Before they can talk, babies use gestures to communicate: sentiments such as “take this away,” “look over there,” and “put me down” can be made abundantly clear without words. Chimps gesture to each other, as well, pointing out particular spots where they’d like to be scratched or groomed. These symbolic gestures are believed to be an important precursor to language. Now, researchers have observed ravens using gestures in the wild—the only non-primates seen doing so.
Posts Tagged ‘animal behavior’
Ravens Appear to Communicate Using Gestures–A First for Non-Primates
Supergene Allows Butterflies to Copy the Wings of Their Toxic Neighbors
Heliconius numata (top) mimics the wing
pattern of Melinaea mneme (bottom).
What’s the News: A single species of butterfly in the Amazon is able to copy the wing patterns of several neighboring species to avoid being eaten by hungry birds—a wide-ranging talent that has long perplexed evolutionary biologists. Now, an international team of scientists studying the mimicking butterfly Heliconius numata has finally solved this puzzle that plagued even Charles Darwin.
Writing in the journal Nature, researchers found that a specific supergene—a cluster of genes that is passed on to offspring as one big chunk—controls the different elements of wing patterns, allowing related butterflies to display distinct markings despite having the same DNA. “These butterflies are the ‘transformers’ of the insect world,” lead researcher Mathieu Joron said in a prepared statement. “But instead of being able to turn from a car into a robot with the flick of switch, a single genetic switch allows these insects to morph into several different mimetic forms.”
Small, Sneaky Squid Produce Big Sperm
What’s the News: In the squid world, the body size of male spear squid determines the mating strategies they use. Small male squid, which have no chance of physically competing with their larger rivals, must try to get with the females of the species on the sly. Now, researchers in Tokyo have learned that this difference in mating behavior has resulted in the evolution of divergent sperm types, though perhaps not in the way you’d think: diminutive male squid actually produce larger sperm than big male squid.
Bullied Boobies Grow Up to Become Bullies Themselves
Researchers at Wake Forest University in North Carolina have now learned that Nazca boobies perpetuate a “cycle of violence”: bullied chicks tend to become bullies and pass on the pain. When parent birds leave their nests to eat, baby boobies are often visited by sexually and physically abusive non-breeding adults; the chicks, when grown, are more likely to abuse unrelated chicks. “The link we found indicates that nestling experience, and not genetics, influences adult behaviour,” lead researcher David Anderson told BBC.
Fish Join the List of Tool-Using Animals (Probably)
In Australia’s Great Barrier Reef, a professional diver has photographed a blackspot turkfish smashing a clam against a rock to get the tasty treat on the inside—this appears to be the first documented case of a fish using a tool. But some people argue that this behavior, which is similar to a seagull cracking open a shell by dropping it onto a hard surface, does not constitute tool use because the “tool” is fixed and the animal never actually holds it.
See a nice round-up video of the news and the tool-use debate at HuffPost.
Image: Scott Gardner/Coral Reefs, DOI:10.1007/s00338-011-0790-y
Grudge-Holding Crows Pass on Their Anger to Family and Friends
What’s the News: A few years ago scientists learned that American crows can recognize and remember human faces, particularly faces they associate with bad experiences. Now, new research published in the Proceedings of the Royal Society B shows that the birds can share that knowledge of dangerous humans with other crows.
Pheromone in Squid Eggs Transforms Males Into Furious Fighters
Yesterday we reported on a new study that showed shining a laser on certain neurons in mice brains could make them angry and aggressive. But with squid, you don’t need a laser to make the males get mean. All you need is to expose them to a particular chemical. From DISCOVER blogger Ed Yong:
In a flash, schools of male longfin squid can turn from peaceful gatherings to violent mobs. One minute, individuals are swimming together in peace; the next, they’re attacking one another. The males give chase, ramming each other in the sides and grappling with their tentacles.
These sudden bouts of violence are the doing of the female squid. Males are attracted to the sight of eggs, and females lace the eggs with a chemical that transforms the males into aggressive brutes.
For plenty more about how this chemical whips the males into an angry frenzy—and why—check out the rest of Ed’s post at Not Exactly Rocket Science.
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Proved by Science: Sleepy Bees Are Sloppy Dancers
Honeybees usually get about eight hours of sleep a night (lucky things!), but what happens when evil researchers keep them up all night?
The first study of sleep in bees, published this week in the Proceedings of the National Academy of Sciences, found that the tired bees lag just like sleep-deprived humans do. Too bad bees don’t have coffee. Says lead researcher Barrett Klein:
“When deprived of sleep, humans typically experience a diminished ability to perform a variety of tasks, including communicating as clearly or as precisely. We found that sleep-deprived honey bees also experienced communication problems. They advertised the direction to a food site less precisely to their fellow bees.” [Daily Mail]
So how do you keep bees awake when they don’t need to cram for a calculus final? You make them magnetic. Klein attached a piece of either steel or non-magnetic metal to the bees’ backs. Then all through the night, the researchers swung a magnet over the hive three times a minute–a device they call the “insominator.” This jostled the bees with the magnetic steel on their backs and kept them from sleeping.
Picked-On Marmots May Inherit Their Low Social Position
In the rigid social universe of Revenge of the Nerds-style 1980s movies, jocks beget jocks beget jocks, and the bespectacled geeks they push around beget generations of the same. But could being a victim of social bullying actually be inherited? A new study of DISCOVER’s favorite rodent, the marmot, shows that at least in the animal kingdom, the answer can be yes.
Daniel Blumstein and colleagues tracked yellow-bellied marmots that make their home in the Colorado Rockies for a five year period, from 2003 to 2008. For their study out in the Proceedings of the National Academy of Sciences, the team tracked the family relationships of the individual marmots, as well as who antagonized whom.
Marmots don’t have Facebook yet, but animals living among clusters of burrows in Colorado do interact enough for observers to plot networks with each marmot as a node. An exchange might be friendly, such as a marmot grooming a neighbor or settling down tranquilly nearby. Or a social interaction might go sour, with one marmot nipping or chasing another. “Marmots are grumpy with each other,” Blumstein says, but rarely cause serious injuries. [Science News]
Study: A “Pessimistic” Dog Is More Likely to Destroy Your Slippers
Doggie separation anxiety–the whining, scratching, and general misbehaving that happens when some dogs are left home alone–is somehow linked to the dog’s general outlook on life, new research says. Coauthor Emily Blackwell explains that she wondered whether the behavior she’d observed during high school in her own anxiety-prone dog was normal.
“So many people think [separation-related behavior] is just something dogs do.” … They think the dog is angry the owner is leaving, say, and exacting its revenge on the owner’s slippers. [ScienceNOW].
For the study, published in Current Biology, the team investigated the link between this separation anxiety trait and a pessimistic attitude. To test pessimism, 24 dogs were trained to associate a full food bowl with one side of a room and an empty bowl with the opposite side.
The dogs learn quickly “if it’s on one side, to race over and nearly knock over the screen to get it,” says Blackwell. “If it’s on the other side, they look around and quite often give us a big sigh.” Some dogs amble over to check out the empty bowl; others just lie down. [ScienceNOW]
Mirror, Mirror: Study Says Monkeys May Recognize Their Own Images
Luis Populin never meant to study whether monkeys recognize themselves in the mirror. As DISCOVER blogger Carl Zimmer notes at the Loom, Populin’s team was working on a different project that required putting mirrors in monkey cages to stimulate their brains. Quite by accident, he noticed that monkeys with electrodes attached by the researchers spent an awful long time gawking at themselves in the mirrors.
The researchers published their findings this week in PLoS One, in which they write:
We hypothesize that the head implant, a most salient mark, prompted the monkeys to overcome gaze aversion inhibition or lack of interest in order to look and examine themselves in front of the mirror. The results of this study demonstrate that rhesus monkeys do recognize themselves in the mirror and, therefore, have some form of self-awareness.
For a video of a monkey checking itself out in the mirror, as well as much more detail about the study, its implications, and other primatologists’ doubts about it, check out Zimmer’s post.
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Image: Populin et. al.
New Caledonian Crows—the Bird Geniuses—Blow Our Minds Again
In New Caledonia, an island off the eastern coast of Australia, a crow is hunting for beetle grubs. The larvae are hidden within a decaying tree trunk, which might seem like an impregnable fortress. But the New Caledonian crow is smarter than the average bird. It uses a stick to probe the tunnels where the grubs are sheltered. The grubs bite at intruders with powerful jaws but here, that defensive reflex seals their fate; when they latch onto the stick, the crow pulls them out.
This technique is not easy. Birds need a lot of practice to pull it off and even veterans can spend a lot of time fishing out a single grub. The insects are fat, juicy and nutritious but do they really warrant the energy spent on extracting them? The answer is a resounding yes.
Check out the rest of this post, including video of the crows at work, at Not Exactly Rocket Science. (The video above, of the birds making hooks, is from a different study a few years ago.)
And for plenty more about bird geniuses, be sure to read the DISCOVER feature “Who You Callin’ Bird Brain?” It includes more avian smarts, such as hiding food underground and going back later to move it, just in case other birds were watching the first time and thought about stealing a meal.
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4 Messages a Pantomiming Orangutan Might Be Trying to Convey
Stop patting yourself on the back. You’re not so special. Orangutans, a new study suggests, also use complex gestures or pantomimes to communicate.
Looking through twenty years worth of orangutan observations, researchers believe they have found 18 examples of pantomimes. The study, which appeared today in Biology Letters, supports the claim that we’re not unique when it comes to abstract communication and lends credence to other observations of great ape gesturing, according to lead researcher Anne Russon.
[Orangutans and chimpanzees were already known] to throw an object when angry, for example. But that is a far cry from displaying actions that are intentionally symbolic and referential–the behaviour known as pantomiming. “Pantomime is considered uniquely human,” says Anne Russon from York University in Toronto, Canada. “It is based on imitation, recreating behaviours you have seen somewhere else, which can be considered complex and beyond the grasp of most non-human species.” [New Scientist]
Of the eighteen observed orangutan pantomimes, four took place between orangutans and 14 between a human and an orangutan. If you ever find yourself in the Indonesian jungles, here are some examples of messages that you might expect:
Chimps Kill for Land–but Does That Shed Light on Human Warfare?
Chimps kill chimps. And according to a 10-year study of Ngogo chimps in Uganda, they do it to defend and extend their territory. John Mitani documented 21 chimp-on-chimp killings during the study, 18 of which his team witnessed. And when the chimps kill another, they take over its land.
Because of the 1 percent difference of DNA between us and our ape cousins, it can be irresistible to anthropomorphize them, referring to their deadly attacks upon each other with terms like “murder” or “crime.” And given the murders over territory that litter human history books, it’s hard not to see echoes of our ourselves in chimp “warfare.”
Chimpanzee warfare is of particular interest because of the possibility that both humans and chimps inherited an instinct for aggressive territoriality from their joint ancestor who lived some five million years ago. Only two previous cases of chimp warfare have been recorded, neither as clear-cut as the Ngogo case [The New York Times].
But not so fast, says DISCOVER’s own award-winning blogger Ed Yong. He contacted chimp expert Frans de Waal, who would like to dissent:
“There are many problems with this idea, not the least of which is that firm archaeological evidence for human warfare goes back only about 10-15 thousand years. And apart from chimpanzees, we have an equally close relative, the bonobo, that is remarkably peaceful… The present study provides us with a very critical piece of information of what chimpanzees may gain from attacking neighbours. How this connects with human warfare is a different story” [Not Exactly Rocket Science].
For much more, check out Yong’s full post on the study.
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Not Exactly Rocket Science: Chimpanzees Murder for Land
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DISCOVER: Chimps Show Altruistic Streak
Image: John Mitani
