Percival Lowell mapped the straight lines he observed on the Martian surface, which he believed to be intentionally engineered canals.
Bridge on the Moon
Robert Dyrda
This image shows the region on the Moon in which John J. O'Neill reported seeing a gigantic natural bridge in 1953.
The Face on Mars
NASA
In the 1970s, the Viking mission took this image of a formation in the Cydonia region of Mars that resembled a human face.
...Or Is It?
NASA/JPL/Malin Space Science Systems
In 2001, the Mars Orbiter Camera acquired this high-resolution image of the same formation in Cydonia, which showed the "face" to actually be a highly eroded mesa that looks like a human face at certain times, due to shadows and lighting.
The Inca City
NASA/JPL/Malin Space Science Systems
In 1972 scientists on the Mariner 9 mission gave the informal name "Inca City" to this area of intersecting ridges in the south polar region of Mars.
Like yellow fever, dengue is hemorrhagic and spread by the Aedes mosquito. Unlike yellow fever, dengue is commonly an urban infection and has no effective vaccine. While infected persons will develop immunity after a bout with the disease, it persists in densely populated locales because it exists in four different strains. Antibodies for each one are useless against the others. Dengue periodically appears in large outbreaks, the most recent of which is in Rio de Janeiro, where an estimated 100,000 people have been infected so far in 2008.
Because little can be done about the virus once it infects, efforts to control dengue are focused on controlling the mosquito which carries it. Anyone in this country who has lived in an area in which West Nile virus is a threat is doubtless familiar with the need to remove standing water with vigilance. Whether kicking over discarded tires or emptying plastic cups left in the rain, any disruption of the mosquito's breeding grounds means a reduction in larvae which may survive to become dengue hosts.
Enterovirus 71
Hand, foot and mouth disease is a pretty common childhood illness caused by a variety of viruses generally considered to be benign. Infected kids get a mild fever and spots around their mouths; the whole thing lasts a few weeks. No big deal -- until one of the strains, enterovirus 71, decides to ratchet things up substantially and become highly lethal. Cases of sudden death from EV71 in children have been steadily increasing in Asia since the late 1990s. The most recent outbreak, which began in early May in southern China, has already claimed the lives of nearly 40 children under the age of six, with the number of reported infections climbing into the tens of thousands.
It's unclear just how the fatal strain of EV71 manages to kill, but the evidence so far seems to indicate that it travels into the brain stem of a child and from there shuts down the respiratory system. Like many of the viruses on this list, no treatment or vaccine exists. What's worse, there is no reason to think it won't make its way to the U.S. And, as Dr. Dowell explains, "if it does come to the U.S., there's no real reason to think that we would do any better with it than the Chinese in Anhui providence have."
Influenza A (Avian Flu)
Cynthia Goldsmith
All that stands between us and an influenza pandemic on a scale that could dwarf the Spanish Flu of 1918 is a handful of genetic mutations in a virus known to have a high mutation rate. Presently, the influenza variant known as H5N1—commonly called the avian flu—can only readily move from an infected bird to a human. We have been lucky to limit its spread to no further than any one single family cluster, but that is largely due to the fact that it has yet to acquire the ability to move effectively from human to human. It could simply be a matter of the virus having yet to land in someone already infected with another strain of influenza for H5N1 to pick up the genetic material necessary to make the leap.
To give you a little historical perspective of where we may be headed, consider the influenza pandemic of 1918. The overall mortality rate of that flu was considerably higher than the normal annual rate of flu infections, topping out around 2 percent. The H5N1 variant has shown itself to have a mortality rate in the neighborhood of 60%. According to Dr. Dowell, "if there are a few mutations in that virus and it acquires the ability to spread efficiently from person to person, it's hard to imagine historically anything to compare it with."
Vibrio Cholerae
Within hours of contracting cholera, it is possible to die. The bacteria attach to the wall of the small intestine and immediately begin producing toxic proteins that induce severe, unrelenting diarrhea. Without a very simple remedy of salt and sugar water, a person can dehydrate to the point of dangerously low blood pressure, followed by shock and heart failure.
Fortunately, it is relatively easy to control. With proper sanitation and access to clean water, cholera infections are readily kept at bay. When good medical care is available, the mortality rate stays below 1 percent. It's when conditions are bad that cholera thrives. During the Rwandan genocide of 1994, nearly 80 percent of infected, unaccompanied child refugees in Zaire died within the course of a single month.
The world is currently in the midst of the longest running cholera pandemic, which has persisted as it has because the strain responsible manages to hide in people without infection more capably than previous variants. Some estimates put the ratio at 50:1 for carriers to actively infected. It has this year appeared as an exceptionally large outbreak in sub-Saharan Africa. It's also been seen in Vietnam and last fall in Iraq.
Extensively Drug Resistant Tuberculosis
Tuberculosis was once called consumption, because of the way it would overtake a person's being, appearing to consume them from within. Infection causes the victim's eyes to redden and swell, and skin slowly to go pale; the incessant coughing eventually brings up blood. It is an old disease. Its effects have been seen in the bones of prehistoric man. It has managed to insinuate itself in the human population so thoroughly that the World Health Organization estimates one out of every three people on Earth has been exposed to it.
For a disease with which we have had such a long and intimate relationship, one would hope we'd have a pretty good handle on things by now. While we have for many years been adeptly developing antibiotics to fight TB, the tuberculosis bacterium has in many ways been more adept at surviving them. Of particular concern are the strains of TB classified as multiple-drug-resistant (MDR-TB); at the top of that list is XDR-TB, or extensively-drug-resistant tuberculosis.
XDR-TB is of great concern because it is now resistant to not only the first- and second-line antibiotic agents, but one of the third line as well. The strain is making us reach deep within our well of defenses, and the current concern is that it will soon outpace the remainder of the third line. It has a much higher mortality rate than even MDR-TB, and can be a terribly severe infection. Fortunately, the trade-off for all its virulence is that it does not spread easily among healthy populations, which may be why it is not as widespread as we might expect. Among those with already compromised immune systems, however, it is capable of reaching epidemic proportions.
10 of the world's deadliest diseases—and why they might wipe us out yet
Salmonella and E. coli
This year's big foodborne threat is killer tomatoes. Two years ago, spinach up and vanished from grocery store shelves around the country. Michael Pollan will be the first to tell you why: "Eighty percent of America's beef is slaughtered by four companies, 75 percent of the precut salads are processed by two and 30 percent of the milk by just one company." The consolidation of the industrial food supply necessarily means that any pathogen which enters the system will have no trouble finding its way to your dinner plate, heedless of global distances.
Compounding that problem, we have the issue of antibiotics being administered as a preventative measure in livestock and poultry. Animals are routinely fed these medicines as part of their diet, whether they are sick or not. This indiscriminate use has undoubtedly led to a reduced efficacy of antibiotics in humans. Dr. Arjun Srinivasan, a medical epidemiologist with the CDC, notes that we don't know whether overuse of antibiotics in humans is ultimately worse than overuse in animals, but that "there are those who say, if you look at the absolute amount of antibiotics that are used in animals, [it] vastly outweighs the amount that's used in humans. So therefore, that may actually be a larger component" of the problem.
trouble finding its way to your dinner plate, heedless of global distances.
Compounding that problem, we have the issue of antibiotics being administered as a preventative measure in livestock and poultry. Animals are routinely fed these medicines as part of their diet, whether they are sick or not. This indiscriminate use has undoubtedly led to a reduced efficacy of antibiotics in humans. Dr. Arjun Srinivasan, a medical epidemiologist with the CDC, notes that we don't know whether overuse of antibiotics in humans is ultimately worse than overuse in animals, but that "there are those who say, if you look at the absolute amount of antibiotics that are used in animals, [it] vastly outweighs the amount that's used in humans. So therefore, that may actually be a larger component" of the problem.
Yellow Fever Virus
The first of two agents on our list spread by the Aedes mosquito, the yellow fever virus wasn't been much of a concern in the latter half of the twentieth century. Malaria control efforts in the 1950s successfully decimated the Aedes population, and with it the occurrence of yellow fever. In the past few decades, however, the mosquito has returned and is ranging much further than previous generations. It's also making its way into urban environments, which it has done in the past—an outbreak nearly wiped Memphis off the map in 1878—but in recent memory, it has been confined to the tropical jungles.
The fever gets its name from the jaundice it can cause after a few days of infection. Later comes internal bleeding (it's a hemorrhagic fever like Ebola and Marburg) followed by bloody vomit with the consistency of coffee grounds. What is most worrying about its return to cities is that it achieves a higher mortality rate among dense, unexposed populations—up to 30 percent. Recent outbreaks in Paraguay and the Ivory Coast have health officials racing to vaccinate as quickly as possible. While an effective vaccine exists, there is no treatment and no cure.
Shanghai SARS Alert
Nobody used to pay much mind to the coronaviruses. While the genus is home to two species responsible for the common cold, they haven't received the attention given to other cold-causing viruses because coronaviruses are difficult to grow in a lab environment. That all changed very quickly in 2003 when a new respiratory disease began killing doctors and nurses and showing the potential to spread at pandemic levels was identified as a previously unknown coronavirus. The infection was severe acute respiratory syndrome, or SARS, and it held the world's attention for just under a year before it disappeared in the summer of 2003.
The global public health response was a near-unparalleled success. Within weeks, control efforts led by the World Health Organization had identified a totally novel agent, devised a diagnostic test, and instituted plans for quarantine and isolation. It is undoubtedly a result of those efforts that the outbreak was contained before it could reach pandemic levels.
And while it is no longer topping watch lists, two questions persist: how did it get to humans and where did it come from? As Dr. Scott Dowell, head of the CDC's Global Disease Detection Program explains, "how it is that one of these animal pathogens acquires the ability to spread efficiently among humans is something that we don't do a very good job explaining or predicting."
Coronaviruses are known to mutate rapidly, so there may have been some biological basis to its sudden appearance and virulence, but it was still very much a surprise. Where it currently lies in wait is even more of an unknown. There is evidence the 2003 outbreak originated in a wildlife market in southern China, but the exact species of animal from which it came is still very much in contention.
Liver Infected With Ebola
This hemorrhagic fever has gained a special notoriety for being a quick and exceptionally deadly killer. Ebola is known as the fever that kills with a million cuts, because it causes a reaction in the blood that produces microscopic holes in the capillary walls. The patient then bleeds to death internally. Mortality can be as high as 90 percent. It is invariably a headline-grabber when outbreaks strike. But it's not on this list because it's presently a significant threat (it's not). It's here for two reasons.
The first has to do with a trait Ebola shares with the SARS coronavirus—its zoonotic host is a mystery. Although the virus has been known to us since the mid-1970s, we are still largely in the dark about what its reservoir is in nature. Even after a comprehensive study of tens of thousands of animals in outbreak regions, no virus was found. That points to the difficulty public health officials face when unknown threats emerge—we have a very hard time tracking some viruses we've known about for decades, so you can imagine the mounting complications when starting from zero.
The second reason it's on this list is to place it within the context of the rest of the agents. While it is a ravaging disease, it presents little threat outside of where it appears locally. It is not communicable through the air, and only spreads from person to person; often because of poor hospital conditions in the areas in which it appears. In addition, it presents symptoms very quickly—infected persons are likely to be isolated before getting very far. All the rest of the diseases on this list can spread far and wide, which makes them much more threatening.
cuts, because it causes a reaction in the blood that produces microscopic holes in the capillary walls. The patient then bleeds to death internally. Mortality can be as high as 90 percent. It is invariably a headline-grabber when outbreaks strike. But it's not on this list because it's presently a significant threat (it's not). It's here for two reasons.
The first has to do with a trait Ebola shares with the SARS coronavirus—its zoonotic host is a mystery. Although the virus has been known to us since the mid-1970s, we are still largely in the dark about what its reservoir is in nature. Even after a comprehensive study of tens of thousands of animals in outbreak regions, no virus was found. That points to the difficulty public health officials face when unknown threats emerge—we have a very hard time tracking some viruses we've known about for decades, so you can imagine the mounting complications when starting from zero.
The second reason it's on this list is to place it within the context of the rest of the agents. While it is a ravaging disease, it presents little threat outside of where it appears locally. It is not communicable through the air, and only spreads from person to person; often because of poor hospital conditions in the areas in which it appears. In addition, it presents symptoms very quickly—infected persons are likely to be isolated before getting very far. All the rest of the diseases on this list can spread far and wide, which makes them much more threatening.
Methicillin-Resistant Staphylococcus Aureus
Methicillin-resistant Staphylococcus aureus,—or MRSA,—is a mutant variant of the common staph infection found in hospitals and nursing homes. What sets it apart from common staph is its resistance to a wide range of commonly used antibiotics. In the late 1990s, it began to appear in people who hadn't been anywhere near a health-care institution. They were struck with what scientists have taken to calling Community-Associated MRSA. The disease appears in places where daily, close contact is the norm: schools, day-care centers, and prisons, for example. If caught early, before it gets into the bloodstream, it is usually treatable with low-grade antibiotics, and its spread can be controlled. It may even be remedied without antibiotics by draining the lesions it raises on the skin. Once it passes that early stage, however, it can become a much more difficult infection to eradicate.
MRSA is an important warning sign because doctors are frequently having to use the strongest antibiotics to treat it. We know this to be an effect of antibiotic overuse. The end result is a breed of bacteria against which we have little, if any recourse for a cure. "The challenge that we'll face is that a growing number of bacterial infections will be more and more difficult to treat. The reports are rare, but we're already seeing [cases] of bacteria... where there are no effective antibiotics to treat the infection," says Dr. Srinivasan. Right now, these cases are appearing only in hospitals and only in the most immunocompromised patients, but that was once the case for drug-resistant staph, too.
The only real, immediate course of action is education and vigilance about proper antibiotic use, because, as Dr. Srinivasan notes, "our ability to develop new drugs has already been surpassed by the speed with which bacteria are developing resistance." Several institutions have undertaken awareness campaigns, like the CDC's "Get Smart" program and the Infectious Diseases Society of America's "Bad Bugs, No Drugs," both of which have had good success educating both patients and health-care workers.
Stunning pictures of some of North America's most impressive animal camouflage
Petal Perfect
Art Wolfe
Instead of webs, the goldenrod crab spider, Misumena vatia, uses camouflage to ambush its prey, slowly changing color to match the flower on which it’s perched. It does this by moving yellow pigment closer to or farther from its outermost layer of cells. The species is most often found among yellow and white blooms, but it can morph into a green or bluish hue when necessary, or even take on reddish spots or stripes. Thus disguised, the arachnid waits frozen, its front legs poised to snap closed in a deadly embrace on hapless insects that come into range. The spider’s venomous bite can take down bugs as large as butterflies and bumblebees.
Off the Hook
Art Wolfe
Here, a speckled sanddab nestles into the ocean floor, its skin mottled to mimic the pebbly background. A member of the flounder family, Citharichthys stigmaeus can change its topside appearance with cells called chromatophores. Pigment granules in these cells migrate closer to the cell surface to create patterns on its brown skin. This camouflage hides the fish from predators off the Pacific coast where it’s found and enables it to surprise its prey—smaller bony fishes, shrimp and worms.
Ebony and Ivory
Art Wolfe
Its unique black-and-white coloring helps the many-spotted tiger moth both stand out and blend in. Native to the western U.S., this moth may feed on mildly toxic plants like milkweed, taking the plant poisons into its own body as a natural defense against predators. Most often, the species’ white body advertises “I taste bad” to birds who spot it flying in the air, says biologist Rebecca Simmons of the University of North Dakota. But when it comes to rest against a dappled background, like the one pictured here, Hypercompe permaculata’s coloring also breaks up the outline of its body, allowing it to blend in and hide from birds that might not heed its white warning.
Hide Your Young
Art Wolfe
Huddled together against a rocky Canadian cliff face, a typical nesting site, these two gyrfalcon chicks blend into the marbled stone. Adult Falco rusticolus patrol the air in arctic regions, feeding on their tundra neighbors, the well-hidden ptarmigan and other smaller birds. Gyrfalcons are clad in inconspicuous gray, white and brown feathers, with a light underside.
Countermeasures
Art Wolfe
The round object in the center-right of this photo is no rock—it’s a rock ptarmigan hiding motionless among the stones and moss of the Alaskan tundra. (Look for its beak to spot its head.) In the winter snow, Lagopus muta exchanges its brown feathers for white, maintaining year-round protection from its main predator, the gyrfalcon. In the spring, males retain their white feathers after the snow disappears, advertising themselves to potential mates. Once they’ve mated, and before the brown feathers grow back, males roll around in the dirt, creating a makeshift camouflage, which is eventually replaced by a summer disguise like the one on the female shown here.
A Cross to Bear
Art Wolfe
Known for its distinctive high-pitched call, the spring peeper frog’s coloring ranges from grayish to reddish brown, a fitting adaptation to the leaves and dead grass of its wooded habitat in the eastern and midwestern United States. Darker markings, including the cross on its back, help break up Pseudacris crucifer’s silhouette against its surroundings. To add to the illusion, the tiny frog can also adjust its hue slightly within the gray-brown range to better match its environment.
New research shows that some strains of bacteria can be tricked into killing off their own kind; it may have future applications in medicine
P. Dendritiformis Colony
Bacterial infections are the number one killer in hospitals, and while most can be treated with antibiotics, there are many strains that have developed resistance to the drugs. New research from Tel Aviv University and Texas University suggests that bacteria can be outsmarted by turning their natural defense mechanisms against them, which can completely wipe them out without using antibiotics.
When bacteria are starved or exposed to other stressors, they release a chemical that kills off some of the colony so that the rest can survive. But, according to Eshel Ben-Jacob of TAU, co-author of the study, they exhibit a kind of “rudimentary social intelligence” which prevents them from killing the entire colony. The new research exploits that idea by exposing two neighboring sibling colonies to the same chemical signal.
The result was that the siblings—which came from the same original colony—killed each other off. And, when the chemical messages between the sibling colonies were cut off, the bacteria stopped dying.
Custom-Made Bacteria The bacteria used in the study, Paenibacillus dendritiformis, was developed by Ben-Jacob specifically for this type of experiment. According to Ben-Jacob, P. dendritiformis have a complex social life and display relatively large, striking patterns that make reactions to the chemicals easy to observe. The bacteria have genes specific to cannibalism, communication, and have a highly developed defense system, which makes them ideal for exploring ways in which to exploit these features.
P. dendritiformis is not pathogenic, so there is no risk of infection for the researchers. The bacteria are also representative of many strains that are resistant to antibiotics, which makes them a good model for experimentation.
Smart Bugs According to Ben-Jacob, bacteria are surprisingly intelligent: “In the medical community, they perceive the bacteria as a collection of dumb creatures, but they actually not.” This collective intelligence can and should be used to turn the bacteria against itself, rather than spending time and money developing antibiotics, he says.
In this study, each bacteria colony is around four inches in diameter, and the number of bacteria is around ten times the world’s human population. Every individual bacterial cell is in constant communication with all the rest. “Think of it as if ten times the number of people on earth were all connected by SMS to every other one, sending messages all the time. It is even better than fastest kid texting today,” said Ben-Jacob.
Courtesy Nikon Small World Photo Micrography Competition: Photographed by Dr. Rachel Fink
These adorable little creatures look like a trio of dapper dandies stuffed into acorns, but they’re actually mini-squids. The gestation period of squid eggs varies according to the temperature of the water in which they were laid (in warm climes, they can hatch in around 11 days; in colder waters, it can take up to 27). The embryos here are still young, but they’re already differentiated enough to have eyestalks and mouths, and you can just make out the budding tentacles.
Embryonated eggs of Oryzias latipes (Japanese rice fish) in Java moss (12x)
Courtesy Nikon Small World Photo Micrography Competition; Photographed by Alex Griman
Here’s a fun fact about the Japanese rice fish: it was the first vertebrate to mate in outer space. On a 1994 mission of the Space Shuttle Columbia, four carefully selected rice fish, including a lusty young “playboy,” were placed in a sealed aquarium and left alone to do their thing (click here for a play-by-play). After some missteps—the playboy apparently struggled to keep his balance in zero-g and mistakenly executed “a circle dance of courtship” around another male—the proper rice fish finally managed to connect. A few days later, a fry of baby fish was hatched from fertilized eggs much like the ones pictured above.
Chick embryo (6x):This shot of a nine-day-old chick embryo won first place in the popular vote on Nikon Small World’s website. The New York Times’s John Tierney thinks that’s just because it’s so dang cute, but I beg to differ: as ridiculously cool as it is, it looks something like a fruit snack-cum-monster. De Azevedo obtained this image by staining the embryo with green dye, immersing it in wintergreen oil, and photographing it with a stereomicroscope. Courtesy Nikon Small World Photo Micrography Competition; Photographed by Tomas Pais de Azevedo
Nikon’s annual Small World Competition has been awarding prizes to the country’s best microscope-aided photography since 1977. The contest winners always present a reliably fascinating and freakish slice of life at a Lilliputian level. Last week, this year’s 115 winners were announced.
Since this is a column about reproduction—and since everyone loves to gaze upon an embryo every now and then—here’s a selection of the best of the unborn, ranging from the merely small to the seriously minuscule.
