aatish

Dissecting the language of the birds, or how to talk to a songbird

Odin_hrafnar — The Norse god Odin had two songbirds, named thought and mind, whose daily tweets were the source of his knowledge on our mortal affairs.

Young children have an uncanny ability to pick up new languages. Not only do they soak up vocabulary, they also construct new sentences of their own. This ability to use grammar is the essence of language. It’s not enough to know the meanings of words, you also have to understand the structures and rules by which words are put together.

The predominant view has been that humans are unique in this ability. But any time that we utter the words ‘uniquely human’, scientists seem to take it as a challenge to disprove this notion. And language is no exception. If you’re looking for the species that most closely matches our linguistic prowess, surprisingly, you won’t find it in the apes, the primates, or even in the mammals. You have to travel to a far more distant relative, all the way to a family of birds known as the songbirds.

The vocal life of a songbird is similar to ours in many ways. They learn songs by imitating their elders. Like human speech, these songs are passed down from one generation to the next. Songbirds are also best equipped to learn songs in their youth, and they have to practice to develop their ability. They can improvise and string together riffs into new songs, and over generations these modified songs can turn into new dialects. And like us, they come hard-wired with ‘speech-centers’ in their brain that are dedicated to language processing.

But languages are not just learned, they can also be invented. A striking example comes from the deaf community of Nicaragua in the 1970s. Back then, deaf people in Nicaragua were isolated both physically and through language. By the 1980s, the government set up schools for the deaf to teach them Spanish and how to lip-read. This turned out to be an unsuccessful endeavor. The teachers were growing increasingly frustrated as they were not getting through to the students.

However, things were quite different from the point of view of the students. For the first time, they were in contact with many other deaf people, and they started to exchange gestures that they had invented in isolation. At first the teachers thought this gesticulation was a kind of mime, but the reality was far more interesting. By getting together and pooling their ideas, these children had actually invented a new type of sign language, complete with its own grammatical structure. Here was proof that a new language could be born out of cultural isolation, a testament to our innate abilities to understand grammar. And in a few generations, users of this language were employing newer, more nuanced grammatical structures.

And this re-invention of language has been mirrored in the songbirds. An experiment from 2009 by Fehér and colleagues took newly hatched songbirds of the zebra finch species and raised them in sound proof chambers. They did this during their critical period of language development. Much like the Nicaraguan children, these birds were raised in a world without song. What happened next is quite surprising.

Continue reading Dissecting the language of the birds, or how to talk to a songbird

Launch speed of the leaping sifaka

Update: Added discussion on launch angle at the end of the post.

Edit: The final numbers in this post went through a few rounds of revision. What is the world coming to, when you have to track down missing factors of 2 in your blog posts?!

This week, I’m looking at the strategies and mechanisms by which different animals solve the problem of getting around. I started off by writing about how birds and aquatic animals conserve energy on-the-go. This post is another spinoff on the theme of locomotion.

Here’s a clip from one of my favorite documentaries, David Attenborough’s Life of Mammals. It shows the incredible sifaka lemur of Madagascar, a primate that has a really remarkable way of getting around. (If the embed doesn’t work, you can watch it here)

As they launch out from the trees, they almost look like they’re defying gravity. And so, taking inspiration from Dot Physics, I thought it might be interesting to put physics to use and analyze the flight of the sifaka.

I loaded the above video into Tracker, a handy open source video analysis software. I can then use Tracker to plot the motion of the sifaka. I chose to analyze the jump at about 21 seconds in. I like this shot because it isn’t in slow motion (that messes up the physics), the camera is perfectly still (we expect no less from Attenborough’s crew), and the lemur is leaping in the plane of the camera (there are no skewed perspective issues that would be a pain to deal with). The whole jump lasts under a second, but at 30 frames per second, there should be plenty of data points.

This is what it looks like when you track the sifaka’s motion:

The red dots are the position of the sifaka at every frame. That’s the data. In order to analyze it, we need to set a scale on the video. I drew this yellow line as a reference for 1 unit of size (call it 1 sifaka long). And how big is that?

If we believe this picture that I found on the National Geographic website, then a sifaka is about half the size of this folded arms dude.

Now, to the physics..

Continue reading Launch speed of the leaping sifaka

A revealing photograph

While looking around on Flickr for images for the previous post, I came across this captivating photograph taken by Toni Frissell.

toni frissell float — More than meets the eye?

It’s a gorgeous shot on aesthetic grounds. Perfect lighting and composition, a beautiful subject, and a strikingly dramatic moment. And seen another way, it’s a metaphor for what Empirical Zeal is all about: diving beneath the surface, and looking at things from a different point of view.

It turns out that this photograph is a neat illustration of two interesting physical phenomena. Can you guess what they are? And here’s another (admittedly odd) question. Can we use this photograph to work out the density of this woman?

(Answers below the fold)

Continue reading A revealing photograph

Marine animals save energy by coasting like birds

It feels good to be an animal. Unlike trees that are tethered to the ground, we animals have the incredible ability to travel. And we do so in a variety of ways. Some like to walk, others run. Others get around by swimming or flying. There are climbers, leapers, and hoppers, and others that prefer to roll and tumble.

Locomotion certainly affords us a great deal of freedom, but it comes at a considerable energy cost. Through countless generations of incremental evolution, our bodies have arrived at many solutions to balancing our energy budget. Fish have streamlined profiles, birds have hollow bones to stay light, and kangaroos have spring loaded hind legs that seamlessly capture and release the energy needed for flight. In the African savannah, predators chase down their prey using long, muscular legs that give them an efficient stride.

In addition to changes in form, animals can also use strategies to travel more efficiently. Birds that need to fly a long distance often make use of a curious technique. They flap their wings to gain height, and once they builds up enough height, the wings stop moving and they glide back downwards. Many birds repeat this wave-like motion in flight, instead of flying at a fixed altitude.

It’s like the difference between cycling on flat terrain or on an undulating, hilly road. In one case you pedal at a steady pace, in the other you alternately pedal hard and don’t pedal at all. The reason that birds adopt this undulating flight strategy is that it saves them energy.

But what’s special about air? What about animals that live in water? In the ocean, swimming is the equivalent of flying. So do marine animals adopt similar swimming strategies to conserve energy? To answer this question, an international group of researchers led by Adrian Gleiss attached sensors onto sharks and seals. They monitored the swimming motion of the whale shark, the white shark, the northern fur seal, and the southern elephant seal.

Here is an animation that they made directly from their recordings, that shows a whale shark swimming.

Continue reading Marine animals save energy by coasting like birds

I made it to the 3QD finals!

I’m very excited to report that my post on blind cavefish made it to the list of finalists for the 3QuarksDaily Science Prize 2011. I’m in the company of some seriously excellent writers, all of whom I admire. A big thanks to everyone who voted me in and helped spread the word about this very young blog. You’re all incredible!

Here are the other finalists:

Cosmic Variance: The Fine Structure Constant is Probably Constant
Dr. Carin Bondar: Sacrifice on the Serengeti
Highly Allochthonous: Levees and the Illusion of Flood Control
Laelaps: The Pelican’s Beak – Success and Evolutionary Stasis
Oh, For the Love of Science: Prehistoric Clues Provide Insight into Climate’s Future Impact on Oceans
Opinionator: Morals Without God?
Scientific American Guest Blog: Serotonin and Sexual Preference: Is It Really That Simple?
Starts With A Bang: Where Is Everybody?

They’re all excellent posts, and it’s great to see science writing getting some love.

Why a quantum particle is not like a water drop. A tale of two slits, part 1

I want to describe a certain beautiful experiment, perhaps the most beautiful experiment in science. This is an experiment that has captivated me from the time that I first heard about it in high school. That’s because it’s simple to understand, and yet it captures the essence of what is truly messed up about quantum mechanics. This is a tale of two slits. And it would be no exaggeration to say that through these slits, we encounter a word that is so strange, it is beyond our human capacity to imagine.

The story is about the nature of light and matter. And it is driven by a fervent battle of ideas between some of the greatest minds in science. It begins at the turn of the eighteenth century.

By then, Isaac Newton had already made a name for himself as the biggest badass in science. He invented calculus (edit: although the origins of calculus are somewhat mired in controversy), devised the law of gravity and formulated the laws that govern how things move. That’s pretty eventful for a few decades (in fact, he did much of this work in a single year), and it’s almost inhuman that all this came from a single person.

And things were just getting started. By the turn of the century, Newton had turned his considerable attention towards the problem of light. How does it work? What is it made of? Using a series of simple, methodical experiments, he argued that if you stripped light down to its tiniest constituents, you would end up with particles that he called corpuscles. This idea was widely adopted, and became the mainstream scientific opinion for over a hundred years.

There were always doubters to this idea, but they weren’t many of them, and they weren’t popular. It was another brilliant English scientist, Thomas Young, who would take the next step in understanding light.

Young was quite the Renaissance man. In addition to being a physicist, he made significant contributions to fields as diverse as music, language (he compared the vocabulary and grammar of 400 different languages), Egyptology (he partly deciphered Egyptian hieroglyphics from the Rosetta stone) and the physiology of vision.

But what Young considered his greatest achievement (and he had a few) was overthrowing Newton’s century-old notions of light. In its place, he argued that light was not made up of particles, but was instead a wave, quite like the ripples on the surface of water.

At first, he met with huge resistance to his ideas. But in 1803, Young convinced his skeptics with a simple, game-changing experiment.

Continue reading Why a quantum particle is not like a water drop. A tale of two slits, part 1

Dude, what’s up with these surfer geese?

A friend of a friend of a friend (all kayakers) was recently out filming his buddies play in a huge wave. By chance, he recorded this incredible video. It shows a gaggle of geese floating down a river that is at its highest flow in 27 years. They start approaching a fairly intimidating wave (a gnarly wave, in the standard paddler’s lexicon). You can hear the wave roaring loudly..

What comes next is utterly surprising. Take a look at the video:

It looks like a dangerous situation, but these geese appear to be in control.

Seemingly effortlessly, they glide over to center of the river and catch the wave. They have incredible skill and control as they guide themselves right into the wave, while facing backwards. And they manage to surf it without being swept over. It looks like they are making a determined effort to stay there. You can even watch one of the geese that doesn’t quite make it, and it starts flapping its wings to get further upstream.

I did some cursory googling around, and I couldn’t find an example of this behavior being documented before. So what I’d like to know is, what is going on here? Are they in any real danger here? Maybe they are trying not to get separated from the young ones in the rapid, by collecting together at surfable waves. Or perhaps by surfing a wave, they can catch fish that are being swept up in the backflow. My friend Deepak pointed out that fly fisherman often fish near rapids, so there might be something to this idea.

However, I don’t see them feeding in this video. And if they judged a wave to be truly threatening, I would imagine that they could just as easily try to swim out of the way, or fly over it (although this may pose a new set of problems.)

But there is another explanation for their behavior, one that’s harder to verify empirically. Maybe, just maybe, what you are seeing are these geese having fun.

It could be that they’re just enjoying playing in the wave. And in doing so, they’re teaching the kayakers a thing or two about their sport.

What do you think is going on in the video? I’m curious to know. Post your thoughts in the comments below.

Vote for your favorite online science writing

Update: They’ve kept voting open till Friday, June 10. Please vote!
Update: Voting closes in one day – on Wednesday, June 8. Please vote!

The excellent blog 3quarksdaily has an annual science writing competition, where they reward the best posts on science over the last year. This year, it’s being judged by the particle physicist and cosmologist Lisa Randall.

There are lots of great nominations. You can check out the list here. It’s now open to online votes, and the top 20 entries will be passed to the editors for the next round of selection. So, get out there, and start reading! And don’t forget to vote. You’ll learn about some fascinating stuff, and you’ll be encouraging science writing.

2011 3QD science prize nominees

Flies alter their ejaculate to get the best bang for the buck

drosophila mating — Smarter than you think..

Sex is war. It’s a battle for limited resources.

The source of sexual conflict is this: sperm is a relatively cheap resource for males to produce, whereas producing eggs and rearing offspring is a much larger investment on the part of the female. Darwin was the first to realize the implications of this. He reasoned that this imbalance should result in males competing with each other to fight for the limited resource, and females exerting a strong choice on who to mate with. Taken together, male competition and female choice were the two pillars of the theory that he called sexual selection.

The battle of the sexes is not a new idea, but it has changed with the times.

In the 1960s and 70s, the sexual revolution was eroding away conservative ideas about sex. This was the era of promiscuity. And this changing social fabric was being mirrored in science. The ‘free love’ era brought about an equally potent, but more silent, revolution within biology – one that completely shook up our old, prudish notions of reproduction. Research from these decades onwards taught us that in almost all animals, from insects to birds and mammals, females typically copulate with multiple males. We learned that promiscuity is not a freak event, it’s actually the norm. What this implies is that, like any modern war, the battle of the sexes is a messy and involved affair, often leading to surprising and unexpected consequences.

For one thing, it’s being fought on many fronts. In many species, competition between males for the egg doesn’t stop at intercourse. Even after the female is inseminated, the battle rages on inside her reproductive tract. In this alien battlefield, the sperm cells of different males compete with each other to fertilize the eggs. Meanwhile, the reproductive organs of the female can still exert control by choosing between the different sperm.

And just like the Greeks who sneaked into Troy, the soldiers in this battle use every trick at their disposal to gain an upper hand. Some males do the equivalent of taking their ladies out to a fancy restaurant – they present females with a nutritious meal in their sperm, at substantial cost to themselves (delightfully, biologists call this a prenuptial gift). Others resort to date rape – their sperm includes a harmful cocktail of drugs that alter the females’ behavior in their favor. Even more chilling, there are species in which the males engage in traumatic insemination, where they essentially rape the females. Other males are just outright weird. Some leave their penis behind to plug the vagina from use by other males. Others have smelly sperm that repels other males. And others have spiky penises, that scrape the vagina clean of the sperm of competitors.

Not a pleasant lay. That thorny structure is the penis of a bean weevil.

Continue reading Flies alter their ejaculate to get the best bang for the buck

Seeking symmetry on a sunday morning (updated)

I spent last Sunday hiking with friends in the Shawangunk Ridge, in New York state. The Gunks, as it is locally known, is a ridge of bedrock that extends from the northernmost tip of New Jersey to the Catskill Mountains in New York. It was an incredibly foggy day, so we didn’t get to see any of the scenic vistas. But we did get to enjoy the weirdly diverse vegetation, all of which was covered in dew. The highlights were hiking through a beautiful ice cave, and having lunch on a ledge overlooking a 180 feet (54.6 m) tall waterfall. That’s a few feet higher than the vertical drop of Niagara falls. Check out some of my pictures below (fullscreen for full effect).

In the last image, you can use the people as a scale to get a sense of the size of this waterfall. The vertical cliff face that you see was once the site of a geological fault, where a crack formed in the bedrock and broke the symmetry. Rock on one side of the fault then slipped under, as rock on the other side got pushed above. Erosion has since gotten rid of the topsoil at this fault line, exposing the layers of bedrock beneath. It’s a striking testament to the power of geological forces.

The layers of rock that you see have been dated to about 430 million years ago. This was an interesting time in our history. It is when our ocean-dwelling fish ancestors started incorporating a new invention into their bodies – bone. It was also the time when these ancestors (who would later give rise to amphibians, reptiles, birds and mammals) parted ways with the ancestors of some rather interesting characters. These were the Coelacanth and the Lungfish, the so-called ‘living fossils’ of the ocean.

Latimeria_Chalumnae_-_Coelacanth_-_NHMW — Meet the Coelacanth. One of our more interesting relatives

Of course, there’s really no such thing as a living fossil, as Darwin was well aware when he coined this phrase. Every species alive today has been evolving for just as long as we have (and usually much longer, because evolution is measured in generations and not years). But the Coelacanth, and to a lesser extent the Lungfish, are the few cases where this phrase is appropriate. Fossil records and genetic comparisons bear out that Coelacanths have indeed not changed a whole lot for hundreds of millions of years. Our ancestors from this time may, at least superficially, have looked something like this.

Continue reading Seeking symmetry on a sunday morning (updated)