# News this Week

Science  07 Oct 2011:
Vol. 334, Issue 6052, pp. 22
1. # Around the World

1 - Namibia
Germany Returns Colonial-Era Skulls to Namibia
2 - Ottawa
Canada's Top Court Keeps Injecting Drug Use Site Open
3 - Tokyo
Nuclear Power Takes Hit as Science Spending Rises
4 - Faroe Islands
Project to Sequence Entire Population Announced
5 - Farmington, Connecticut
Jackson Lab Branch Comes to Connecticut
6 - Washington, D.C.
House Bill Would Boost NIH's 2012 Budget by 3.3%
7 - Marshall Islands
Giant Sanctuary for Sharks

## Namibia

### Germany Returns Colonial-Era Skulls to Namibia

The skulls of 20 Namibians killed by German colonists a century ago returned to Namibia on 4 October. The skulls have been part of the anatomy collection at the Charité University Hospital in Berlin and the Berlin Medical Historical Museum for more than a century. Namibian leaders asked in 2008 that they be returned. In a project launched last year, researchers have been working to identify where the estimated 7000 skulls in the hospital's collections came from, and which ones should be repatriated.

The scientists studied inscriptions on the skulls referring to catalogs or publications, says Charité anatomist Andreas Winkelmann, one of the project's leaders. They also looked for indicators of sex, age of death, and traces of disease such as scurvy, which was rampant at a prison camp on Namibia's Shark Island where many of the skulls came from.

The project is ongoing, Winkelmann says. “We also want to find out more about the scientific historical context. We have not yet looked at who was involved in the collecting and why they did what they did.”

Museum director Thomas Shnalke noted at a press conference last week in Berlin that German science carries a “burden of guilt” from that time. “We accept that, and would like to ask for forgiveness.”

http://scim.ag/Namibianskulls

## Ottawa

### Canada's Top Court Keeps Injecting Drug Use Site Open

The Supreme Court of Canada has ruled that a “safe injection site” in Vancouver that aims to thwart the spread of HIV can continue to operate, providing a place for people to inject drugs under medical supervision and without the threat of arrest.

The federal government, including the minister of health, had argued that the facility, called Insite, should close because it violated the country's laws about possession and trafficking of controlled substances. “The effect of denying the services of Insite to the population it serves and the correlative increase in the risk of death and disease to injection drug users is grossly disproportionate to any benefit that Canada might derive from presenting a uniform stance on the possession of narcotics,” the court wrote in its unanimous decision.

Studies have shown that Insite has reduced overdose deaths and the risk of becoming infected with HIV and also led to increased use of addiction treatment programs. Insite kept its doors open during the court challenge and for now will continue to operate under an “exemption” to the federal substance control laws.

## Tokyo

### Nuclear Power Takes Hit as Science Spending Rises

Japan's ministry of education wants to boost overall science-related spending next year by 5.8%, to $14.7 billion. But spending on nuclear-related research will drop 9.8%, to$2.3 billion.

The ruling Democratic Party has proposed $918 million in new programs to accelerate the efforts of renewable and alternative energy schemes. Work on induced pluripotent stem cells and regenerative medicine will jump by 40%, to$69 million, and space-related research, including Earth observation, which will go up by 36%, to $631 million. Rank-and-file researchers will benefit from a 6% increase, to$3 billion, in competitively reviewed grants, including substantial growth in a multi-year grant category created last year.

Although increasing reliance on nuclear power remains official government policy, the radiation release from the damaged Fukushima Daiichi Nuclear Power Plant has turned many politicians and the public against that energy source. Japan's troubled experimental fast breeder reactor, Monju, would receive a “maintenance budget” pending a review of the nation's energy policy http://scim.ag/Japanbudget

## Faroe Islands

### Project to Sequence Entire Population Announced

The inhabitants of the Faroe Islands could become the world's first fully sequenced population, researchers announced at a meeting on personal genomes at Cold Spring Harbor Laboratory last week. The project, dubbed FarGen, aims to sequence the entire genome of every citizen and to use the information for health care and research in the self-governing Danish dependency. A pilot project sequencing the genomes of 100 individuals is under way. If all goes according to plan, the rest of the 50,000 Faroe Islanders will follow in the next 5 years, scientists said.

Researchers in other countries, such as Iceland, Estonia, and the United Kingdom, are building national genetic biobanks, but this is the first project aimed at compiling whole genomes for everyone. The cost for the project would be roughly $50 million, if sequencing prices keep falling at the current rate. Full funding has not yet been secured, however. And its scientific value will depend on how many citizens sign up for it, cautions geneticist Markus Nöthen of the University of Bonn in Germany. “This is a brave step, but it will only be successful if enough people take part,” he says. http://scim.ag/Faroes ## Farmington, Connecticut ### Jackson Lab Branch Comes to Connecticut Connecticut is offering$291 million to help open a new offshoot of the Jackson Laboratory (JAX), a genetics research institute best known as a leading breeder of research mice. On 30 September, Connecticut Governor Dannel Malloy announced the collaboration, which aims to make Farmington a hub of genetically customized “personalized medicine.”

The state made a compelling case,” said Edison Liu, JAX's president and CEO. He calls the location—within a short drive of bioscience hubs in Boston, New York City, and New Haven—“ideal.”

The deal calls for constructing 16,000 square meters of new lab space for 30 senior scientists on the campus of the University of Connecticut, Farmington. Planners forecast that the research center could employ 600 employees within 20 years.

Before ground can be broken, however, the Connecticut Legislature will need to sign off on bonds to float the project, with a review expected to start next month. JAX estimates that, over the next 20 years, it will add another $809 million from grants, gifts and business income to the state money. http://scim.ag/JacksonLab ## Washington, D.C. ### House Bill Would Boost NIH's 2012 Budget by 3.3% A House of Representatives subcommittee last week released a 2012 draft spending bill with surprisingly good news for the National Institutes of Health (NIH): The agency's budget would increase by$1 billion to $31.7 billion, a 3.3% increase compared to this year's level. The proposed spending boost matches the president's request and reverses a$190 million cut approved by a Senate committee on 21 September. The bill does not mention NIH's plan to create a National Center for Advancing Translational Sciences and to abolish the National Center for Research Resources. (The Senate bill would make these changes.)

Although the House appropriations subcommittee isn't expected to meet to approve the bill, the draft gives the panel a marker for upcoming negotiations with its Senate counterpart on an “omnibus” measure that would fund most, if not all, of the federal government. http://scim.ag/HouseNIH

## Marshall Islands

### Giant Sanctuary for Sharks

The lions of the sea just got additional safe haven in the Pacific. Last week, the Republic of the Marshall Islands declared its waters—1.9 million square kilometers—off-limits to shark fishing and banned the import and export of shark products. The island nation joins five other countries in setting up shark sanctuaries, and this one is expected to eventually expand to 4 million square kilometers.

As the ocean's top predator, sharks help keep the marine food chain in balance and maintain healthy fisheries, says Matt Rand, director of global shark conservation at the Pew Charitable Trusts in Washington, D.C. They also boost the local economy by serving as tourist attractions. About 30% of shark species are threatened, and not enough is known about many of the rest to determine their conservation status, says Rand, but some at-risk species, like the oceanic white tip, will get a reprieve thanks to the new Marshall Islands law.

2. # Random Sample

## Noted

It's tough getting older, but this is one birthday we're happy to celebrate. Science's daily online news site ScienceNOW turns 15 today. In the past decade-and-a-half, ScienceNOW has covered the hottest—and some of the most bizarre—stories in science, from early claims for martian life to fellatio among fruit bats. Check out our full coverage (http://scim.ag/ScienceNOW15) and share your favorite ScienceNOW stories.

## Roses Are Red, Roses Are Bluish

A 25-year struggle to sell genetically-engineered “blue” roses in the United States took a big step forward last week. The U.S. Department of Agri culture won't regulate U.S. efforts to grow and sell the flowers after concluding that two mauve hybrids created by Australia-based Florigene don't pose a risk to ecosystems or the economy. In the 1990s, an Australian offshoot of U.S.-based biotech pioneer Calgene Inc. won the race to find and patent “blue genes” to create roses of an unnatural hue (Science, 1 June 1990, p. 1074). Success, however, came slowly: The company didn't unveil its blue roses until the mid-2000s, and started selling them in Japan in 2009. Next month, Florigene hopes to begin growing 3 million to 6 million blue roses annually in the United States for the cut-flower market. But there are no plans to sell whole plants to home gardeners.

## Finger Drawings From a Prehistoric Preschool

Among the prolific paintings and other art in the 8-kilometer-long Rouffignac cave system in southwestern France are a number of unusual markings known as finger flutings, which were made by people dragging their hands through the soft silt that lines the cave's walls. By analyzing the finger flutings of modern humans, researchers discovered that the ratio of the distance between the three middle fingers indicates that many of the cave artists were very young children, one as young as 2 or 3 years old, the researchers reported 2 October at the archaeology of childhood conference in Cambridge, U.K. Some of these flutings were too steady for a toddler, they found, suggesting that an adult guided the child's hand. Since the children's drawings seemed to be concentrated in one chamber, the researchers believe that the alcove may have been a sort of art school. And some of the drawings were high on the walls and on the ceiling, suggesting that the children were lifted.

## By the Numbers

23,000 — Air miles (and carbon footprint) the average astronomer logs each year traveling to meetings and observatories, according to astrophysicist Philip Marshall of the University of Oxford.

100 meters — Estimated thickness of snow on parts of Saturn's moon Enceladus, according to data presented last week at a planetary sciences meeting.

## Following Berlusconi's Risqué Gaze

If Silvio Berlusconi leers at someone to his right, Italy's conservative voters will tend to glance in that direction, too, as if to see what he's looking at. Right-wing Italians seem to naturally track the gaze of those in power, says Marco Tullio Liuzza, a social neuroscientist at the Sapienza University of Rome.

Liuzza and colleagues organized 28 subjects into right- and left-leaning voters, and sat them in front of a computer screen displaying a range of Italian politicians. The images included Prime Minister Berlusconi and left-leaning Antonio Di Pietro. The subjects were instructed to pay attention to the color of a square positioned between the politician's eyes, and to look left or right, depending on its color. But while the subjects waited for the square to change, the team also quickly shifted the gaze of the politican in the image, making the image appear to glance right or left.

Right-wing voters were more likely to follow the direction of Berlusconi's gaze than Di Pietro's and would follow Berlusconi's gaze even when the box color instructed the voters to look in the opposite direction, the team reported in a study published online in PLoS ONE last month. That result, they suggested, is similar to behavior observed in monkeys in which subordinate primates follow the gaze of dominant monkeys much more than those big cheeses returned the favor. Left-leaning voters, however, were less inclined to follow Di Pietro's gaze, Liuzza says.

But there's an important caveat: This study was conducted in 2009, long before Berlusconi became embroiled in numerous sex scandals, Liuzza notes. “It would be interesting to see if this effect would disappear now that the confidence in Berlusconi's coalition has drastically dropped.”

3. # Newsmakers

## World's Smallest Periodic Table, Engraved on a Human Hair

It's not quite angels dancing on the head of a pin, but scientists have squeezed a reproduction of the entire periodic table onto a human hair—and the 2012 Guinness World Records book has acknowledged that reproduction to be the smallest in the world.

The hair initially belonged to chemist Martyn Poliakoff at the University of Nottingham in the United Kingdom. During a visit to the Nottingham Nanotechnology and Nanoscience Centre, Poliakoff contributed a hair for the creation of a special version of the periodic table. The researchers engraved the hair by irradiating it with gallium ions at high speeds, breaking off tiny flakes in the shape of the table. When completed, the table was about 90 micrometers long and almost 50 micrometers tall (including the actinides and lanthanides). The engraved hair earned the title of “smallest periodic table”—and the hair itself was returned to Poliakoff as a birthday gift.

## Ig Nobels Honor Bladder Control, Beer Bottle Mating

Full bladders affect short-term memory and attention span—but can aid in impulse control. Tortoise yawning is not contagious. How do you rouse a deaf person in the event of a fire? Wasabi. These are a few of the research findings honored at Harvard University on 29 September as part of the 2011 Ig Nobel Prizes.

Most Ig Nobel awards go to recently published work, but a 1983 study of why male Buprestid beetles try to mate with a certain brand of Australian beer bottle netted the Ig Nobel biology prize for Darryl Gwynne and David Rentz, entomologists with the Commonwealth Scientific and Industrial Research Organisation in Canberra. The color and shape of the bottle is a turn-on for the beetles, they found, and a series of bumps on the glass seal the deal.

The ceremony had a somber moment, as two longtime Ig Nobel participants were memorialized. Mathematician and pioneer of fractal geometry Benoît Mandelbrot, 85, and Harvard University chemist William Lipscomb, 91 (who also won a real Nobel Prize), both passed away within the last year. They were frequent participants in the traditional Ig Nobel “Win a Date With a Nobel Laureate” contest. This year, the prize was a date with Lou Ignarro (Nobel Prize for physiology or medicine 1998).

http://scim.ag/_IgNobels

## CFS Researcher Fired

Judy Mikovits, who for 2 years has championed the controversial theory that XMRV, a mouse retrovirus, has links to chronic fatigue syndrome (CFS), was fired on 29 September. The next day, a blogger raised questions about a slide Mikovits presented at a scientific meeting, triggering a probe by Science of a figure in a paper it published by Mikovits and colleagues in October 2009.

The Whittemore Peterson Institute for Neuro-Immune Disease (WPI), a private organization in Reno, Nevada, devoted to CFS research and treatment, said it fired Mikovits for withholding a cell line from a co-worker. In a termination letter dated 30 September, Annette Whittemore, CEO of WPI, charged Mikovits with being “insubordinate and insolent.” Mikovits, who was immediately locked out of her lab, responded that she withheld the cell line because the co-worker failed to take her direction.

That same day, a blog written by graduate student Abbie Smith at the University of Oklahoma, Oklahoma City, noted that Mikovits had presented a slide at a recent CFS meeting that looked identical to an image in the 2009 Science paper. But the slide had different patient numbers and unique experimental conditions. Science Executive Editor Monica Bradford said the journal was contacting the authors to review the description of the slide in the original paper.

Mikovits and collaborator Francis Ruscetti of the National Cancer Institute in Frederick, Maryland, say patient numbers were changed to protect privacy and no wrong-doing occurred. http://scim.ag/_Mikovits

4. Geology

# An Epoch Debate

1. Gaia Vince*

There's no dispute that humans are leaving their mark on the planet, but geologists and other scientists are debating whether this imprint is distinctive and enduring enough to designate a new epoch: the Anthropocene.

“Each time I see it, it's dramatic; the equivalent of listening to a particularly impressive bit of Mozart—like the opening of Don Giovanni, or the bit where Don gets dragged down to the pits,” says geologist Jan Zalasiewicz of the University of Leicester in the United Kingdom.

The object of his awestruck tone seems unremarkable: a stripe of black rock abutting a pale gray section of cliff in Dob's Linn gorge in the United Kingdom. But to geologists, this slice of shale represents one of the major transitions in Earth's history. It is the location for a “golden spike,” an internationally agreed-on marker for the boundary between two different geological periods, eras, or epochs. In this case, the golden spike marks the boundary between the Ordovician and Silurian periods, two planetary states so different from each other that, to geologists, the rocky evidence for each is clearly distinguishable. The Ordovician ended some 445 million years ago as rapid glaciation and other global changes triggered the planet's fifth mass extinction event, wiping out more than 60% of marine life.

Now, scientists say, the planet has crossed another geological boundary, a transformation that will leave its own signature stripe in the rocks—and humans are the change-makers. An influential group of geologists, ecologists, and biologists argue that humans have so changed the planet that it is entering another phase of geological time, called the Anthropocene, “the Age of Man.” Humanity, they contend, can be considered a geophysical force on a par with supervolcanoes, asteroid impacts, or the kinds of tectonic shift that led to the massive glaciation of the Ordovician.

“The Dob's Linn golden spike marks a revolutionary period in the Earth's history,” Zalasiewicz says. “I feel quite the same sense of awe when I think about the kinds of large-scale geological changes that we are making to our planet now.”

From the invention of agriculture and domestication of animals to the creation of cities, humans have been altering the landscape ever since the Holocene epoch began 11,500 years ago at the end of the last ice age. But, until recently, people have only changed their local environments. The industrial revolution increased the extent and reach of our impact, making it truly global. And after World War II, the system-wide human effect on our planet accelerated dramatically to the extent that the human-wrought changes may be considered comparable, many scientists say, to geological transformations of the past, like that of the Ordovician to the Silurian.

It was Nobel laureate Paul Crutzen who first came up with the term “Anthropocene.” In an article in Nature in 2002, Crutzen argued that human changes have moved the planet out of the Holocene into a much less climatically stable age. The notion took hold. A wide range of scientists have used the term to describe our unprecedented, planetwide environmental effects, some of which are immediately obvious from satellite images of Earth. But formally accepting the Anthropocene as a geological term is a more controversial matter. After all, changes that appear vast from our human perspective might be invisible on a geological time scale. And debates over designating a new epoch, era, or period can take decades—even centuries—to resolve.

In 2009, the International Commission on Stratigraphy, the body charged with formally designating geological time periods, decided the Anthropocene concept “has some merit.” It set up the Anthropocene Working Group, chaired by Zalasiewicz, to investigate the proposed age and report back. This February, members of the group published their initial findings in a special issue of the Philosophical Transactions of the Royal Society A. The group reported a wide range of human impacts on the planet that will leave a stratigraphically significant mark on the geological record.

### A Global Perspective on the Anthropocene

Ever since humans launched Sputnik into space, we've been able to observe our planet and its changes from a truly global perspective. Satellites and improved data collection and analysis have allowed scientists to measure the anthropogenic influence on a range of Earth systems, enabling researchers to track rates of deforestation in the Amazon, Arctic ice melt, trails of air pollution, the extent of sea-level rise, and many other regional and global phenomena. These tools are enabling scientists to look at human changes to the planet's atmosphere, hydrology, lithosphere, and biota—and infer which changes are profound enough to be measurable millions of years hence.

Although he may often sound like an Anthropocene convert, Zalasiewicz says he hasn't officially made up his mind. “What we're trying to do is to ask how different is our current world from that of a prehuman equivalent. And to what extent is the present state of the planet and its various changes in biology, chemistry, geography converted into geology?” he says.

The Anthropocene debate is continuing next week at the 2011 Geological Society of America conference in a session chaired by Stanley Finney, a geologist at California State University, Long Beach, who is the current chair of the International Commission on Stratigraphy. Finney is one of the most outspoken skeptics of the Anthropocene designation. He agrees that humans are changing the planet but questions how much of a mark will be left in the strata. “Many of our visible impacts could be removed through erosion,” he says.

## The writing in the rocks

Erle Ellis, an ecologist at the University of Maryland, Baltimore County, comes down firmly on the side of designating a new epoch, a view colored by his investigations into how humans have altered the planet's land covering. Ellis, a member of the Anthropocene Working Group, calculates that 80% of Earth's land surface has been modified by humans, with about 40% currently being used to produce food—a figure that doesn't include land used for timber plantations. Such deforestation and conversion to cropland or savanna leaves clear signs in the geological record; palynologists, who study pollen paleontology, can date humankind's ancient agricultural forays with great accuracy. The current unprecedented rate of deforestation—80,000 km2 per year—will also be easy to spot in the rock record, Ellis says. There are now more trees in agricultural land than in forests.

The human impact on biodiversity will influence the types and dispersal of fossil remains. “Biostratigraphy is a very effective way of recognizing one's place in deep time,” Zalasiewicz says. Consider that more than 90% of total vertebrate biomass today is made up of humans and domesticated animals, up from 0.1% 10,000 years ago. And if the prediction of some biologists comes true, Earth will experience the sixth mass extinction event in its 4.5-billion-year history because of hunting, overfishing, habitat loss, pollution, and climate change; that would offer another, sobering piece of evidence for the Anthropocene.

Although humans have changed Earth's biota and its hydrology through damming rivers, creating reservoirs, sucking dry aquifers, and melting glaciers, the geologists who will ultimately judge the Anthropocene case may end up focusing more on alteration of the planet's lithosphere, its rocky shape. Some suggest that humanmade infrastructure will fashion a unique and enduring strata. “In the eyes of a geologist, we're making really quite interesting patterns out of our raw materials,” Zalasiewicz says. “Wherever a road was buried, it would look like a rather strange and distinctive fossil river channel, but one which is quite rectangular in shape and with a particular pattern of gravel and other materials like concrete that are not typical of river channels. Millions of years from now, a geologist would see this and raise an eyebrow. A lot that we're producing is distinctive.”

Cities, too, would leave their marks. Some may erode away, but others, particularly those like Amsterdam or New Orleans that are in low-lying coastal zones and could become “fossilized” as sediments accumulate over them, would leave their signatures of foundations, plumbing, and rubble in the lithostrata. “Peel back the pavements and the human interventions are already writ in the rocks,” says Simon Price, an urban geoscientist with the British Geological Survey. “We're witnessing a geological process, but it's by our hands, not by glaciers or rivers.”

### A Sign of Our Times

If we are living in a new geological phase called the Anthropocene, when did it begin? In other words, where does its golden spike belong?

Many human-driven planetary changes have their roots in the industrial revolution, when the human population reached 1 billion. Atmospheric carbon dioxide from fossil fuels started to build from around 1800, although it probably took 50 to 100 years before new concentrations of light carbon accumulated in measurable levels in marine shells. That change could be the marker for the golden spike designating the beginning of the Anthropocene. There is a precedent: The boundary between the Paleocene and the Eocene epochs of the Cenozoic era is based on a change of carbon isotope chemistry.

But the scale of our impact accelerated rapidly after 1945 when population doubled (from 3 billion in 1950 to 6 billion by 2000). As a result, some think the golden spike—officially known as a Global Boundary Stratotype Section and Point—should be set around 1945, which handily provides a marker that's sudden, distinctive, and global: the introduction of radioactive nuclei into the environment from the first atomic-bomb tests in Alamogordo, New Mexico. “The golden spike could be put into a layer of accumulating lake sediments in which the radioactive cesium first appears,” geologist Jan Zalasiewicz of the University of Leicester in the United Kingdom says.

From a geological perspective, it doesn't matter whether the spike is at 1800, 1945, or 2050, Zalasiewicz says, because millions of years in the future, with error bars of thousands of years, that kind of distinction will be impossible to perceive. Events that look abrupt in the strata may have taken millions of years to occur, and many changes take time to reveal themselves. For example, the temperature rise at the beginning of the Holocene was fairly abrupt, but it still took some 5000 years for sea-level rise to catch up.

“The golden spike we choose would be a time boundary that we use with full knowledge that most changes on Earth are happening in different places at different times,” Zalasiewicz says. “It's useful and instructive to think of [the Anthropocene] from the far future perspective, but in practice we're dealing with it today. So we have to adopt as precise a time scale as we can.”

Humans are changing the lithostratigraphy in now easily visible ways. Mining and other excavations remove four times as much sediment as the world's glaciers and rivers move each year, and massive land-forming projects have created entire islands in the United Arab Emirates and elsewhere.

Other anthropogenic changes are not obvious from Google Earth but will leave an enduring legacy. Long-lasting alterations to the planet's chemistry are already evident: The world is currently being flooded with light carbon (the C-12 isotope rather than C-13) due to fossil-fuel burning, and there is now a measurable difference—consistent around the world—in the carbon composition of biological specimens such as sea shells, coral, and the shells of plankton foraminifera, which will be preserved in the strata. Chemostratigraphy will also reveal the appearance of novel chemicals, such as PCBs, plastics, radioactive isotopes like cesium from atomic tests (see sidebar, p. 37), and newly common materials, from metals such as aluminum (which doesn't naturally appear in its elemental state) to nitrates (which humans have made abundant through fertilizer production and fossil-fuel burning).

The nitrates in agricultural runoff also cause the massive dead zones that currently affect 250,000 km2 of the world's oceans. Similar zones have been recorded in the planet's paleontological record, and the current ones likely will be as well. Ocean acidification, too, is a measurable result of anthropogenic carbon emissions being dissolved in the oceans—they are now more acidic than at any time in the past 800,000 years or more.

The working group is still gathering evidence that human changes such as these will leave an enduring legacy, then they will assess it and decide whether the Anthropocene should be formalized on the geological time scale, and if so, at what level: an age, epoch, era, or a period.

Finney questions how relevant the geological time scale is to the Anthropocene. In 100,000 years from now, people will not be digging the strata to find out about the world as it was in 2011, he argues; there are far better tools for that. Geologists now and in the future will use the human calendar and the many cultural records that are kept in order to look back to this time. The Anthropocene may be a useful general term, Finney says, but it has no place on the official stratigraphic time scale.

Ellis disagrees. “It's really helpful and relevant to think like a geologist, even though I'm not one. It frames our impacts on a bigger planetary perspective. To be able to look back at the rocks and say, ‘Something happened here that cannot be explained by anything other than human impact’ is really powerful,” Ellis says.

“I think we're challenging the traditional view that geology always looks backwards. Geology is happening all around us now at a rate that we can certainly discern,” says Will Steffen, executive director of the Australian National University's Climate Change Institute in Canberra. “Different eras and epochs in the past have been defined by changes in climate and biodiversity. We're already experiencing both of these, and for the first time we are aware of doing so and actually driving these changes.”

Zalasiewicz's working group is aiming to deliver a final report at the 2016 International Geological Congress in South Africa. But there's unlikely to be a quick vote then on whether the Anthropocene deserves the title of epoch—or period or age. The Ordovician-Silurian boundary at Dob's Linn was finally agreed on in 1986, more than a century after its proposal by geologist Charles Lapworth. Only about half of the major boundaries in the Phanerozoic—our current geological eon covering the past 542 million years—have been fixed; the rest are still being argued over. Geologists, like their subject, are resistant to rapid change.

5. # A Global Perspective on the Anthropocene

Ever since humans launched Sputnik into space, we've been able to observe our planet and its changes from a truly global perspective. Satellites and improved data collection and analysis have allowed scientists to measure the anthropogenic influence on a range of Earth systems, enabling researchers to track rates of deforestation in the Amazon, Arctic ice melt, trails of air pollution, the extent of sea-level rise, and many other regional and global phenomena. These tools are enabling scientists to look at human changes to the planet's atmosphere, hydrology, lithosphere, and biota—and infer which changes are profound enough to be measurable millions of years hence.

6. Geology

# A Sign of Our Times

1. Gaia Vince

When did the Anthropocene begin? Many human-driven planetary changes have their roots in the industrial revolution, but some think the marker should be set at 1945, when radioactive nuclei were first introduced into the environment.

If we are living in a new geological phase called the Anthropocene, when did it begin? In other words, where does its golden spike belong?

Many human-driven planetary changes have their roots in the industrial revolution, when the human population reached 1 billion. Atmospheric carbon dioxide from fossil fuels started to build from around 1800, although it probably took 50 to 100 years before new concentrations of light carbon accumulated in measurable levels in marine shells. That change could be the marker for the golden spike designating the beginning of the Anthropocene. There is a precedent: The boundary between the Paleocene and the Eocene epochs of the Cenozoic era is based on a change of carbon isotope chemistry.

But the scale of our impact accelerated rapidly after 1945 when population doubled (from 3 billion in 1950 to 6 billion by 2000). As a result, some think the golden spike—officially known as a Global Boundary Stratotype Section and Point—should be set around 1945, which handily provides a marker that's sudden, distinctive, and global: the introduction of radioactive nuclei into the environment from the first atomic-bomb tests in Alamogordo, New Mexico. “The golden spike could be put into a layer of accumulating lake sediments in which the radioactive cesium first appears,” geologist Jan Zalasiewicz of the University of Leicester in the United Kingdom says.

From a geological perspective, it doesn't matter whether the spike is at 1800, 1945, or 2050, Zalasiewicz says, because millions of years in the future, with error bars of thousands of years, that kind of distinction will be impossible to perceive. Events that look abrupt in the strata may have taken millions of years to occur, and many changes take time to reveal themselves. For example, the temperature rise at the beginning of the Holocene was fairly abrupt, but it still took some 5000 years for sea-level rise to catch up.

“The golden spike we choose would be a time boundary that we use with full knowledge that most changes on Earth are happening in different places at different times,” Zalasiewicz says. “It's useful and instructive to think of [the Anthropocene] from the far future perspective, but in practice we're dealing with it today. So we have to adopt as precise a time scale as we can.”