If you’ve hung around a big-city park, you may think that pigeons are countless — or uncountable. But according to scientists from New Zealand, pigeons now join the short list of animals that can count — or at least, can places images containing two countable items in numerical order.

It’s blue news for those who think only humans deserve human capacities. From empathy and altruism to murder and war, animals seem to have caught on to some of our best — and worst — tricks.

Now Damian Scarf, a post-doctoral researcher at the University of Otago, with his colleagues, has taught three pigeons to order pairs of numbers in the range from one through nine.

This is not exactly counting, but it certainly is a sign of numerical awareness in birds.

More important, the researchers have taught these retired racing pigeons the concept of smaller-to-larger, Scarf says. “Previously, this number abstraction was only known in primates, and now we have shown that it is not unique to primates.”

Serious screen-time serves science

The experiment began with a year-long training period, during which the birds were shown pairs of images, each containing one, two or three countable items. If the birds pecked at both images, smaller number first, they were rewarded with some wheat. (Although the images never contained a numeral, we refer to the “number” they contain for brevity.)

To prevent the birds from focusing on color, shape or other non-numerical details, the images showed a range of items, so that the only correct answer would reflect their number rather than other distinctions.

“The training time reflects how difficult it is for them to abstract,” Scarf says. “It’s such a foreign situation, number is not the first port of call when presented with a stimulus to discriminate. That’s why we had so many shapes, colors, surface areas.”

Even if the birds originally made their judgments based on color, “we pushed them to use a different strategy, to break away from that. Number is not the default discrimination mechanism” for pigeons, says Scarf, who worked under advisor Michael Colombo of Otago.

A genius for abstraction?

This does not mean that the birds are counting, says Scarf. “It’s more a fuzzy representation in the brain of what ‘three’ is. We can apply this verbal label to three, but they cannot. Pigeons, and animals in general, don’t have a definite idea of a number, that’s why they don’t perform perfectly, and why we see the distance effect.”

When the numbers on the test pair are further apart, Scarf found, “the fuzziness overlaps a little less.”

A greater distance between the numbers produced a quicker response and greater accuracy. For adjacent numbers, like four and five, the birds scored about 66 percent accuracy, compared to more than 95 percent for numbers separated by at least six. Once the difference rose to at least three, the pigeons did as well as monkeys in a path-breaking 1998 study that opened the field of numerical “thinking” in animals.

Scarf stresses that the birds were not just regurgitating what they had learned, but were learning numerical rules. “The goal was to find out whether they could acquire an abstract rule. We were just training for one through three, but they learned some flexibility, an abstract, ascending rule for ordering numbers” that would apply to other numbers on the screen.

Rooted in evolution, but where?

Being able to recognize that one thing is more numerous than another could help an animal survive, Scarf says. “When food is available in multiple places, an animal has to develop an optimal strategy for figuring out where the most food is, and I think we have subverted that capacity for this task.”

Where this capacity arose is anybody’s guess at this point. The evolutionary lineage of mammals and birds divided about 300 million year ago, Scarf says. “If this derived from a common ancestor, it’s very old. It’s also possible that primates and birds have evolved this independently.”

“I do think it’s important, just as our study of mirror self-recognition in monkeys, from the fundamental standpoint of how these abilities come about,” says Luis Populin, a professor of anatomy at the University of Wisconsin-Madison, who has found that, under certain conditions, monkeys can recognize themselves in a mirror. “It’s very nice and is yet another step toward understanding how our cognitive functions develop.”

You have to hand it to these birds, which have set a new standard for avian aptitude. “The new part is the idea that this abstraction of numbers is not tied to training,” says Scarf. “Most numerical tests with animals involve training and testing with the same numbers, but we were training with a limited set of numbers and testing them with numbers outside the range. They learned an abstract rule, and that’s what makes this study unique.”

If you drop a worker ant from an Amazonian treetop, what happens? In the species Cephalotes atratus, 87 percent of the time, that ant will wind up back where it started — a few meters lower down the same tree. Drop things that drift down at random, and only 5 percent of them will hit the tree.

In other words, these ants are controlling their flight — even though they don’t have wings.

That finding, which Stephen Yanoviak, Robert Dudley and Michael Kaspari¹ reported in 2005, provides a great starting point for untangling one of the mysteries of biology:

When and how did so animals take to the air?

Fly high

Flight is pretty common — among critters with wings, or something that resembles them, like a stretched membrane of skin. Birds, bats, moths and butterflies can fly. Even some lizards, snakes, fish and squirrels can glide under control toward the ground, which is not the same thing as falling.

Studies of ants in South America provide good data on “controlled aerial descent,” says Dudley, a professor of integrative biology at the University of California at Berkeley. In the course of some rather entertaining research, he and his colleagues have found that Cephalotes atratus ants:

During the controlled descent, at speeds above 4 meters per second, the ants perform “rapid postural adjustments,” Dudley says. “The limbs are moving, it’s not like a paper airplane.”

Dudley, an expert in the biomechanics of flight, says hundreds of species of tree-living ants in tropical Amazonian forests have evolved controlled gliding. Dropping to the forest floor can make them a meal for a mean and hungry ground-dwelling ant.

Looking at evolution

Perhaps the coolest part of the story is its evolutionary angle. Previously, scientists intrigued by the origin of flight have looked for evidence of wings and feathers, which appear more than 100 million years back in the fossil record.

But if flight really originated in arthropods that could not survive a fall from a tree or a cliff, that could wind the evolutionary clock back a good deal further. (Arthropods are animals with external skeletons and jointed legs, including spiders, insects and crustaceans like the horseshoe crab.)

Gliding under control is neither rare nor constrained to ants, Dudley says. “There are wingless aphids and flat spiders that live under the bark that can glide at a 45° angle. Controlled aerial descent has hundreds or thousands of independent origins in terrestrial arthropods.”

As old as the hills?

Over all, Dudley says, directed descent probably originated about 280 million years. If jumping like a flea or grasshopper is also deemed a form of flight, the origin could date back more than 400 million years.

The gliding hypothesis would not only help explain the origin of a common and cool behavior, but could take wind out of the sails for a favorite anti-evolutionary argument. Creationists, Dudley notes, have long demanded to know how wings evolved by asking, “What good is half a wing?” But according to the gliding hypothesis, wings unable to hold an animal airborne could still have evolved to help control a descending behavior that had long been in existence.

Flight of the control freaks?

Controlled gliding, Dudley says, “preceded the origin of wings, and so the evolution of flight is more about control than about the formation of wings.”

The new analysis “addresses qualms about the [supposed] lack of intermediate forms in the fossil record,” Dudley says. “Here is a viable intermediate form. There are lots of behavioral and ecological contexts where stubby, partial airfoils are useful.”

– David J. Tenenbaum

El Niños, the global cycles of weather that are driven by a hot spot in the tropical Pacific Ocean, have been linked to drought, storms and famine in many parts of the tropics.

Today, a study in Nature finds that deadly conflicts have started twice as often during the el Niño years – but only in the many countries affected by el Niño.

Scientific interest in el Niño mushroomed during the 1980s, when climate experts began to correlate historic cycles of anchovy harvests along the west coast of South America with changes in weather thousands of kilometers distant, and eventually unraveled a planetary cycle driven by the appearance of huge pools of warm water in the western Pacific.

Because the warming seemed to coincide with Christmas, it was called el Niño, for the Christ Child.

El Niño is now recognized as the warm-water segment of the el Niño Southern Oscillation (ENSO), which also includes a cold-water counterpart called la Nina. Now acknowledged as an engine of global climate, el Niño is linked to prolonged droughts, heat waves and crop failures.

Previous efforts to study whether weather and global warming could affect war have related past environmental changes with conflict and the decline of civilizations, says Solomon Hsiang, who completed the new study as a graduate student at the Lamont Doherty Earth Observatory at Columbia University. But the studies tended to be case-by-case, he notes, and “even if every conflict or collapse happened at random, some would occur during a period of environmental change, so this isn’t compelling evidence.”

Looking carefully

To study the issue more systematically, Hsiang and collaborators Mark Cane and Kyle Meng:

The data showed that conflicts are twice as likely to start during an el Niño, says Hsiang, and that 21 percent of overall conflicts can be attributed to el Niño. The increase was only seen in countries strongly affected by el Niño.

Surprisingly, the average changes wrought by an el Niño are quite minor, Hsiang admits – about 0.05°C rise in temperature, and about 0.1 millimeter reduction in daily rainfall.

Small is … powerful?

How could such minor changes affect warfare?

A study that correlates data does not show why they are related, but there are many ways that seemingly small effects could change human behavior, says Hsiang, who is now at Princeton University, especially considering that averages can conceal major alterations in different locations:

However, Marshall Burke, who published an influential 2009 paper ¹ that found a significant increase in warfare during hot weather in sub-Saharan Africa, noted by email that the increase in conflict was seen only inside the el Niño region, and thus, “We might conclude that these global market mechanisms are not at work.”

Still, the new study adds something to the discussion, Burke says. “The [Hsiang] paper’s main innovation is in linking historical changes in the global climate to conflict risk, whereas past studies (including ours in PNAS) looked only at the effect of local weather variations on conflict.”

Burke, a Ph.D. candidate at UC Berkeley department of agricultural and resources economics, added, “They provide very convincing evidence that ENSO-related changes in the global climate are strong drivers of conflict risk in the regions whose weather is affected by ENSO.”

Looking at limits

Mark Cane, a climate scientist at Columbia’s Lamont-Doherty Earth Observatory and a co-author of the new study, said weather does not equal destiny. “No one should take this to say that climate is our fate. Rather, this is compelling evidence that it has a measurable influence on how much people fight overall.”

Ultimately, the motivation for the new study was to peer through the keyhole of time and anticipate a warmed world, Hsiang says, but he admits that the predictive power is limited. “In relationship to global warming, we want to be careful. El Niño is very different … in terms of its spatial pattern, the changes on the ground, and the rate of change. Until we have a much better grasp of these, it’s very hard to take these results and produce any kind of projection for future climate change.”

Still, he adds, “The debate until now has been whether there is any reason to believe that a shift in climate can produce conflict.” Now, “The question is not whether it’s possible, but how much global climate will influence conflict.”

– David J. Tenenbaum

We approach the Cave of the Mounds, a landmark (so to speak) in Southwest Wisconsin, along a walkway painted with fossils and markings that start at the Ordovician era (450 million years ago), when the limestone beneath our feet was deposited as a rain of sea shells on an ocean floor. Finally, at the cave’s entry, the asphalt calendar enters the last million years, when the cave started to be excavated by flows of acidic water.

The geological markings under our feet are one indication that the cave-men and -women who operate this site are intent on linking past and present, above- and below-ground.

Cave of the Mounds was discovered in 1939 by workers blasting in a limestone quarry on one of the highest spots in southern Wisconsin. Today, it is a tourist destination with a message — a cool, underground mecca, strategically illuminated, where tour guides leave the nettlesome lectures above ground, and offer easy-to-digest science along the cave’s alleyways.

The above ground section of the site features resurrected prairies and oak savannas, but the main attraction is the stalactites hanging over stalagmites, flowstone, the fossils embedded in ancient limestone, and the rare opportunity to see geology at work as you observe the earth from the inside out.

Aftermath of a flood unparalleled

What caused the huge erosion features, ancient shorelines, and scoured potholes in the “channeled scablands” in Eastern Washington state? In 1923, J. Harlen Bretz coined that ominous moniker and proposed that the features had been created by a gigantic flood.

During this time, geology was ruled by a “uniformitarianism” dogma, which highlighted gradual processes like deposition and erosion, and discounted the power of sudden events like floods (and perhaps even earthquakes, tsunamis and volcanoes).

Skeptics demanded to know the source of all that water in an arid region, and Bretz had a reputation as a kook. Then, geologists gradually realized that the ice-age flood had originated to the east, in glacial Lake Missoula, which had been plugged by the lobe of a glacier emanating from Canada.

In the 1950s, the idea that this huge lake had eaten through an ice dam and then coursed downstream with phenomenal power started gaining acceptance, and in 1979, Bretz, age 96, received the highest award from Geological Society of American for solving this great Earth riddle. Today, scientists believe the floods may have recurred every few years or decades as the ice age was waning, around 14,000 years ago.

The evidence for the floods comes in all sizes. Alternating stacks of coarse gravel and fine sand show gravel left by flood currents under sand left by slower water when the floods receded. A dry river bed called the Grand Coulee, in Eastern Washington, was gouged by the astonishing flow of uncorked glacial melt water. The periodic cascades that shaped Dry Falls, now in Sun Lakes State Park are considered the largest known waterfalls in Earth’s history.

The unbearable whiteness of being

The world’s largest field of gypsum dunes, at White Sands National Monument in south-central New Mexico, could arouse anybody’s inner drywaller, as gypsum is the mineral basis for both drywall and plaster. But here, where 275 square miles of gypsum dunes have built a hot, severe and scorchingly beautiful landscape, there’s not a sheet of drywall in sight.

Set aside as a national monument by President Herbert Hoover in 1933, the dunes trace their origin to vast deposits of hydrated calcium sulfate — gypsum — that were laid down on an ancient lake a quarter-billion years ago. After a geological uplift, they were exposed roughly 10 million years ago, and eventually moved to the present site in a geologic eye-blink — the last 7,000 years.

Mammoth tracks have been seen in the dunes, but they could get buried with time: Some dunes are moving 30 feet a year, as the wind piles them up on the windward side and gravity avalanches them down the lee.

The gypsum dunes are said to be the largest in the world, but what’s most amazing is not the geology, but the evolutionary adaptations life has used to survive these harsh conditions. At least seven species of animals, including three lizards, that are closely related to darker varieties living in the surrounding desert have turned white for camouflage in this bleached world. (The drywalling lizard or the plastering mouse must be here somewhere!)

Visiting the Sands? Ponder a trip to Trinity, the site of the first test of the atomic bomb.

Science museums: Try the trifecta!

The Windy City boasts not just one, but three cool science destinations, all next door to each other on the Museum Campus along the shore of Lake Michigan.

To explore some of the world’s biological and cultural wonders, spend the day at the Field Museum of Natural History, a collision of anthropology, botany, geology, paleontology and zoology. The permanent exhibits include the DNA Discovery Center, a journey through four billion years of earthly life, and Sue, the largest (and most expensive?) complete skeleton of the ferocious T. rex. Among the temporary exhibits was a recent one on the horse and its deep relationship with humans (an exhibit that particularly excited one horse-crazy Why Filer).

If your palate is whetted for a wetter world, walk to the Shedd Aquarium to explore underwater life from the Amazon, the Caribbean and both poles. Green sea turtles, beluga whales, moray eels, piranhas and penguins will be among your hosts.

If otherworldly science is more your thing, visit the Adler Planetarium. Chat about the stars with real space scientists at their Space Visualization Laboratory, or just sit back and watch the star show. Adler’s centerpiece is the Doane Observatory, the largest publicly accessible telescope in the Chicago vicinity. While you can only peer through the lens after dark, this could make for a great conclusion to your trip.

Discover a life aquatic

An Australian freshwater crocodile grows in Baltimore. Seriously. The National Aquarium Baltimore boasts more than 660 species of fish, birds, amphibians, reptiles and mammals, totaling around 16,500 marine creatures.

In addition to its rich marine menagerie, the aquarium has a collection of special exhibits and interactive oceanic enjoyment. See the world through a dolphin’s eyes at Our Ocean Planet, a show that teaches visitors about dolphins and the connections between people and their seafaring friends. Or soak in ocean sensations with a movie at the 4-D Immersion Theater, where you can experience sea life in multiple dimensions, including the smell and feel of (simulated) mist and wind. Or take an expert-led tour, including behind-the-scenes peek of the sharks’ quarters.

The aquarium is also a center for conservation. For example, its Marine Animal Rescue Program tracks the progress of rescued animals after release. Other conservation projects include restoring wetlands and investigating the impacts of mercury on the marine food chain. After all, protecting the life that sustains the ocean ecosystem benefits everyone—not just aquarium visitors.

An excursion exotic to Melville

What’s more breathtaking than seeing the world’s largest animals in the wild? Whale watching puts you up close and personal with these magnificent marine mammals. Since the 1950s, in a 180° turnaround from Herman Melville’s day, people have been flocking by the boatloads to glimpse whales doing what they do rather than to kill them.

Both the U.S. east and west coasts have whales to watch, though you must catch them in the right season during their migration. There’s no guarantee, but on the western seaboard, you could spot orcas and gray whales. The east is home to the right, fin and sei whales. Humpbacks, minkes, and blue whales troll both coastlines.

Several cetaceans (a scientific category including whales, dolphins and porpoises) are endangered, including the North Atlantic right, blue, fin, sei and gray whales. In any case, marine mammals are heavily protected by law, so whale watching should be done with professionals who obey the rules.

Celebrating, protecting southern nature

With more than 500 full-time employees and an annual budget exceeding $30-million, Audubon Nature Institute sounds more like a business than a private, non-profit organization dedicated to explaining and preserving the wonders of nature with a Cajun flavor. The group operates a zoo, aquarium and assorted parks in and around New Orleans. The Aquarium of the Americas focuses on the Caribbean, Amazon, Gulf of Mexico (complete with oil-drilling replica) and Mississippi River.

A primate exhibit in the Audubon Zoo shows dozens of our opposable-thumbed relatives. Its 360 species of animals include a jaguar shown in a replica Amazon jungle. The “Embraceable Zoo” is devoted to full-contact animal admiration, and you can also eyeball, if not pet, a prickly Indian crested porcupine. Audubon maintains two locations that focus on captive breeding and survival of endangered species; these are closed to the public, but we expect to see you at the new insectarium, located in the old Federal customs house, for the beetle races on Sept. 3.

North Carolina: decapitation capitol

Every summer, vacationers flock to North Carolina’s coast for a beach getaway. But beach vacations would have been a hard sell early in the 18th century, as the coast was the stomping grounds of the South’s most feared pirate, Edward Teach, otherwise known as Blackbeard.

Nowadays, the area is proud of its sordid past, attracting pirate-curious tourists and archaeologists alike. In 1996, Blackbeard’s biggest and final ship, Queen Anne’s Revenge, was found off the coast of Beaufort, where it had been hiding for more than 270 years. While the dives did not uncover much treasure, archaeologists estimate the wreckage holds up to 750,000 artifacts, some of which are displayed at Beaufort’s North Carolina Maritime Museum.

Blackbeard is a primary local industry. Ocracoke Island, a favored Blackbeard anchorage, was where he met his fate at the hands of what he mocked as a rabble of “cowardly puppies.” Bath has the legendary ball of light, presumed to be Blackbeard’s ghostly severed head.

So why watch Johnny Depp impersonate a pirate at the multiplex when you can check out the history of this famous scoundrel? Like we said, this old, dead, head-free pirate is a godsend for small business…

Tar is my name. Fossils are my fame

If you’re stuck for a scientific sojourn in Southern California, head for the pits. Since long before there was a Los Angeles, the La Brea Tar Pits have been an oozing, 3-D flypaper for animals, now with that all-too-trendy urban accent. Asphalt, we learn, is not just good for roads, but also for trapping live animals and preserving their fossils. Since their first description in a scientific publication in 1875, the pits have produced prodigious prizes for paleontology. The onsite Page Museum houses more than 650 species of plants and animals, all removed from the black goo, and dating back 11,000 to 50,000 years.

The tar pits were a graveyard for thousands of carnivores, including the dire wolf, coyote and saber-toothed cat, and a smaller number of herbivores, including mammoth and bison. In an effort to transcend the “heroic” era of paleontology and flesh out (if we can put it that way) a comprehensive picture of life in the era of ice, researchers have recently shifted their focus to fossils of plants and smaller animals, including millipedes, 31 species of mollusks, and 25 species of beetles.

Listen hard: Hear the galaxies?

Love big? Dig distant, mysterious and unfathomably old? At the Very Large Array, in western New Mexico, you can gawk at 27 giant antennas used by astronomers to “listen” to radio signals from the universe. When you’re done rubber-necking the hardware, check out exhibits at the visitor center.

Then climb an observation tower to get another view of the world’s premier radio telescope zoo. Notice how every single antenna has silently and inexorably changed its orientation, and is now pointing to another invisible spot in the heavens? You are looking at visual proof of our planet’s normally insensible rotation.

It takes a lot of work, and some hefty equipment, to pry loose the secrets of the universe, and here, the scale of the operation is written across the desert. Since 1980, the VLA has, alone or in tandem with other telescopes, been collecting the astrophysical evidence for the formation and destruction of stars and galaxies. The new “enhanced VLA” can “hear” three times as many radio bandwidths as the VLA and is 10 times more sensitive. How sensitive is that? They say it could hear a cellphone calling from Jupiter…

Go under cover in the capital city

Explore life under cover (and the technology that allows a spy to hide in plain sight) at the International Spy Museum, the only public museum of its kind in the United States. With the largest public collection of international espionage artifacts, the museum provides a unique global perspective of this covert profession — said to be the second oldest — and how it has shaped the past and present.

Before you start your mission, you are challenged to adopt a secret identity. As you snoop about, you’ll discover the Secret History of History, which highlights the influence of spies through the ages; gadgets and stories of espionage during the American Civil War, World War II, and Cold War; and a gallery of spy technology. You can even see if you have what it takes to be an agent in the Operation Spy interactive experience, in which you must find a missing nuclear trigger before it ends up in the wrong hands. Just don’t blow your cover!

Visit the “Boneyard”

Warplanes go to the desert to die, and there, for a fee, you can tour thousands of mothballed fighters, bombers and helicopters at the 309th Aerospace Maintenance and Regeneration Center. Bus tours run from the Pima Air and Space Museum, on the outskirts of Tucson, Ariz. With more than 4,200 planes, the “boneyard” is the ultimate in aerial combat nostalgia.

Some of these planes will be scrapped, others may be sold or salvaged for parts, or pressed back into service during future wars. Seldom celebrated, but perhaps more important from a technological point of view, the site also stores 350,000 tools used to make these machines, including, we presume, the one-of-a-kind tools and dies used to shape jet engines, wings and fuselages.

Ogling killing machines may seem macabre, but then, if you are a U.S. taxpayer, you’ve already paid for this stuff… might as well check it out, and witness how the technology of aerial warfare has changed over the decades!

Edison’s Garden of Invention

In 1887, after he had patented the first practical electric light bulb, mega-inventor Thomas Edison invented an inventor’s playground in West Orange, N.J., just outside Manhattan. Edison stocked the lab with every resource needed to crank out movie cameras and projectors, teletypes, recording and playback devices, batteries and countless other electric gadgets for the fast-modernizing nation.

With labs focusing on chemistry and physics, and with shops devoted to woodworking and metal-working, Edison could concentrate on his strong points: cranking out ideas and masterminding publicity stunts that helped ensure his commercial success. During World War I, 10,000 people cranked out electrical devices for the military at the factories clustered around the lab. Edison worked at the West Orange lab until his death in 1931.

Think of Edison as primarily an inventor? Then you have to wonder how his name wound up on the companies selling electricity to New York and Chicago. God may have made the Garden of Eden, but Thomas Edison made the garden of invention in north Jersey, and it awaits your visit.

– David J. Tenenbaum & Jenny Seifert

Fish in the Gulf of Mexico: How safe?

The fire and deadly explosion of the Deepwater Horizon drilling rig on April 20, 2010 spewed a gusher of crude oil — about 4.4 million barrels — into the Gulf of Mexico.

The blowout flooded all levels of the Gulf with oil. And that oil, combined with millions of gallons of an oil-degrading chemical, raised questions about the health of Gulf seafood, both shellfish and finfish.

Fishing is major in the Gulf of Mexico, which in 2008 produced 15 percent of total weight of U.S. commercial fishing, and which has more sport fishers than any other American region.

Within two weeks, as a precaution to prevent the sale of contaminated fish, the government began closing parts of the Gulf to commercial fishing.

A report published today in Environmental Health Perspectives reviews the aftermath: How big was the threat? Did the closures harm the fishing industry by giving, in effect, official endorsement to the idea that the fish were contaminated? Were there any gaps in protection?

Not very filthy

The report came to an optimistic conclusion: government-sponsored studies of Gulf fish since the blowout found no significant contamination with heavy, persistent compounds called polycyclic aromatic hydrocarbons. “I don’t know that we have any evidence that the fish were contaminated, ever,” says study first author Julia Gohlke, an assistant professor of environmental health science at the University of Alabama-Birmingham.

PAHs can cause cancer and are often used as a measure of hydrocarbon contamination. According to the new study, “Federal seafood testing results released to date” show PAH levels at roughly 1 percent of the “level of concern” that the Food and Drug Administration established for assessing food safety after the Deepwater blowout.

Other results, she says, have focused on total hydrocarbons derived from oil, rather than PAHs. “My analysis looked at what the government has done,” she says. “There are independent reports of contamination that I tried to include, but they did not measure PAHs, only total petroleum hydrocarbons.”

Large oil spills are so ominous that people can overreact, says Gohlke. “People see an oil spill and fisheries closures and assume everything must be contaminated, and nobody wants to eat anything. There is a misunderstanding of what is considered contamination. There is now a large dataset, at this point, to show there hasn’t been significant hydrocarbon contamination to date.”

Gohlke and colleagues looked at data on the BP blowout, and previous oil spills from around the world, to compare toxicity levels and evaluate the procedures used to close and open fisheries. The project was funded by a grant from the Walton Family Foundation to the Environmental Defense Fund.

Looking at samples taken during and after the blowout, no results suggested that eating fish – whether with shells or fins – would contain elevated levels of PAHs, says Gohlke, who cautions that monitoring should continue for years because buried oil may re-enter the water and contaminate fish.

After the BP spill, fishing was banned in as much as 37 percent of the Exclusive Economic Zone in the Gulf of Mexico, which extends 200 nautical miles from the coast. These bans were precautionary, since they were made in advance of contamination tests, says Gohlke.

Although “safe, not sorry” can be justified, closures can also have unintended consequences, or even backfire, she says. “Part of me thinks the precautionary approach is appropriate, but I don’t know how it has contributed to consumer confidence. Without sufficient risk communication, precautionary closures may create an expectation that the fish is contaminated. The last survey I saw, from February, suggested people were still considering Gulf seafood to be contaminated.”

“I think they make some pretty good recommendations to continue monitoring for PAHs,” says Ron Kendall, director of the Institute of Environmental and Human Health at Texas Tech University. “There is a lot of debate about underwater oil mats that are still floating, and how much oil may still be on the seafloor or in coastal marshes. With hurricane season approaching, we don’t know what kind of remobilizing of suspended oil and the mats will take place.”

To date, Kendall says, the data show that seafood has safe levels of PAHs, but “You’ve got to understand that all this oil is not gone. This story is still unfolding.”

Trust Charles Darwin to be his own severest critic. Having expounded a revolutionary evolutionary theory of natural selection, he realized that the past gives birth to the present. Darwin knew about fossils, including the famous, three-section trilobites, that dated to the Cambrian period, now known to have begun about 540 million years ago.

Never one to duck logic, Darwin wrote:

Indeed, according to J. William Schopf, professor and director of the Center for the Study of Evolution and the Origin of Life at UCLA, what came before was totally mysterious when Darwin wrote “Origin of Species” in the 1850s. “Darwin knew about the Cambrian era, and the big extinctions after that were known, but he knew nothing about the earlier fossil record. This was the case for about 100 years.”

And then, starting in 1953, University of Wisconsin-Madison geologist Stanley Tyler noticed ring-like structures in rocks in Minnesota and Ontario’s Gunflint formation.

The rock — a fine-grained quartz relative called chert — was 1.9 billion years old – almost four times as old as the earliest Cambrian fossils.

Tyler, collaborating with Elso Barghorn at Harvard, recognized the circular structures as stromatolites, mushroom-shaped rocks formed by layers of microorganisms called cyanobacteria. In 1965, the two reported that stromatolites were the oldest fossils ever seen.¹

I can see you now!

Why did it take so long for Precambrian life to be recognized? “They had assumed that it would be like younger life, there would be coral, snails and trilobites,” said Schopf, an expert on the oldest life. “The basic problem was that a wrong assumption had been made. Life in the Precambrian turned out to be substantively different in organization and size.”

By exploring the interior of rocks using an increasing array of scientific techniques, Schopf and a growing group of colleagues have found life as early as 3.5 billion years ago.

Not bad for a planet with an estimated age of 4.7 billion years.

Double-not-bad, considering the exceeding scarcity of truly ancient rocks, hidden through the constant tectonic churning of the crust. The oldest rocks yet located are 3.8 billion years old, but any fossils they contain have been distorted by severe heat and pressure.

Still, Schopf said, four lines of evidence show the ancient roots of life on our planet: microfossils, molecular biomarkers, proportions of carbon isotopes and stromatolites. Stromatolites are layered rock formed by layers of microorganisms called cyanobacteria (formerly blue-green algae), which produce oxygen in sunlight.

While some of the fossilized microorganisms found in ancient rock apparently have gone extinct, the cyanobacteria closely resemble living organisms, Schopf told an audience at the University of Wisconsin-Madison on April 26. “Cyanobacteria do the same sort of photosynthesis as a blade of grass today. These are the guys that invented this process, probably 3-plus billion years ago.”

As testimony to nature’s predilection for retaining stuff that works, other fossil microorganisms resemble modern counterparts that require oxygen, cannot tolerate oxygen, or use it when convenient. “We’ve found 12 to 15 major families of cyanobacteria, the same ones that are important today, the same ones that are seen throughout the geological record,” Schopf says.

Tyler did not live to see the publication of his 1965 article, but it revolutionized paleontology, and has been cited by scientists at least six times since 2010.

“Stanley Tyler was a hero for this world,” says Schopf. “As [microbiologist Louis] Pasteur said, chance favors a prepared mind. Here was an economic geologist [concerned with finding minerals and mines] … and yet he saw these scrubbly things, and thought, ‘I bet they are fossils,’ even though they were almost two billion years old. This is the guy who made the discovery.”

– David J. Tenenbaum

The prospect of peak coffee raises the menace of massive caffeine withdrawal, with hordes of headachy addicts rendered into grouchy slackers. Could a cut in coffee production also cost us the many health benefits that coffee seems to provide?

For ages, the bitter black brew has been scorned as jet fuel for jittery insomniacs, providing nothing more than a momentary surge of focus and energy.

But recently, some researchers are starting to see java as the juice of the gods: In some studies, coffee appears to be protective against dementia, type 2 diabetes and even several types of cancer.

Coffee, it turns out, is loaded with polyphenols, anti-oxidant chemicals that fight damaging free radicals, which are implicated in many of the diseases of aging.

Caveat quaffer

Before we fill our cup with a discussion of the health benefits of coffee, remember these cautions:

For all these reasons, we are not prescribing coffee as medicine. But then, do we drink coffee for medicine, or for the taste, the excuse to talk things over with a friend, the acceleration physical and mental energy?

So bottoms up, and let’s check some recent studies showing how coffee affects dementia, diabetes, cardiovascular disease and cancer

Coffee: Good for your brain?

Many studies over the past decade have suggested that coffee can partly block Parkinson’s disease, a movement disorder that afflicts millions of elders. In 2006, ² researchers reported on a 22-year study of Finns – who boast Earth’s highest average coffee consumption – and found that people who drank more than 10 cups a day had about one-quarter the risk of Parkinson’s as non-drinkers. (Do Finns ever finish guzzling? While only 5 percent of the sample abstained, about 10 percent drank at least 10 cups a day!)

The researchers suggested that since Parkinson’s may be caused by oxidative attack on neurons, coffee’s protection may arise from its anti-oxidants.

Several studies – the results are inconsistent but suggestive – have linked caffeine and coffee with a reduction in Alzheimer’s disease. In 2010, after a 21-year study, researchers from Finland and Sweden³ reported that “coffee drinking of three to five cups per day at midlife was associated with a decreased risk of dementia/Alzheimer’s disease by about 65 percent at late-life.”

Research using mice with a genetic tendency to Alzheimer’s shows that coffee and caffeine improve learning and memory while reducing the beta amyloid plaques that mark Alzheimer’s. In 2011, when Gary Arendash and Chuanhai Cao of the University of South Florida compared coffee, caffeine and decaf,⁴ coffee was most effective at stimulating chemicals that apparently defend against Alzheimer’s. The researchers wrote that “coffee may be the best source of caffeine to protect against [Alzheimer's disease]” because another coffee chemical acts with caffeine to enhance protection.

Arendash did not respond to our email but said in 2009 that he’s seen “evidence that caffeine could be a viable ‘treatment’ for established Alzheimer’s disease, and not simply a protective strategy. That’s important because caffeine is a safe drug for most people, it easily enters the brain, and it appears to directly affect the disease process.”

Coffee ‘n cancer

Can coffee help protect against cancer? Sometimes.

Photo Florida Alzheimer’s Disease Research Center

Caffeine removed harmful beta amyloid plaques from the brains of mice that simulate Alzheimer’s disease.

A study of coffee and liver cancer followed 60,323 Finns for a median of 19.3 years. After adjusting for factors like age, alcohol and smoking, the hazard ratio of those who drank four to five cups was 0.44.

Hazard ratio means the probability of an outcome, compared to the reference group (non-drinkers, in this case). All other things being equal, abstainers were three times as likely to get liver cancer as those who swilled eight cups a day.⁵

To decipher conflicting or inconclusive studies, scientists can pool data using meta-analysis, a technique that sets standards for acceptable studies and then statistically groups the results.

In 2010, Mia Hashibe, in the department of family and preventive medicine at the University of Utah re-analyzed⁶ nine studies and found a 39 percent reduction in mouth and throat cancers among people who drank at least four cups. “Since coffee is so widely used and there is a relatively high incidence and low survival rate of these forms of cancers, our results have important public health implications that need to be further addressed,” said Hashibe. With such a large sample, “We had more statistical power to detect associations between cancer and coffee.”

If we shift the focus to all cancers, a new meta-analysis⁷ of 59 studies showed that each additional cup of coffee reduced the incidence of cancer by 3 percent.

The results concerning breast cancer are less encouraging. A 2008 report⁸, based on data from 85,987 women, found no significant link to coffee, decaf or tea, except for a slight reduction in breast cancer among post-menopausal women who ingested a significant amount of caffeine.

Similarly, a 2009 study in the Netherlands ⁹ found no association between coffee and breast cancer.

Ironically, coffee contains a chemical that could stimulate the many breast cancers that respond to estrogen by growing, according to Clinton Allred, an assistant professor of nutrition at Texas A&M University. Allred, who has found large amounts of a plant estrogen called trigonelline in coffee, says, “This is one of the least studied compounds I have ever been around.”

In the lab, Allred showed that trigonelline can affect cells even when it is thousands of times more dilute than the effective concentration of isoflavone, a common plant estrogen found in soy.

Allred is not worried about trigonelline, since people have been guzzling coffee for a long time, and plant chemicals consumed in a whole food or beverage act differently than they do in isolation in the lab. “People with a healthy diet that is high in plant products are exposed to these kinds of compounds all the time.”

A diabetes connection?

Could coffee slow the epidemic of type 2 diabetes, which disrupts sugar metabolism, which raises blood sugar that harms small blood vessels in the kidney, eye and heart? A 2006 study¹⁰ of 88,259 American women showed that drinking at least four cups of coffee reduced the diabetes rate to 53 percent of the rate among non-drinkers. Although both coffee and decaf (but not tea), were beneficial, diabetes prevention was most closely linked to coffee intake rather than caffeine intake.

According to a meta-analysis¹¹ based on more than 450,000 people from Asia, North American and Europe, “Every additional cup of coffee consumed in a day was associated with a 7 percent reduction in the excess risk of diabetes type 2. … Drinking three to four cups of coffee per day was associated with an approximate 25 percent lower risk of diabetes… .”

If coffee reduces diabetes, could it deter cancers associated with diabetes? A 2007 exploration¹² of the soaring rate of cancer after World War II in Japan linked coffee to reductions in liver and pancreatic cancer in men, and liver, colon and endometrial cancer in women. The authors speculated that coffee could reduce resistance to insulin, “and may thereby reduce the risk of diabetes-related cancers such as colon, liver, pancreas and endometrium.”

A matter of the heart

A 2010 study¹³ of 37,514 Dutch people found a slight benefit for coffee in heart disease: People who drank two to three cups a day had only 79 percent the rate of heart disease as abstainers, but the reduction was not statistically significant. Above 4 cups per day, the rate returned close to the no-coffee rate. Coffee did not affect the rate of strokes.

However, Swedish researchers studied¹⁴ people after a heart attack, and found that drinking one to three cups of coffee reduced the odds of dying to 68 percent of the risk for abstainers.

We put down our coffee mug with a jittery hand, wondered whether swilling coffee could harm the heart, and phoned Richard Page, a professor of medicine at the University of Wisconsin-Madison. Page, an expert in arrhythmias – the irregular heart rhythms that can cause deadly heart attacks – said, “It’s hard to demonstrate a relationship between caffeine consumption and arrhythmias, but there are case reports. I see a number of patients with arrhythmias, particularly atrial fibrillation, and occasionally we see some relationship with excessive consumption of caffeine.”

Although Page was not alarmed by coffee, he was not so sure about the mega-doses that were linked to health benefits in some studies. “I would be cautious; I have heard of a couple of adolescents developing atrial fibrillation (a hard-to-treat arrhythmia) after taking monster energy drinks; I don’t think such high doses of caffeine are good for people.”

The bottom line

If Captain C seems helpful against some cancers, dementia and diabetes, is it guaranteed to extend your life? No. A European study¹⁵, for example, found that “Neither coffee nor tea consumption was associated with stroke or all-cause mortality.”

A long American study, using data from 41,736 men (followed for 18 years), and 86, 214 women (24 years), found a slight, significant trend toward fewer deaths from all causes; those who drank at least six cups a day had a death rate just 80 percent (men) to 83 percent (women) of the non-drinkers. The main benefit was a reduction in cardiovascular disease.

However, coffee consumption did not affect cancer deaths, after adjusting for factors like obesity and smoking, and the authors concluded, ¹⁶ “The possibility of a modest benefit of coffee consumption on all-cause and cardiovascular disease mortality needs to be further investigated.”

Not exactly a ringing endorsement, but then, did we promise a simple answer?

Would you like your triple-espresso with soy milk?

For decades, one name has dominated discussion of the ancient New World: Clovis. Tools representing the characteristic Clovis technology, first found in Clovis, New Mexico, in 1929, have long been considered the product of the first inhabitants of the Americas. With a tool style that’s been found across much of North America, Clovis was the best-selling brand in “the first Americans” competition.

Clovis technology is apparently a home-grown phenomenon, as it’s never been found in Northeast Asia, the source of migrants into the New World.

The oldest solid date for Clovis people is 13,100 years ago, says Michael Waters, an archeologist at Texas A&M University. Now, in an article in Science on March 25, Waters and colleagues argue that tools have been found near Austin, Texas, that date to 15,500 years ago.

The researchers found 15,528 artifacts at a site called Buttermilk Creek. Most of their finds were flakes busted off while making stone tools, but the site also yielded 56 stone choppers, points and scrapers.

Using a technique that calculated when an object was last in direct sunlight, “We took the most conservative route to estimate the age,” says Waters, who directs the Center for the Study of the First Americans at A&M. The stone tools and flakes were probably made by a band of hunter-gatherers who paused at the creekside site.

Looking for a date

Because no organic remains were available for carbon-dating, the scientists relied for dating on optically stimulated luminescence, or OSL. “OSL has been around for a long time, has been employed in geology for 30-plus years” for dating windblown sand and silt, says Waters. “It’s been compared to radiocarbon dates, toe-to-toe, and in all cases, OSL ages have been determined to be comparable.”

The OSL dating, which essentially figures how long something has been buried, took place at the University of Illinois, in Chicago, under the direction of Steven Forman.

The find at Buttermilk Creek is the latest — and one of the better documented — archeological sites to break the Clovis barrier. Others pre-Clovis finds have been made in Oregon, Wisconsin, Pennsylvania and even Chile.

The news got WhyFilers wondering:

How convincing?

To get the skinny on the Texas discovery, we phoned Steve Shackley, a professor of anthropology at the University of California at Berkeley. “Proof does not exist in science,” he told us, “but Mike [Waters] has made good, defensible arguments.”

Much of the discussion about the Buttermilk Creek site concerns the vertical position — the stratigraphy — of stone artifacts, and the Waters team went to great lengths to show that older material was under younger stuff, as expected in an undisturbed site. Undetected dislocations can confuse archeologists, who tend to think deeper is older and shallower is younger.

Buttermilk Creek actually offers a three-fer: Clovis artifacts are sandwiched above those now identified as pre-Clovis, but below artifacts are in a more modern style. “This site has all these time periods, superimposed, in the correct order,” says Shackley. Because Waters is “one of the foremost” experts in analyzing the geology of archeological sites, “I think it’s going to be difficult to defeat his stratigraphic work. He’s been very careful about it.”

Douglas Bamforth, an archeologist at the University of Colorado, says the Waters team has avoided three errors that often destabilize ancient archeological claims:

“They have absolutely dated the site, they absolutely have artifacts, and the article talks in great detail about how intact the sediment was, they have really addressed whether the artifacts are in place,” says Bamforth. “They have refitted the [stone] flakes to the tools; I am totally convinced they have an intact site” and solid dates.

But that does not prove, to Bamforth, that the artifacts are pre-Clovis — they may be early Clovis. “The deep levels at the site are certainly older than the oldest carbon-14 date on Clovis-style projectile points, which Waters very emphatically argues is the beginning of the Clovis period. But the first problem with seeing the deep levels as different from Clovis is that there seems to be exactly nothing in those levels that differs from Clovis [as the site does not contain arrow- or spear-points that would prove or disprove the case]. … So I do not see why the site is not just early Clovis.”

Not so fast!

Aware that the latest find may be seen as final vindication for the “Clovis was not first” viewpoint, we phoned Thomas Dillehay, professor of anthropology at Vanderbilt University and the University of Southern Chile, who fought for decades to have Chile’s Monte Verde site recognized as pre-Clovis. Now that Monte Verde is finally accepted as one of the best-confirmed pre-Clovis sites, we figured the experience would make Dillehay receptive to the new find.

We were wrong. “I have a mixed opinion,” Dillehay told us, proceeding to list some shortcomings in the study. “It would be most convincing if there was standard radiocarbon dating, and even better if those dates were taken from features like hearths and food stains. OSL dating has become more reliable, but it’s still not as reliable as carbon-14, although the sequences do line up very nicely with sediment dating.”

Dillehay has questions about the three-layer sandwich of pre-Clovis, Clovis and post-Clovis material. “I’m not saying the materials are mixed. Geologists, to identify the strata, applied these excellent, meticulous sediment and particle analyses, but there was no clear visible stratigraphy to distinguish Clovis from pre-Clovis, and again this does not meet standard archeological criteria.”

Dillehay also points to the lack of “diagnostic, complete projectile points in either the Clovis and pre-Clovis material. In a discipline that has placed incredibly heavy emphasis on formal projectile points as the primary criteria for acceptance of a site, along with C-14 [radioactive carbon] dating, and geologic stratigraphy, I find this sort of acceptance, which seems to be uncritical, to be a major shift in the discipline.”

Still, Dillehay says “the interdisciplinary work is first rate, and I admire the multidisciplinary approach. But had there been C-14 dating and diagnostic projectile points, all this extraneous analysis would probably not be needed.”

It certainly would be nice to find arrow- or spear-points, says Waters, but “You can’t dictate what you will find. You have to roll with the punches.” Further excavation may or may not reveal a “smoking gun projectile point,” Waters adds. “We don’t know what kind of weaponry they used. In Siberia and Alaska, people were using a lot of bone, ivory and antler weaponry, and it might be that early folks in North America were using this as well.”

But due to heat and humidity, such organic material would not be preserved in the Texas site, he says.

Migration routes

The timing of human occupation of North America bears heavily on their migration route from Northeast Asia, which is accepted, for geographic and genetic reasons, as the source of the first Americans. The melting of the last ice age during the Clovis period, starting roughly 11,000 years ago, producing an ice-free corridor through Northwest Canada that would have allowed transit into the North American interior.

But the region was clogged with glaciers a few thousand years earlier, meaning that any early immigrants would have moved along the coast, either on foot, or via short hops in boats.

The possibility of coastal movement got a boost in a study¹ published March 4, which reported the discovery of stone tools dating from 11,400 to 12,200 years ago on the Channel Islands west of Los Angeles.

According to study leader Jon Erlandson, an archeologist at the University of Oregon, the ancient residents of these offshore islands made delicate stone tools to hunt in the ocean. “The points we are finding are extraordinary, the workmanship amazing. They are ultra thin, serrated and have incredible barbs on them. It’s a very sophisticated chipped-stone technology.”

The stone artifacts are quite different from the fluted points left throughout North America by Clovis and the later Folsom peoples, who hunted big game on land, said Erlandson. “This is among the earliest evidence of seafaring and maritime adaptations in the Americas, and another extension of the diversity of Paleoindian economies.”

The find is yet another reason to doubt that Clovis was first, says Shackley. “When you get dates to 11,000 or 12,000 years ago, out on islands, that makes it tough for the Clovis-firsters, who reject maritime entry. On the Channel Islands, they had get out there by boat,” and if they were already using boats, that means they could also have boated down the West Coast, he adds. “A lot of people accept that now.”

But even if people did move south along the coast rather than inland, Dillehay says they probably needed a long time to reach Chile. “There are hundreds if not thousands of rivers that descend the western slope of the mountain chain from Alaska to Tierra del Fuego, and every river, whether major or secondary, is a temptation to head upriver,” slowing the overall southward movement.

Photo: University of Oregon Northern Great Basin Field School

In Paisley caves in south-central Oregon, researchers uncovered pre-Clovis artifacts and the oldest human DNA discovered in the Americas. Radiocarbon dates show that people lived in the caves between 12,000 and 14,340 years ago.

And if Monte Verde was occupied by 14,500 years ago, this logic suggests that people reached North America much earlier than even the 15,500 pre-Clovis date in Texas.

Should we trademark the “pre-pre-Clovis” brand?

At any rate, the increasing number of solid pre-Clovis finds answers a riddle: How did Clovis artifacts appear in so many places at roughly the same time? According to the Waters report, “These data are evidence that by 15.5 ka [thousand years ago], human populations occupied the continental United States… . The sites of Cactus Hill, Virginia, and Miles Point, Maryland, hint that these [pre-Clovis] technologies may have been present a few millennia earlier. This early occupation of North America provides ample time for people to settle into the environments of North America, colonize South America by at least about 14.1 to 14.6 ka (Monte Verde, Chile), develop the Clovis tool kit, and create a base population through which Clovis technology could spread.” ²

When science gets ossified

Although we’ve covered the Texas discovery as a bit of gee-whiz archeology, it’s more accurate to say that the discipline proceeds by stacking study atop study, says Sissel Schroeder, a professor of anthropology at the University of Wisconsin-Madison and expert on ancient peoples of the Americas. Although most of the signs left by people who lived in North America will never be found, if they even still exist, “We work with the best information we have. The very small samples of data can make some of our interpretations less robust. Archeology is a cumulative science, so future finds can potentially add confirmatory evidence, or can disconfirm earlier conclusions; you just have to be open to recognizing that your interpretations could change.”

But scientists, like other people, can get stuck, she adds. “It seems easy for certain interpretive frameworks to become quite entrenched, and repeated over and over again. Into the 1920s, it was hugely debated that there were even people in the Americas” at the end of the last ice age. “There were a number of very provocative finds that led scholars to suggest that people had been here at the end of the Pleistocene [about 12,000 years ago], but wasn’t until the find at Folsom, New Mexico [in 1926] that scholarly acceptance began to develop.”

The Folsom find, soon followed by the discovery of those distinctive fluted points near Clovis, New Mexico, sparked “a transformative intellectual step for archeologists,” says Schroeder. “This was a radical shift in thinking.”

“You build a reputation based on a particular perspective,” says Bamforth, “and it’s hard to see evidence that is in opposition; we all believe we are really good at what we do.” Those who gain fame for overturning the conventional wisdom can wind up in the opposite corner, defending their own views long after contradictory evidence arises.

Some early claims for pre-Clovis sites were based on faulty excavation or inaccurate dating, which left a tradition of doubt, Bamforth says. For example, erroneous radiocarbon dates arose after dig sites were contaminated with groundwater. And European-style artifacts unearthed in the Hudson River valley, once interpreted as evidence for ancient European immigration, actually came from ship’s ballast that was dumped into the river, Bamforth told us.

Once archeologists got used to refuting claims, that skeptical attitude itself became entrenched, says Bamforth. “Because people were making such poor claims, very powerful people in the field clamped down on any claims for antiquity, and often the rejected claims turned out to be correct. People at the Smithsonian famously had nothing to do with Folsom until finally the evidence carried the day. There’s a famous photo showing a Folsom spearpoint between the ribs of an extinct bison. That’s proof you can’t argue with.”

Clovis-first is dead, at long last!

After 40 years of assault, Clovis-first seems dead at last. The Texas find “anchors the fact that people were here in the 14,000 or 15,000 year range, there is no longer an argument with that,” says Bamforth.

As the technology of archeology improves, Waters expects some of the most interesting finds to emerge from South America. “We have this North American bias. I’ve heard a lot about early sites in South America of the same age [as the Texas site] or older that nobody hears about. If you think about the immensity of South America, there is no way Clovis was first. There are going to be some amazing finds in the next 10 years, given the South American evidence, the work with genetics and DNA. The story of the first Americans is going to stay exciting.”

– David J. Tenenbaum

Even people who can’t distinguish the periodic table from a dining table know arsenic is poisonous, although few realize why. Arsenic is chemically akin to phosphorus, one of life’s essential elements. But it’s not identical, and when arsenic substitutes for phosphorus, it produce a toxic compound instead of a protein or chunk of DNA.

So we weren’t the only ones to be surprised by a study in today’s Science that identifies a bacterium that thrives on arsenic, at least in the lab, and incorporates this normally-poisonous element into proteins, fats and DNA.

Image: Wikipedia

A more typical reaction to arsenic comes from the elderly poisoning victims in the macabre comedy “Arsenic and Old Lace.” In that play and movie, two dotty spinsters spiked elderberry wine with arsenic, strychnine and cyanide for a freelance euthanasia project.

The new study is the first to show that it is possible to substitute for one of the elite elements (carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur) that were thought to be found in all life, says Ariel Anbar, a professor of earth and space exploration at Arizona State University. “No one has previously shown that arsenic can be substituted, and I am not aware that anyone has found a substitution for any of the six essential elements. And that’s why this is a big deal.”

Arsenic: It’s what’s for dinner

Felisa Wolfe-Simon, a former post-doctoral fellow with Anbar, gathered sediment and water from salty, alkaline, arsenic-rich Mono Lake in California and placed them in cultures intended to replicate Mono Lake water.

Images courtesy of Science/AAAS

These bacteria, viewed under an electron microscope, metabolized arsenic as if it were phosphorus. Mouseover to see the same strain of bacteria growing with phosphorus but without arsenic.

“Over time we made serial dilutions, one in 10, one in 10,” always including a strain of lake microbes, says Wolfe-Simon.

Wolfe-Simon, who is now at the NASA Astrobiology Institute and U.S. Geological Survey, says the dilutions removed “essentially all” of the phosphorus. In some samples, she jacked up the arsenic roughly 2,000 times above the concentration in Mono Lake, which gets its arsenic from rocks and is already about 20,000 times above the Environmental Protection Agency standard for arsenic in drinking water.

“This is a huge amount of arsenic,” Wolfe-Simon says. “It’s surprising that they could grow, even with phosphorus, in that condition.”

Although the bacteria died in the absence of phosphorus and arsenic, they survived if only arsenic was available. “The arsenic seems to be substituting for phosphorus,” says Wolfe-Simon. “We have identified arsenic in cellular structures that are consistent with where we would expect to see phosphorus.”

Photo: ©2010 Henry Bortman

Mono Lake, California, is salty, alkaline conditions, and toxic to many organisms. The lake is ideal for the study of extremophiles, microbes that live under bizarre temperature or chemistry.

Stepping out of line

This elemental swaperoo could operate more broadly, since the elements in each column of the periodic table have chemical similarities. If one neighbor of phosphorus can sustain life without phosphorus, could the elements below carbon, nitrogen or oxygen do the same?

Photo: ©2010 Henry Bortman

“This is not just about arsenic or Mono Lake,” says Wolfe-Simon. Life on Earth and the rest of the universe will be limited if it always requires six elements, but “If microbes can use arsenic as they can use phosphorus, that opens the door. What else can life do that is not yet known?”

In searching for life in the universe, NASA has focused on liquid water, another prerequisite for known life, but Anbar asserts that a search for the chemistry of life should stay broad. “Felisa’s results say we should think harder about which elements we should follow. We don’t want to be too influenced by the particular example of life on Earth. We want to push the boundaries.”

Call it “Arsenic in a new place.” Roll cameras!