“We call it fishing for electrons.” That’s environmental engineer Craig Criddle describing a new way that he and his colleagues have discovered for generating electricity from sewage.

Wait. What?

Brilliant, right? The Stanford team hopes this breakthrough technology will be used to harvest energy in places such as sewage treatment plants, or to break down organic pollutants in the “dead zones” of lakes and coastal waters where fertilizer runoff and other organic waste can deplete oxygen levels and suffocate marine life.

And this new power all starts with wired microbes. The mini power plants produce electricity as they digest plant and animal waste from wastewater. Right now, still in the laboratory phase, their prototype is about the size of a D-cell battery and looks like a chemistry experiment, with two electrodes, one positive, the other negative, plunged into a bottle of wastewater.

Inside that murky vial, attached to the negative electrode like barnacles to a ship’s hull, an unusual type of bacteria feast on particles of organic waste and produce electricity, which is captured by the battery’s positive electrode.

Scientists have long known of the existence of what they call exoelectrogenic microbes—organisms that evolved in airless environments and developed the ability to react with oxide minerals rather than breathe oxygen as we do, to convert organic nutrients into biological fuel.

Over the past dozen years or so, several research groups have tried various ways to use these microbes as bio-generators, but tapping this energy efficiently has proven challenging. Part of that challenge for the Stanford team is the cost of the oxide minerals necessary to make it happen. “We demonstrated the principle using silver oxide, but silver is too expensive for use at large scale,” says team member Yi Cui. “Though the search is underway for a more practical material, finding a substitute will take time.”

The Stanford engineers estimate that the microbial battery can extract about 30 percent of the potential energy locked up in wastewater. That is roughly the same efficiency at which the best commercially available solar cells convert sunlight into electricity.

Their study was published recently in the Proceedings of the National Academy of Sciences.

Image: Xing Xie, Stanford University

Studies of bears and sea lions have enabled us to understand how these mammals reserve energy in the form of fat and blubber, sustaining them through winter or allowing them to travel great distances. And they aren’t alone in facing such physical challenges. Great white sharks also need a way to store energy during their long migrations, but until recently, their specific mechanism was unknown. (Maybe no one wanted to get too close to them…)

Great white sharks migrate between foraging and reproductive areas, traveling over 2,500 miles annually. While they are not known to be picky eaters, there is little food available far out in the Pacific Ocean.

Researchers at Stanford University and the Monterey Bay Aquarium studied how great whites could accomplish such a journey while fasting. But again, because great whites are, shall we say, just a wee bit dangerous, scientists needed to find ways to study the sharks’ lives without risking their own.

“The most difficult thing about this research was finding a way to bring all of the different sources of data together into a coherent and robust story,” said Gen Del Raye, a Stanford undergraduate who initiated the project. He knew that if they succeeded, they might shed light on storage strategies for other ocean mammals.

First the team studied a (well-fed) great white shark living at the Monterey Bay Aquarium. Over time the shark gained mass (but still maintained its flattering, streamline figure) and simultaneously increased in buoyancy.

Next the researchers pulled data from shark archival tags. Shark location information is time-stamped, enabling researchers to focus on one specific behavior, “drift-diving.” Huge marine animals sometimes act like hang gliders—they relax their fins while currents and momentum carry them forward. Drift-diving data provided the final clue to the research team: they established that migrating sharks lost buoyancy over time.

By measuring the rate at which sharks sink during drift dives, the researchers were able to estimate the amount of oil in the animals’ livers, which accounts for up to a quarter of their body weight. Sharks store oil before migration (making them float) then gradually use that energy throughout their journey (making them sink).

“Sharks face an interesting dilemma,” said Sal Jorgensen, a research scientist at the Monterey Bay Aquarium. “They carry a huge store of energy in the form of oil in their massive livers, but they also depend on that volume of oil for buoyancy. So, if they draw on those reserves, they become heavier and heavier.”

The new research paper might not only be used to help solve mysteries about other marine animals, but can also be used to assist conservation efforts around coastal feeding grounds.

“We have a glimpse now of how white sharks come in from nutrient-poor areas offshore, feed where elephant seal populations are expanding—much like going to an Outback Steakhouse—and store the energy in their livers so they can move offshore again,” said researcher Barbara Block, a professor of marine sciences and a senior fellow at the Stanford Woods Institute for the Environment. “It helps us understand how important their near-shore habitats are as fueling stations for their entire life history.”

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: Pterantula (Terry Goss)/Wikipedia

A team of scientists, led by Stanford’s Kevin Arrigo, broke through some of the Arctic ice last July as part of the NASA ICESCAPE mission and found the complete opposite—abundant life!

“If someone had asked me before the expedition whether we would see under-ice blooms, I would have told them it was impossible,” says Arrigo. “This discovery was a complete surprise.”

The researchers discovered an abundance of phytoplankton—microscopic life that forms the base of the marine food chain. Phytoplankton require sunlight for photosynthesis, just like plants. And sunlight has a tough time penetrating thick sea ice.

But that thick sea ice is changing. Not only are warmer temperatures thinning the ice, but as the ice melts in summer, it forms pools of water that act like transient skylights and magnifying lenses. These pools focus sunlight through the ice and into the ocean, where currents steer nutrient-rich deep waters up toward the surface. Phytoplankton under the ice evolved to take advantage of this narrow window of light and nutrients.

The phytoplankton displayed extreme activity, doubling in number more than once a day. Blooms in open waters grow at a much slower rate, doubling in two to three days. These growth rates are among the highest ever measured for polar waters. Researchers estimate that phytoplankton production under the ice in parts of the Arctic could be up to 10 times higher than in the nearby open ocean.

The phytoplankton bloom discovered by Arrigo and his colleagues in the Chukchi Sea (just north of Alaska) extends tens of meters deep in spots and about 100 kilometers (62 miles) across.

“At this point we don’t know whether these rich phytoplankton blooms have been happening in the Arctic for a long time and we just haven’t observed them before,” Arrigo says. “These blooms could become more widespread in the future, however, if the Arctic sea ice cover continues to thin.”

The discovery of these previously unknown under-ice blooms could have serious implications for the broader Arctic ecosystem, including migratory species such as whales and birds. Phytoplankton are eaten by small ocean animals, which are eaten by larger fish and ocean animals.

“It could make it harder and harder for migratory species to time their life cycles to be in the Arctic when the bloom is at its peak,” Arrigo says. “If their food supply is coming earlier, they might be missing the boat.”

The research is published this week in Science.

Image: NASA

The origin of our species was once firmly rooted in eastern Africa, but a new discovery may have shifted those roots much further to the south.

Exactly when and from where our species, Homo sapiens, first evolved and left Africa has been the subject of fierce debate. Most fossil and genetic evidence placed these origins in eastern Africa between 150,000 and 200,000 years ago. But a new study published earlier this month online in the Proceedings of the National Academy of Sciences reveals that our species may have evolved in southern, not eastern Africa.

Most Africans south of the Sahara are descended from early farmers spreading from western Africa about 8,000 years ago. But nestled within this vast dispersal of farmers are pockets of hunter-gatherers: The Khomani Bushmen of the Namibian Desert, the Pygmies of the central African rainforests, and the click-speaking Hadza and Sandawe of Tanzania. These peoples’ anatomy, culture, and language are distinct from their neighbors, and many believe that they offer a window into our species’ earliest days. But genetic data of these groups has been limited, and many questions on their origins remain.

The study’s authors, led by Brenna Henn of Stanford University, sought to fill in the gaps. “We started [this] project because southern Africa has been poorly sampled. Very few other studies have ever published on them in the last decade, certainly never with more than a dozen individuals,” says Henn.

Henn and colleagues analyzed over 55,000 individual points on the genomes of people from six hunter-gatherer populations, comparing them alongside other African populations. The team used this data to construct a genetic map of prehistoric Africa.

Not only had the hunter-gatherers been genetically isolated from the farming groups for thousands of years, they were also genetically distinct from each other.

In addition, long before the farmers swept across the continent, these hunter-gatherer groups were already well-established in their respective locales.

How does this relate to modern human origins? By using genomic data and a computer model, the team found the most likely starting point to be closest to the most ancient populations: southern Africa. Other experts have hypothesized this to be the case, and recent archaeological discoveries and climatic evidence have lent additional support to the fact that this region of Africa hosted our most ancient ancestors.

But the team has many questions left to answer. Henn and her colleagues also detected rapid evolutionary change among the groups, which may trace back thousands of years. They found that the Hadza of Tanzania have been going through a rapid decline, called a bottleneck, but have yet to understand why. “We would like to know when this bottleneck started – did it happen when the agriculturalists moved in?  Why don’t all hunter-gatherer populations show this signature?” says Henn.

Anne Holden, a docent at the California Academy of Sciences, is a PhD trained genetic anthropologist and science writer living in San Francisco.

Image of the Khomani courtesy of Brenna Henn

The evolution of our species’ most famous traits – big brains, walking on two legs, language – took hundreds of thousands of years. But in some cases, evolution doesn’t always take its sweet time.

In a new study published in BMC Evolutionary Biology, an international team of scientists believe they’ve found an example of evolution only a few thousand years in the making.

The research team, led by Andres Moreno of Stanford University, studied FOXI1, a gene involved in water retention in the kidneys. Moreno and his colleagues collected DNA samples from Europeans, East Asians, and the Yoruba, an African tribe living on the southern edge of the Sahara Desert. An analysis of the FOXI1 gene in each group found a considerably different genetic change in the Yoruba, compared to the other groups. This mutation in the Yoruba’s FOXI1 gene may improve tribe members’ ability to retain water, a big advantage if you live near a desert.

The team calculated that the FOXI1 gene mutation evolved between 10,000 and 20,000 years ago, just as the Sahara Desert was drying out from a brief wet spell. As a consequence of an increasingly harsh climate, the ancestors of the modern Yoruba evolved a way to retain water more efficiently than humans in other parts of the world.

This is not the first time scientists have demonstrated unique adaptations in our species’ more recent history. The July 2 issue of the journal Science reported the discovery of a 3,000-year-old genetic mutation that has allowed native Tibetans living at high altitudes to breathe easier than their low-altitude neighbors.

But this FOXI1 gene mutation has wider implications, especially in the light of our changing planet. The last several decades have seen temperatures rise, forests dwindle, and deserts expand, so mutations like the Yoruba’s may eventually help us adapt to the harsh effects of global warming.

As anthropological geneticist Anne Stone of Arizona State University told New Scientist, “Over the long term, if the Earth keeps warming, I would not be surprised to see genetic shifts.” Whether those will take the shape of improved water retention, resistance to disease or changes in body shape, however, remains to be seen.

How do you think humans will evolve over the next 10,000 years? Let us know!

Anne Holden, a docent here at the California Academy of Sciences, is a PhD trained genetic anthropologist and science writer living in San Francisco.

Image by Melvin “Buddy” Baker

Biologists at UC Berkeley initially broke down gecko movement up walls to figure out how they travel up walls. You can watch our Science in Action piece called “Bio-Inspiraton: Gecko Adhesive” about that research.

Since then, scientists’ imaginations have taken over. What can we accomplish using the same properties geckoes use to climb vertically? Last winter, the New York Times reported on a new tape based on gecko’s feet from biologist Kellar Autumn of Lewis & Clark College.

The tape, which is reusable, was so strong, Mr. Autumn said, that when they tested it, he was able to stick his 50-pound, 8-year-old daughter to a window with it.

That was a little more than two years ago; there are now at least 50 patent applications pending in gecko-adhesion technology, Mr. Autumn said, and he holds several patents himself.

The latest entry in gecko-adhesion technology is Stickybot, a robot developed at Stanford that can climb walls. The newest versions of the adhesive that holds Stickybot to the walls was published earlier this month in the journal Applied Physics Letters.

The molecules of gecko toe hair interact with the wall through a molecular attraction called the van der Waals force. A gecko can hang and support its whole weight on one toe by placing it on the glass and then pulling it back.

That’s because the toe of a gecko’s foot contains hundreds of flap-like ridges called lamellae. On each ridge are millions of hairs called setae, each one 10 times thinner than a human’s. Under a microscope, you can see that each hair divides into smaller strands called spatulae, making it look like a bad case of split ends. These split ends are so tiny (a few hundred nanometers) that they interact with the molecules of the climbing surface.

The new and improved versions support higher loads and also allow Stickybot to climb surfaces such as wood paneling, painted metal and glass. The material is strong and reusable, and leaves behind no residue or damage.  Robots that scale vertical walls could be useful for accessing dangerous or hard to reach places.

Next up for Stickybot, the technology of turning around, also gecko-inspired. According to Stanford’s Mark Cutkosky, “The new Stickybot that we’re working on right now has rotating ankles, which is also what geckos have.”

But wait there’s more… The Stanford team has started developing Z-Man—a gecko adhesive for human climbing.  Watch out, Peter Parker!  Spiders have nothing on geckos…

Awesome, right?

Creative Commons image by Bjørn Christian Tørrissen

In case you were wondering what an atoll is, according to the Encyclopedia of Earth:

Atolls are circular, oval, or horseshoe-shaped arrays of coral reef islands that are perched around an oceanic volcanic seamount and encircle a shallow central lagoon…. Because atoll formation requires coral reef building, atolls are limited to tropical waters.

(View this great animation here of an atoll forming over 30 million years.)

Healthy Fishing

To gain new insights on the ecology of reef fishing, Stanford researchers are comparing and contrasting the reefs of two atolls—Palmyra and Tabuaeran.

Palmyra is a protected U.S. wildlife refuge and prohibits fishing along its shores. Tabuaeran is part of the Republic of Kiribati and is home to about 2,500 people who depend on the reef for food and income.

Signs of a healthy marine ecosystem usually include the presence of large fish and sharks. “Palmyra has some of the highest densities of sharks and other large fish of any coral reef in the world,” said Douglas McCauley, a graduate student at Stanford. “That’s clear within seconds of jumping in the water there.”

But in Tabuaeran, where fishing is a way of life, sharks and other large species are in short supply, McCauley said. “That was surprising, because Tabuaeran is a somewhat lightly populated island. Most people arrived only a few decades ago, and fishing there is still very artisanal in nature.”

Big fish grow and reproduce slowly, so their populations take longer to recover, he added. “It appears that it takes very little harvesting to reduce populations of these sensitive, large reef fish.”

The Stanford researchers are hoping to pass this information along to the people of Tabuaeran so they can fish more sustainably. Over the past three years, the team taught science classes at local schools on topics such as reef ecology and genetics and conducted town hall meetings at every village on the atoll.

Because the livelihoods of so many Tabuaerans depend on healthy fisheries, locals are eager to preserve fish numbers, McCauley said. “Those who depend most on the environment can and should be its best stewards,” he added.

Millennium Atoll: A Pristine Ecosystem

Millennium Atoll, also part of the Republic of Kiribati, is one of the most remote, pristine atolls in the world. Its lagoon is highly enclosed, sealing it away from the outside world. Californian and Hawaiian scientists studied its life and published their findings last week in PLoS One:

This is the first comprehensive survey of the lagoon at Millennium Atoll, which contains some of the few remaining coral reefs that are relatively unaltered by human activity. The lagoon of the atoll is home to a variety of unique organisms that are threatened in many areas of the world.

Valuable resource species such as clams, sharks, Napoleon wrasse, sea turtles, and lobster are fairly abundant at Millennium but have been seriously overexploited elsewhere around the world.

Protection of Millennium’s coral reefs should be a priority for the Republic of Kiritbati as these habitats are not only unique but are some of the world’s least impacted reef systems.

Atolls Growing, Not Shrinking

Finally, last month Australian researchers published the incredible finding that despite warnings of small atolls and islands disappearing with sea level rise, they have found that in the Pacific, some have actually grown in the last 60 years.

Despite evidence of the sea level rising as high as five inches in the region, of the 27 islands they studied, four decreased in size, but the rest remained the same or grew.

It may simply be due to the nature of atoll formation itself. From New Scientist:

Because the corals are alive, they provide a continuous supply of material. “Atolls are composed of once-living material,” says Arthur Webb, “so you have a continual growth.”

The researchers stress these results reflect a small portion of atolls in one area in the Pacific and that “warnings about rising sea levels must still be taken seriously.”

With so much research emerging about atolls, it’s obvious we still have a lot to learn. These little islands are making big waves in the scientific community.

This is the first oceanographic research voyage sponsored by NASA.  The ICESCAPE (Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environment) mission plans to take an up-close look at how changing conditions in the Arctic are affecting the ocean’s chemistry and ecosystems that play a critical role in global climate change.

NASA is hoping that this mission enhances the satellite data that already is collected of the area. More than 40 scientists, including six from Stanford University, will spend five weeks at sea sampling the physical, chemical, and biological characteristics of the ocean and sea ice.

According to today’s Stanford Report:

They will gather data on the state of the ice, the ocean and the microscopic plants and animals that dwell therein. The tiny organisms regulate the flow of carbon into and out of the sea, and the scientists are seeking to assess how the melting ice is affecting the organisms and ecosystem.

“The ocean ecosystem in the Arctic has changed dramatically in recent years, and it’s changing much faster and much more than any other ocean in the world,” said ICESCAPE chief scientist Kevin Arrigo, PhD, of Stanford. “Declining sea ice in the Arctic is certainly one reason for the change, but that’s not the whole story. We need to find out, for example, where the nutrients are coming from that feed this growth if we are going to be able to predict what the future holds for this region.”

(The Stanford team will be blogging about their adventures and research. You can follow them here.)