A 17th-century Dutch drawing of a dodo (via Wikimedia commons)

Dodo (Raphus cucullatus)

The dodo has become synonymous with extinction. To “go the way of the dodo,” for example, means that something is headed out of existence. The three-foot-tall, flightless bird lived on the island of Mauritius in the Indian Ocean. They probably ate fruit. Though the birds did not fear humans, hunting was not a huge problem for the birds as they didn’t taste very good. More troublesome were the other animals that came with people—like dogs, cats and rats—that destroyed dodo nests. Human destruction of their forest homes was also a contributor to the dodo’s decline. The last dodo was seen on the island sometime in the late 1600s.

Georg Steller's drawing of the sea cow that bears his name (via Wikimedia commons)

Steller’s sea cow (Hydrodamalis gigas)

Georg Steller first described his sea cow in 1741 on an expedition to the uninhabited Commander Islands off the coast of Kamchatka. The placid sea creature probably grew as big as 26 feet long and weighed around 8 to 10 tons. It fed on kelp. Just 27 years after Steller’s discovery, however, it was hunted to extinction.

Audubon's painting of great auks (via Wikimedia commons)

Great auk (Pinguinus impennis)

Millions of these black-and-white birds once inhabited rocky islands in some of the coldest parts of the North Atlantic, where the sea provided a bounty of fish. Though their population numbers probably took a hit during the last Ice Age, it was the feathers that kept them warm that led to their downfall. The soft down feathers were preferred pillow filling in Europe in the 1500s and in North America in the 1700s. The dwindling birds were further doomed when their eggs became a popular collector’s item. The last live auk was seen in Newfoundland in 1852.

Martha, the last passenger pigeon (via Wikimedia commons)

Passenger pigeon (Ectopistes migratorius)

The passenger pigeon was once the most numerous bird species in North America, making up 25 to 40 percent of all birds on the continent. There were as many as 3 to 5 billion of them before the Europeans arrived. They would migrate in huge flocks consisting of millions of birds. In the 1800s, however, they became a popular food item. Tens of thousands could be killed in a day. By the end of that century, when laws were finally passed to ban their hunting, it was too late. The last wild bird was captured in 1900. Martha, the last of her kind, died in 1914 at the Cincinnati Zoological Garden.

Audubon's painting of Carolina parakeets (via Wikimedia commons)

Carolina parakeet (Conuropsis carolinensis)

The eastern United States once had its own native parrot, the Carolina parakeet. But farmers cut down their forests and made fields, and then killed the birds for being pests. Some birds were taken so that their feathers could adorn ladies’ hats, and others became pets. The last wild parakeet was killed in 1904 in Florida. The last captive bird, which oddly enough lived in the same cage in which the passenger pigeon Martha died (above), died in 1918.

Captive thylacines in Washington, D.C., c. 1906 (via Wikimedia commons)

Tasmanian tiger, a.k.a. the thylacine (Thylacinus cynocephalus)

The thylacine wasn’t really a tiger, though it got that name for the stripes on its back. The largest carnivorous marsupial, it was once native to New Guinea, Tasmania and Australia. It had already become rare by the time Europeans found Australia, confined to the island of Tasmania. In the 1800s, a bounty was put on the species because it was a danger to the sheep flocks on the island. The last wild thylacine was killed in 1930, though some may have survived into the 1960s.

A male golden toad (via wikimedia commons)

Golden toad (Bufo periglenes)

They lived in the Monteverde Cloud Forest Preserve in Costa Rica. Most of the year, they were hard to find, and scientists think they may have lived underground. But during the rainy season of April to June, they would gather in small, temporary pools to mate. The population crashed in 1987 due to a bad patch of weather and none have been seen since 1991. No one is sure what happened, but climate change, deforestation and invasive species have all been suggested as possible culprits.

That's not a polar bear, it's a "spirit bear" (courtesy wikipedia)

Generally, having white fur is only good if you live in a white environment. The arctic fox, for example, would probably be eaten pretty quickly if it lived in Florida. Likewise, black bears that inherit two copies of a recessive gene for a white coat tend not to live very long, becoming victims of wolves or grizzly bears.

Except on a few small islands in western Canada that lack wolves and grizzly bears. On those islands, 20 to 30 percent of the black bears are white. They are known as “spirit bears” or Kermode bears. Native American tradition from the region says that the spirit bears lived on the ice-covered landscape of times long ago. Scientists, however, have hypothesized that the white color is a more recent mutation that has become prevalent on these islands due to genetic drift.

Whenever the trait developed, it may have given the white bears some sort of advantage. In a new study, published in the Biological Journal of the Linnean Society, biologists from British Columbia started looking at the diet and foraging behavior of the white and black bears. Both types eat the same kind of food, and go after it in the same ways. The difference comes during the autumn salmon run. During the day, the white bears are about 20 percent more efficient in their fishing compared with the black bears. The biologists say that the white fur is less visible in the water during the day and the salmon are less likely to try to evade the white bears. The spirit bears are able to fatten up faster for winter, which translates to better survival.

It’s not all good news for the Kermode bears of western Canada, however. As in many other places along the west coast of North America, the spirit bears’ salmon are on the decline.

Thomas Vignaud of Marseille, France took this photograph, labeled Young fish dart by a jellyfish in the sea, in the Mediterranean Sea in September 2007. With it, he won the Natural World Category of Smithsonian magazine’s 5th Annual Photo Contest.

Have you taken an amazing photograph? Hurry up and enter our 7th Annual Photo Contest. The deadline is Tuesday, December 1, 2009, at 2pm Eastern Standard Time (EST).

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2005 U.S. water use, by percent (source: USGS)

The American population is getting more efficient at using our water supply. We used 410 billion gallons of water per day in 2005, according to new estimates from the U.S. Geological Survey, and this hasn’t changed much since the USGS first started reporting on the topic in 1950, despite a 30 percent increase in population since then.

It’s where our water goes that made me blink: 49 percent is used in the production of electricity and another 31 percent for irrigation in agriculture. The stuff we drink and wash our clothes in and water our lawns with is only a small percentage. The irrigation number isn’t too shocking as agriculture is a huge industry in this country. But I had no idea we were using so much water to turn on our lights. The USGS explains:

Water for thermoelectric power is used in generating electricity with steam-driven turbine generators….Cooling-system type is the primary determinant for the amount of consumptive use relative to withdrawals. Once-through (also known as open-loop) cooling refers to cooling systems in which water is withdrawn from a source, circulated through heat exchangers, and then returned to a surface-water body. Large amounts of water are needed for once-through cooling…Recirculation (also known as closed-loop) cooling refers to cooling systems in which water is withdrawn from a source, circulated through heat exchangers, cooled using ponds or towers, and then recirculated. Subsequent water withdrawals for a recirculation system are used to replace water lost to evaporation, blowdown, drift, and leakage. Smaller amounts of water are withdrawn for recirculation cooling than for once-through cooling.

The amount of our water that goes to power generation has increased over the last 20 years. The industry as a whole has become more efficient in its water use (the average amount of water used in the production of a kilowatt-hour of electricity has declined since 1950), but that is because there are more power plants that use recirculation cooling in which the water is used over and over.

Climate change is likely to change our available water supply over the next century. Greater efficiency can only help in the management of this resource, especially if it becomes more scarce. I’ll make no recommendations about how to change our water management, but just looking at the chart above gives me some ideas about where we should target our efforts.

Falkland sheep have no need to worry about wolves these days (courtesy of Flickr user ShimShamB)

When Charles Darwin’s reached the Falkland Islands on his famed voyage, he discovered there a “large wolf-like fox” found nowhere else in the world. “As far as I am aware,” he would later write in The Voyage of the Beagle, “there is no other instance, in any part of the world, of so small a mass of broken land, distant from a continent, possessing so large an aboriginal quadruped peculiar to itself.” The human population on the island, however, was quickly increasing and the canid’s numbers were dwindling. Darwin predicted the species would soon go the way of the dodo, and he was right. The species went extinct in 1876, killed off for its fur and to protect the sheep population.

Since Darwin’s time, scientists have puzzled over his wolf-like canid, now known as the Falklands wolf. The species was the only native terrestrial mammal found on the island; there were no mice or porcupines or deer. And the islands lie 300 miles from the mainland. Where did the wolf come from and how did it get to the Falklands? Could Native Americans have brought the wolves to the island?

To get a picture of the wolf’s history, scientists isolated DNA from four museum specimens of the Falklands wolf, including one that had been collected by Darwin himself. (Their study appears in Current Biology.) They compared the DNA of their specimens with that of other canids, including several South American species (foxes, the maned wolf, and the bush dog) and members of the Canis genus (which includes the gray wolf and coyotes). With the DNA data, they created a phylogenetic tree that let the scientists see which species were the most closely related to the Falklands wolf and when the Falklands wolf branched off as a new species (that is, when they became isolated on the islands).

The four museum specimens diverged from their closest relatives about 70,000 years ago, which the scientists think is when the species came to the Falkland Islands. That was during the last ice age and long before humans showed up in the area (nixing the Native American theory). The wolves probably floated to the islands on ice or logs or perhaps walked over a glacier. Once on the islands, they would have feasted on penguins, geese and pinnepeds.

The scientists now have a new mystery: The analysis revealed the maned wolf to be the Falklands wolf’s closest relative, but the two species diverged from each other over 6 million years ago, several million years before canids populated South America from the north. There aren’t yet any canid fossils from this time period—something to look for.

Why does a rooster have a wattle?

Research has shown that when hens are choosing a mate they prefer roosters that have larger, brighter combs and ones that frequently perform the tidbitting behavior. This makes sense because the characteristics of the comb have been shown to correlate with how healthy the male is, and tidbitting behavior provides the hen with nutritionally important food items and shows the male’s status. But the presence of the wattles has long been a puzzle because they haven’t been shown to serve a similar purpose.

Carolynn Smith (a friend and former colleague) and her current colleagues at Macquarie University in Australia set out to discover the purpose behind the wattle by studying red junglefowl (Gallus gallus), which are the wild brethren of the chickens we eat (their study appears in the journal Animal Behaviour). Cutting off the wattles of roosters and seeing how the behavior of hens changed wasn’t an option. Instead, Smith created four animated roosters. The animated roosters (see second part of the video below) all acted the same, performing the tidbitting routine over and over, and they all looked the same, except for their wattles. One had a normal wattle, one was missing his, a third had a wattle that didn’t move, and the fourth had an extra floppy wattle.

A test chicken would be placed inside a test pen with two “audience hens,” a couple of buddies intended to make the test hen more comfortable in the less familiar surroundings (fowl are social creatures). One of the videos was then played for the test chicken and her response was recorded: How quickly did she respond to the animated rooster? How quickly did she start searching for food (the normal response to a male tidbitting)? And how long did she search for food?

The test hens responded more quickly to the tidbitting males that had the normal or stationary wattles, less quickly to the one with the extra floppy wattle (the wattle moved so much that it swung up the side of the rooster’s head and appeared much smaller than it was) and slowest to the male lacking wattles. After the hen’s attention was gained, though, she reacted about the same to each of the four animated chickens. Smith suggests that the wattle helps a rooster gain a hen’s attention when he is tidbitting, rather like a human guy wearing flashy clothes while doing his best dance moves to try and pick up chicks.

Photos and video courtesy of Carolynn Smith.

You may recognize Felicia Day as Dr. Horrible’s red-haired obsession (or maybe from that appliance commercial). And if you’ve been reading this blog, you probably have heard of NASA’s Spitzer Space Telescope, which was responsible for last month’s discovery of a massive ring around Saturn. Add the two together and you get the latest video about colliding galaxies from IRrelevant astronomy. If you find this one funny, and if you are geeky enough to recognize names like Sean Astin and George Takei, you’ll probably spend the rest of the day giggling as you watch earlier episodes from the series. They can be found intermingled with more traditional educational videos on the telescope’s YouTube site. Enjoy!

weed chainsaw massacre (courtesy of flickr user 19melissa68)

Here’s a shocker: Horror films like Texas Chainsaw Massacre don’t get the chainsaw spatter right, according to the Journal of Forensic Sciences.

The reason for the study is sad—a woman was reported missing in 2005, and the police found evidence that she had been killed and dismembered in her basement (a few dabs of fresh paint on the walls, small pieces of bone, a receipt for an electric chainsaw). The investigators, possibly having watched a few too many horror films, didn’t think that there was enough blood and tissue spatter in the small room if a human body had been dismembered there by someone wielding a small chainsaw. And there was the question of whether or not the chainsaw itself was powerful enough to accomplish the job without getting stuck in flesh and bone.

A University of South Dakota pathologist got involved. He obtained the same kind of chainsaw indicated in the receipt and a 200-pound female pig, deceased, and created a room the approximate size of the basement using white sheets. He let the pig rest for two days to simulate the time between when the woman had been reported missing and when the chainsaw was purchased. And then he started hacking away.

The chainsaw was certainly powerful enough to cut through the tissue and bone. And the pathologist discovered that if the blade was held parallel to the floor there was very little spatter, similar to what was found at the crime scene. (Vertical positioning of the blade or use of a freshly killed pig increased the amount of spatter on the sheets.) The researcher concluded:

These experiments have shown that a human body may be easily dismembered with a chainsaw, even a smaller electric-powered model….Despite popular beliefs fueled by crime scene shows on television and recent Chainsaw Massacre movies, postmortem dismemberment does not necessarily produce a large amount of blood spatter at a dismemberment scene….With a horizontally oriented chainsaw, therefore, the majority of the tissue and blood will be found on the ground beneath the saw. If the chainsaw discharge chute, however, is not directed towards the ground, then a large volume of blood and tissue, and subsequent spatter, could be expected some distance from the saw.

Something to consider when writing or filming your next scary movie.

The Abbé Nicolas-Louis de Lacaille was the first to find this cluster of stars, in 1751 while on an astronomical expedition to the Cape of Good Hope (South Africa). The Kappa Crucis Cluster (NGC 4755), which resides near the Southern Cross, received the nickname the “Jewel Box” during the next century, when astronomer John Herschel viewed it through his telescope and saw the stars were different colors—pale blue and orange. He wrote: “The stars which compose it, seen in a telescope of diameter large enough to enable the colours to be distinguished, have the effect of a casket of variously coloured precious stones.”

We now know that the cluster is about 6,400 light-years away from Earth and around 16 million years old. The stars in the Jewel Box all formed from the same cloud of dust and gas, are about the same age and have similar chemical compositions. The image above was taken recently with MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile. Scientists use clusters like this one to study the evolution of stars. (Image credit: ESO. Click here to find additional images of the cluster, including one from the Hubble Space Telescope.)

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H1N1 (swine) flu is in the news again (courtesy of flickr user Dr Craig)

Around the country, people are lining up to be vaccinated against the H1N1 flu virus. Surprising Science has spent the last three days discussing the history and science of vaccines (see A Brief History and How Vaccines Work, Success Stories, and A History of Vaccine Backlash). Today we answer some of the more common questions about the swine flu vaccine.

Who should get the H1N1 flu vaccine?

There is currently not enough vaccine for everyone who wants it. Vaccines take time to produce and this one has been rolling off the line for just a few weeks. As of Tuesday there were about 22.4 million doses available around the United States. The goal is to have 250 million doses by the end of flu season next spring. The Centers for Disease Control and Prevention have recommended that certain groups get vaccinated first:
•    pregnant women
•    people who live with or care for children under six months of age
•    young people age six months to 24 years
•    people 25 to 64 who are at higher risk for flu complications due to a health condition or compromised immune system
•    health care and emergency medical service personnel

Why are these groups first?

Pregnant women and young people seem to be especially vulnerable to the H1N1 virus. Babies under six months of age cannot be vaccinated, so it is important to limit their exposure to the virus by vaccinating people who care for them. People with certain health conditions or who have a compromised immune system have a higher risk of having serious flu complications if they get the flu. And medical personnel are the people most likely to come in contact with the virus.

What if I’m not in one of these groups?

Wait your turn. There will be enough vaccine eventually. And if you get the H1N1 flu, it won’t be fun but also probably won’t do you long-term harm. In the meantime, the CDC recommends taking everyday preventative actions like hand washing and avoiding contact with sick people. (And if you get sick, please stay home.)

Is the vaccine safe?

The H1N1 vaccine is made the same way as the seasonal flu vaccine. The manufacturers just tweaked the recipe with the new virus. The Food and Drug Administration approved the vaccine in September. People with allergies to chicken eggs, however, should not be vaccinated as eggs are used to make the vaccine.

I got a seasonal flu vaccine last month. Why won’t that work against H1N1?

For the same reason that your flu vaccine from last year doesn’t protect you from this year’s seasonal flu: There are many different types of flu virus, and they mutate over time. When you are exposed to one type, your body’s immune system learns to protect you from that type only. The others are too different to register with your immune system as the same virus.

I’ve heard that in other countries the vaccine contains squalene. What is it and why is it in their vaccine and not ours? And what about thimerosal?

Squalene is a type of naturally-occurring oil found in plants and animals (including humans). Squalene is a component of some adjuvants of vaccines. Adjuvants help a vaccine’s effectiveness by boosting the immune response. Some countries have added the squalene-containing adjuvant to their vaccine mix for H1N1 because it causes a lower dose of vaccine to be effective; that is, it will allow people to get more doses out of the same batch of vaccine. The World Health Organization has found no evidence of any adverse events in vaccines containing the squalene adjuvant.

The United States government chose not to use any adjuvants in the H1N1 mix in this country. However, some formulations of the vaccine do contain thimerosal, a mercury-based preservative that has been used in vaccines for decades. Getting mercury injected into your body may sound a little scary. But concerns about safety of thimerosal are unfounded. Some parents worry that thimerosal may cause autism in young children, but there is no evidence of this. Several studies in recent years have examined the possibility, but no association has ever been found.

It’s kind of startling that the idea of vaccines ever caught on. There is an amazing amount of trust needed: A person—often a complete stranger—is injecting you with a foreign substance. You have to trust that the substance is really what you’ve been told it is, that it has been sufficiently tested and is safe, and that it will work as advertised and not hurt you.

An 1802 illustration depicts Edward Jenner vaccinating a young woman. Several former patients demonstrate the effects of the vaccine—miniature cows erupt from their bodies. (Courtesy of the National Library of Medicine)

Despite this, most people trust the doctors, science and government and do get vaccinated. A small percentage, however, choose not to be vaccinated (or not to have their children vaccinated). And it’s been this way almost since Edward Jenner first began vaccinating people against smallpox (see the illustration).

Decades after Jenner’s discovery, the British government got involved in vaccination by passing a law in 1840 that provided free smallpox vaccinations to the poor. But later efforts didn’t go over so well. A 1853 law required all infants be vaccinated in the first three months of life and threatened parents who did not vaccinate their children with a fine or imprisonment. Riots soon broke out in several towns. In London, an Anti-Vaccination League was founded. In 1867, after the law was extended to children up to age 14, the Anti-Compulsory Vaccination League was founded. Opposition now focused on the law’s threat to personal liberty. (“As parliament, instead of guarding the liberty of the subject, has invaded this liberty by rendering good health a crime…parliament is deserving of public condemnation.”)

In the late 19th century, anti-vaccination movements spread across Europe and into the United States, where they succeeded in repealing compulsory vaccination laws in several western and Midwest states.

But despite the controversy, protests and pamphlets, the doctors, science and governments eradicated smallpox from the United States by 1950 and from the entire world by 1980.

Along the way, though, anti-vaccination sentiments have resulted in serious harm. For example, when the majority of the residents of Stockholm, Sweden refused vaccination for smallpox in the early 1870s, they were left vulnerable to the disease. The city experienced a major epidemic in 1874, after which vaccination was again popular.

Efforts to eradicate polio—a disease now confined to just a few countries—came off track in Nigeria due to a 2004 rumor that the vaccine “contained birth control drugs as part of a secret western plot to reduce population growth in the Muslim world.” Polio is on the rise again in Nigeria, and more than 100 children have been left paralyzed by the disease this year.

And in places like Europe, Australia and the United States, in communities where parents have stopped vaccinating their children for fear that common childhood immunization causes autism (a fear that is completely unfounded), diseases that had become rare—like measles and pertussis—are making a comeback, as Wired magazine notes in their November issue:

“I used to say that the tide would turn when children started to die. Well, children have started to die,” [pediatrician and vaccine researcher Paul] Offit says, frowning as he ticks off recent fatal cases of meningitis in unvaccinated children in Pennsylvania and Minnesota. “So now I’ve changed it to ‘when enough children start to die.’ Because obviously, we’re not there yet.”

The anti-vaccination movement ebbs and flows over time, with fear of disease fighting mistrust of doctors, science and government. Which will win? If history is any guide: neither. But doctors, science and government will all need to work together to find a way to protect public health. And then, perhaps, they will find more vaccine success stories along the way.

Tomorrow—Vaccine Week, Day 4: Swine Flu Edition

A sign warning of a smallpox hospital during a 1953 outbreak of the disease in Yorkshire, England (WHO photo, courtesy of the National Library of Medicine)

Smallpox: Once one of the world’s most dreaded diseases, smallpox killed as many as 30 percent of people who became infected with it and left survivors deeply scarred; no effective treatment was ever found. English physician Edward Jenner in 1796 discovered how to use cowpox virus to vaccinate individuals against smallpox. Vaccination efforts grew over the next century. The last reported case in the United States occurred in 1949, and vaccination ended here in 1971. The last case of smallpox in the world occurred in Somalia in 1977, and the disease was declared to be eradicated in 1980.

Polio: The virus mainly attacks children under the age of three, and infection can result in severe paralysis and death. Vaccines developed in the 1950s and 1960s have eliminated the disease from much of the world. However, cases are still found in several countries, and immunization efforts continue in Africa and Asia.

Measles: Measles is a respiratory disease that is accompanied by a rash. In the United States and other countries where measles vaccination is common, incidence of the disease has become rare, which is good because it can lead to pneumonia, encephalitis or death. Worldwide, there are about 10 million cases of measles each year and 197,000 deaths. But if there were no vaccinations, the World Health Organization has estimated that 2.7 million people would die of the disease each year.

Hib meningitis: The bacterium Haemophilus influenzae type b causes meningitis and pneumonia. It used to be the leading cause of bacterial meningitis in children. However, since the development of vaccines for the disease in the 1990s, it has been nearly eliminated in industrialized nations. The story isn’t so positive in the developing world, though. There, Hib infects about three million individuals and kills about 386,000 each year, mostly children under the age of five.

Tetanus: “He stepped on a rusty nail and died” was once a common epitaph. Tetanus, also called lockjaw, isn’t actually caused by the rust; it’s caused by the spores of the bacterium Clostridium tetani. A person becomes infected when dirt enters a wound. Babies can also become infected at birth following a delivery under non-sterile conditions. Infection results in stiffness, muscle spasms and, about a fifth of the time, coma and death. With increased rates of vaccination, though, incidence of the disease is declining worldwide.

Diphtheria: This upper respiratory tract infection is caused by the Corynebacterium diphtheriae bacterium. It has a fatality rate of about 5 to 10 percent, though that rate climbs to 20 percent among the very young and the elderly. Vaccination has driven the incidence of the disease in the United States from hundreds of thousands of cases per year in the 1920s to just a handful of cases today.

Tomorrow—Vaccine Week, Day 3: A History of Vaccine Backlash

La Vaccine, 1827 (courtesy of the National Library of Medicine)

In light of President Obama’s declaration of “national emergency” imposed by the outbreak of the H1N1 virus, Surprising Science is setting this week aside to discuss the history and science of vaccines and their importance in battling viruses and diseases, including swine flu.

More than two millennia ago in China or India, someone noticed that people who suffered and recovered from certain diseases never became reinfected. In a leap of logic, the person who noticed the connection tried to prevent the disease by inoculating themselves (or perhaps someone else) with a bit of infected matter.

That idea, now called vaccination, bumbled along through history until 1796. That’s when an English physician named Edward Jenner noticed that milkmaids rarely got smallpox, though they often had blisters from cowpox, which they caught from their cows. Jenner thought that the cowpox might prevent the women from getting smallpox. To test his idea, he took some material from the cowpox blister of a milkmaid and inoculated 8-year-old James Phipps. Six weeks later, Jenner injected young Phipps with fluid from a smallpox sore; Phipps didn’t contract smallpox.

Over the next decades, smallpox vaccination spread, and it was a common practice by the end of the 19th century. Around that time, two more vaccines were developed—by Louis Pasteur—against anthrax and rabies. The 20th century would see the development of vaccines for more than a dozen other diseases, including polio, measles and tetanus.

Long after Jenner’s first discovery, biologists would discover how vaccines work to prime our immune systems to fight off infections:

Though the original smallpox vaccine used a related virus, cowpox, most vaccines use a weakened or dead form of whatever disease they’re meant to prevent. Some of these vaccines will also include a substance called an adjuvant that boosts the effectiveness of the vaccine. (Scientists figured out the workings of alum, one type of adjuvant, last year.)

When the vaccine is injected, a person’s immune system recognizes it as a foreign substance. Immune cells called macrophages digest most of the foreign material, but they keep a portion to help the immune system remember it. These identifying molecules are called antigens, and macrophages present these antigens to white blood cells called lymphocytes (which come in two types: T cells and B cells) in the lymph nodes. A mild immune response occurs, and even after the vaccine material is destroyed, the immune system is primed for a future attack.

The next time that a microbe with those antigens enters the body, the lymphocytes are ready to quickly recognize the microbe as foreign. When that happens, B cells make antibodies that attack the invading microbe and mark it for destruction by macrophages. If the microbe does enter cells, T cells attack those infected cells and destroy them before the disease can multiply and spread. The microbe is defeated before it can get a foothold in the body, before the person gets sick.

Tomorrow–Vaccine Week, Day 2: Success Stories

ASTER image of Morenci open-pit copper mine in southeast Arizona (credit: NASA)

Splatter of colors
Seen high up from outer space
Pretty like a rainbow
–Natalie, age 8, Illinois

Mining doesn’t generally result in a prettier landscape, but it seems when you view the landscape through NASA’s ASTER instrument on the satellite Terra, beauty easily emerges. The image above is the Morenci open-pit copper mine in southeast Arizona. The mine is the largest producer of copper in North America. (The author of the poem is a Girl Scout; NASA partnered with some scouts last year and challenged them to write poems based on the agency’s images.) NASA highlights this and other images from its vast library in the NASA Images blog, which was begun earlier this year.

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• In air and space news, one lucky robot is predicted to sail on Titan, one of Saturn’s moons. The idea to cruise in space was inspired by the discovery that Titan resembles Earth in many habits, particularly weather-wise. Titan experiences rain, wind, and has many lakes, however, liquid methane and ethane take the place of water. Ellen Stofan, a geologist with Proxemy Research in Maryland, explains that the lake-lander will fulfill one of the three-probe plan to explore this interesting moon. A “balloon-mounted vehicle and an orbiter” will complete the mission, enabling NASA to fully view and discover every region of Titan.

• From the BBC comes news of a “veggie spider” or Bagheera kiplingi, the only arachnid to feast only on plants. Avoiding ants and waiting patiently to snag a piece of its’ favored acacia plants – known as Beltian bodies, the spider really has to work for its’ vegetarian meals. Found in Central American and Mexico, this spider is perhaps the only one not feared by the people.

• Due to excessive animal poaching (104 per day!), African elephants will be extinct in little over 15 years, according to the International Fund for Animal Welfare. Despite the international ban on ivory sales, the illicit trade continues.

— Compiled by Audrey Reinhardt