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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.

In light of President Obama’s declaration that the outbreak of the H1N1 virus is a national emergency, Surprising Science is setting this week aside to discuss the history and science of vaccines and their importance in battling diseases, including swine flu. See Monday’s post for part 1, A Brief History and How Vaccines Work, and yesterday for part 2, Success Stories.

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

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. See yesterday’s post for part 1, A Brief History and How Vaccines Work.

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

Charles Darwin at museum. Photo by Sarah Zielinski

First of all, many thanks to Greg Laden for filling in for me on the blog for the last couple of weeks while I was away on my much-needed vacation. Where did I go? Mainly to Cambridge, England, but my travels also took me to Cardiff (in Wales), London and Paris.

I went to Cambridge to visit some friends, not to see any of the Charles Darwin-related sites, such as his room at Christ’s College. And though I had intended to see the movie Creation about Darwin (which I will blog about sometime in the next couple of weeks), it seemed that almost everywhere I turned, except for Cardiff, I couldn’t avoid the man.

The first hint came on a tour of Cambridge, where Darwin was one of the four scientists proudly touted as having a connection to the university (the other two were Francis Crick and James Watson, who discovered the structure of DNA while working at the university, and Rosalind Franklin, a Cambridge alum whose X-ray data was used in their discovery).

The next day, on the hunt for ichthyosaurs, I headed to the Sedgwick Museum of Earth Sciences. The museum is tiny but crammed with an enormous number of fossils and rock samples in dozens of old-fashioned cases. At one end, easily overlooked in one glass-topped case, sits several small fossils that Darwin found while on his Beagle journey. And the other end is dominated by a brand new exhibition, Darwin the Geologist, which highlights Darwin’s geological finds.

Even an afternoon in the Cambridge Botanic Garden had its Darwin connection: The garden was begun by Cambridge professor John Stevens Henslow, best known for inspiring Darwin in natural science.

In London, a few days later, I headed to the Natural History Museum. Surely I would not encounter Darwin if I skipped their new Darwin Centre. Wrong. Just last year the museum restored their life-size statue of the man to its original place in the Central Hall.

By that time, I realized that since Darwin was everywhere I looked, I might as well join my friends on a visit to Cambridge’s Fitzwilliam Museum to see the Endless Forms exhibition about how visual arts influenced Darwin and how Darwin’s theories and discoveries then influenced visual arts.

By the time I left for Paris, however, I thought that that was the last of Darwin on my vacation. But I was wrong. Strolling through the Jardin des Plantes, there was the man peeking up from little displays on topics such as pollination and co-evolution.

This truly is the Year of Darwin. At least on my vacation.

Sunset at the North Pole (courtesy of flickr user lanz)

It has been 100 years (and two days) since the New York Times announced that Robert E. Peary had reached the North Pole on April 16, 1909, making him the first man to do so. (News traveled much slower back then.) Of course, the Times was conveniently ignoring their rival, the New York Herald, which just the week before had named Frederick A. Cook the first man to reach the Pole, on April 21, 1908.

But the Times, the National Geographic Society and even Congress declared Peary the winner. That hasn’t stopped a century of heated discussions on the matter, though. Smithsonian magazine weighed the arguments earlier this year in “Who Discovered the North Pole?” The writer, Bruce Henderson, doesn’t declare either the winner, but he makes a good case for Cook.

The Times took up the matter again yesterday, and this time John Tierney argues that neither Peary nor Cook reached the North Pole. In his blog TierneyLab, he asks “Who Was First at the North Pole?” The next person to make the claim was Richard Evelyn Byrd Jr., who reportedly flew over the Pole in 1926. But Byrd’s diary evidently says he fell short. Norwegian Roald Amundsen followed up his South Pole discovery with further explorations, and he flew a dirigible over the North Pole in 1926. But does flying over the Pole count? If it doesn’t in your book, the first person to travel to the Pole across the ice was Ralph Plaisted from Minnesota. He took a snowmobile to the North Pole in 1968.

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A male midwife toad carries fertilized eggs on his legs. (© blickwinkel / Alamy)

Before Charles Darwin, there was Jean-Baptiste Lamarck, the French naturalist who proposed that an organism could pass to its offspring characteristics that it acquired during its lifetime. The classic example is the idea that giraffes got their long necks by gradually stretching them over successive generations in response to the need to reach food high in the trees. Darwin’s theory—which held, in contrast, that giraffes with the longest necks were more likely to survive and reproduce—eventually won out, though Lamarckism persisted well into the 20th century (particularly in the Soviet Union, where it was revived as Lysenkoism).

One proponent of Lamarckism in the 1920s was Austrian biologist Paul Kammerer, who undertook a series of experiments on amphibians, including the midwife toad. These toads are special because they copulate on land and then the male keeps the eggs out of the water by carrying them around, on land, stuck to his own legs.

By placing the toads in an arid, hot environment, Kammerer induced the toads to mate in the water. Under these conditions, the toads simply deposited the eggs into the water—the male did not carry them—and only a few hatched into tadpoles. But later generations who grew up under normal conditions preferred to copulate in the water, and some males developed a trait called “nuptial pads” on their forelimbs (black spots that are used for gripping females and are common on water-dwelling toads). Kammerer believed that this was evidence that Larmarckian evolution was real.

In 1926, however, a herpetologist determined that the nuptial pads on the only specimen remaining from Kammerer’s experiment were simply black spots created by injections of India ink. And six weeks after the herpetologist’s paper appeared in Nature, Kammerer killed himself.

Kammerer denied injecting the frog, but his experiments were never repeated and he is often held up as an example of Lamarckian fraud. Nothing was ever proven, though, and nuptial pads have since been found in a wild midwife frog, proving they are a possible trait. Now, in a new paper, University of Chile biologist Alexander Vargas argues that Kammerer’s experiments produced intriguing evidence of epigenetics, in which a gene’s expression can change but not its underlying sequence, years before scientists discovered this non-Mendelian form of inheritance.

In Kammerer’s time, traits were thought to be inherited in a strict Mendelian fashion, in which genes obey statistical laws. We now know that genetics are far messier; the DNA sequence of a gene is only one part of the picture. For instance, with DNA methylation, a methyl group attaches to DNA resulting in less expression of the gene. Environmental factors can influence DNA methylation, and this can look something like Lamarckian evolution.

Vargas argues that moving the toad eggs from land to water changed their environment, and that change could have caused alterations in gene methylation. And epigenetic mechanisms are now known to influence some of the features that became altered in Kammerer’s toads, such as adult body size and egg size. “Rather than committing fraud,” Vargas writes, “it seems that Kammerer had the misfortune of stumbling upon non-Mendelian inheritance at a time in which Mendelian genetics itself was just becoming well accepted.”

President Barack Obama presents the Medal of Freedom to Stephen Hawking in the East Room of the White House. (Official White House Photo by Chuck Kennedy)

Stephen Hawking, the renowned theoretical physicist from Great Britain, was one of two scientists among yesterday’s recipients of the Presidential Medal of Freedom. Here’s what President Obama had to say about Hawking:

Professor Stephen Hawking was a brilliant man and a mediocre student when he lost his balance and tumbled down a flight of stairs. Diagnosed with a rare disease and told he had just a few years to live, he chose to live with new purpose and happily in the four decades since he has become one of the world’s leading scientists. His work in theoretical physics, which I will not attempt to explain further here, has advanced our understanding of the universe. His popular books have advanced the cause of science itself. From his wheelchair, he’s led us on a journey to the farthest and strangest regions of the cosmos. In so doing, he has stirred our imagination and shown us the power of the human spirit here on Earth.

Scientists don’t often receive the Medal of Freedom, the highest civilian honor in the United States, and it’s far rarer to find a British scientist on the list. But Hawking is special. He has not only made significant advances in fields like theoretical cosmology and quantum gravity, but he has also been a successful writer of popular science books, both while dealing with a form of amyotrophic lateral sclerosis (ALS) that has put him into a wheelchair and made him dependent on a computer for speech.

The British Embassy here in Washington, D.C., hosted a small party for Hawking last night, and I had the privilege to attend with some of the city’s science elite: John Holdren, the president’s science advisor; Arden Bement, director of the National Science Foundation; Ralph Cicerone, president of the National Academy of Sciences. (Odd moment: meeting Jim Guy Tucker, former governor of Arkansas and self-described Hawking fan.)

Hawking gave a small speech in which he emphasized the importance of freedom in science. Galileo Galilei (who, in an odd coincidence, died exactly 300 years before Hawking was born) had been imprisoned in his home by the Catholic Church for the crime of saying the Earth moved around the Sun. Hawking said that, had he lived in Galileo’s time, he might have been put in jail for his own scientific work, but that would not have stopped him from thinking about the universe.

Fifty years ago, Mary Leakey discovered the first known East African hominid. Image credit: Bettman/Corbis

The next time a creationist spouts some nonsense about how the lack of a fossil record undermines the theory of evolution, direct them to the hominid family tree. If you haven’t read much about human origins lately, it might come as a surprise that so many species have been identified (and more all the time).

One of the most important fossils, and one that marked an important turning point in paleoanthropology, was discovered 50 years ago this month by Mary Leakey. She (and her husband; I suppose we must mention him) spent decades looking for fossil hominids in Kenya’s Olduvai Gorge before finding their first: a skull of Australopithecus boisei, a.k.a. Paranthropus boisei, a.k.a. Zinjanthropus boisei, a.k.a. “Nutcracker Man,” which lived about 1.8 million years ago.

As the list of possible names suggests, paleonthropologists have argued quite a bit about exactly how to classify the various hominids. But this fossil clarified one important point. Before Mary Leakey’s discovery, many experts thought that hominids evolved in Asia. After her discovery, it was clear that hominids evolved in Africa. The newfound skull also showed that other poorly understood fossils, such as the Australopithecus africanus that had been discovered earlier in South Africa, were part of our own distinguished lineage rather than merely ancestors of apes.

Louis Leakey examines Australopithecus boisei. Image credit: Bettmann/Corbis

Smithsonian ran a story a few years ago about the absurdly paleoanthropologically prolific Leakey family, including son Richard who grew up digging for bones. It helps explain why it’s easier to find a photo of Louis showing off the Nutcracker skull than Mary:

Although Louis grabbed the headlines, it was his second wife, Mary, an archaeologist, who made many of the actual finds associated with the Leakey name. Until later in their relationship, when their marital ties all but snapped for both personal and professional reasons, she let her husband bask in the limelight while she conducted her beloved fieldwork….

Then, in 1959, came the now-famous discovery, in Olduvai, of a 1.75-million-year-old skull that Leakey named Zinjanthropus boisei, and which he asserted was the “connecting link between the South African near-men . . . and true man as we know him.” The skull was similar to those of the robust ape-man creatures that had been found in South Africa, but differed from them in having heavier bones and bigger teeth. Nearly three decades of work had at last been rewarded, it seemed, and the huge publicity surrounding the find propelled the Leakeys—particularly Louis, though Mary had actually discovered the skull—to still greater fame.

Here’s to the next 50 years of discoveries about human origins.