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

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

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

nextArticle.image_alt|e
iStock
arrow
Animals
Pigeons Are Secretly Brilliant Birds That Understand Space and Time, Study Finds
iStock
iStock

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]

nextArticle.image_alt|e
iStock
arrow
Animals
Squirrels Are Probably More Organized Than You, Study Finds
iStock
iStock

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]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios