City size plays crucial role in migration patterns

People from smaller cities are more likely to migrate than people from larger cities, according to a new study by UCL academics.

The study, published today in the open access journal PLOS ONE, looked at internal migration patterns across the USA, finding that the size of origin and destination cities play a crucial role in the behaviour of people who move from one place to another.

Inhabitants of smaller cities -- of fewer than 100,000 inhabitants -- are twice as likely to migrate than those of cities with a population greater than ten million. Those who do migrate are more likely to move to a city of a similar size.

People already living in larger cities are less likely to migrate, but when they do, they are more likely to move to similarly sized large cities.

Lead researcher, UCL PhD student Rafael Prieto Curiel (UCL Mathematics), said: "The results could have an impact on future integration policies as governments can more accurately predict where citizens are likely to move from and to within their country.

"Migrants contribute to the prosperity of their destination with skills and activities, but migration requires integration policies and social support systems to allow newcomers to settle into a new environment and therefore fully contribute locally."

Ensuring newcomers are able to settle into a new area and contribute their skills and expertise can be important in combatting issues such as segregation, inequality and loneliness.

Professor Steven Bishop (UCL Mathematics) said: "The new scaling model has not previously been used to identify migration patterns. It applies a mathematical formula to migratory patterns relative to city size. When taken into account along with other existing models that focus on the distance between origin and destination cities, we have found that the laws of scaling are a significant feature of human migration patterns.

"The model can be used to more accurately predict population movement as it corrects biases which occur in other methods. This is an important, data-led development in revealing how communities and regions will grow and develop in the future."

The study considered a city as having more than 50,000 inhabitants, with anywhere less than this considered to be a rural area. The cities considered varied from populations of just over 50,000 to nearly 20 million in the New York metropolitan area.

The researchers found that international migration follows a different pattern, with individuals more likely to head to a large city where they are perhaps more likely to find jobs, housing and other people of a similar culture. More data on the origins of international migrants is needed to extend this work.

The research followed a collaboration between UCL, Italy's national research body Consiglio Nazionale Delle Ricerche (CNR) and the University of Pisa.

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Stripes may be cool -- but they don't cool zebras down

Barrels used in the experiment.

Susanne Åkesson, a biologist at Lund University in Sweden, refutes the theory that zebras have striped fur to stay cool in the hot sun. That hypothesis is wrong, she and her colleagues show in a study recently published in Scientific Reports.

There has been an ongoing discussion among researchers, dating back to Darwin, on why zebras have their signature black and white stripes.

One of several theories is that it keeps them cool in the sunshine. The black stripes get warmer than the white areas, and the theory states that this creates small vortexes when the hotter air above the dark fur meets the cooler air above the white fur. According to the theory these vortexes works as a fan to cool the body.

To test this theory, the researchers filled big metal barrels with water and covered them with skin imitations in different colours: black and white stripes, black, white, brown and grey. They then placed the barrels in the sun and later measured the temperature in each barrel. Not surprisingly, the black one was the hottest and the white one the coolest. The striped and grey barrels were similar, and in these the temperature did not go down.

"The stripes didn't lower the temperature. It turns out stripes don't actually cool zebras," says Susanne Åkesson.

Eight years ago she and her colleagues from Hungary and Spain presented another theory, where they claim that bright fur works as an optical protection against blood-sucking horseflies and other insects that bite. Horseflies are attracted by polarised light, the sort of light that appears when sunbeams are reflected on a dark surface. If the sunbeams are reflected on a white surface there will be no polarised light -- hence the protection.

Two years ago Susanne Åkesson, the Hungarian physicist Gábor Horváth and their colleauges were awarded with the Ig Nobel Prize for their research on polarised light, horseflies and why these blood-sucking insects bother dark horses a lot more than they bother white horses.

From Science Daily

Novel HIV vaccine candidate is safe and induces immune response in healthy adults and monkeys

Scientists are working to develop a preventative vaccine that could finally put an end to the epidemic for which there are 1.8 million new infections each year.

New research published in The Lancet shows that an experimental HIV-1 vaccine regimen is well-tolerated and generated comparable and robust immune responses against HIV in healthy adults and rhesus monkeys. Moreover, the vaccine candidate protected against infection with an HIV-like virus in monkeys.

Based on the results from this phase 1/2a clinical trial that involved nearly 400 healthy adults, a phase 2b trial has been initiated in southern Africa to determine the safety and efficacy of the HIV-1 vaccine candidate in 2,600 women at risk for acquiring HIV. This is one of only five experimental HIV-1 vaccine concepts that have progressed to efficacy trials in humans in the 35 years of the global HIV/AIDS epidemic.

Previous HIV-1 vaccine candidates have typically been limited to specific regions of the world. The experimental regimens tested in this study are based on 'mosaic' vaccines that take pieces of different HIV viruses and combine them to elicit immune responses against a wide variety of HIV strains.

"These results represent an important milestone. This study demonstrates that the mosaic Ad26 prime, Ad26 plus gp140 boost HIV vaccine candidate induced robust immune responses in humans and monkeys with comparable magnitude, kinetics, phenotype, and durability and also provided 67% protection against viral challenge in monkeys," says Professor Dan Barouch, Director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center and Professor of Medicine at Harvard Medical School, Boston, USA who led the study.

He adds: "These results should be interpreted cautiously. The challenges in the development of an HIV vaccine are unprecedented, and the ability to induce HIV-specific immune responses does not necessarily indicate that a vaccine will protect humans from HIV infection. We eagerly await the results of the phase 2b efficacy trial called HVTN705, or 'Imbokodo', which will determine whether or not this vaccine will protect humans against acquiring HIV."

Almost 37 million people worldwide are living with HIV/AIDS, with an estimated 1.8 million new cases every year. A safe and effective preventative vaccine is urgently needed to curb the HIV pandemic.

In the 35 years of the HIV epidemic, only four HIV vaccine concepts have been tested in humans, and only one has provided evidence of protection in an efficacy trial -- a canarypox vector prime, gp120 boost vaccine regimen tested in the RV144 trial in Thailand lowered the rate of human infection by 31% but the effect was considered too low to advance the vaccine to common use.

A key hurdle to HIV vaccine development has been the lack of direct comparability between clinical trials and preclinical studies. To address these methodological issues, Barouch and colleagues evaluated the leading mosaic adenovirus serotype 26 (Ad26)-based HIV-1 vaccine candidates in parallel clinical and pre-clinical studies to identify the optimal HIV vaccine regimen to advance into clinical efficacy trials.

The APPROACH trial recruited 393 healthy, HIV-uninfected adults (aged 18-50 years) from 12 clinics in east Africa, South Africa, Thailand, and the USA between February 2015 and October 2015. Volunteers were randomly assigned to receive either one of seven vaccine combinations or a placebo, and were given four vaccinations over the course of 48 weeks.

To stimulate, or 'prime', an initial immune response, each volunteer received an intramuscular injection of Ad26.Mos.HIV at the start of the study and again 12 weeks later. The vaccine containing 'mosaic' HIV Env/Gag/Pol antigens was created from many HIV strains, delivered using a nonreplicating common-cold virus (Ad26).

To 'boost' the level of the body's immune response, volunteers were given two additional vaccinations at week 24 and 48 using various combinations of Ad26.Mos.HIV or a different vaccine component called Modified Vaccinia Ankara (MVA) with or without two different doses of clade C HIV gp140 envelope protein containing an aluminium adjuvant.

Results showed that all vaccine regimens tested were capable of generating anti-HIV immune responses in healthy individuals and were well tolerated, with similar numbers of local and systemic reactions reported in all groups, most of which were mild-to-moderate in severity. Five participants reported at least one vaccine-related grade 3 adverse event such as abdominal pain and diarrhea, postural dizziness, and back pain. No grade 4 adverse events or deaths were reported.

In a parallel study, the researchers assessed the immunogenicity and protective efficacy of the same Ad26-based mosaic vaccine regimens in 72 rhesus monkeys using a series repeated challenges with simian-human immunodeficiency virus (SHIV) -- a virus similar to HIV that infects monkeys.

The Ad26/Ad26 plus gp140 vaccine candidate induced the greatest immune responses in humans and also provided the best protection in monkeys -- resulting in complete protection against SHIV infection in two-thirds of the vaccinated animals after six challenges.

The authors note several limitations, including the fact that that the relevance of vaccine protection in rhesus monkeys to clinical efficacy in humans remains unclear. They also note that there is no definitive immunological measurement that is known to predict protection against HIV-1 in humans.

Writing in a linked Comment, Dr George Pavlakis and Dr Barbara Felber from the National Cancer Institute at Frederik, Maryland, USA say: "Efficacy studies are necessary to determine protective ability in humans and also for the discovery of correlates of protection and for determining whether the same or different immune correlates apply for different vaccine regimens. It remains to be determined whether improved efficacy over RV144 will be achieved by either of the present efficacy trials (NCT02968849; NCT03060629). New vaccine concepts and vectors are in development and can progress to efficacy trials, which is an important process since development of an AIDS vaccine remains urgent. Despite unprecedented advances in HIV treatment and prophylaxis, the number of people living with HIV infection continues to increase worldwide. Implementation of even a moderately effective HIV vaccine together with the existing HIV prevention and treatment strategies is expected to contribute greatly to the evolving HIV/AIDS response. It is therefore essential that a commitment to pursue multiple vaccine development strategies continues at all stages."

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Global warming may be twice what climate models predict

What will the future hold?

Future global warming may eventually be twice as warm as projected by climate models under business-as-usual scenarios and even if the world meets the 2°C target sea levels may rise six metres or more, according to an international team of researchers from 17 countries.

The findings published last week in Nature Geoscience are based on observational evidence from three warm periods over the past 3.5 million years when the world was 0.5°C-2°C warmer than the pre-industrial temperatures of the 19th Century.

The research also revealed how large areas of the polar ice caps could collapse and significant changes to ecosystems could see the Sahara Desert become green and the edges of tropical forests turn into fire dominated savanna. "Observations of past warming periods suggest that a number of amplifying mechanisms, which are poorly represented in climate models, increase long-term warming beyond climate model projections," said lead author, Prof Hubertus Fischer of the University of Bern.

"This suggests the carbon budget to avoid 2°C of global warming may be far smaller than estimated, leaving very little margin for error to meet the Paris targets."

To get their results, the researchers looked at three of the best-documented warm periods, the Holocene thermal maximum (5000-9000 years ago), the last interglacial (129,000-116,000 years ago) and the mid-Pliocene warm period (3.3-3 million years ago).

The warming of the first two periods was caused by predictable changes in the Earth's orbit, while the mid-Pliocene event was the result of atmospheric carbon dioxide concentrations that were 350-450ppm -- much the same as today.

Combining a wide range of measurements from ice cores, sediment layers, fossil records, dating using atomic isotopes and a host of other established paleoclimate methods, the researchers pieced together the impact of these climatic changes.

In combination, these periods give strong evidence of how a warmer Earth would appear once the climate had stabilized. By contrast, today our planet is warming much faster than any of these periods as human caused carbon dioxide emissions continue to grow. Even if our emissions stopped today, it would take centuries to millennia to reach equilibrium.

The changes to the Earth under these past conditions were profound -- there were substantial retreats of the Antarctic and Greenland ice sheets and as a consequence sea-levels rose by at least six metres; marine plankton ranges shifted reorganising entire marine ecosystems; the Sahara became greener and forest species shifted 200 km towards the poles, as did tundra; high altitude species declined, temperate tropical forests were reduced and in Mediterranean areas fire-maintained vegetation dominated.

"Even with just 2°C of warming -- and potentially just 1.5°C -- significant impacts on the Earth system are profound," said co-author Prof Alan Mix of Oregon State University.

"We can expect that sea-level rise could become unstoppable for millennia, impacting much of the world's population, infrastructure and economic activity."

Yet these significant observed changes are generally underestimated in climate model projections that focus on the near term. Compared to these past observations, climate models appear to underestimate long term warming and the amplification of warmth in Polar Regions.

"Climate models appear to be trustworthy for small changes, such as for low emission scenarios over short periods, say over the next few decades out to 2100. But as the change gets larger or more persistent, either because of higher emissions, for example a business-as-usual-scenario, or because we are interested in the long term response of a low emission scenario, it appears they underestimate climate change.," said co-author Prof Katrin Meissner, Director of the University of New South Wales Climate Change Research Centre.

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Fragment of impacting asteroid recovered in Botswana

Botswana meteorite.

On Saturday, June 23, 2018, a team of experts from Botswana, South Africa, Finland and the United States of America recovered a fresh meteorite in Botswana´s Central Kalahari Game Reserve (CKGR).

The meteorite is one of the fragments of asteroid 2018 LA which collided with Earth on June 2, 2018 and turned into a meteor fireball that detonated over Botswana a few seconds after entering the atmosphere. The incident was witnessed by a number of spectators in Botswana and neighbouring countries and was captured on numerous security cameras.

Asteroid 2018 LA was detected in space eight hours before hitting Earth. It was detected by the Catalina Sky Survey, operated by the University of Arizona and sponsored by NASA as part of its Planetary Defence mission. This is the third time in history that an asteroid inbound to hit Earth was detected early and only the second time that fragments were recovered. After disruption, the asteroid fragments were blown by the wind while falling down, scattering over a wide area. Calculations of the landing area were done independently by a US-based group headed by Peter Jenniskens, a subject expert of the NASA-sponsored SETI Institute in California, as well as Esko Lyytinen and Jarmo Moilanen of the Finnish Fireball Network (FFN).

The first meteorite was found after five days of walking and scouring around by a team of geoscientists from Botswana International University of Science and Technology (BUIST), Botswana Geoscience Institute (BGI) and University of Botswana´s Okavango Research Institute (ORI). The Department of Wildlife and National Parks granted access and deployed park rangers for protection and participation in the search. The importance of the find is two-fold: It has enormous scientific value and it allows to better calibrate the so-called "Earth Defense" against impacting asteroids.

Jenniskens, who traveled to Botswana to assist in the search, teamed up with Oliver Moses (from ORI), to gather security surveillance videos in Rakops and Maun, to get better constraints on the position and altitude of the fireball´s explosion. Professor Alexander Proyer, from BIUST, led the joint expedition while Mohutsiwa Gabadirwe, BGI senior curator, coordinated access to the protected fall area in the game reserve. Professor Roger Gibson, Head of School at the School of Geosciences at the University of the Witwatersrand in Johannesburg, South Africa, also assisted in locating the fall area. The meteorite was eventually spotted by BIUST geologist Lesedi Seitshiro. The search for more fragments of the meteorite continues. Dr Fulvio Franchi of BIUST, is leading the follow-up search team joined by Tomas Kohout of the FFN and the University of Helsinki.

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Ancient DNA testing solves 100-year-old controversy in Southeast Asian prehistory

Skull from a Hòabìnhian person from Gua Cha archaeological site, Malaysian Peninsula.

Two competing theories about the human occupation of Southeast Asia have been debunked by ground-breaking analysis of ancient DNA extracted from 8,000 year-old skeletons.

Southeast Asia is one of the most genetically diverse regions in the world, but for more than 100 years scientists have disagreed about which theory of the origins of the population of the area was correct.

One theory believed the indigenous Hòabìnhian hunter-gatherers who populated Southeast Asia from 44,000 years ago adopted agricultural practices independently, without the input from early farmers from East Asia. Another theory, referred to as the 'two-layer model' favours the view that migrating rice farmers from what is now China replaced the indigenous Hòabìnhian hunter-gatherers.

Academics from around the world collaborated on new research just published in Science which found that neither theory is completely accurate. Their study discovered that present-day Southeast Asian populations derive ancestry from at least four ancient populations.

DNA from human skeletal remains from Malaysia, Thailand, the Philippines, Vietnam, Indonesia, Laos and Japan dating back as far as 8,000 years ago was extracted for the study - scientists had previously only been successful in sequencing 4,000-year-old samples from the region. The samples also included DNA from Hòabìnhian hunter-gatherers and a Jomon from Japan - a scientific first, revealing a long suspected genetic link between the two populations.

In total, 26 ancient human genome sequences were studied by the group and they were compared with modern DNA samples from people living in Southeast Asia today.

The pioneering research is particularly impressive because the heat and humidity of Southeast Asia means it is one of the most difficult environments for DNA preservation, posing huge challenges for scientists.

Professor Eske Willerslev, who holds positions both at St John's College, University of Cambridge, and the University of Copenhagen, led the international study.

He explained: "We put a huge amount of effort into retrieving ancient DNA from tropical Southeast Asia that could shed new light on this area of rich human genetics. The fact that we were able to obtain 26 human genomes and shed light on the incredible genetic richness of the groups in the region today is astonishing."

Hugh McColl, PhD student at the Centre for GeoGenetics in the Natural History Museum of Denmark of the University of Copenhagen, and one of the lead authors on the paper, said: "By sequencing 26 ancient human genomes - 25 from South East Asia, one Japanese Jōmon - we have shown that neither interpretation fits the complexity of Southeast Asian history. Both Hòabìnhian hunter-gatherers and East Asian farmers contributed to current Southeast Asian diversity, with further migrations affecting islands in South East Asia and Vietnam. Our results help resolve one of the long-standing controversies in Southeast Asian prehistory."

Dr Fernando Racimo, Assistant Professor at the Centre for GeoGenetics in the Natural History Museum of the University of Copenhagen, the other lead author, said: "The human occupation history of Southeast Asia remains heavily debated. Our research spanned from the Hòabìnhian to the Iron Age and found that present-day Southeast Asian populations derive ancestry from at least four ancient populations. This is a far more complex model than previously thought."

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First dogs in the Americas arrived from Siberia, disappeared after European contact

A ritual burial of two dogs at a site in Illinois near St. Louis suggests a special relationship between humans and dogs at this location and time (660 to 1350 years ago).

A study reported in the journal Science offers an enhanced view of the origins and ultimate fate of the first dogs in the Americas. The dogs were not domesticated North American wolves, as some have speculated, but likely followed their human counterparts over a land bridge that once connected North Asia and the Americas, the study found.

This is the first comprehensive genomic study of ancient dogs in the Americas to analyze nuclear DNA, which is inherited from both parents, along with mitochondrial DNA, which is passed down only from mothers to their offspring. By comparing genomic signatures from 71 mitochondrial and seven nuclear genomes of ancient North American and Siberian dogs spanning a period of 9,000 years, the research team was able to gain a clearer picture of the history of the first canine inhabitants of the Americas.

The oldest dog remains in the Americas date to about 9,000 years ago, many thousands of years after people began migrating over a land bridge connecting present-day Siberia and Alaska. The ancient dogs analyzed in the new study likely originated in Siberia, the researchers found. The dogs dispersed to every part of the Americas, migrating with their human counterparts.

These dogs persisted for thousands of years in the Americas, but almost completely vanished after European contact, the researchers found.

"This suggests something catastrophic must have happened, and it's likely associated with European colonization," said senior lead author Laurent Frantz, a lecturer at Queen Mary University and co-investigator at the University of Oxford. "But we just do not have the evidence to explain this sudden disappearance yet."

"By looking at genomic data along with mitochondrial data, we were able to confirm that dogs came to the Americas with humans, and that nearly all of that diversity was lost -- most likely as a result of European colonization," said Kelsey Witt, who led the mitochondrial DNA genome work as a graduate student in the laboratory of University of Illinois anthropology professor Ripan Malhi, who also is an author of the study.

"Few modern dogs have any trace of these ancient lineages," said Witt, now a postdoctoral researcher at the University of California, Merced.

The team also discovered that the genomic signature of a transmissible cancer that afflicts dogs appears to be one of the last "living" remnants of the genetic heritage of dogs that populated the Americas prior to European contact.

"This suggests that this tumor originated in or near the Americas," Witt said.

The new findings reinforce the idea that early human and dog inhabitants of the Americas faced many of the same challenges after European contact, Malhi said.

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Frigid polar oceans, not balmy coral reefs, are species-formation hot spots

Greenland icebergs

Tropical oceans teem with the dazzle and flash of colorful reef fishes and contain far more species than the cold ocean waters found at high latitudes. This well-known "latitudinal diversity gradient" is one of the most famous patterns in biology, and scientists have puzzled over its causes for more than 200 years.

One frequently advanced explanation is that warm reef environments serve as evolutionary hot spots for species formation. But a new study that analyzed the evolutionary relationships between more than 30,000 fish species concludes that the fastest rates of species formation have occurred at the highest latitudes and in the coldest ocean waters.

Over the past several million years, cool-water and polar ocean fishes formed new species twice as fast as the average species of tropical fish, according to the new study, which is scheduled for publication July 4 in the journal Nature.

"These findings are both surprising and paradoxical," said University of Michigan evolutionary biologist Daniel Rabosky, lead author of the study. "A number of hypotheses explain extreme tropical diversity as the result of faster rates of species formation, but it's never been tested in fishes.

"Our results are counterintuitive and unexpected, because we find that speciation is actually fastest in the geographic regions with the lowest species richness."

The authors admit they cannot fully explain their results, which are incompatible with the idea that the tropics serve as an evolutionary cradle for marine fish diversity. The findings also raise questions about whether the rapid cold-ocean speciation the team documented reflects a recent and ongoing expansion of marine diversity there.

Common sense suggests that a high rate of new species formation will eventually lead to impressive levels of biodiversity. But that depends on how many of the newly formed species survive and how many go extinct. And extinction rates could not be addressed through the methods used in the current study.

"The number of species you find in a region is largely a balance between the rate at which new species form and the rate at which extinction eliminates them," Rabosky said. "The rapid speciation of fishes in cold, high-latitude oceans that we documented will only cause diversity to increase if it is generally higher than extinction.

"Extinction is the missing piece of this puzzle, but it's the most difficult thing to understand. We're now using both fossils and new statistical tools to try to get a handle on what extinction might have been doing in both the polar regions and the tropics."

In the study, Rabosky and colleagues from eight institutions tested the widely held assumption that species-formation rates are fastest in the tropics by examining the relationship between latitude, species richness and the rate of new species formation among marine fishes. They assembled a time-calibrated evolutionary tree of all 31,526 ray-finned fish species, then focused their analysis on marine species worldwide.

Genetic data were available for more than one-third of the fish species analyzed in the study, and the evolutionary tree was time-calibrated using a database of 139 fossil taxa.

An evolutionary tree, also known as a phylogenetic tree, is a branching diagram showing the inferred evolutionary relationships among various species. The tree assembled for this project is one of the largest time-calibrated phylogenetic trees ever created for any group of animals, according to Rabosky.

The researchers estimated geographic ranges for most of the marine fish species, including all species with genetic data. Then they used complex mathematical and statistical models to estimate the rates at which different groups of fishes split into new species.

"The computational challenges for analyzing these types of data are pretty extreme," said study co-author Michael Alfaro, an evolutionary biologist at the University of California, Los Angeles. The analyses in the study required the equivalent of thousands of desktop computers running continuously for many months, he said.

Some of the fastest rates of new species formation occurred in Antarctic icefish and their relatives. Other temperate and polar groups with exceptionally high speciation rates include snailfish, eelpouts and rockfish.

Three of the largest coral reef-associated fish groups -- wrasses, damselfish and gobies -- showed low to moderate rates of species formation.

"The fact that coral reefs support many more fish species than polar regions despite these lower rates may have a lot to do with their long history of connectivity and ability to act as a refugia," said co-author Peter Cowman of the Australia Research Council Centre of Excellence for Coral Reef Studies, and previously of Yale University. "Our research certainly paints coral reef diversity in a new light."

"Who would have thought that you'd have these really explosive rates of species formation happening in the coldest Antarctic waters, where water is literally at the freezing point and fish like the icefish have to have all kinds of really crazy adaptations to live there, like special antifreeze proteins in their blood to keep it from freezing," Rabosky said.

Rabosky is an associate professor in the U-M Department of Ecology and Evolutionary Biology and an associate curator at the U-M Museum of Zoology.

The authors of the Nature paper, in addition to Rabosky, Alfaro and Cowman, are U-M's Jonathan Chang, Pascal Title and Matt Friedman; Lauren Sallan of the University of Pennsylvania; Kristin Kaschner of the University of Freiburg; Cristina Garilao of GEOMAR Helmholtz Centre for Ocean Research; Thomas Near of Yale University; and Marta Coll of the Institute of Marine Science in Barcelona, Spain.

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Bacteria-powered solar cell converts light to energy, even under overcast skies

Using bacteria that convert light to energy could be a step toward wider adoption of solar power in places where overcast skies are common.

University of British Columbia researchers have found a cheap, sustainable way to build a solar cell using bacteria that convert light to energy.

Their cell generated a current stronger than any previously recorded from such a device, and worked as efficiently in dim light as in bright light.

This innovation could be a step toward wider adoption of solar power in places like British Columbia and parts of northern Europe where overcast skies are common. With further development, these solar cells -- called "biogenic" because they are made of living organisms -- could become as efficient as the synthetic cells used in conventional solar panels.

"Our solution to a uniquely B.C. problem is a significant step toward making solar energy more economical," said Vikramaditya Yadav, a professor in UBC's department of chemical and biological engineering who led the project.

Solar cells are the building blocks of solar panels. They do the work of converting light into electrical current. Previous efforts to build biogenic solar cells have focused on extracting the natural dye that bacteria use for photosynthesis. It's a costly and complex process that involves toxic solvents and can cause the dye to degrade.

The UBC researchers' solution was to leave the dye in the bacteria. They genetically engineered E. coli to produce large amounts of lycopene -- a dye that gives tomatoes their red-orange colour and is particularly effective at harvesting light for conversion to energy. The researchers coated the bacteria with a mineral that could act as a semiconductor, and applied the mixture to a glass surface.

With the coated glass acting as an anode at one end of their cell, they generated a current density of 0.686 milliamps per square centimetre -- an improvement on the 0.362 achieved by others in the field.

"We recorded the highest current density for a biogenic solar cell," said Yadav. "These hybrid materials that we are developing can be manufactured economically and sustainably, and, with sufficient optimization, could perform at comparable efficiencies as conventional solar cells."

The cost savings are difficult to estimate, but Yadav believes the process reduces the cost of dye production to about one-tenth of what it would be otherwise. The holy grail, Yadav said, would be finding a process that doesn't kill the bacteria, so they can produce dye indefinitely.

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Our human ancestors walked on two feet but their children still had a backup plan

This is the 3.32 million-year-old Australopithecus afarensis foot from Dikika, Ethiopia, superimposed over a footprint from a human toddler.

More than 3 million years ago, our ancient human ancestors, including their toddler-aged children, were standing on two feet and walking upright, according to a new study published in Science Advances.

"For the first time, we have an amazing window into what walking was like for a 2½-year-old, more than 3 million years ago," says lead author, Jeremy DeSilva, an associate professor of anthropology at Dartmouth College, who is one of the world's foremost authorities on the feet of our earliest ancestors. "This is the most complete foot of an ancient juvenile ever discovered."

The tiny foot, about the size of a human thumb, is part of a nearly complete 3.32-million-year-old skeleton of a young female Australopithecus afarensis discovered in 2002 in the Dikika region of Ethiopia by Zeresenay (Zeray) Alemseged, a professor of organismal biology and anatomy at the University of Chicago and senior author of the study. Alemseged is internationally known as a leading paleontologist on the study of human origins and human evolution.

"Placed at a critical time and the cusp of being human, Australopithecus afarensis was more derived than Ardipithecus (a facultative biped) but not yet an obligate strider like Homo erectus. The Dikika foot adds to the wealth of knowledge on the mosaic nature of hominin skeletal evolution" explained Alemseged.

Given that the fossil of the tiny foot is the same species as the famous Lucy fossil and was found in the same vicinity, it is not surprising that the Dikika child was erroneously labeled "Lucy's baby" by the popular press, though this youngster lived more than 200,000 years before Lucy.

In studying the fossil foot's remarkably preserved anatomy, the research team strived to reconstruct what life would have been like years ago for this toddler and how our ancestors survived. They examined what the foot would have been used for, how it developed and what it tells us about human evolution. The fossil record indicates that these ancient ancestors were quite good at walking on two legs. "Walking on two legs is a hallmark of being human. But, walking poorly in a landscape full of predators is a recipe for extinction," explained DeSilva.

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