Dodos Were Probably Pretty Smart, Study Finds

Because the dodo went extinct less than a century after humans first arrived on its native island of Mauritius, our knowledge of the large flightless bird is limited and comes almost exclusively from drawings and descriptions by sailors who saw it in the 17th century. Dodos had no instinctual fear of humans, who eventually hunted them into extinction, so they got a reputation for being dumb—the very embodiment of a creature destined for obsolescence.

But a new study suggests that the dodo was, in reality, fairly intelligent. Though collecting natural history specimens was not a popular pastime in the age of the dodo, scientists at the American Museum of Natural History and the Natural History Museum of Denmark managed to get ahold of one of the rare preserved dodo specimens—a skull housed in the collections of London’s Natural History Museum.

After scanning the skull, lead researcher Eugenia Gold created virtual endocasts—casts of the interior cavity of the skull showing impressions left by the brain. With these 3D models, she and her team were able to compare the dodo’s brain to those of several varieties of pigeons (the dodo’s closest living relative) and an extinct island bird known as the Rodrigues solitaire (its closest dead one). As they report in an article in the Zoological Journal of the Linnean Society, the dodo's brain was quite normal relative to its body size, indicating the bird wasn't particularly dim-witted.

Virtual endocasts of the dodo's brain

“It’s not impressively large or impressively small—it’s exactly the size you would predict it to be for its body size,” Gold explains in an AMNH press release. “So if you take brain size as a proxy for intelligence, dodos probably had a similar intelligence level to pigeons. There’s more to intelligence than just overall brain size, but this gives us a basic measure.” But if they were anything like pigeons, dodos were probably pretty clever. Though they’re more often thought of as urban pests, pigeons are able to distinguish between live and pre-recorded videos of themselves, and have been trained to serve as spies, couriers, and even cancer spotters

All images courtesy the American Museum of Natural History

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Jana Mueller
Ravens Can Figure Out When Someone Is Spying on Them
Jana Mueller
Jana Mueller

Corvids, the family of birds that includes crows and ravens, are canny beasts. They've been known to exercise self-control, count, hold grudges, and more. Now, new research suggests they possess at least a rudimentary Theory of Mind—the ability to attribute mental states to others.

A study in Nature finds that ravens can tell when someone else can see them, guarding their food when a peephole to their cache is open. While previous research suggested that birds might have an awareness of other animals' mental states, the results have been inconclusive. The Nature study is evidence that corvids can do more than just track other birds' gaze; they may understand the concept of "seeing."

Vienna-based researchers set up two rooms separated by windows that could be closed with covers. These covers had peepholes in them that could also be opened or closed. First, the 10 ravens were each allowed to cache food, while other birds were in the next room and the windows were open or closed. Then, they were trained to look through the peepholes to find food in the other room, so that they knew that the holes could be used to see through the window covers. Afterwards, each of the ravens was again presented with food with one of the two peepholes open. The adjacent observation room didn't have any birds in it, but the researchers played the sounds of another raven recorded during one of the previous trials.

When the birds heard the sounds of another raven in the next room, and the peephole was open, the birds behaved as if they knew they were being watched—they hid their cache of food quickly and didn't add more food to it as often, as if they knew that it might be compromised. However, they behaved normally when the peephole was closed.

This suggests that ravens don't just track their competitors' gaze to know when they’re being watched, but can infer from past experience when they can be seen.

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iStock
Why Do Dogs Crouch Forward When They’re Playing?
iStock
iStock

Whether they're tilting their heads or exposing their bellies for rubs, dogs are experts at looking adorable. But these behaviors do more than elicit squeals from delighted humans; in many cases, they serve important evolutionary functions. A prime example is the "play bow": If you've ever seen a dog crouch forward with its elbows on the ground and its rear end in the air, wagging tail and all, then you know what it is. The position is the ultimate sign of playfulness, which is important for a species that often uses playtime as practice for attacking prey.

The play bow first evolved in canids as a form of communication. When a dog sees another dog it wants to play with, it extends its front paws forward and lifts up its behind as a visual invitation to engage in a friendly play session. Dogs will "bow" in the middle of playtime to show that they're having fun and wish to continue, or when a session has paused to signal they want to pick it back up. Play bows can also be a sort of apology: When the roughhousing gets too rough, a bow says, “I’m sorry I hurt you. Can we keep playing?”

Play between canines often mimics aggression, and starting off in a submissive position is a way for all participating parties to make sure they’re on the same page. It’s easy to see why such a cue would be useful; the more puzzling matter for researchers is why the ancestors of modern dogs evolved to play in the first place. One theory is that play is crucial to the social, cognitive, and physical development of puppies [PDF]. It’s an opportunity for them to interact with their own kind and learn important behaviors, like how to moderate the strength of their bites. Play also requires the animals to react quickly to new circumstances and assess complex actions from other dogs.

Shiba inus playing outside.
Taro the Shiba Inu, Flickr // CC BY 2.0

Another evolutionary explanation is that playtime prepares puppies for the hunting they do later as adults. Watch two puppies play and you’ll see them stalking, biting, and pouncing on one another—all behaviors canines exhibit in the wild when taking down prey.

Of course, it’s also possible that dogs simply play because it’s fun. This is a strong case for why pet dogs continue to play into adulthood. “Devoting a lot of time to play may be less advantageous for a wild species who spends much of its time hunting or foraging for food, searching for mates, or avoiding predators,” Dr. Emma Grigg, an animal behaviorist and co-author of The Science Behind a Happy Dog, tells Mental Floss. “Many domestic dogs are provisioned by humans, and so have more time and energy to devote to play as adults.”

Because play is a lifelong activity for domestic dogs, owners of dogs of all ages have likely seen the play bow in person. Wild canids, like wolves, foxes, and coyotes, tend to reserve this behavior for members of their own species, but pet dogs often break out the bow for their humans—or anyone else who looks like they might be up for a play session. Grigg says, “One of my dogs regularly play bows to her favorite of our cats.”

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