MIT SciWrite

Your computer screen, from an angle

Anna Ho — Thu, 02 May 2013 16:11:09 +0000

We can probably agree that this rectangle is pink.

Now, keep the rectangle on display, and stand up so that you’re looking down at your screen from a sharp angle. If you have a laptop, you can tilt your screen to achieve the same effect.

See that?

On many LCD screens the square becomes bright blue. (More recent models with higher pixel density, including the Macbook Pros with Retina Displays, have fixed this problem.)

Why?!

Well, it’s not simply because your screen is flat. If you take a pink marker and color in a square on a piece of paper, you can tilt it all you like and the color won’t change.

To make matters even more confusing, try looking at the square from the left or from the right: nothing changes. If you look from below, the square glides into a shade of red, instead of blue.

To understand why this happens, we need to talk about two aspects of your visual world: (1) brightness and (2) color. In particular, we need to talk about how your computer communicates that information to your eyes when displaying an image.

* * *

(1) Brightness

How bright an object is is not the same as how bright it looks.

When we say an object is bright, we mean that it’s giving off a lot of light. So, if Light Bulb B emits twice as much light as Light Bulb A, it would make sense to say that “Light Bulb B is twice as bright as Light Bulb A.” If we think of light as a tiny stream of particles called photons, then this is the same thing as saying that twice the number of photons are coming from Bulb B, as from Bulb A. To add some mathematician jargon to the mix, there is a linear relationship between how bright an object is, and the number of photons it emits: five times the number of photons means five times as bright, half the number of photons means half as bright, and so on. So far, so good.

Now, when you look at a light bulb, photons wash into your eyes. Every fraction of a second, your eyes send a status report to your brain, which interprets the raw information and comes up with a conclusion about how bright the bulb is. If you stare at Bulb A for ten seconds, then stare at Bulb B for ten seconds, your eyes will have received twice the number of photons from B as from A, so you’d think that your brain would conclude that B is twice as bright.

Strangely, no. Your brain actually prevents you from figuring out that “brightness” and “photon count” have a linear relationship. If the two bulbs are very bright to begin with, the message from your brain will actually be: “B’s not that much brighter than A.” If the two bulbs are very dim to begin with, the message from your brain will actually be: “B’s WAY brighter than A!” More generally: your brain is much more sensitive to differences between dark shades, than it is to differences between light shades. There is not a linear relationship between how bright an object seems to us, and how many photons it emits: there is instead what is called a logarithmic relationship. In other words: the brighter two objects are, the less pronounced the difference in their brightness.

This is a very good thing. If our brains didn’t curb how bright an object can seem, the world would be overwhelmingly dazzling.

Looking at an image on your computer screen adds an extra layer of complexity to this whole process. Light from the object goes to your camera, which stores the information, and passes it to your computer when you hit “download.” Your computer stores the image, and displays it on command. Light isn’t going directly from the object to your eyes: it’s going from your computer screen to your eyes. Your computer, by “storing the image,” has essentially memorized what it looks like for you: all the colors, all the patches of dark and light.

Your computer has limited memory resources. It would be a waste to spend those limited resources on subtle distinctions between bright shades, because your logarithmic brain can’t distinguish between them anyway. So, when storing an image, your computer allocates more memory to keeping dark shades distinct, than it does to keeping light shades distinct; it saves images logarithmically.

We didn’t evolve to stare at logarithmic computer screens, though; your brain applies its usual logarithmic correction to any photons you receive. If your computer sends you photons from an image that is already logarithmic, then your brain will over-compensate, and you will see too many dark shades and not enough light shades. The image will look distorted. To prevent this from happening, your computer converts its logarithmically stored image to a linear brightness scale, before displaying it to your eyes. The process of preparing an image for view is called gamma correction, and as long as you look at your screen face-on, it works.

And what if you don’t look face-on? Well, try looking at this text from above and below. From above, the letters get bleached out, and from below they get darker and bolder. For a more dramatic example, let’s use this gradient, which has a range of brightnesses. Same procedure: look face-on, then from above, then from below.

Same thing. From above, you see more bright shades, and from below, you see more dark shades.

This is because of the gamma correction. When applying it, your computer makes two assumptions: 1) that your eye will apply its usual logarithmic correction, and 2) that you are looking at your screen face-on. (1) is guaranteed, but (2) is not, particularly when articles are published about what happens when you look at your screen from an angle. If you stand up and look down, the gamma correction is insufficient, which is why there are too many light shades. As you crouch, and peer up at your screen, the gamma correction is too high, which is why there are too many dark shades. It’s only “just right” face-on.

(2) Color

We’ve been thinking of light as a stream of particles. To talk about color, it’s easiest to think of light as a wave, instead:

If it disturbs you to switch so readily between the particle interpretation and the wave interpretation, don’t worry. It should. The marriage of these two interpretations disturbed the 20th century physicists who thought it up. It continues to surprise physicists today. For the purpose of this article, we’re just going to accept it as a fact of nature.

Color is determined by how stretched or scrunched a light wave is. The distance between two peaks is biggest for red waves (they are the most stretched out) and smallest for purple waves (they are the most scrunched.) Here’s a visual:

If you’re ever mixed paints, you know that certain colors can be mixed to create certain other colors. Clearly, colors are related to – and even made of – each other. The same is true of colored light, although it mixes differently than colored paint. Mixing all the colors of light yields white, instead of the gross brown color you get when you mix all your paints.

Your computer screen is a master color-mixer: using only red light, green light, and blue light as ingredients, it creates all the colors that you see. Look at this Venn diagram:

This guides how your computer mixes colors. As you can see, mixing red and green yields yellow, mixing red and blue yields magenta, and mixing blue and green yields a bright blue called cyan. Mixing all three in equal amounts yields white. Alternatively, you can get white with blue + yellow, with magenta + green, or red + cyan. In other words: if you take blue away from white, you get yellow. If you take magenta away from white, you get green. These pairs (blue-yellow, magenda-green, red-cyan) are called color opponents, because the absence of one means the presence of the other.

Armed with this understanding of how colors add and subtract, let’s take a look at your screen again. Your screen is made of lots of “picture elements” (pixels), each of which is made of three subpixels: a red subpixel, a green subpixel, and a blue subpixel. Each subpixel is a gatekeeper for its representative color: the red subpixels, for example, control how much red is able to pass through the screen to your eyes. If each subpixel lets all of its light through, the pixel looks white. If the red and blue subpixels let their light through, but the green shuts up shop, we see magenta. Similarly, if only the red subpixel let their light through, we see a red pixel. The color of each pixel on your screen depends on what its constituent red, blue, and green subpixels are doing.

Each subpixel has remarkably precise control over exactly how much light passes through: it’s not just “all” or “none”. To understand how it does this, we can think of each subpixel as two layers of fences. The first layer has vertical slits. If the outgoing light wave is also oriented vertically, it can slot right through the fence. When it gets to the second fence, though, it’s in trouble, because the second fence layer has horizontal slits: the light wave is blocked.

The subpixel’s function as a gatekeeper comes from the layer of molecules that is sandwiched between the two fences. The molecules can rotate the light wave anywhere between zero and ninety degrees. Zero degrees, and none of the light will make it through the second fence, since it will all be vertically oriented. Ninety degrees, and all of the light will be able to slot through the first and second fence, since it will have started out vertically oriented and ended horizontally oriented. Anywhere in between, and some of the light will make it through the second fence, but not all.

The fact that each subpixel can control exactly how much of its color gets through – that it’s not all-or-nothing – is how we get such a huge variety of colors. The total color we see from one pixel is determined by the precise light-rotating technique of each component subpixel.

Like the gamma correction, though, this process assumes that you’re looking at your screen face-on. When you look at your screen from an angle, the colors that were supposed to be blocked actually leak through.

Let’s get to the punchline. Why does the viewing angle matter? Well, the outer layer has horizontal slits. So, the light that emerges from your screen will always be horizontally oriented. Picture a gigantic fan, held parallel to the ground: it extends in all directions left and right, but not up or down. This is how light emerges from your computer screen: flat, parallel to the ground. So, if you move your head so that you’re above or below the screen, you dramatically reduce the amount of light that reaches you. Remember, though, that from this angle, blocked colors leak through!

Look back at our pink rectangle from before. Each pixel in that rectangle has the same color: a result of the combined efforts of red, green, and blue subpixels. Each red subpixel is letting 100% of its light through (in other words, is rotating the light the full 90 degrees, so that it can slip out of the second gate and into our eyes) while the green and blue subpixels are blocking half of their light: they rotate it part of the way, and only let 50% through. When you look from above, what was once blocked is now leaking: you see more green and blue than you did from face-on. Red was never blocked, though, so you don’t see it from above. The net effect: a combination of green and blue, and no red. That’s cyan! That explains why we see cyan from above.

But shouldn’t that mean that we see cyan from above and below? Yes – if it weren’t for the gamma correction. If you recall, the gamma correction controls brightness. Face-on, the “bright” color is red (since more of it is let through) and the dimmer, darker colors are green and blue. From above, the opposite is true.

Now, recall that from above, the gamma correction undercompensates: there’s too much sensitivity to light shades. That supports the fact that we see cyan. From below, though, the gamma correction overcompensates: there’s too much sensitivity to dark shades! Too much sensitivity to, in this case, red.

And that’s what we see.

The Search for the Loneliest Whale in the World (Pt. 3)

Hannah Cheng — Mon, 11 Mar 2013 16:46:12 +0000

This is the final installment in a three-part series about the decades-long search for a mysterious whale whose calls have been haunting researchers for years. Part 1 can be read here and Part 2 is available here.

52 Hertz is a mystery, but so many of people’s common questions–Is he deformed? Is he really alone? Is he even really a whale?–could be answered with simple observation. Why hasn’t there been any? Why haven’t we studied 52 Hertz more closely?

For one thing, the Navy, which remains an important source of marine bioacoustics data, is not interested in finding a single benign whale. They have different things to worry about.

Then there’s the fact that even if private researchers want to use the Navy’s data for a civilian project, they would have to deal with the time lag between 52 Hertz passing the hydrophones and actually processing the data. Though the Woods Hole team had managed to construct maps of 52 Hertz’s journeys, this information had only become available miles and days after the whale had passed. The raw data has to be processed by trusted ex-Navy specialists before being handed over to NOAA or Woods Hole to be logged and analyzed further. The data also has to be declassified before researchers can release their findings to the public—even if revelations about a whale’s social status hardly seems like a threat to national security.

Using delayed data allowed oceanographers to map 52 Hertz’s travels whenever he was within the hydrophone system’s range. Photo: Jayne Doucette

Not much can be done about declassifying data in a timely manner. But nowadays, the actual data-gathering process about a whale’s location seems like it could be done in the private sector in a speedy manner. After all, we have GPS tags and near-instant satellite communication, right?

Christopher Clark, at the Cornell Lab of Ornithology, has created hydrophone systems that relay information within fifteen minutes of detecting a whale for his Right Whale Listening Network project. Created with funding from oil companies seeking to reduce fatal collisions between their freighters and endangered whales, these microphones are equipped with advanced computers technically very similar to an iPhone. These recorders can convey data in near-real time, with smart processors programmed to identify whale-like sounds so that only pertinent clips are sent to human analysts for verification. Corporate ships then can be warned of a whale’s presence quickly—possibly quickly enough for a person intentionally tracking a whale to make a visual.

Unfortunately, these sophisticated auto-detection buoys are expensive to install, costing over $100,000 per unit. A corporation would choose to install these where their ships are likely to run into pregnant right whales calving in shallow waters, close to shore, rather than out in the deep. Using hydrophones to intentionally make visual contact with a single deep-sea individual would not rank high on any corporation’s priorities. That leaves the search up to researchers, whose pocketbooks are much more limited.

Traditional stationary hydrophones are not the only option available to interested researchers. Woods Hole has recently come up with another solution: re-purposing some torpedo-shaped robots that can navigate themselves to record and identify whale calls with an suite of acoustic software and to report the whale’s location almost instantly via a satellite connection.

Though Clark’s auto-detection buoys and Woods Hole’s new autonomous gliders were developed in order to quickly locate and report the locations of endangered whales to protect them from ship collisions, researchers could potentially use this kind of technology to find a targeted whale. But again, according to Clark, priorities work against 52 Hertz.

“There typically isn’t that urgency of knowing something within twenty to thirty minutes. You don’t need to know whether there’s a whale half an hour ago,” he said. Gathering data about seasonal and spatial movements of viable whale families requires long-term monitoring, and since time is money, researchers have to choose their goals wisely.

In economical terms, finding a single, anomalous whale doesn’t make as much sense as locating and tracking sustainable populations. The most efficient business plan for researchers’ limited budget and purposes would be to invest most of a project’s money into processing data, the real meat to be had from fieldwork. Using cheap, long-term hydrophone networks to collect a significant amount of data may take months or years, but processing that data would then take mere weeks.

Even though corporations and institutions rank 52 Hertz a low priority, Clark is also unabashedly optimistic that people’s natural curiosity will find a way around funding issues. Having witnessed technology make extraordinary leaps in the past twenty years, he believes it is only a matter of time before any regular Joe has access to cost-efficient technology to jury-rig their own hydrophone system—meaning that one day, anyone who hopes to track 52 Hertz down for a hug simply has to have the initiative to begin searching.

***

During 52 Hertz’s breakthrough into pop culture, tentative theories solidified into fact without any real scientific backing. Researchers drawn into the 52 Hertz phenomenon shake their heads at the hype, but at the same time they recognize that beneath the embellishments, Watkins’ whale is still interesting. Maybe 52 Hertz is not the hero in some one-whale-against-the-whole-ocean epic, but he is a thread people can follow into the world of marine biology and bioacoustics.

Will knowing more facts about Watkins’ whale and the possibility of other hybrid whales interacting normally with regular citizens of the sea destroy the magic and charm of 52 Hertz?

This seems unlikely. 52 Hertz has become a disembodied idea, an icon, and a beacon for positive modes of creation and exploration. As Christopher Clark sees it, if 52 Hertz wakens the public’s imaginations and makes them curious about listening to the vast library of sounds from the ocean, then all the better for science in the long run.

“If you had went to an old library,” says Clark, referring to the pioneering days that had discovered 52 Hertz, “You would have found [just] a handful of papers of blue whales or fin whales. And that situation has changed dramatically in twenty years because more people are listening, and the more we listen, the more we discover, and the more we realize we don’t know.”

“You can’t stop curiosity, and we should promote curiosity,” he added. “We’re all better off for it.”

The Search for the Loneliest Whale in the World (Pt. 2)

Hannah Cheng — Wed, 06 Mar 2013 16:50:38 +0000

This is the second installment in a three-part series about the decades-long search for a mysterious whale whose calls have been haunting researchers for years. Part 1 can be read here.

The researchers who listened to 52 Hertz’s calls over the years never had to lay eyes on the whale, mainly because they lacked the funds and opportunity to perform such a needle-in-the-haystack search. Bill Watkins and his group had to be satisfied with tracking him from the East Coast while he swam along the West Coast through data provided to them by the Navy.

A hydrophone used to record underwater sounds. Photo credit: Hannes Grobe.

The U.S. Navy had originally installed these billion-dollar hydrophone systems in deep waters to detect Soviet submarines during the Cold War. Laying down hundreds of miles of cable across the sea floor was an incredible investment of time and manpower for a project that was not really understood or well-tested. Fortunately, the gamble paid off. The North Pacific system was stable and sensitive enough to detect approaching subs lurking in the distances. But once the Cold War ended, the Navy was not quite sure what to do with the hydrophone systems.

They decided to open the recording systems up for civilian use. Visiting the hydrophones, let alone using them, still requires a security clearance, but having access to the data they gather is an immense boon for scientists who would not be able to afford installing such an expansive open ocean system on their own dime. With the Navy’s acoustic data, marine biologists and bioacoustics experts were able to map seasonal migratory patterns of blue and fin whales for the first time.

Oceanographers at Woods Hole and researchers at the National Oceanic and Atmospheric Administration (NOAA) have shared the Navy’s data on marine mammals since the early 1990s. Watkins was the first person to identify 52 Hertz as a baleen whale. These days, researchers tend to think 52 Hertz is probably a hybrid between a blue whale and a fin whale, two closely related suborders of baleens.

There is also the possibility that 52 Hertz could be a linguistic hybrid. Whales have very localized dialects, meaning that a blue whale from the Atlantic would sound different from a blue whale from the Pacific. There are even regional differences between the North and South Pacific blue whales.

Does this mean that neither blue nor fin whales can hear or understand 52 Hertz? Christopher Clark, director of the bioacoustics research program at the Cornell Lab of Ornithology, does not think so.

“[Whales] share many characteristics in their social structure,” Clark says. “When you get into their social sounds, that’s where you get this rich mixture of loudness, and the structures are very context-dependent…that’s where you find there’s a great deal of overlap between these kinds of sounds between different kinds of species.”

The easiest social sound to recognize and compare between species is the male mating song, which Clark termed “very elaborate acoustic displays” to advertise a whale’s robustness. These are the sounds that Watkins’ group was using to track their whales, leading to most researchers referring to 52 Hertz as a “he.”

“The males make the loudest call, so we could probably pick them up from farther away,” says David Mellinger, project leader and senior researcher of NOAA’s ocean sounds research group. When asked if females were just too quiet for hydrophones to pick up, he conceded that “there could be females [with 52 Hertz] that are just quieter or just silent. It could be that this male just travels alone for parts of the time.”

So 52 Hertz: the lonely whale, or the loner whale?

Until further research can be done, all we can do is speculate. There is no proof that other whales shun him upon contact—just as there is no proof that they don’t. 52 Hertz could be meeting up with friendly whales somewhere in uncharted waters, leaving them to follow a favored food source up and down the latitudinal lanes of the North Pacific—or he could be just as lonely as the world at large pictures him. From here, any more speculation about the individual 52 Hertz has no scientific bearing.

His call still may be a result of deformation, but the fact that he managed to survive for the twelve years that Watkins tracked him is a testament that he is not debilitated. With extended observation, any combination of possibilities could be rendered as fact.

The Search for the Loneliest Whale in the World (Pt. 1)

Hannah Cheng — Tue, 05 Mar 2013 15:13:04 +0000

Somewhere off the west coast of British Columbia wanders a whale—at least, his voice can be heard there. He appears to be alone.

Simply by eavesdropping, scientists have deduced a few details about this whale. He swims the cold waters of the North Pacific, probably in pursuit of food and love. In all likelihood, he is a baleen whale: a long, grey tanker with a pointed head and generous lower jaw. For food, he would chase clouds of plankton and tiny shrimp-like creatures called krill, gulping gallons of water into his mouth and pushing it all out through two long furry-looking plates sprouting from the roof of his mouth where one would expect teeth. These plates, called baleen, filter krill and other crustaceans out of the expelled water. Miraculously, these tiny creatures are all the sustenance this giant mammal needs to survive.

The baleen whale suborder includes blue whales (above) and fin whales. 52 Hertz could be either. (Photo: Creative Commons)

For love, he calls out in long, low moans. Each intonation lasts anywhere from five to fifteen seconds, and he waits up to thirty seconds between each cry, taking ten minute breaks between each song. He will sing like this for hours. His voice carries for miles, and any females nearby would surely take note of his voice’s strength and range, the variety of his repertoire, the duration of his song. In the murky dark where a whale can barely see its own tail, the quality of these musical elements should prove that he is a worthy mate.

Despite his efforts, he receives no reply. Meet 52 Hertz: the loneliest whale in the world.

It was 1989. At the Woods Hole Oceanographic Institute in Massachusetts, William “Bill” Watkins, the man who invented the first underwater recording system, was in charge of categorizing the mysterious moans and groans resonating through the ocean. His team had begun cataloguing whale mating calls, specifically tracking males because they vocalize so frequently. One day, Watkins noticed a high, unique voice easy to hear and identify over other background noises: the call of that lonely whale wandering the North Pacific alone.

There was something strange about this whale. The harmonic intervals—the rise and fall of his calls—resembled those of baleen whales, but these patterns were unlike any the team had heard so far. Even more notably, certain kinds of vocalizations, typically too low for humans to hear unaided, averaged to about 52 hertz.

In acoustics, increasing the number of hertz shifts the sound’s frequency higher, towards mosquitoes and cartoon characters and away from timpani drums and James Earl Jones. The corresponding vocalizations for a regular blue or fin whale falls somewhere around 15-20 hertz, the kind of frequency that you can feel in your bones when a car blasting a deep bass drives by but can barely register hearing (the human hearing range falls between 20 to 20,000 hertz). So transposing a regular whale’s call from 20 to 52 hertz means that a sound that usually registers as a marrow-deep mumble suddenly takes form as a recognizable note: still low by human standards, 52 hertz is on par with a lowest toot on a tuba.

This spectrogram of 52 Hertz’s calls was posting on the NOAA wesbite. Click on the picture to hear a recording of an actual 52hz call sped up to 520hz so it is easily audible to humans.

Why was this whale’s call comparatively so high? Was he deformed? Did he represent a previously undiscovered species? Was he a hybrid? Did the strange frequency of his voice isolate him from other whales?

At the time, Watkins had no answers; marine bioacoustics was still a young field, and Watkins and his team were not quite sure just how rare or important this anomaly was in the grand scheme of things. They did not linger on it much before returning to their research.

But something strange happened in the coming years. The whale continued swimming up and down the North Pacific alone, regularly passing within range of the Navy’s hydrophone system. In 1992, the Navy declassified more data that they had gathered, allowing Watkins and his colleagues to begin tracking this odd, tuba-sounding whale more closely. And for the next dozen years, they tracked it, assembling remarkably detailed maps of its migratory patterns.

Then, on September 24, 2004, just as the resulting paper was being prepared for publication in Deep Sea Research, Watkins succumbed to cancer. Mary Ann Daher, a marine biologist and colleague of his, became the corresponding author for the Woods Hole team’s work, which was published later that year. Then, on December 8, Reuters published a short article focusing on two key details from the research paper: the whale’s migratory patterns had seemed “unrelated to the presence or movements of other whale species” and its calls “did not match those from any other species.”

News articles multiplied in national and local papers, shifting focus from the whale’s research significance to its status as a lone whale with a unique voice. Among the journalists who followed up was Andrew Revkin at the New York Times, who wrote two articles about the case. The first focused on the research itself. The second examined the flood of empathy and sympathy for a creature that nobody had even laid eyes on, a reaction that continues to this day.

Since the research paper’s release, 52 Hertz, as the mystery mammal came to be called, has become associated with loneliness and isolation, inspiring a number of artistic works. Alternative rock band Dalmatian Rex and the Eigentones features “The Loneliest Whale in the World” on their Psychedelic Monsters album. Comedian Kate Micucci wrote a humorous song “Doreen the Whale,” while musician Laura Ann Bates performed a more somber “The Loneliest Creature on Earth.” Artist Mike Ambs runs an audio project called the loneliest mix, designed to share blue whale calls one mix-tape at a time. German author Agnieszka Jurek put together a book, 52 Hertz Wal, illustrated by Thies Schwarz. And, perhaps most ambitiously, director/writer Joshua Zeman is in the process of filming a full-length documentary on 52 Hertz’s discovery and people’s desire to connect and communicate with the lonely creature.

Yet 52 Hertz still swims on, alone. For despite the popular desire to find and maybe befriend him, we don’t know how to find 52 Hertz. We don’t even really know what he looks like.

Breaking the Cheetah Curse – Part III

Zahra Hirji — Wed, 27 Feb 2013 19:09:59 +0000

This is final installment of a three-part series about the idiosyncrasies of the cheetah–and the myriad struggles zoos face when attempting to mate these majestic felines in captivity. Part 2 can be read here; Part 1 is here.

Compared to other big cats, cheetahs are high maintenance. Captive cheetahs are prone to stress. They need space to run around and prefer privacy. Males need opportunities to live with other males; females need space to live alone. Attentive animal keepers need to correctly identify when a female is heat and then walk through male introductions. If a given male does not work out, ideally other eligible bachelors will be on hand.

It can be taxing for zoos to juggle specific cheetah mating demands along with those of other animals. But large, private off-site facilities, or “breeding centers,” offer a solution.

“You can look at the numbers over the last 25-30 years and the facilities that have by far had the best success are the ones that are keeping the larger numbers of cheetahs,” says Steve Bircher.

Cheetah cubs Carmelita and Justin, shortly after their May 2012 birth. Photo by Adrienne Crosier, Smithsonian Conservation Biology Institute

A handful of centers were initially built in the 1980s. Only in the last ten years have new centers cropped up, including the Smithsonian-run one in Virginia. The centers are spread out across the United States, from Florida to California. They range in size from 1,800 acres to 10,000 acres, and house between 12 to 30 cats.

One lingering issue is money. “When half of the [cheetah] population are in eight facilities, those eight facilities are really absorbing the cost,” says Smithsonian’s Adrienne Crosier. On average, it takes $9,000 to maintain one cheetah per year. This means centers with 15 plus cheetahs like Front Royal are spending upwards of $135,000 annually on cheetahs. Crosier is currently working on a proposal to share these costs across all AZA affiliated institutions.

Despite being one of the most studied animals, and the community commitment to these facilities, it is still a struggle to breed captive cheetahs. According to the AZA, at least 25 cubs a year are needed to maintain the current captive population and even more births are needed to increase it. Thus far in 2012 there have only been 14 cubs born, including the 2 cubs from the Smithsonian. Last year, only 12 cubs were born; in 2010, there were around 20 cubs.

Part of this difficulty stems not from getting cheetahs to mate generally, but getting the right cheetahs to mate. The heyday of captive cheetah breeding was in the 1990s. Since then, managers have been “more selective” with cat mating recommendations. And today many genetically valuable cheetahs are nearing or already past their breeding prime.

The goal is to breed cheetahs naturally, but especially with the other populations, assisted reproductive strategies could help. According to the AZA, artificial insemination “is the most practical” method. In the 1990s, female cheetahs were one of the first big cats to be successfully inseminated with male sperm outside of intercourse. But cheetah artificial insemination trials have not worked in the past 10 to 12 years, says Crosier. Even though “we changed virtually nothing.”

Another option is in vitro fertilization, where an egg and sperm are removed from a female and male cheetah, respectively. The fertilization, or combination of the egg and sperm, is done in the lab rather than in the cat. Then the fertilized egg is reinserted into a cheetah. This process oftentimes requires two females: one who donates the egg, and the other who brings the baby to term.

Crosier and colleagues have studied cheetahs beyond their breeding prime, ages nine and over. They discovered that the uteruses of older felines are prone to disease, likely a result of stress and genetic legacy issues, but their eggs are healthy. These findings were published in the journal Biology of Reproduction in 2011.

Although still in research phase, the eventual goal is to use the older females eggs for in vitro fertilization. The fertilized eggs will then be inserted into younger, healthy females. This method would preserve the genetic diversity of the older captive cheetahs, says Crosier.

Another option is ditching the genetic restrictions all together. If managers “pay less attention to higher levels of inbreeding,” Mother Nature may take care of the rest, suggests Bircher, who readily admits he is not a geneticist. History has shown that cheetahs are very resilient, he adds.

But the Smithsonian Institution, for one, has no intentions of ignoring genetics, says Crosier. For cheetahs, and many other captive endangered animals, preserving genetic diversity is just as important as making new babies.

***

Today, Ally’s two young carefree cubs can be seen zooming around their pen in Washington D.C. Despite their rocky entrance into this world, they are healthy and playful. But in the not-so-distant future, the cubs will start their own breeding journeys.

“If you have one animal breed and its offspring never breeds, we are losing that genetic line,” says Laurie Marker. The importance of these cubs mating cannot be overstated.

Hand-raised cubs are often handicapped by a lack of exposure to other cheetahs. Aware of this, keepers at the Smithsonian have been arranging regular play dates with the other zoo cheetahs and strict about not excessively handling the cubs. Whether the young cats successfully receive enough social skills for mating, only time will tell.

But let’s say they do – then what? “Can we still save the species?” asks Marker, who more than Crosier and Bircher is focused on wild populations.

The distant end goal is to eliminate the human stresses on wild cheetahs and rebuild their population, potentially using captive born cheetahs for this mission. But until captive breeding success rates skyrocket, the struggle of the wild cheetahs is largely being put on hold.

However, cheetahs on exhibit like Carmelita and Justin are helping to make this point. As “great little ambassadors for their species,” said Crosier, the two fluff balls are promoting awareness about cheetah conservation in their own adorable way.

Breaking the Cheetah Curse – Part II

Zahra Hirji — Tue, 26 Feb 2013 14:37:39 +0000

This is the second part of a three-piece feature on the idiosyncrasies of the cheetah–and the myriad struggles zoos face when attempting to mate these majestic felines in captivity. Part One is here; the final installment will be posted tomorrow.

Cheetahs exude elegance. With a more slender frame than lions and tigers, the sleek hunters are built to run fast—70 miles per hour fast—and look good doing it. Prized for their beauty and hunting prowess, owning cheetahs was a symbol of wealth and power in places like Egypt, India, and China. Records of collecting cheetahs date back to 3000 BC. But even back then mating cheetahs was recognized as a near impossible task.

The first record of a successful cheetah mating in captivity did not occur until the 1600s at the home of ostentatious cheetah collector Akbar the Great. A famous Indian mogul, he was purported to have owned over 1,000 cheetahs and used them as hunting companions. The second instance occurred around 300 years later at the Philadelphia Zoo in 1957. Both matings were “accidental.”

Photo by Janice Sveda, Smithsonian’s National Zoo

Admittedly historical cheetah collectors and zoos were not trying too hard to mate cheetahs, as wild cheetahs were seemingly abundant and easily obtainable. This relaxed breeding attitude made its own small dent in wild populations: Between 1829, when the first known cheetah was showcased in a zoo, and 1994, over 1,567 wild-caught cheetahs were transferred to some 373 facilities. Until the 1960s, most of those captive cats died within a year.

Everything changed in 1973. The United States passed the Endangered Species Act, the result of an international agreement to protect animals in danger of extinction like the cheetah. This move effectively ended the commercial cat trade overnight, says Steve Bircher, curator of mammals and carnivores at the St. Louis Zoo and director for the Center for Cheetah Conservation in Africa. Cheetahs could still travel across borders for research purposes, but the process was heavily regulated by the Department of Fish and Wildlife.

Most wild-caught cheetahs exported to zoos around the world came from Namibia. As a result, the wild populations there plummeted. When the Endangered Species Act was passed, the Namibian government decided to end its export of cheetahs categorically to all countries, says Bircher.

Except for a “gift of ten cheetahs” given to the United States in 2002 from Namibia’s President Sam Nujoma, no cheetahs have legally left the African country in over forty years, explained Laurie Marker, director of the Namibian-based nonprofit Cheetah Conservation Fund. During recent decades, Namibia’s cheetah population has rebounded slightly and now the county hosts the largest wild population with approximately 3,500 cats.

Without easy access to cheetahs, zoos were forced to redefine themselves. They shed their prodigal past and confronted the question that had nagged animal keepers for centuries, “Why are cheetahs so hard to mate in captivity?” A wave of research followed and zoos started working together. Leading the collaboration was the Association of Zoos and Aquariums, which developed the first long-term cheetah species survival plan (SSP) in 1984. The plan, which is updated annually, includes a cheetah census, as well as target cheetah population numbers, breeding strategies, and research goals.

Cheetahs were not the first animal, nor the last, to be recognized by the AZA as candidates for a species survival plan. Today there are hundreds of different SSPs for animals of all kinds, including reptiles, birds, and many mammals. But the 1980s efforts to thoroughly study and tailor captive cheetah breeding strategies paved the way for more species-specialized zoo management practices.

Observations of wild cheetahs in their natural habitat, open savannahs, revealed that they have a unique social structure. Lions live in large families called prides. Tigers and leopards are mostly solitary. Cheetahs are somewhere in the middle: female cheetahs live alone, except during child rearing, and males tend to live together in small packs, called coalitions.

The two sexes only interact to breed, and even then females are only interested if they are cycling, or in heat. Thus, the initial zoo strategy of bunking female and male cheetahs together defied the cats’ very nature.

While some researchers started watching cheetahs from afar, another group took an opposite approach and starting collecting blood, urine, and stool samples. Written into the cheetah’s genes, researchers stumbled upon the cat’s dark history. Around 10,000 years ago, cheetahs nearly went extinct. An estimated 10-20 individuals survived, the ancestors of all living cheetahs today. Consequently, current “cheetahs have almost zero percent of genetic variability,” says Steve Bircher. They are “all like brothers and sisters.”

Could the lack of genetic diversity having a lingering effect? Studies of male cheetah sperm showed startlingly low sperm counts; about one-tenth the normal counts of lions, tigers, and domestic cats, according to Bircher. This was initially thought to explain low captive birth rates until it was realized that wild Namibian males with similarly low sperm counts reproduce just fine.

“Lack of genetic variability is not what has hampered the cheetah ability to breed,” says Bircher. “Quite simply, it’s how we managed cheetahs.”

***

After Ally’s brief encounter with Caprivi, her body started changing. Hormone levels skyrocketed, and at meal times she gorged herself. Still, it took two months to definitively confirm that she was pregnant. By that point, she’d already moved to the facility’s maternity ward – a much larger pen with full surveillance.

Then, on the morning of April 22, 2012, Ally stopped eating, a sure sign that she was about to give birth. Keeper Lacey Braun stayed overnight, but Ally showed no change. The next morning, at 9:30 am, a boy cub was born. It was a huge victory for the National Zoo – but for the cheetah staff, the work wasn’t over yet.

Similarly to what had happened to her, Ally disappointingly abandoned her cub. “We see a lot of maternal neglect in this species, especially with first-time mothers. This was her first pregnancy,” Adrienne Crosier says.

When Braun retrieved the newborn, it had stopped breathing. Alone with the cub, she frantically pressed his chess to get the lungs pumping air again. Again and again she tried, until finally he stirred. With a rush of relief, she immediately started on the hand-rearing process. With a little baby bottle, she fed him kitten formula, the same kind available at any pet store.

To the zookeepers’ surprise, Ally resumed normal non-pregnant behavior almost immediately. “Based on Ally’s body condition and weight gain, we really thought there were multiple cubs in the litter,” says Crosier. The team anxiously watched and waited all day until it became clear Ally would not be going back into labor. With the cubs and her own life at stake, the caretakers finally intervened and moved Ally to the on-site animal hospital.

An x-ray revealed three cubs still in utero. An emergency C-section, a risky operation, was the only option. “There were about ten of us there. We had three teams of two,” says Crosier. There was one team for each cub. “The first cub had a heart beat after the surgery, but it took two hours to get him breathing easily,” says Crosier. To everyone’s relief, the first cub survived. Unfortunately the second and third cubs died.

A father on a mission, Caprivi was brought into the hospital to donate plasma, nutrient rich blood, to the cubs. This material is normally passed to cubs through nursing, but Ally was in no condition to help. Due to the operation, describes Crosier, “Ally lost a lot of blood. She was pretty close to losing her life as it was on the table.”

After that night at the hospital, the family split. Ally remained hospitalized for a week, eventually returning to her independent life; Caprivi joined his brothers; and the two cubs spent their first three weeks in a clean, isolated hospital room under intensive supervision.

On May 18, 2012, nearly four months after Ally’s fence introduction with Caprivi, the precious cubs made the near 70 mile drive to Washington D.C., their current home. There the cats were named Carmelita and Justin after the 2012 American Olympic sprinters Carmelita Jeeter and Justin Gatlin, and placed on exhibit over the summer.

Breaking the Cheetah Curse – Part I

Zahra Hirji — Mon, 25 Feb 2013 02:48:13 +0000

This is three-piece story about the idiosyncrasies of the cheetah–and the myriad struggles zoos face when attempting to mate these majestic felines in captivity.

A pair of cheetah cubs, a brother and sister named Justin and Carmelita, has charmed Smithsonian National Zoo visitors in Washington D.C. since their public debut in July 2012. The eleven-month old cats have shed their baby fuzz for sleek orange fur patterned with black spots. Yet despite their adult stature, the cats still act like rambunctious youngsters, chasing each other around their pen and playfully wrestling.

This is all good for now – but in a year’s time these young cats will be taken off exhibit, just like their parents before them, and started down parallel paths to confront their destiny as genetically robust cheetahs, sired to save their species from extinction.

Ally, the proud mother of new cheetah cubs. Photo courtesy of Mehgan Murphy, Smithsonian’s National Zoo.

The world has undergone a massive cheetah drain over the last century largely due to loss of natural habitats and conflicts with humans. Wild cheetah populations have plunged 90 percent, from around 100,000 cheetahs in the early 1900s to roughly 10,000 today. The situation is further complicated by low genetic variability among the species. Saving the cheetahs from extinctions means not only increasing numbers, but also ensuring the new population is genetically healthy.

In recent decades, zoos like the Smithsonian have taken on this challenge. But there’s a hitch: breeding cheetahs in captivity is not easy. And despite decades of advances in understanding cheetah biology and behavior, and cultivating cheetah-appropriate reproduction strategies, current captive birth rates are still failing expectations.

***

Off a quiet road, hidden in the Virginia wilderness lies the Smithsonian Conservation Biology Institute, the National Zoo’s private breeding and research facility. Built in 2007, the 3,200-acre plot comfortably houses multiple species, including one of the largest cheetah populations in the United States with 17 cats.

On January 20, 2012, Adrienne Crosier, a cheetah research biologist, noticed one of the Smithsonian female cheetahs repeatedly peeing in the same spot in her pen. Ally had never been an easy cat to interpret: Abandoned by her mom as a two-month-old, she was a “nervous” youngster. For this reason, Crosier had kept close watch on Ally for years to see if the shy, petite feline would ever showed signs that she was ready to mate. Cheetah-reared cubs can mate as early as two or three, but the biologist still had doubts about Ally at age four.

One of fewer than fifty experts in cheetah reproduction worldwide, Crosier has worked with wild and captive cheetahs for over a decade. At the Smithsonian’s Virginia campus, she advocates natural cheetah breeding, but also researches assisted reproduction methods such as artificial insemination. Her work contributes to a global effort spearheaded by the nonprofit Association of Zoos and Aquariums (AZA) to save the endangered felines from elimination.

Compared to other big cats, cheetahs are especially prone to disease and physiological abnormalities due to low genetic variability. Subsequently, the AZA has mandated that breeders only mate cheetahs from different lineages to produce cubs with good, diverse genes.

That cold day in January, Crosier had a hunch Ally was in heat, or “estrus, and ready to mate. Along with lead cheetah keeper Lacey Braun, Crosier decided to play matchmaker. Ally was temporarily whisked from her pen. Three male brothers, all equally recommended by the AZA as potential suitors, were then paraded in for a “smell test.”

The siblings curiously toured the pen, nose to the ground. Within minutes, Caprivi, a young, spry four-year old had detected the intoxicating scent of a female in heat and was enamored. Anxious to meet the mysterious feline, Caprivi started cooing excitedly, a cheetah-specific vocalization called stutter barking.

Caprivi’s brothers were not interested – not an uncommon occurrence, as cheetahs can be incredibly picky about mate choice compared to other big cats, including lions, tigers, and leopards. The two apathetic brothers were sent back to their pen, while the courting cats were prepped for a standard first cheetah date: a “fence introduction.” Caprivi was moved to an adjacent holding area, and Ally was returned to her enclosure. A metal fence separated the two pens. Despite living in the same facility for over two years, this was the first time the cats had met.

Would Caprivi like Ally in the flesh – and would she like him back? If either cat hisses, howls, or displays any other type of aggressive behavior, their breeding is called off. The keepers remain nearby, like bouncers, ready to break up a fight.

Upon seeing Ally at last, Caprivi only got more excited. He eagerly ran to the shared fence, crooning in pleasure. Ideally, Ally would also have run to the fence to touch noses or dip her hips suggestively. Instead, she stood still and silent.

Since there was no aggressive behavior, however, Crosier and Braun made the call to bring the cats into the same pen and see what happened. Whether the cheetahs mated was up to Ally: She could either sit on her butt, sending a hard Not Interested message, or take to the eager suitor.

Within ten minutes of sharing a pen the cats had mated. After which, they quickly separated – typical behavior for cheetahs, who even in the wild are more inclined towards one-night stands rather than committed relationships.

The entire courtship, from introduction to mating, took less than a day, but the ramp-up for this pairing was years in the making. It involved thousands of dollars, the coordination of three zoos, and years of closely monitoring the cheetahs.

At this point, Caprivi’s job was done. But for Ally and the zookeepers, two months down the line a turbulent delivery loomed.

The Prismatic Typewriter

Trent Knoss — Mon, 17 Sep 2012 19:34:04 +0000

The Olivetti Lettera 35 typewriter is a bona fide endangered species these days. The clunky clack-clacking word processor that filled Italian offices circa 1970 is mostly relegated to curio shops, hobbyist attics, and eBay now. I hadn’t seen any in years and yet as I enter a darkened corner of the M.I.T. Museum, one appears before me like a phantom out of thin air thin air. I don’t believe in ghosts, but I’m coming around to holograms.

My brain knew, on some level, not to trust my lying eyes. It understood that what I’m seeing is actually a light interference pattern transposed on to a reflecting surface by a split laser beam. Yet the spectral image is so tantalizingly lifelike that it isn’t so hard to imagine an author’s fingers tapping away at its keys. A single page – crinkled, ink-stained, and the only “real” thing about the exhibit – rests above the ribbon spool; it contains the faded text of a Jorge Luis Borges poem. Borges would certainly recognize the motif; the plot of his 1942 story “Death and the Compass” turns on a cryptic page found in a murdered man’s typewriter.

Suffice to say, Dora Tass’s Perturbing Object casts a spooky spell. As mixed media art, it’s a commentary on modern day communication, a riff on the notion that words and ideas are transmitted via intangible means. As science, it’s an example of holography’s enduring power to entice the eye as it interacts with that most fickle substance, light. The artist has clearly gone to great (wave)lengths to calibrate the 3D image fidelity; this is no cheap parlor trick like Pepper’s Ghost, which uses lights and mirrors to create a hologram-like effect. Unlike two-dimensional media, each piece of a transmission hologram, no matter how small, contains the entire image. I tilt my head and the refraction contorts, adjusting to my glance. A half step to one side and it dissipates entirely. I play with other angles, searching for the precise point where my brain sees a typewriter instead of an empty wall.

Tass’s artwork is surrounded in the hall by holography displays from other international artists. Wandering through, I admire a bust of Aphrodite; a cascade of color-morphing leaves; a molten obelisk; and the most prominent display, a tight-lipped visage of Queen Elizabeth. But walking home, I keep returning to that typewriter; it takes up quiet residence in my thoughts. We think of holograms as vaguely futuristic (even though they’ve been around for the better part of six decades). But will they become the way that humans experience the recent past, too? Our cultural artifacts preserved in virtual verisimilitude? The bulkiness of an Olivetti transformed into pure light?

The Weak Link in the Chain: Intelligence

Dan Falk — Wed, 28 Mar 2012 21:27:33 +0000

In my previous blog post, I talked about the likelihood – or unlikelihood – of your existence. The fact that you’re here, and I’m here, is contingent on a vast array of happenings that all had to come about first.

To narrow things down a bit, let’s say that the first few hurdles have already been met: Suppose we already have a universe with the sorts of physical parameters and physical laws that we now observe. And let’s say that universe is filled with an enormous number of stars with an enormous number of planets. Given all of that, what are the odds that you’d end up with (a) living things and (b) intelligence?

Over the last decade or so, astronomers have found more than 500 planets orbiting stars beyond our own sun. Recently, the first “potentially habitable” planet was announced, based on data from the orbiting Kepler telescope. NASA already sponsors research on “astrobiology” – roughly, the science of figuring out what kind of life might be “out there.” And most scientists, I suspect, wouldn’t be shocked if some sort of definitive sign of extraterrestrial life were discovered within the next couple of decades. Thrilled, but not shocked. We don’t have any numbers yet, of course, but it’s worth noting that simple one-celled creatures sprung up on our planet within 1.7 billion years or so of its formation (which doesn’t mean life sprang up overnight; but still, that’s sort of fast in terms of the planet’s 4.5-billion-year history).

But intelligent life is another matter. On our planet, intelligence is the new kid on the block. Our own species, Homo sapiens, have been around for about 200,000 years – a mere speck in terms of Earth’s history. And we’ve only been using the tools of science for about 400 years.

Now, it’s hard to draw conclusions based on one data point, but we can always engage in a bit of educated speculation. This is where things get messy, but, they get messy in an interesting way. A good starting point is the late 20^th-century debate between two great evolutionary biologists, Stephen J. Gould and Simon Conway Morris.

Stephen Jay Gould argued, in a nutshell, that the appearance of human beings was highly contingent, that is, it was dependent on a whole series of earlier evolutionary happenings, and therefore very “unlikely.” As Gould explained in his book, Wonderful Life: Life as we know it would have been profoundly different if conditions at the start of the evolutionary process, and along the way, had been only slightly different. The very features that make human beings human – intelligence and language in particular – are radically contingent. In Gould’s words: “Replay the tape a million times from the beginning, and I doubt that anything like Homo sapiens would ever evolve again.”

Note, Gould fought tirelessly against the Creationist movement, but religious opponents of Darwinism, whether creationists or proponents of “intelligent design,” just loved hearing about how unlikely it was for humans to appear on this planet: after all, they argued, what better proof that a loving God had engineered it all.

At any rate, Gould’s view wasn’t the only game in town, even among evolutionists. Simon Conway Morris takes quite a different view, hinted at in the title of his book, Life’s Solution – Inevitable Humans in a Lonely Universe. Replay the tape, he says, and the same broad patterns will emerge. The reason is something called “convergence”: roughly, if similar environments appear, then similar adaptations will appear also. For example, the eye has evolved as many as 40 times, in various lineages, over millions of years.

On the other hand, the very things that seem to make humans human – such as the use of complex symbolic language – appear to have arisen only once. Moreover, full-blown language seems to have appeared only after Homo sapiens had already lived on this planet for tens of thousands of years. In other words, while language may have arisen as an adaptation, it isn’t just a matter of biology. As Ian Tattersall of the American Museum of Natural History puts it: “Human symbolic consciousness, which is the underpinning of our cognitive singularity, is a very recent acquisition in the human lineage. And, even more importantly, it’s not a simple extrapolation of the trends that preceded it.”

Which means that even if life itself is common in the universe, linguistic, symbol-using creatures like ourselves may be quite rare indeed. This may be the reason that all of our SETI efforts – the search for extraterrestrial intelligence, primarily via searches for radio signal – have turned up nothing, after a half-century of scanning the heavens.

In Part One of this blog post, I mentioned one of the works of literature that re-kindled my interest in this subject – Italo Calvino’s Cosmicomics. I focused in particular on the short story “How Much Shall We Bet,” in which two characters make an endless series of bets regarding what sorts of things will happen in their universe. They’d don’t specifically bet on the appearance of intelligent life, but they may as well have; it underlies all the other developments that come after.

In Calvino’s story, the character named Dean is the skeptic; he always bets no. And in this case, I’d have to side with him. Worlds may be likely, oceans and continents may be likely, even life may be likely. But the stuff that makes us human – from ploughs to pyramids, from fettucini to Facebook – may be unique to our world, the slings and arrows of outrageous fortune, never to be repeated.

Update on the Satellite that Fell From the Sky

Conor Myhrvold — Fri, 09 Mar 2012 22:05:18 +0000

In mid-January I reported on the remains of a Russian satellite discovered on a remote beach in the Grenadines. The satellite washed ashore in mid-December and I concluded that its history – including how it got there – was an unsolved mystery.

Well, it appears to no longer be a mystery, as more details have emerged. Dwight Parsons, a local tour operator in the Grenadines, commented on my personal website with additional details on the satellite discovery, which he says he was part of, on December 6, 2011 at 10 AM on Petit Tabac island. He says the satellite was pulled and tied up 34 days later (as my mid-January photos depict).

The satellite fragment was indeed part of a Russian Soyuz 3 Rocket by Arianne Space Solutions. The US Embassy in Barbados, not the Grenadines, confirmed that it was similar to a piece that washed up in Barbados in July 2011. Three informative pieces on CNN iReport located here, here, and here contain photos of the satellite soon after the discovery.

The purpose of the satellite and the larger program it was part of remains unknown.