which they descended, pet dogs have weaker senses of hearing and smell, and they’re worse at problem-solving tasks. But this isn’t a problem, per se; they’ve simply evolved and been bred to prioritize one set of survival skills (coexisting with people) over another (sharp senses and keen minds).


The bond between us and our dogs is real, and may trace all the way down into dogs’ DNA. Experiments have found that the most sociable pet dogs have genetic mutations that appear to make them more interested in people. Without these abnormalities, experts say, we might never have been able to domesticate dogs in the first place.

Dogs make our lives a whole lot happier and healthier. (You can’t argue with science!) Looking to return the favor? Consider a monthly subscription to BarkBox. Your favorite pup will get a package filled with treats, toys, and other goodies. Visit BarkBox to learn more.