When it comes to picking up clever tricks and learning to do something the way everybody else does it, social animals like humans, birds, and monkeys excel. One individual looks at what others in the group are doing and quickly learns to follow suit—an invaluable skill that scientists previously thought evolved in step with communal living.
But what about an individual that doesn’t live in a group and spends most of its life in solitude–would it still have that ability to watch and learn? Cognitive biologist Anna Wilkinson set out to answer that question by studying the red-footed tortoise, one of the loneliest beasts on the planet. These South American tortoises grow up without parents or siblings, and adults rarely cross paths. If a head-bobbing display determines that a stranger is of the opposite sex, the two will mate perfunctorily–otherwise they just ignore each other [ScienceNOW]. Yet in a new study published in Biology Letters, Wilkinson showed that even these hermits possess the ability to learn by watching others.
When vervet monkeys play follow the leader, they prefer to follow a female. That was the conclusion of Erica van de Waal, whose lengthy study of these primates in South Africa will be published this week in the Proceedings of the Royal Society B. When her team presented them with a tricky contraption they had to open to reach a tasty snack, the monkeys learned better if they watched a female from their group demonstrate the solution rather than a male.
Seeking some answers to how social learning works in monkeys, van de Waal and her colleagues headed to Loskop Dam Nature Reserve. It took four months, they say, just to acclimate the wild animals to the presence of humans. Once the monkeys were comfortable having scientists around, Van de Waal gave each group a wooden box containing a slice of apple. To get to the apple, the monkeys had to either pull open the door at one end or slide aside a door at the other. Half the box was painted black to differentiate the two ends [ScienceNOW].
Here’s a neat dolphin trick that doesn’t involve jumping through hoops. While dolphins sleep overnight (with half their brains and one eye at a time), they begin to show signs of the kind of insulin resistance that marks type 2 diabetes in humans. But when they wake up and have their breakfast, they switch back to their normal state. A research team led by Stephanie Venn-Watson announced the findings at the American Association for the Advancement of Science meeting in San Diego, and said that dolphins’ apparent ability to switch insulin resistance on and off could lead to better understanding of the disease in humans.
Insulin helps people control their levels of blood sugar, and the resistance to it inherent in type 2 diabetes means those levels can get way too high. The dolphins, though, switch on this temporary insulin resistance to their advantage, boosting blood sugar levels overnight. “Bottlenose dolphins have large brains that need sugar,” Dr Venn-Watson explained. Since their diet is very low in sugar, “it works to their advantage to have a condition that keeps blood sugar in the body… to keep the brain well fed” [BBC News].
It may not come as much of a surprise to dog-owners, but it seems that dogs and babies share similar logical abilities, as shown by a study published in Science.
Experimenters started out with a classic logic experiment, which goes like this: researchers hide a toy in location “A” multiple times while looking at a 10-month-old baby and talking to him (“Look, I have this nice ball!”). When asked to find the toy, the baby always goes to location “A.” The experimenter then hides the toy at location “B,” again while interacting with the baby. But this time, when asked to find the toy, the baby continues to search for it at location “A.” The findings hold, even when a team changes experimenters midtest. Researchers believe that infants make this error because they believe the adults have taught them something fundamental about the world (i.e., “Your toy will always be at location ‘A’”) [ScienceNow].
Pigeons alert their flockmates to impending danger not through vocalization, but by making a whistling sound with their wings as they take off in response to a threat, according to a study published in the journal Proceedings of the Royal Society B. Researchers say other birds may also have co-opted the basic mechanical sounds of flight for communication purposes.
Biologists were curious about how all the pigeons in a huge flock knew to launch themselves into the air at the same moment. Because the birds don’t use vocal calls to alert their peers, scientists hypothesized they convey the message using their wings. Researchers first recorded the sounds made by crested pigeons flying happily around a feeder, then sent in a decoy of a hawk, and recorded their flight from the faux predator. When the researchers later played the sound back for a flock of birds, they didn’t so much as twitch at the normal recording. But the rapid clap-clap-clap of the alarmed bird sent them fleeing. Similarly, when the volume or speed of the recording was manipulated, birds only reacted to emergency wing whistles [Discovery News]. Although it’s not yet known exactly how the birds make these sounds, the study’s results could do more than increase our understanding of bird communication. They could also help repel the pesky birds from places where they are annoying or even harmful, like public parks and airports.
Male Brazilian free-tailed bats sing intricate songs to attract females and deter other males using a set syllabic order and syntax, according to a study published in the journal PLoS One. The bats can even add their own creative touches to the croonings.
By examining 400 songs produced by 33 free-tailed bats, researchers found that all the bats produce songs with a common hierarchical structure. “All are constructed from the same four types of syllables and all syllables are combined in the same way to form three types of phrases,” says [lead author Kirsten] Bohn. These phrases can be either chirps, trills or buzzes [BBC News], and the complexity of the songs rival those only of birds and whales, leaving those produced by mice in the dust. The bats may vary their songs to appeal more to females or to convey different sentiments. “Within the broad rules, the bats are quite versatile” [BBC News], Bohn says.
In the first experiment linking cognitive ability to reproductive success, researchers found that the male bowerbirds with the best problem-solving capabilities also mated the most often, according to a study published in the journal Animal Behaviour.
The Australian bowerbird is known for its elaborate courtship behavior. During breeding season, males build a special platform, or bower, on the forest floor to lure females, and they decorate it with rare objects such as blue feathers and shiny bits of glass. They accompany this with varied vocalizations, hopping, and tail-bobbing [ScienceNOW Daily News]. To evaluate which males had the best problem-solving abilities, scientists placed a red object in the birds’ bowers–a color the birds disdain. In one experiment, three red objects were placed in the bower and covered by clear plastic that the bird had to take off in order to remove the noxious items. In the next, the red object was securely nailed to the nest, so the only way to make it less visible was to cover it with leaves and twigs.
A quartet of clever rooks have provided evidence that one of Aesop’s fables could have a basis in fact. The tale in question tells the story of a thirsty crow. The bird comes across a pitcher with the water level too low for him to reach. The crow raises the water level by dropping stones into the pitcher. (Moral: Little by little does the trick, or in other retellings, necessity is the mother of invention) [AP]. In the new lab experiment, four rooks each dropped stones into a clear plastic tube, which raised the water level high enough to bring a floating worm within reach.
Rooks and crows are both in the corvid family, which researchers say rivals the great ape family for intelligence and tool use–the only other animal that has performed a comparable task was an orangutan, who spat into a tube to gain a floating peanut. Says study coauthor Nathan Emery: “We have performed a large number of studies on both corvids … and apes, and have found that the crow’s performance is on a par or often superior to apes. However, it is not particularly useful to say that one species is more or less intelligent than another because often the playing fields aren’t even” [The Independent].
Using the first known animal instruments, orangutans use leaves to make their voices sound deeper, perhaps thereby tricking predators into thinking the apes are bigger than they really are, according to a study published in the journal Proceedings of the Royal Society B.
Orangutans produce a noise known as “kiss squeaks” to let predators like snakes and leopards know that they’ve been spotted, and can use their lips and fingers or folded leaves to make the sound. To find out more about why the animals produce the noise, researchers recorded kiss squeaks between 2003 and 2005 near a research station … on the island of Borneo. The team noted whether the sounds had been made with hands, leaves, or lips alone [National Geographic News]. They found that squeaks made using only the lips had a higher pitch than those produced using hands, and that leaf-produced pitches had the lowest frequency and therefore the deepest sound.
Cotton-top tamarin monkeys can distinguish between “right” and “wrong” grammatical patterns, according to a study published in the journal Biology Letters. The findings suggest that humans share the ability with other species to identify certain patterns that are crucial to spoken communication.
Researchers wanted to find out if the monkeys, which do not communicate using spoken language, could recognize grammatical sequences. To do this, the scientists familiarized the monkeys with a series of sounds and patterns. They did this by first playing recordings of humans saying two-syllable nonsense words, and familiarized the monkeys with either a prefix or a suffix. “In the prefixation condition, they heard ‘shoy-bi’, ‘shoy-la’, ‘shoy-ro’ and so on,” explained Ansgar Endress, lead author of the study. “The idea is that they get used to the pattern if you play it long enough” [BBC News].
The next day the scientists played new words for the prefix monkeys, but this time included some words in which the prefix had been changed to a suffix, like “na-shoy.” (They did the reverse for the suffix monkeys.) The scientists hypothesized that when the monkeys heard this “incorrect” sequence of sounds, they would be more likely to look at the loudspeakers from which the sounds were coming, the same way a human would. For example, if a person said he or she “walked to the store,” and then [used] the word “edwalk” instead of “walked,” the listener, used to hearing “walked” might stare at the speaker as if to say, “Huh?” [Discovery News].
Many animals depend on stealth to catch prey, but a small tentacled water snake resorts to downright trickery. That’s what a Vanderbilt University scientist found when he analyzed the way the snake captures fish, according to a study published in the Proceedings of the National Academy of Sciences.
The snake, which is native to Southeast Asia, takes advantage of a well-known reflex that fish possess. The mechanism occurs when a fish’s ear senses changes in water pressure due to movement nearby, which is all it takes to initiate the fish’s escape response, called the C-start — one of the most well studied neural circuits in vertebrates. Two large nerve cells, known as Mauthner cells, run along either side of the fish’s body and detect water disturbances. The cell closest to the signal will fire action potentials that stimulate trunk muscles on the opposite side of the body while simultaneously inhibiting the muscles on the near side. As a result, the fish turns away from the disturbance and flees. This whole process takes less than a tenth of a second [The Scientist]. The reflex causes the fish’s body to form a “C” as it turns away from the source of the underwater vibration—but in this case, that leads the fish right into the snake’s jaws.
To get inside the head of a homing pigeon as it navigates towards its roost, researchers turned a flock of pigeons into cutting-edge techno-birds. The scientists outfitted the birds with “neurologgers” consisting of an electroencephalograph (EEG) to read the bird’s brain waves and a GPS tracker to record its location; by matching a bird’s position to its brain activity, the researchers could determine the bird’s reaction to the landscape below it. They found that, just like humans, the pigeons use visual landmarks in their navigation.
How homing pigeons find their way back to a starting point is not completely known. Studies have shown that the birds variously use the position of the Sun and the Earth’s magnetic field as a compass, and sense of smell and visual cues as navigation aids. But the use of visual cues has been difficult to study, because if a bird flies over a landmark and doesn’t change its course, it’s impossible to know whether the bird has not perceived the cue or is ignoring it [The New York Times].
A tiny fish common in European streams may learn in a more sophisticated way than has ever been recorded among animals and which mimics human learning. In a study published in the journal Behavioral Ecology, scientists found that the nine-spined stickleback fish used the success and failures of their peers to gauge where they should seek food.
The fish were shown to display a type of learning known as “hill-climbing,” in which an entity continually looks for a better solution to a problem; in this case, one fish copied others that were more successful in finding food. Researchers caught 270 nine-spined sticklebacks in Leicester, England. The fish were organized into experimental groups. These fish groups then took turns as either free swimmers in a tank with worm-yielding feeders at the end, or as “learners” in a transparent, partitioned-off area of the specially designed tank. One of the two feeders released more worms than the other [Discovery News].
The first group of free-swimming fish quickly learned which feeder was full of worms, and were then put into the observers’ chamber. Next, researchers switched which feeder held the worms, and the fish in the observation tank watched the next fish group identify the new worm-filled feeder. After switching the two groups of fish again, the original group made a beeline for the feeder full of worms that their peers had fed from.
Scientists have long been impressed with bats’ echolocation calls, the brief bursts of sound that bounce off surrounding objects and allow the bats to navigate in the dark. But now researchers have found a new level of sophistication in those cries. A new study of greater mouse-eared bats proves that bats can distinguish between the calls of different individual bats. Researchers say this could explain how they remain in a group when flying at high speeds in darkness, and how they avoid interference with one another’s echo-location calls [The Guardian].
In the study, published in the journal PLoS Computational Biology, lead researcher Yossi Yovel played the recordings of bat cries back to his test subjects. “Each bat was assigned two others it had to distinguish between,” Dr Yovel explained. “So we trained bat A on a platform, playing a sound from bat B on one side and from bat C on the other. He had crawl to where the ‘correct’ sound was coming from” [BBC News]. For a correct answer, the bat was rewarded with a mealworm.
When a banana is at stake, a low-status capuchin monkey may deceive the other monkeys in his troupe in order to get his hands on that tasty fruit. A new study of monkeys in an Argentinian national park found evidence that lowly monkeys give spurious alarm calls in order to scare off more dominant monkeys competing for food.
Tufted capuchin monkeys give a two-syllable “hiccup” call when they detect danger, like an approaching ocelot. Lead researcher Brandon Wheeler was studying a group of capuchins eating food left on platforms constructed in trees, when he noticed some of the monkeys made the calls when predators weren’t around. “They were giving the same calls that they give for cats extremely frequently,” he says. “When they do, other individuals often run out off the platform, which potentially leaves [the platform] available for whoever called to jump in to get some food” [ScienceNOW Daily News].
80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles on the day's most compelling topics.
80beats is written by Veronique Greenwood and Valerie Ross. This team darts through each day's science news faster than the ruby-throated hummingbird that beats its wings 80 times per second. Send ideas, tips, suggestions, and complaints to [azeeberg at discovermagazine dot com].
When it comes to picking up clever tricks and learning to do something the way everybody else does it, social animals like humans, birds, and monkeys excel. One individual looks at what others in the group are doing and quickly learns to follow suit—an invaluable skill that scientists previously thought evolved in step with communal living.
When vervet monkeys play follow the leader, they prefer to follow a female. That was the conclusion of Erica van de Waal, whose lengthy 
Here’s a neat dolphin trick that doesn’t involve jumping through hoops. While dolphins sleep overnight (with 
It may not come as much of a surprise to dog-owners, but it seems that dogs and babies share similar logical abilities, as shown by a 
In the first experiment linking 
Using the first known animal instruments, 
Cotton-top tamarin monkeys can distinguish between “right” and “wrong” grammatical patterns, according to a 
To get inside the head of a homing pigeon as it navigates towards its roost, researchers turned a flock of pigeons into cutting-edge techno-birds. The scientists outfitted the 
A tiny 
Scientists have long been impressed with bats’ echolocation calls, the brief bursts of sound that bounce off surrounding objects and allow the 
When a banana is at stake, a low-status capuchin 
