Amazing Science

The Great Oxidation Event occured around 2.3 billion years ago, when it was no longer possible for newly created oxygen to be captured in chemical compounds. Instead, it started to accumulate as oxygen in the oceans and in the atmosphere. Before this event, in the Earth's early atmosphere, there were only traces of free oxygen. All life was based exclusively on anaerobic processes - chemical reactions that did not require oxygen. With the emergence of cyanobacteria that oxidized water with the help of light and produced oxygen as a by-product, the conditions for life on Earth gradually began to transform.

However, little is known about the possible interplay between the origin of multicellularity, diversification of cyanobacteria, and the rise of atmospheric oxygen. The team tested whether the evolution of multicellularity overlapped with the Great Oxidation, and whether multicellularity is associated with significant shifts in diversification rates in cyanobacteria.

The results indicate an origin of cyanobacteria before the rise of atmospheric oxygen. The evolution of multicellular forms coincided with the onset of the Great Oxidation Event and an increase in diversification rates, suggesting that multicellularity could have played a key role in triggering cyanobacterial evolution. In prior studies, geochemists challenged the simple notion of an up-only trend for early oxygen and provided the first compelling direct evidence for a major drop in oxygen after The Great Oxidation event some, which was critical for the origin and evolution of the first forms of eukaryotic life. The second big step in the up-only hypothesis occurred almost two billion years later, coinciding with the first appearances and earliest diversification of animals.

The meteorite  on February 14th weighed about 10,000 tons. According to NASA, the power released during the explosion was equivalent to 500 kiloton, which is 30 times the power of the bomb that destroyed Hiroshima.

NASA experts describe the Chebarkul meteorite as the second largest since 1908, when a meteor hit Tunguska in Siberia. Such a meteor strike can be expected every 100 years, a NASA expert said.

Chelyabinsk meteorite fragments are already on sale on one of the most popular online auctions, Ebay. Not only the citizens of Russia are among the vendors but also Americans are involved.

Astronomers could not trace the Chelyabinsk meteor because this celestial body was approaching from the Sun, and telescopes did not see it in the sunshine, Deputy Director of the Sternberg Astronomical Institute at the Moscow State University Sergei Lamzin said. "It was impossible to detect it, because it was flying fromthe Sun. But if it was flying at night, our MASTER telescopes’network could have traced it", Lamzin said to journalists. MASTER telescopes can observe bursts in the Universe, watch comets, meteors and space debris. The system includes telescopes, located in the Tunka valley, Moscow region, Kislovodsk, in the Urals and in Blagoveschensk.

In the period of time around the fall of the Chelyabinsk meteor, the Russian Meteor weather satellite registered an increase in the concentration of water molecules in the orbit that possibly indicates that the space "guest" was a comet.

Researchers say the meteorite exploded into at least seven large pieces and hundreds of small ones. One of the bigger fragments plunged into the local Chebarkul Lake, forming an 8-meter ice hole.

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An asteroid half the size of a football field passed closer to Earth than any other known object of its size on Friday, the same day an unrelated and much smaller space rock blazed over central Russia, creating shock waves that shattered windows and injured 1,200 people.

Asteroid 2012 DA14, discovered just last year, passed about 17,200 miles from Earth at 2:25 p.m. EST (1925 GMT), closer than the networks of television and weather satellites that ring the planet.

"It's like a shooting gallery here. We have two rare events of near-Earth objects approaching the Earth on the same day," NASA scientist Paul Chodas said during a webcast showing live images of the asteroid from a telescope in Australia.

Scientists said the two events, both rare, are not related -the body that exploded over Chelyabinsk, Russia, at 10:20 p.m. EST Thursday (0320 GMT Friday) came from a different direction and different speed than DA14.

"It's simply a coincidence," Chodas said.

NASA has been tasked by the U.S. Congress to find and track all near-Earth objects that are .62 miles in diameter or larger.

The effort is intended to give scientists and engineers as much time as possible to learn if an asteroid or comet is on a collision course with Earth, in hopes of sending up a spacecraft or taking other measures to avert catastrophe.

About 66 million years ago, an object 6 miles in diameter smashed into what is now the Yucatan Peninsula in Mexico, leading to the demise of the dinosaurs, as well as most plant and animal life on Earth.

Scientists estimate that only about 10 percent of smaller objects, such as DA14, have been found.

"Things that are that tiny are very hard to see. Their orbits are very close to that of the Earth," said Paul Dimotakis, a professor of aeronautics and applied physics at the California Institute of Technology in Pasadena.

Scientists have peered for the first time into the interior of a lake hidden beneath the Antarctic ice sheet. Subglacial Lake Whillans, located less than 400 miles from the South Pole, had sat isolated under the ice for hundreds of thousands of years—perhaps up to a million years. But over the last week a team of ice drillers has used a jet of hot water to melt a narrow hole into the lake through 2,600 feet of ice.

Final confirmation that the lake had been reached unfolded inside a steel shipping container parked on the ice sheet on four massive skis. Seventeen people crowded into this mobile control room as a video camera was lowered into the borehole. All eyes were riveted to a computer monitor. A scene reminiscent of cosmic wormhole travel unfolded on it: the camera steered into the black void at the center of the screen; the smooth, round, undulating walls of ice-hole scrolled by on the edges.

Billowing clouds obscured the camera’s view in the lower reaches of the hole. Then, as the swirling silt settled, a fuzzy picture emerged: the camera lay on its side, its lens looking across a muddy brown bottom strewn with small rocks. Wisps of mud drifted above. The image, knitted in rows of grainy pixels, echoed the first pictures of the Martian surface, radioed back by the Viking lander almost 40 years ago.

The door of the control room opened and in stepped a woman covered head to ankle in a sterile white Tyvek suit—Jill Mikucki, a microbiologist from the University of Tennessee in Knoxville who had helped lower the camera into the lake. Mikucki pointed her own little Canon at the image on the computer monitor and tried to snap a photo—“Oh,” she murmured, disappointed: the cold had killed her batteries. She paused. “It’s beautiful,” she said, forced to appreciate it in the moment—“really beautiful”—then she hurried out to help retrieve the camera.

Greenland was about eight degrees warmer 130,000 years ago than it is today, an analysis of an almost three-kilometer-long ice core in Greenland has revealed. It is important to understand what happened in Greenland during the Eemian period because the temperatures experienced then are "within the realms of where we are heading", says Etheridge.

However, he says the previous warming was due to the Earth receiving more of the Sun's radiation due to its orbit at the time, while today's warming is being driven by increases in greenhouse gases in the atmosphere. The study also shows sea levels were on average 6 meters higher.

The results provide "important benchmarks for future climate change projections" in temperature and the contribution of the two main ice sheets to sea level rises, Rubino says. He says the study also reveals the Greenland ice sheet did not melt as much as previously thought so was not the major contributor to sea level at that time. "It shows the major contribution to sea level rises was not coming from the Greenland ice shelf," he says. "It was previously believed that Greenland melted entirely during the Eemian, but in fact the ice sheet was not that much different from what it is now."

For centuries people have tried to predict earthquakes-with no success. Magnetic signals from rocks deep inside the earth are the latest prospect.

The dream is to be able to forecast earthquakes like we now predict the weather. Even a few minutes' warning would be enough for people to move away from walls or ceilings that might collapse or for nuclear plants and other critical facilities to be shut down safely in advance of the temblor. And if accurate predictions could be made a few days in advance, any necessary evacuations could be planned, much as is done today for hurricanes.

Scientists first turned to seismology as a predictive tool, hoping to find patterns of foreshocks that might indicate that a fault is about to slip. But nobody has been able to reliably distinguish between the waves of energy that herald a great earthquake and harmless rumblings.

Seismologists just can't give a simple yes or no answer to the question of whether we're about to have a large earthquake, said Thomas Jordan, director of the University of Southern California's Southern California Earthquake Center at a meeting of the American Geophysical Union (AGU) in San Francisco in December.

So some scientist have turned their attention to other signals, including electricity, that might be related to activity occurring below ground as a fault prepares to slip

One theory is that when an earthquake looms, the rock "goes through a strange change," producing intense electrical currents, says Tom Bleier, a satellite engineer with QuakeFinder, a project funded by his parent company, Stellar Solutions, of Cambridge, Massachusetts.

"These currents are huge," Bleier said at the AGU meeting. "They're on the order of 100,000 amperes for a magnitude 6 earthquake and a million amperes for a magnitude 7. It's almost like lightning, underground."

Five years ago, the last report of the Intergovernmental Panel on Climate Change painted a gloomy picture of our planet’s future. As climate scientists gather evidence for the next report, due in 2014, Michael Le Page gives seven reasons why things are looking even grimmer.

Kaffeklubben Sø, the world's most northerly lake, was entombed beneath a near-permanent layer of ice some 2400 years ago. Now it is beginning to thaw – and some of the organisms that disappeared from its waters are beginning to return. The finding is the latest evidence that warmer temperatures in polar regions can result in rapid ecological changes.

Located at 83° 37' north, on the coastal plain of northern Greenland, the 48-hectare Kaffeklubben Sø looks out over the Arctic Sea. "It's kind of the end of the earth," says Bianca Perren of the University of Franche-Comté in Besançon, France. One to two metres of ice cover the lake year-round, but a "moat" of water forms around the edge of the lake in summer when average temperatures rise to 1.6 °C.

The lake formed about 3500 years ago when local precipitation increased, says Perren. A few species of silica-shelled algae called diatoms lived in the young lake, but their populations declined as regional temperatures cooled, and they vanished entirely 2400 years ago. All that survived under the ice were hardy cyanobacteria, which require little light and can survive even under several metres of ice.

A couple of brief summer thaws allowed diatoms to return briefly, but the lake remained nearly barren until around 1960, when the first diatom species returned. The latest water samples, collected by Perren and her colleagues, contain some 20 species.

Our planet's magnetic field is in a constant state of change, say researchers who are beginning to understand how it behaves and why.

Every few years, scientist Larry Newitt of the Geological Survey of Canada goes hunting. He grabs his gloves, parka, a fancy compass, hops on a plane and flies out over the Canadian arctic. Not much stirs among the scattered islands and sea ice, but Newitt's prey is there--always moving, shifting, elusive. His quarry is Earth's north magnetic pole. Scientists have long known that the magnetic pole moves. James Ross located the pole for the first time in 1831 after an exhausting arctic journey during which his ship got stuck in the ice for four years. No one returned until the next century. In 1904, Roald Amundsen found the pole again and discovered that it had moved--at least 50 km since the days of Ross.

The pole kept going during the 20th century, north at an average speed of 10 km per year, lately accelerating "to 40 km per year," says Newitt. At this rate it will exit North America and reach Siberia in a few decades. Keeping track of the north magnetic pole is Newitt's job. "We usually go out and check its location once every few years," he says. "We'll have to make more trips now that it is moving so quickly." Earth's magnetic field is changing in other ways, too: Compass needles in Africa, for instance, are drifting about 1 degree per decade. And globally the magnetic field has weakened 10% since the 19th century. When this was mentioned by researchers at a recent meeting of the American Geophysical Union, many newspapers carried the story. A typical headline: "Is Earth's magnetic field collapsing?" Probably not. As remarkable as these changes sound, "they're mild compared to what Earth's magnetic field has done in the past," says University of California professor Gary Glatzmaier.

Sometimes the the whole magnetic field of Earth completely flips. The north and the south poles swap places. Such reversals, recorded in the magnetism of ancient rocks, are unpredictable. They come at irregular intervals averaging about 300,000 years; the last one was 780,000 years ago. Are we overdue for another? No one knows.

Researchers from Amherst College and The University of Texas at Austin have described a new technique that might one day reveal in higher detail than ever before the composition and characteristics of the deep Earth.

There's just one catch: The technique relies on a fifth force of nature (in addition to gravity, the weak and strong nuclear forces and electromagnetism) that has not yet been detected, but which some particle physicists think might exist. Physicists call this type of force a long-range spin-spin interaction. If it does exist, this exotic new force would connect matter at Earth's surface with matter hundreds or even thousands of kilometers below, deep in Earth's mantle. In other words, the building blocks of atoms—electrons, protons, and neutrons—separated over vast distances would "feel" each other's presence. The way these particles interact could provide new information about the composition and characteristics of the mantle, which is poorly understood because of its inaccessibility.

"The most rewarding and surprising thing about this project was realizing that particle physics could actually be used to study the deep Earth," says Jung-Fu "Afu" Lin, associate professor at The University of Texas at Austin's Jackson School of Geosciences and co-author of the study appearing this week in the journal Science.

This new force could help settle a scientific quandary. When earth scientists have tried to model how factors such as iron concentration and physical and chemical properties of matter vary with depth—for example, using the way earthquake rumbles travel through the Earth or through laboratory experiments designed to mimic the intense temperatures and pressures of the deep Earth—they get different answers. The fifth force, assuming it exists, might help reconcile these conflicting lines of evidence.

Earth's mantle is a thick geological layer sandwiched between the thin outer crust and central core, made up mostly of iron-bearing minerals. The atoms in these minerals and the subatomic particles making up the atoms have a property called spin. Spin can be thought of as an arrow that points in a particular direction. It is thought that Earth's magnetic field causes some of the electrons in these mantle minerals to become slightly spin-polarized, meaning the directions in which they spin are no longer completely random, but have some preferred orientation. These electrons have been dubbed geoelectrons.

In a probable scenario for climate change, New Orleans will no longer exist. Neither will Atlantic City, N.J. Boston will look much like it did in the 17th century, before the city was dredged up to build a port. And Florida will no longer keep its distinct appendage shape.

These geographical changes due to sea-level rise are only the beginning, scientists bluntly stated at a briefing yesterday convened by Senate Environment and Public Works Committee Chairwoman Barbara Boxer (D-Calif.).

"Today's talk underscored what I already knew, but gives me more facts," said Boxer. "We have to act because our children and our grandchildren need us to act."

Storms are likely to travel in different patterns than they did before, much like Superstorm Sandy did. Increasing temperatures are changing the cycles of plants and trees and extending the pollination period to exacerbate allergies. In the hottest cities, it will be uncomfortable to step outside during the day. And limited agricultural growth will severely strain the world's ability to feed itself, said a panel composed of two atmospheric scientists, one public health expert and one biological oceanographer.

"The last two years [2011 and 2012] have had the largest number of billion-dollar events," said Donald Wuebbles, a professor of atmospheric sciences at the University of Illinois.

Rising temperatures will increase human exposure to mold, microbial pathogens and infectious diseases, said John Balbus, senior adviser for public health at the National Institute of Environmental Health Sciences. Studies are indicating that the greatest heat-related harm come may not from extreme exposure but rather from the lower but more frequent stress of increasingly hot summer days.

"We've seen the geographical range of ticks that cover Lyme disease shift northward, and is predicted to shift further northward in the United States and in Canada," said Balbus, adding that there are limited studies on the actual incidence of Lyme disease.

Melting ice is causing heat exchanges between the oceans and the atmosphere that were not possible before, said James McCarthy, a professor of biological oceanography at Harvard University.

"Storms like Superstorm Sandy that begin in the tropics and escape the tropics [now] because of the exceptionally warm surface water remain intense until landfall," he said. "When that storm hits, as it did, we have unprecedented potential for disruption."

A meteor that exploded over Russia this morning was the largest recorded object to strike the Earth in more than a century, scientists say. The explosion rivaled a nuclear blast, but the space rock was still too small for existing advance-warning networks to spot. Infrasound data collected by a network designed to watch for nuclear weapons testing suggests that today's blast released hundreds of kilotons of energy. That would make it far more powerful than the nuclear weapon tested by North Korea just days ago and the largest rock crashing on the planet since a meteor broke up over Siberia's Tunguska river in 1908.

"It was a very, very powerful event," says Margaret Campbell-Brown, an astronomer at the University of Western Ontario in London, Canada, who has studied data from two infrasound stations near the impact site. Her calculations show that the meteoroid was approximately 15 meters across when it entered the atmosphere, and put its mass at around 40 tons. "That would make it the biggest object recorded to hit the Earth since Tunguska," she says.

The meteor appeared at around 09:25 a.m. local time over the region of Chelyabinsk, near the southern Ural Mountains. The fireball blinded drivers and a subsequent explosion blew out windows and damaged hundreds of buildings. So far, more than 700 people are reported to have been injured, mainly from broken glass, according to a statement from the Russian Emergency Ministry.

This map shows Earth’s surface superimposed on a depiction of what a new University of Utah study indicates is happening 1,800 miles deep at the boundary between Earth’s warm, rocky mantle and its liquid outer core. Using seismic waves the probe Earth’s deep interior, seismologist Michael Thorne found evidence that two continent-sized piles of rock are colliding as they move atop the core. The merger process isn’t yet complete, so there is a depression or hole between the merging piles. But in that hole, a Florida-sized blob of partly molten rock -- called a “mega ultra low velocity zone” -- is forming from the collision of smaller blobs on the edges of the continent-sized piles. Thorne believe this process is the beginning stage of massive volcanic eruptions that won’t occur for another 100 million to 2100 million years.

Each year, hundreds of millions of metric tons of dust, water, and human-made pollutants make their way into the atmosphere, often traveling between continents on jet streams. Now a new study confirms that some microbes make the trip with them, seeding the skies with billions of bacteria and other organisms—and potentially affecting the weather. What's more, some of these high-flying organisms may actually be able to feed while traveling through the clouds, forming an active ecosystem high above the surface of the Earth.

The discovery came about when a team of scientists based at the Georgia Institute of Technology in Atlanta hitched a ride on nine NASA airplane flights aimed at studying hurricanes. Previous studies carried out at the tops of mountains hinted that researchers were likely to find microorganisms at high altitudes, but no one had ever attempted to catalog the microscopic life floating above the oceans—let alone during raging tropical storms. After all, it isn't easy to take air samples while your plane is flying through a hurricane.

Despite the technical challenges, the researchers managed to collect thousands upon thousands of airborne microorganisms floating in the troposphere about 10 kilometers over the Caribbean, as well as the continental United States and the coast of California. Studying their genes back on Earth, the scientists counted an average of 5100 bacterial cells per cubic meter of air. Although the researchers also captured various types of fungal cells, the bacteria were over two orders of magnitude more abundant in their samples. Well over 60% of all the microbes collected were still alive.

The researchers cataloged a total of 314 different families of bacteria in their samples. Because the type of genetic analysis they used didn't allow them to identify precise species, it's not clear if any of the bugs they found are pathogens. Still, the scientists offer the somewhat reassuring news that bacteria associated with human and animal feces only showed up in the air samples taken after Hurricanes Karl and Earl. In fact, these storms seemed to kick up a wide variety of microbes, especially from populated areas, that don't normally make it to the troposphere.

Although many of the organisms borne aloft are likely occasional visitors to the upper troposphere, 17 types of bacteria turned up in every sample. Researchers like environmental microbiologist and co-author Kostas Konstantinidis suspect that these microbes may have evolved to survive for weeks in the sky, perhaps as a way to travel from place to place and spread their genes across the globe. "Not everybody makes it up there," he says. "It's only a few that have something unique about their cells" that allows them survive the trip.

Researchers believe that ancient archaea, similar in shape to this Halobacteria, used aerobic respiration 2.9 billion years ago to produce an active form of vitamin B6

Billions of years ago, a tiny, single-celled organism started using oxygen. It is not exactly known when this happened, or why, but a team of scientists has come closer than ever before to finding that out. They have identified the earliest known example of an aerobic metabolism, the process of using oxygen as fuel. The discovery may even provide clues as to where the oxygen came from in the first place.

To travel so far back in time, evolutionary bioinformaticist Gustavo Caetano-Anollés of the University of Illinois, Urbana-Champaign, along with colleagues in China and South Korea, did a bit of molecular sleuthing. They scoured published genomes from all groups of organisms-although they didn't include viruses in this study-focusing on pieces of proteins known as domains. These pieces have their own distinguishing shapes that provide clues to the protein's function and can be categorized based on various characteristics. Just like a Victorian house has certain features that set it apart from a Tudor mansion, researchers can tell the difference between different domains based on their shape.

The team produced a kind of molecular clock by establishing an evolutionary sequence for single-domain proteins. Caetano-Anollés and his colleagues could then tie that sequence to the geologic timeline. By correlating the appearance of domains integral to events such as the rise of eukaryotes, organisms with membrane-bound cellular structures, they could determine an approximate date for the origin of particular domains. "Molecular clocks aren't perfect," Caetano-Anollés acknowledges. "And sometimes they misbehave. But the [domains] that we sampled that were linked to clear-cut events had good agreement."

The researchers found that the most ancient aerobic process was the production of pyridoxal, or the active form of vitamin B6, they report today in Structure. This reaction appeared about 2.9 billion years ago, along with an oxygen-producing enzyme called manganese catalase. This enzyme detoxifies hydrogen peroxide by breaking it down into water and oxygen. Caetano-Anollés hypothesizes that early organisms got the oxygen they needed to produce vitamin B6 from this breakup of hydrogen peroxide. The authors argue that these ancient organisms would have encountered massive amounts of hydrogen peroxide in their environment due to the bombardment of glacial ice by ultraviolet radiation, which can generate the compound.

An unusual event playing out high in the atmosphere above the Arctic Circle is setting the stage for what could be weeks upon weeks of frigid cold across wide swaths of the U.S.

When the sudden stratospheric warming event began in early January, that signaled to weather forecasters that a cool down was more likely to occur by the end of the month, since it usually takes many days for developments in the stratosphere to affect weather in the troposphere, and vice versa. As the polar stratosphere warms, high pressure builds over the Arctic, causing the polar jet stream to weaken. At the same time, the midlatitude jet stream strengthens, while also becoming wavier, with deeper troughs and ridges corresponding to more intense storms and high pressure areas. In fact, sudden stratospheric warming events even make so-called “blocked” weather patterns more likely to occur, which tilts the odds in favor of the development of winter storms in the U.S. and Europe.

The graph shows the evolution of the stratospheric warming event. The contours show absolute heights and the shading are height anomalies in the middle stratosphere, or about 16 miles above the surface. The height anomalies are a good proxy for temperature anomalies in the stratosphere with red representing high heights or warm temperatures and blue low heights or cold temperatures. You can see at the beginning of the loop a cohesive polar vortex along the coast of Northern Eurasia and then this area of higher heights or warm temperaturs rush poleward from Siberia into the polar vortex splitting it into two pieces, one over Eurasia and one over North America. The dramatic rise in heights or temperatures over the Pole is the sudden stratospheric warming. The result is that pieces of the polar vortex move equatorward and with it the associated cold temperatures. Usually something similar occurs in the troposphere in the ensuing weeks.

By considering the unique sea-level "fingerprint" created by a melting ice sheet, a team of geophysicists in North America has developed a new method for pinpointing the sources of global sea-level rise. Their approach could provide a way to measure the impact of the Greenland and West Antarctic ice sheets – the greatest sources of uncertainty in projections of future sea-level changes.

Long-term variations in sea level are caused by processes including thermal expansion of the water, changes in ocean circulation, and changes in the size of glaciers and ice sheets. Measurements from tide gauges indicate a global average sea-level rise of 1–2 mm/yr during the 20th century. However, this estimate ignores geographical variations in sea level, and provides no information about the contribution of different processes.

One possible way to pick apart the total sea-level change is to look for the distinct pattern, or fingerprint, of a melting ice sheet. Close to the ice sheet, for example, the sea level tends to fall. This is a result of both the local uplift of the Earth's crust after being relieved of the great weight of the ice and a reduction in the ice sheet's gravitational pull on the ocean. Moving further away from the ice sheet, however, the sea level rises progressively.

Melt rates of 0.3 and 0.5 mm/yr were assumed for the Greenland (GIS) and West Antarctic (WAIS) ice sheets, respectively, along with their predicted fingerprints. The researchers then applied the Kalman filter to this synthetic dataset, initializing the algorithm with melt rates of zero.

A team at the University of Southampton are pioneering a technique to predict when an ecosystem is likely to collapse, which may also have potential for foretelling crises in agriculture, fisheries or even social systems preventing another "Easter Island" collapse from occuring. The scientists applied a mathematical model to a real world situation, the environmental collapse of a lake in China, to help prove a theory which suggests an ecosystem 'flickers', or fluctuates dramatically between healthy and unhealthy states, shortly before its eventual collapse.

"We wanted to prove that this 'flickering' occurs just ahead of a dramatic change in a system – be it a social, ecological or climatic one – and that this method could potentially be used to predict future critical changes in other impacted systems in the world around us," said John Dearing, head of geography at Southampton.

Eminent Australian scientist Professor Frank Fenner, emeritus professor of microbiology at the Australian National University (ANU), who helped to wipe out smallpox, predicts humans will probably be extinct within 100 years, because of overpopulation, environmental destruction and climate change. Tools, such as that being pioneered at Southampton, may prevent this dire prediction from becoming a reality. If past is prolgue, 70,000 years ago the human population was reduced to small isolated groups in Africa, apparently because of drought, according to a 2010 analysis by researchers at Stanford University. The estimated the number of early humans may have shrunk as low as 2,000 before numbers began to expand again in the early Stone Age.

Tiny bands of early humans, forced apart by harsh environmental conditions, coming back from the brink to reunite and populate the world. Truly an epic drama, written in our DNA." Wells is director of the Genographic Project, launched in 2005 to study anthropology using genetics. The report was published in the American Journal of Human Genetics.

Fenner says homo sapiens will not be able to survive the population explosion and “unbridled consumption,” and will become extinct, perhaps within a century, along with many other species. United Nations official figures from last year estimate the human population is seven billion, and is predicted to pass seven billion next year.