Our very own Ilias Berberi just published his first popular science article about bird flight and bioinspiration — read it here. Way to go Ilias!
Tag / communication
How do babies learn words?
My 10-month old daughter just proved that she understands some words. Now, when we tell her to “clap your hands”, or even just talk about clapping, we get a round of applause. Pretty cute! This wasn’t one of the things we were actively trying to teach her, like “daddy”, “mommy”, “dog”, or “milk” – I haven’t seen evidence that she knows those yet.
It just goes to show how learning works: motivation trumps deliberate efforts to teach. Clapping is just plain fun.
It’s spooky to think about what else she might come to understand without us knowing.
Our research on hummingbird flight is featured in the July 2017 National Geographic!
The article is all about hummingbird science, and how new techniques are allowing us to see aspects of their behaviour that aren’t available to the unaided eye. You can read the print article here, see a beautiful video summary here, and another one here. Here’s one of an Anna’s hummingbird in a wind tunnel. He’s remarkably good at keeping his head steady as the wind ramps up:
The photographer, Anand Varma, took a great shot of my vision experiments at UBC that shows a bird perching in a strange, Tron-like environment of glowing green stripes:
Between getting the scene right, adjusting the lighting, and then waiting for the bird to act in just the right way, this one photograph took an entire week of work (hands on work that is, no photoshop!). Given all the other complex shorts in the article, it’s easy to see how the whole endeavour took a couple of years – much like a scientific study. Working with Anand that week, it was interesting to see how many other parallels there are between what he does and our research. A lot of trial and error, a lot of patience, and a lot of coping with the quirks and surprises of animal behaviour.
The article ends with a scene from the summer when the writer, Brendan Borrell, spent a couple of days with me in the lab. I have the honour of being described as emerging from the lab with a “sheen of sweat” on my forehead. It is embarrassing, but true! It was a hot day and we were working hard in that room.
There is also a nice editorial about the project here.
Girls do science
One of the best things about maternity leave is watching my daughter learn new things, almost daily. A few weeks ago she realized she could control her feet. This week she’s using her hands to grab at objects and starting to pull them in for further, mouth-based inspection. It really is exponential – the more she learns, the more she is able to figure out.
Children also learn a lot from what they hear. And they are apparently sensitive to the particulars at a surprisingly young age. Take, for example, the phrase “some birds fly” vs. the generic version “birds fly”. Psychologists have shown that halflings as young as two years old can tell the difference between these two phrases, and they can also use the generic version appropriately. What’s more, when adults use generic language in conversation with very young children, the children are able to infer new categories and make predictions about the world. This has been shown in experiments where psychologists talk about new, fictional categories (like Zarpies and Ziblets) with children. The results of these studies suggest that children are essentialists: i.e., they tend to carve up the world into categories, and view members of the same category as sharing a deeper, inherent nature. And these categories are easily transmitted through language.
This can have some unintended consequences. In her book The Gardener and the Carpenter, Alison Gopnik describes a study by Susan Gelman and colleagues where mothers and their children were given pictures of people doing stereotyped (a girl sewing) and non-stereotyped (a girl driving a truck) activities, and their conversations were recorded and quantified. It turns out that even mothers who were feminists used generic language most of the time. Moreover, there was a correlation between how often mothers used generic language and how often their children did.
Worst of all, moms used generics that reinforced the very stereotypes they were trying to combat. As Gopnik puts it:
Saying “Girls can drive trucks” still implies that girls all belong in the same category with the same deep, underlying essence.
I can’t help but wonder how this might affect our daughter as she grows up.
Although her book is not meant to be prescriptive, Gopnik does say that we probably can’t avoid this by careful wording – it just wouldn’t work to try to consciously control our language. Instead, the best antidote may be to have children observe many examples and talk to many different people.
Never bar graph temperatures
I’ve been going to a graduate class in science communication this semester. Doug taught us the rule that if you’re using a bar graph, the y axis must start at 0. Otherwise you end up with trickery like this:
The Owl: why kids make great science writers
I finally had a chance to watch Steven Pinker’s excellent lecture on science communication this weekend. Pinker, a psychologist, linguist and top-notch writer, argues that psychology can help us tune up our writing and become better communicators.
His first point is that cognitive psychology points to the model that we should be aiming for: prose that directs the reader’s attention to something in the world that they can then come to understand on their own.
He also discusses why this is so hard to do: The Curse of Knowledge. Once you know a lot about something, it’s hard to put yourself in the mindset of your readers – i.e., the people who don’t know anything about the thing you are trying to write about. This is because it’s hard work, cognitively, to keep track of what other people know. The classic example of this is the false belief task in psychology. If you show a child a box of Smarties (the chocolate candy), and then ask him or her what might be in the box, the child will say candy. Suppose you then reveal that the box actually contains something else – coal. Then close the box and ask the child what another person would think is inside. A 7 year old will correctly say candy, but a child younger than 4 or so will claim that others would think it contains coal. Up until about age 4, we don’t seem to grasp that other people can have false beliefs about the world. Pinker’s point is that this ability – also known as theory of mind – isn’t a cut and dried thing that we suddenly achieve at age 4. It’s a sophisticated skill that proves to be a challenge even for adults.
His advice on writing? It’s pretty standard stuff. Pinker enlists his mom – or in other words, an intelligent reader who just happens to not know a lot about his particular topic already. His other point is to take a break from your writing before you edit, to give yourself time to shift away from the mental state you were in when you wrote it. You can also read your work aloud, since that seems to engage a different mental state as well (I wonder why?). It makes me wonder whether there is anything we can do to harness this mind reboot effect more efficiently. Say you don’t have a lot of time and your mom is not available. How can you reset your brain on demand? I’m thinking of a 20 minute nap, reading some fiction, or doing some physical exercise before editing your paper – which is best? I imagine this is something that cognitive neuroscientists will be able to tell us pretty soon.
Pinker ends with some sage advice: most good writers learn by example. So find a bit of writing that you admire, and try to figure out what makes it great. His choice? The short essay called “The Owl”. It’s remarkable for its clarity and worth checking out in the video below:
If only it was that easy for the rest of us to escape the curse of knowledge.
You can watch the whole lecture by Steven Pinker here. (The Owl is at the 57 minute mark.)
Neanderthals were into birds
Well, into their feathers anyway. Thanks to a new study out this week, we now have paleontological proof that Neanderthals collected birds for more than just food. They probably used bird feathers for decoration – just like we do – suggesting that we aren’t the only hominid species to have developed an artistic culture1.
The research team – led by Clive Finlayson – used a combination of archaeological and paleontological evidence from several different sites where Neanderthals lived during the Paleolithic, ranging from Gibraltar in southern Spain to sites in the near East. For each site, the researchers tallied up the number of different bird species found in the fossil record at the same time and place as the Neanderthals, and they discovered that certain species were most frequent. The most common species were raptors (like vultures, kites and golden eagles) and corvids (like crows and choughs). Crucially, the researchers found that the remains of these particular species are far more abundant at the Neanderthal dwellings than they are at other paleontological sites – suggesting that the bird bones were there for a reason.
Cuttlefish strike a pose for 3D camouflage
In the game of hide and seek, cuttlefish have the upper hand. These chameleons of the sea are astonishingly good at disappearing: they can instantaneously change the colour of their skin to blend in with the background, matching even the finicky details like the pattern of coloured rocks on the ocean floor.
Divers have long known that cuttlefish are masters of the 3D camouflage game, too, and new research from the Wood’s Hole Oceanographic Institute has revealed how they do it.
Alexandra Barbosa, a graduate student, and Dr. Roger Hanlon were interested in the way cuttlefish strike a pose when trying to hide. After encountering a predator, these octopus-like animals will flee among the corals, rocks and algae, and freeze with their arms contorted into shapes that mimic nearby objects – a feat made all the more impressive by the fact that cuttlefish arms can bend in any direction. Some birds and insects are also known to camouflage themselves with body posture, but few come close to cuttlefish in shape-shifting flexibility (see photos of cephalopod camouflage in the wild here).
To understand just how they do it, Barbosa and her colleagues in Dr. Hanlon’s lab presented captive cuttlefish with some highly unusual surroundings: jailbird stripes, in black and white. In response, the cuttlefish got theatrical, raising their arms roughly parallel to the angle of the stripes. And when the researchers shifted the angle of the background image, the cuttlefish stretched their arms into a new position in an attempt to stay hidden.
Cuttlefish posing against different backgrounds. Modified from Barbosa et al. 2011 (see Figure 1).
Intriguingly, not all of the ten individuals tested were able to match the angle perfectly all of the time – but these quirks may not be surprising given that cuttlefish camouflage is so complex. After all, in nature cephalopods get to choose their own hiding places, a decision that might involve several different factors. According to the researchers, camouflaged cuttlefish are even known to gently wave their arms to match the movement of the underwater plants they are trying to mimic.
These results are a clear demonstration that cuttlefish use vision to guide their 3D camouflage, since the study animals matched a flat background image. Moreover, Barbosa and Hanlon have shown that shape-shifting cephalopods can easily handle scenarios that would never occur in the environment where these behaviours evolved, and adjust just as flexibly to this artificial environment as they do in their natural habitats.
Captive experiments like this are just the first step in understanding how cuttlefish use visual cues to hide, and some big questions remain. For instance, little is known about how cuttlefish can detect and match colours so well despite the fact that they are, in effect, colourblind – Hanlon has found that giant Australian cuttlefish can take on the colouration of rocks on the ocean floor even in the middle of the night.
These remarkable split-second decisions about where, and how, to hide might also help us understand something bigger. Strategic camouflage is just one aspect of the surprising intelligence of cuttlefish, which have the largest brains for a given body size of any invertebrate – these animals are also able to learn and communicate with one another at a level that rivals many land-based animals. It will be intriguing to see where hide and seek fits in to the history of cephalopod brain evolution.
Barbosa, A. et al. 2011. Proceedings of the Royal Society B. In press.
How I learned to respect the peahen
Written for the Los Angeles Arboretum.
Meep meep? More like “Honk honk!”
Arboretum regulars will no doubt recognize the call of a startled peahen, but you may not be aware of the clever ways they use it. Not that they try to boast or taunt the enemy, necessarily, but I’m starting to think that the birds at the Arboretum owe a lot to their version of the Road Runner’s call.
How do I know? Some background is in order here: I’m the tall blond woman who has been hanging around the Arboretum morning and night for the past few years, overdressed and hauling a camera, a pair of binoculars, some peanuts and, if I was lucky, a peacock. Working at the park each spring, I often wished I had more time to chat with visitors. But I was preoccupied, and the life of an ornithologist can sometimes feel like that of Wile E. Coyote on a bad day.
For the past four years, I’ve been chasing peafowl across the continent – from Arcadia in February to Winnipeg, Toronto and New York in May and June. Incidentally, the Bronx Zoo is the only place in North America that even comes close to the Arboretum in sheer number of peafowl. Three years into my PhD in biology, and I’ve spent literally hundreds of hours watching these birds.
You may be wondering what got me into this mess.
Species of serendipity
Like most ideas, this one arrived in the shower. I needed to write a post for this week, but my list of topics was wearing thin and the weather is finally starting to get nice enough to distract me. Sure, I had a few promising ideas lined up, but they all need more time to develop. Plus I had a DVD to watch: a Nature of Things episode on serendipity in science due back at the library. Then it hit me – of course! I’ll watch the episode and then write about that.
Serendipity – supposedly one of the top ten most untranslatable words in the English language – was coined in the 1700s by Horace Walpole as a play on the tile of a Persian fairy tale. The Three Princes of Serendip takes place in Sri Lanka. It follows the adventures of three brothers exiled from the island by their father the king, in hopes that his sons might achieve a more worldly education. In the course of their travels, the princes go on to solve many mysteries – like unintentionally tracking down a lost camel on scant evidence – thanks to their sagacity and a series of lucky accidents.
Since Walpole, the word has taken on a close association with Eureka moments in science, starting with Archimedes’ famous bath. Supposedly, the ancient Greek mathematician solved the problem of measuring the volume of irregular objects after noticing how his own body displaced water in the tub.
Scientists have taken a great interest in tracking serendipity, perhaps because it seems to play a role in research success. Wikipedia has an extensive list of celebrated examples, from Viagra to chocolate chip cookies. Many have looked for ways to encourage this kind of scholarly luck. For instance, after his Nobel prize winning work on viruses, the molecular biologist Max Delbrück is perhaps best known for coming up with the principle of limited sloppiness: researchers should be careless enough that unexpected things can happen, but not so sloppy that they can’t reproduce them when they do. Alexander Fleming had this advantage when he discovered penicillin. He first noticed its antibiotic effects in a stack of dirty culture dishes that he hadn’t bothered to clean before leaving for summer vacation.
So how do people study something that is by definition rare and unusual? Psychology Today has summed up some of the latest research on luck, most of it based on surveys of people who claim to be especially serendipitous1. Not surprisingly, they are more competent, confident and willing to take risks than the rest of us. They are also more extroverted and less neurotic than most. Being born in the summer apparently helps as well – especially May.
Other advice might be more practical.
Monkeys draw from memory
We’re a little bit closer to understanding what it’s like to be a monkey, and it’s thanks to the same technology that powers your smartphone: the touchscreen.
The latest victory for touchscreens is in the field of memory research. Scientists have been studying this ability in animals for decades – some birds, for example, are remarkably good at keeping track of the little details they use when foraging. Florida scrub jays collect thousands of acorns in the fall, hiding them as reserves to help get through the winter. Proof that scrub jays can keep track of multiple pieces of information about their caches – including the type of food, its perishability, and how long it ago it was stored – came from some clever experiments where jays learned to store worms and peanuts in sand-filled ice cube trays in the lab1. Rufous hummingbirds perform a similar feat. They can keep track of flowers on their daily foraging routes, including when the nectar for each one should be replenished, and time their visits accordingly. How do we know? Biologists taught hummingbirds in the Alberta Rockies to feed at artificial flowers that could be refilled on schedule2.
There is also a long history of research on the mental capacities of our closest animal relatives, primates. Rhesus macaque monkeys, a lab favourite used in countless studies of pharmacology and physiology, can easily keep track of a set of objects and spot the difference if you show them an altered version later on3. Not surprisingly, primates seem to have better memories than birds. Baboons can learn thousands of different photographic images and retain these memories for years – incredibly, when this particular study went to press, the baboons were up to 5000 and still hadn’t maxed out their capacity4. Pigeons, on the other hand, hit a memory wall at roughly 1000 images4. These abilities might prove useful to primates like the chimpanzees living in the Taï National Park of Côte d’Ivoire, Africa. They make extensive use of their vast forest habitat, visiting hundreds of fruit trees that ripen on different schedules5. The Taï chimps can apparently remember where the especially productive trees are, and will often travel longer distances just to get there5.
But there is something missing from this research. It has to do with a subtle distinction in the way memory works: the difference between recognition and recall. Recognition is the ability to identify something because you’ve experienced it in the past. Recall, which can be more difficult, involves retrieving that memory on demand. Ben Basile and Rob Hampton liken it to the difference between a police lineup and talking to a criminal sketch artist. To recognize something is to see it and sense familiarity; to recollect is to create that experience in its absence.
So far all we have been able to study in animals is recognition. Without language, we can’t get them to describe their memories – until now, that is. Basile and Hampton, two scientists from the Yerkes National Primate Research Center in Atlanta, have figured out how to get monkeys to act like criminal sketch artists6.
Elections are like peacocks
Both are loud, and both cause colourful flashy things to pop up on lawns everywhere. And much like elections, the peacock’s train is a costly endeavour. The species might be better off in terms of survival and abundance if they could just do away with those feathers. In terms of sheer waste, they remind me of the Green party pamphlets in our apartment building entrance way. They were stuffed blindly into all of the available mailboxes – which happen to be for street level businesses on our downtown block, not residents. Nice.
Peacocks and elections are both supposed to experience strong positive feedback effects. In politics, momentum can lead to rapid climbs in popularity. Sexual selection can be similar: as Ronald A. Fisher pointed out, exaggerated male traits can potentially evolve through a process of positive feedback. If enough females prefer the particular male trait initially, and the next generation inherits both the female preference and the exaggerated male trait, it can kick-start a runaway process of sexual selection to extremes.
Despite claims to the contrary, we don’t actually know whether Fisher’s runaway process contributed to peacock evolution. But it may be reasonable to assume that it played at least some role: positive feedback should set up easily so long as mate choice is not very costly for females2.
Thinking about peacocks gave me an insight that may have cured my allergy to all things political, at least temporarily. Not that I don’t care about the election – I do – but I can’t get over my frustration at the kinds of things that count as good arguments in the political sphere. Here’s an example: I’d like to learn more about the Green party, but they seem to support a whole lot of pseudoscientific nonsense. Apparently their health care platform includes homeopathy and various other forms of alternative medical quackery. How can we be sure they won’t apply the same less-than-rational approach to the environment? If only there could be “one true party”, I thought after the leaders’ debate – a notion that, briefly, made me wonder whether I might be a closet fascist.
This doubt came up again when I was reading an article in this week’s Nature about the effect of social media on research priorities. It focused on the controversial and totally unproven “liberation procedure” for MS – extremely popular in Canada but, oddly enough, nowhere else1. The article mentioned that Michael Ignatieff has stated his support for clinical trials of the treatment, despite the recommendation by a panel of CIHR experts that a clinical trial would be premature without further evidence from observational studies1. The authors of the Nature article – a group of doctors and medical researchers in Canada – ended up somewhere close to Ignatieff’s position nonetheless. They concluded that the benefits of a full-blown experimental trial might outweigh the costs if thousands of social media-influenced patients are travelling outside of the country to receive private treatment anyway, “exposing themselves to the risks and costs”1. In other words, popularity is an important – and rational – consideration when it comes to medical science.
I have two things to offer for election day. First, there is a good summary of where the major parties stand on science and research funding here. Some are a lot more rational than others.
On to the peacocks. Democratic elections, like sexually selected traits, are communal illusions. Money is another example. The more you accept them, the more you believe in them, the better they work.
Check out the video below (source link). The peacock jumping spider is definitely worth your time, but skip to 2:45 if you’re in a hurry.
Thanks to Barrie Frost for sending this.
I can haz toxoplasmosis
In which you will learn why online cats are so attractive, and discover a new way to lose hours to the internet.
First, the cats. Charlie and I were hashing out the finer points of Facebook, memes and internet superstars, when, in frustration, I brought up his most hated animal.
“Look. Cute baby videos and LOLcats are popular because people send links to their friends. Nobody sits down and says, ‘Well it’s quarter to 10, the same time I always drink my coffee and look for the latest cute cat photos on the–’ ”
Self defeat and laughter mid-sentence, when I remembered living with my friend Jessica in Toronto. She had a brutal job in psychiatric research north of the city. After a hard day, that was exactly what she did. Nothing cheered this woman up like online cat research.
Felis catus is a polarizing species. Some people despise them. Ancient Egyptians and cat ladies have made a religion out of them. The story goes that wild cats were first domesticated in ancient Egypt for useful things like keeping rats out of grain stores and killing poisonous snakes, but this might be more myth than reality. Cats were probably kept around as tame rat-catchers much earlier, certainly before recorded history, and very likely around the beginning of agriculture itself. People were depicting cats on pottery 10,000 years ago1. Cyprus can boast the first Stone Age cat lover. A 9,500 year old burial site on the island is the earliest evidence of humans bonding with these animals, since a cat was intentionally buried alongside a human body there2. The fact that the cat was not butchered, and the inclusion of decorative seashells and stones in the grave, prove that cats had achieved cultural importance beyond their agricultural utility back then.
The European wildcat Felis silvestris is a close relative of the earliest domesticated species. Photo by Péter Csonka from Wikimedia Commons.
But could the cat haters be right – is there something off about feline love? After all, cats aren’t really that useful, at least not when compared to dogs. Dog people might be pleased to hear that when you consider all living and extinct canid and felid species, dogs have bigger brains than cats – probably because they tend to be the more social animals3. Indeed, dogs adapted readily in response to domestication, evolving a number of cognitive abilities that make them particularly good at understanding human gestures – much better, even, than chimpanzees4. Naïve 4-month old puppies will quickly learn what it means when a human points, without any training or close contact with humans beforehand5. Cats can do this too, but they require a lot more effort to learn how6. Dogs can detect certain forms of cancer in humans by smell, and they are often the first ones to notice that something is wrong with their owners7. I have yet to find any high profile studies on feline pathologists. Which raises the question: if cats could do it, would they care enough to try?
And in a bizarre twist, there’s reason to think that our magnetic attraction to cats might be the result of a real parasitic disease.
“Everyone is special.” The paradoxical refrain of baby boomer parents to their millenial offspring is true, so long as you’re a rodent living in a large, stable group of good communicators.
I recently wrote about the phenomenon of identity signals in animals, where variable colours and patchy-looking patterns can provide signatures of individuality, much like the human face. These are not limited to the visual domain. Think of how easily you can recognize a person’s voice – even someone you don’t know very well – from just a few lines of speech, like when a celebrity turns up in an animated movie.
But I didn’t have a chance to cover the latest news on this topic. In some very plain looking rodents, we now have evidence that individuality evolves1. Some of the plainest looking critters, like the Belding’s ground squirrel shown below, have the most distinctive snarfs and grumbles – and it all has to do with the number of group-mates they typically interact with.
Two Belding’s ground squirrel pups peek out of a burrow. Photo by Alan Vernon from Wikimedia Commons.
The new results came out this month in the high profile journal Current Biology. Previously, researchers had looked for the evolution of individuality in a handful of bird and bat species. The prior studies examined distinctiveness in the begging calls offspring make to their parents, contrasting pairs of closely-related species that vary in the number of offspring in shared “crèche” or communal nest sites2,3. But nobody had tackled the evolution of individuality in a broad context.
Until Kim Pollard, that is. Pollard, a recent PhD graduate from UCLA, and her supervisor Dan Blumstein decided to look at this question in the social marmots. You might remember Blumstein from another recent post; his interests range from mammal conservation and environmental education to the bioacoustics of movie soundtracks.
For Kim Pollard’s study of identity signalling, marmots were an ideal choice. Marmota is a large genus of 14 different species in the squirrel family, all social, and all with their own alarm calls that they use to warn neighbours and family members about nearby predators. Species like the yellow-bellied marmot and Richardson’s ground squirrel also have the ability to recognize each other based on the unique sound of these calls4,5.
Crucially for Pollard and Blumstein, social group size also varies in the genus, ranging from about 5 to 15 individuals per clan or family group. This allowed the authors to test the hypothesis that group size has been an important factor in the evolution of distinctiveness, since, as they put it, “The bigger the crowd, the more it takes to stand out.”
A case of mistaken celebrity
They all look the same to us. Celebrities, that is. And by us, I mean academics.
The proof starts with peacocks. Last fall, I was working on some measurements I took of the crest ornament in these birds. Peafowl have this funky little fan of feathers on top of their heads, and though it’s not that small in the grand scheme of fancy bird plumage ornaments, the peacock’s five centimetre crest looks a bit ridiculous next to the metre-and-a-half long train.
Why bother having a crest when you also have a big train? And why do females wear crests too? In this species, the crest appears to be the only plumage ornament shared by both sexes. Here are some of my pictures from the field, taken on the cusp of the breeding season:
Crests of (a) male and (b-c) female peafowl. Scale bars are 10 cm. Photos by Roslyn Dakin.
Over the years, I’ve measured the crests of close to 150 birds. These data lend some support to the idea that the crest is a signal of health in both males and females, although it might work in slightly different ways for the two sexes1. As you can see from the picture above, there is a lot of variation in how the crests look – and it’s mostly on the female side of the equation. Almost all adult males have tidy looking crests like the one shown in (a), but females often have crests with a lot of new feathers growing in (c). It turns out that males in better condition tend to have fuller, wider crests. The healthiest females, on the other hand, have crests that look most like those of males, with all feathers grown out to the top level (b).
The extreme variability among females leads to an additional hypothesis, and it’s one that I can’t rule out at this time. Perhaps the crest is a signal of individual identity that the birds use to sort out who’s who in their social groups – just as faces do for us. A clue that this could potentially work for peahens is that my field assistants and I can do it. Once you spend enough time hanging around with these birds, you find yourself recognizing certain females that haven’t been captured yet (and that therefore lack identifying leg bands). Your first clue? Usually a unique pattern of crest feathers.
The winning score
As Hollywood gets dolled up for the Oscars, fans at home might surprised to learn that a field biologist could tell us a thing or two about the winning films. Dan Blumstein, a behavioural ecologist who works, quite fittingly, at UCLA, is an expert on yellow-bellied marmots. He might also be the person to turn to if you want to predict the win in the “Best Original Score” category this weekend.
Although Blumstein does most of his work with wild marmots in the Rocky Mountains of Colorado, studying several facets of their behaviour and evolution, he recently published a paper on the science of movie soundtracks1. With Richard Davitian and Peter Kaye from the School of Music at Kingston University in the UK, Blumstein applied techniques from his research on marmot vocal communication to an entirely new question: why are Hollywood moviemakers so good at manipulating our emotions? The results pick up on a common theme in the way humans and other animals use sound.