Jan 19, 2018

Why animals diversified on Earth: Cancer research provides clues

Trilobite fossil
Can tumors teach us about animal evolution on Earth? Researchers believe so and now present a novel hypothesis of why animal diversity increased dramatically on Earth about half a billion years ago. A biological innovation may have been key.

A transdisciplinary and international team, from Lund University in Sweden and University of Southern Denmark presents their findings in Nature Ecology and Evolution.

The new hypothesis holds that the dramatic diversification of animals resulted from a revolution within the animals' own biology, rather than in the surrounding chemistry on Earth's surface.

Life on Earth was dominated by microbes for roughly 4 billion years when multicellular life suddenly -- then in the form of animals in robust ecosystems -- made a vigorous entry. Why animals diversified so late and so dramatically has remained unresolved and is a matter of hot debate.

The diversification of animals occurred over a geologically short period of time and is known as the Cambrian explosion. Many geologists have assumed that the Cambrian explosion was triggered by an increase of atmospheric oxygen.

However, a causal relationship between the Cambrian explosion and increasing atmospheric oxygen lacks convincing evidence.

Historic focus on high oxygen

Indeed, research over the last years weaken the support for a correlation between the Cambrian explosion and increasing atmospheric oxygen. For example, dramatic changes in atmospheric oxygen are noted both before and after the Cambrian, but not specifically when animal diversification took off.

Simple animals are furthermore noted to require surprisingly low oxygen levels, which would have been met well before the Cambrian.

"A heated hunt for the geochemical evidence that oxygen increased when animals diversified goes on but, after decades of discussion, it seems worthwhile to consider the development of multicellularity also from other angles," says geobiologist Emma Hammarlund, PhD and researcher at the division for translational cancer research at Lund University and guest researcher at the Nordic Center for Earth Evolution at the University of Southern Denmark.

Tumors are successful versions of multicellularity, also at low oxygen

In order to understand more about the conditions for multicellular life, Emma Hammarlund contacted tumor biologist, Professor Sven Påhlman at the Department of Laboratory Medicine at Lund University, who has explored the importance of low oxygen concentrations, or so-called hypoxia, in the tumor setting for nearly two decades.

"I wanted to learn what tumor scientists observe on a daily basis, in terms of tissue growth and how it relates to oxygen. Tumours are after all, and unfortunately, successful versions of multicellularity," explains Emma Hammarlund.

The team, including also tumor biologist Dr. Kristoffer von Stedingk at Lund University's Paediatrics division, tackled the historic question of why animals developed so late and dramatically with novel clues from the field of tumour biology.

A shared success factor


Specifically, they tested whether the same molecular tools exploited by many tumors -- to maintain stem cell properties -- could also be relevant to the success of animals in the Cambrian explosion.

Cells with stem cell properties are vital for all multicellular life in order to regenerate tissue. For example, cells in the wall of human small intestine are replaced every 2-4 days, through the division of stem cells.

"Hypoxia is generally seen as a threat, but we forget that oxygen shortage in precise periods and settings also is a prerequisite for multicellular life. Our stem cells are the ones that form new tissue, and they are extremely sensitive to oxygen. The stem cells therefore have various systems for dealing with the effects of both oxygen and oxygen shortage, which is clear in the case of tumors," explains Sven Påhlman.

These systems involve a protein that can 'fool' cells act as if the setting was hypoxic. This can also fool cells to get stem cell-like properties.

Tumor cells cope with oxygen


By studying the ability of tumor cells to imitate the properties of stem cells, Sven Påhlman's team have observed how tumor cells can high-jack specific mechanisms that evade the negative effects that high oxygen has on stem cells. As a consequence, the tumor cells are able to maintain stem cell properties, despite being surrounded by the high oxygen concentrations that are present in the body.

This same ability, according to the authors, is one of the keys that also made animals so successful.

"The ability to construct stem cell properties despite high oxygen levels, so called 'pseudohypoxia', is present also in our normal vertebrate tissue. Therefore, we flip the perspective on the oxic setting: While low oxygen is generally unproblematic for animal cells, the oxic settings pose a fundamental challenge for complex multicellularity. Without additional tools, the oxic setting makes tissue-specific stem cells mature too early," says Sven Påhlman.

A biological revolution

The new hypothesis that gives credit to a biological innovation to have triggered animal diversification is similar to how we think of biological innovations changing life in the past. Just the presence of free oxygen is the result of some microbes finding a way of using sunlight to get energy. This was also a biological event.

A view that fits with other geobiological observations, such that environments with 'enough' oxygen have been present on Earth since long before the Cambrian explosion.

The hypothesis also has implications for how animals may have varying capacities to live in oxygenated environments, and perhaps even for how we see cancer as an evolutionary consequence of our ability to live in oxygenated niches.

Bringing geobiology and cancer research together

Taking an evolutionary approach is unusual for cancer researchers, even though the development of tumors is generally seen as an evolutionary process.

Similarly, geobiological research rarely apply the cellular perspective. But having combined their expertise, both Emma Hammarlund and Sven Påhlman are surprised that we have not previously wondered about our paradoxical ability to renew tissue in the oxic setting.

Read more at Science Daily

Method uses DNA, nanoparticles and lithography to make optically active structures

Northwestern University researchers have developed a new method to precisely arrange nanoparticles of different sizes and shapes in two and three dimensions, resulting in optically active superlattices.
Northwestern University researchers have developed a first-of-its-kind technique for creating entirely new classes of optical materials and devices that could lead to light bending and cloaking devices -- news to make the ears of Star Trek's Spock perk up.

Using DNA as a key tool, the interdisciplinary team took gold nanoparticles of different sizes and shapes and arranged them in two and three dimensions to form optically active superlattices. Structures with specific configurations could be programmed through choice of particle type and both DNA-pattern and sequence to exhibit almost any color across the visible spectrum, the scientists report.

"Architecture is everything when designing new materials, and we now have a new way to precisely control particle architectures over large areas," said Chad A. Mirkin, the George B. Rathmann Professor of Chemistry in the Weinberg College of Arts and Sciences at Northwestern. "Chemists and physicists will be able to build an almost infinite number of new structures with all sorts of interesting properties. These structures cannot be made by any known technique."

The technique combines an old fabrication method -- top-down lithography, the same method used to make computer chips -- with a new one -- programmable self-assembly driven by DNA. The Northwestern team is the first to combine the two to achieve individual particle control in three dimensions.

The study was published online by the journal Science today (Jan. 18). Mirkin and Vinayak P. Dravid and Koray Aydin, both professors in Northwestern's McCormick School of Engineering, are co-corresponding authors.

Scientists will be able to use the powerful and flexible technique to build metamaterials -- materials not found in nature -- for a range of applications including sensors for medical and environmental uses.

The researchers used a combination of numerical simulations and optical spectroscopy techniques to identify particular nanoparticle superlattices that absorb specific wavelengths of visible light. The DNA-modified nanoparticles -- gold in this case -- are positioned on a pre-patterned template made of complementary DNA. Stacks of structures can be made by introducing a second and then a third DNA-modified particle with DNA that is complementary to the subsequent layers.

In addition to being unusual architectures, these materials are stimuli-responsive: the DNA strands that hold them together change in length when exposed to new environments, such as solutions of ethanol that vary in concentration. The change in DNA length, the researchers found, resulted in a change of color from black to red to green, providing extreme tunability of optical properties.

"Tuning the optical properties of metamaterials is a significant challenge, and our study achieves one of the highest tunability ranges achieved to date in optical metamaterials," said Aydin, assistant professor of electrical engineering and computer science at McCormick.

"Our novel metamaterial platform -- enabled by precise and extreme control of gold nanoparticle shape, size and spacing -- holds significant promise for next-generation optical metamaterials and metasurfaces," Aydin said.

The study describes a new way to organize nanoparticles in two and three dimensions. The researchers used lithography methods to drill tiny holes -- only one nanoparticle wide -- in a polymer resist, creating "landing pads" for nanoparticle components modified with strands of DNA. The landing pads are essential, Mirkin said, since they keep the structures that are grown vertical.

The nanoscopic landing pads are modified with one sequence of DNA, and the gold nanoparticles are modified with complementary DNA. By alternating nanoparticles with complementary DNA, the researchers built nanoparticle stacks with tremendous positional control and over a large area. The particles can be different sizes and shapes (spheres, cubes and disks, for example).

"This approach can be used to build periodic lattices from optically active particles, such as gold, silver and any other material that can be modified with DNA, with extraordinary nanoscale precision," said Mirkin, director of Northwestern's International Institute for Nanotechnology.

Mirkin also is a professor of medicine at Northwestern University Feinberg School of Medicine and professor of chemical and biological engineering, biomedical engineering and materials science and engineering in the McCormick School.

The success of the reported DNA programmable assembly required expertise with hybrid (soft-hard) materials and exquisite nanopatterning and lithographic capabilities to achieve the requisite spatial resolution, definition and fidelity across large substrate areas. The project team turned to Dravid, a longtime collaborator of Mirkin's who specializes in nanopatterning, advanced microscopy and characterization of soft, hard and hybrid nanostructures.

Read more at Science Daily

Long-term warming trend continued in 2017: NASA, NOAA

This map shows Earth's average global temperature from 2013 to 2017, as compared to a baseline average from 1951 to 1980, according to an analysis by NASA's Goddard Institute for Space Studies. Yellows, oranges, and reds show regions warmer than the baseline.
Earth's global surface temperatures in 2017 ranked as the second warmest since 1880, according to an analysis by NASA.

Continuing the planet's long-term warming trend, globally averaged temperatures in 2017 were 1.62 degrees Fahrenheit (0.90 degrees Celsius) warmer than the 1951 to 1980 mean, according to scientists at NASA's Goddard Institute for Space Studies (GISS) in New York. That is second only to global temperatures in 2016.

In a separate, independent analysis, scientists at the National Oceanic and Atmospheric Administration (NOAA) concluded that 2017 was the third-warmest year in their record. The minor difference in rankings is due to the different methods used by the two agencies to analyze global temperatures, although over the long-term the agencies' records remain in strong agreement. Both analyses show that the five warmest years on record all have taken place since 2010.

Because weather station locations and measurement practices change over time, there are uncertainties in the interpretation of specific year-to-year global mean temperature differences. Taking this into account, NASA estimates that 2017's global mean change is accurate to within 0.1 degree Fahrenheit, with a 95 percent certainty level.

"Despite colder than average temperatures in any one part of the world, temperatures over the planet as a whole continue the rapid warming trend we've seen over the last 40 years," said GISS Director Gavin Schmidt.

The planet's average surface temperature has risen about 2 degrees Fahrenheit (a little more than 1 degree Celsius) during the last century or so, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere. Last year was the third consecutive year in which global temperatures were more than 1.8 degrees Fahrenheit (1 degree Celsius) above late nineteenth-century levels.

Phenomena such as El Niño or La Niña, which warm or cool the upper tropical Pacific Ocean and cause corresponding variations in global wind and weather patterns, contribute to short-term variations in global average temperature. A warming El Niño event was in effect for most of 2015 and the first third of 2016. Even without an El Niño event -- and with a La Niña starting in the later months of 2017 -- last year's temperatures ranked between 2015 and 2016 in NASA's records.

In an analysis where the effects of the recent El Niño and La Niña patterns were statistically removed from the record, 2017 would have been the warmest year on record.

Weather dynamics often affect regional temperatures, so not every region on Earth experienced similar amounts of warming. NOAA found the 2017 annual mean temperature for the contiguous 48 United States was the third warmest on record.

Warming trends are strongest in the Arctic regions, where 2017 saw the continued loss of sea ice.

NASA's temperature analyses incorporate surface temperature measurements from 6,300 weather stations, ship- and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations.

These raw measurements are analyzed using an algorithm that considers the varied spacing of temperature stations around the globe and urban heating effects that could skew the conclusions. These calculations produce the global average temperature deviations from the baseline period of 1951 to 1980.

NOAA scientists used much of the same raw temperature data, but with a different baseline period, and different methods to analyze Earth's polar regions and global temperatures.

The full 2017 surface temperature data set and the complete methodology used to make the temperature calculation are available at: https://data.giss.nasa.gov/gistemp

Read more at Science Daily

First evidence of sub-Saharan Africa glassmaking

Photo of glass beads.
Scholars from Rice University, University College London and the Field Museum have found the first direct evidence that glass was produced in sub-Saharan Africa centuries before the arrival of Europeans, a finding that the researchers said represents a "new chapter in the history of glass technology."

The discovery is discussed in "Chemical Analysis of Glass Beads from Igbo Olokun, Ile-Ife (SW Nigeria): New Light on Raw Materials, Production and Interregional Interactions," which will appear in an upcoming volume of the Journal of Archaeological Science.

Lead author Abidemi Babatunde Babalola, a recent graduate of Rice with a Ph.D. in anthropology and a visiting fellow at Harvard University, came across evidence of early glassmaking during archaeological excavations at Igbo Olokun, located on the northern periphery of Ile-Ife in southwestern Nigeria. He recovered more than 12,000 glass beads and several kilograms of glass-working debris.

"This area has been recognized as a glass-working workshop for more than a century," Babalola said. "The glass-encrusted containers and beads that have been uncovered there were viewed for many years as evidence that imported glass was remelted and reworked."

However, 10 years ago this idea was challenged when analyses of glass beads attributed to Ile-Ife showed that some had a chemical composition very different from that of known glass production areas. Researchers raised the possibility of local production in Ife, although direct evidence for glassmaking and its chronology was lacking.

"The Igbo Olokun excavations have provided that evidence," Babalola said.

The researchers' analysis of 52 glass beads from the excavated assemblage revealed that none matched the chemical composition of any other known glass-production area in the Old World, including Egypt, the eastern Mediterranean, the Middle East and Asia. Rather, the beads have a high-lime, high-alumina (HLHA) composition that reflects local geology and raw materials, the researchers said. The excavations provided evidence that glass production at Igbo Olokun dates to the 11th through 15th centuries A.D., well before the arrival of Europeans along the coast of West Africa.

Read more at Science Daily

Jan 18, 2018

How massive can neutron stars be?

Emission of gravitational waves during a neutron star merger.
Astrophysicists at Goethe University Frankfurt set a new limit for the maximum mass of neutron stars: It cannot exceed 2.16 solar masses.

Since their discovery in the 1960s, scientists have sought to answer an important question: How massive can neutron stars actually become? By contrast to black holes, these stars cannot gain in mass arbitrarily; past a certain limit there is no physical force in nature that can counter their enormous gravitational force. For the first time, astrophysicists at Goethe University Frankfurt have succeeded in calculating a strict upper limit for the maximum mass of neutron stars.

With a radius of about twelve kilometres and a mass that can be twice as large as that of the sun, neutron stars are amongst the densest objects in the Universe, producing gravitational fields comparable to those of black holes. Whilst most neutron stars have a mass of around 1.4 times that of the sun, massive examples are also known, such as the pulsar PSR J0348+0432 with 2.01 solar masses.

The density of these stars is enormous, as if the entire Himalayas were compressed into a beer mug. However, there are indications that a neutron star with a maximum mass would collapse to a black hole if even just a single neutron were added.

Together with his students Elias Most and Lukas Weih, Professor Luciano Rezzolla, physicist, senior fellow at the Frankfurt Institute for Advanced Studies (FIAS) and professor of Theoretical Astrophysics at Goethe University Frankfurt, has now solved the problem that had remained unanswered for 40 years: With an accuracy of a few percent, the maximum mass of non-rotating neutron stars cannot exceed 2.16 solar masses.

The basis for this result was the "universal relations" approach developed in Frankfurt a few years ago. The existence of "universal relations" implies that practically all neutron stars "look alike," meaning that their properties can be expressed in terms of dimensionless quantities. The researchers combined these "universal relations" with data on gravitational-wave signals and the subsequent electromagnetic radiation (kilonova) obtained during the observation last year of two merging neutron stars in the framework of the LIGO experiment. This simplifies calculations tremendously because it makes them independent of the equation of state. This equation is a theoretical model for describing dense matter inside a star that provides information on its composition at various depths in the star. Such a universal relation therefore played an essential role in defining the new maximum mass.

The result is a good example of the interaction between theoretical and experimental research. "The beauty of theoretical research is that it can make predictions. Theory, however, desperately needs experiments to narrow down some of its uncertainties," says Professor Rezzolla. "It's therefore quite remarkable that the observation of a single binary neutron star merger that occurred millions of light years away combined with the universal relations discovered through our theoretical work have allowed us to solve a riddle that has seen so much speculation in the past."

The research results were published as a Letter in The Astrophysical Journal. Just a few days later, research groups from the USA and Japan confirmed the findings, despite having so far followed different and independent approaches.

Read more at Science Daily

New technique for finding life on Mars

Co-author I. Altshuler sampling permafrost terrain near the McGill Arctic research station, Canadian high Arctic.
Researchers demonstrate for the first time the potential of existing technology to directly detect and characterize life on Mars and other planets. The study, published in Frontiers in Microbiology, used miniaturized scientific instruments and new microbiology techniques to identify and examine microorganisms in the Canadian high Arctic -- one of the closest analogs to Mars on Earth. By avoiding delays that come with having to return samples to a laboratory for analysis, the methodology could also be used on Earth to detect and identify pathogens during epidemics in remote areas.

"The search for life is a major focus of planetary exploration, but there hasn't been direct life detection instrumentation on a mission since the 70s, during the Viking missions to Mars," explains Dr Jacqueline Goordial, one of the study's authors. "We wanted to show a proof-of-concept that microbial life can be directly detected and identified using very portable, low-weight, and low-energy tools."

At present, most instruments on astrobiology missions look for habitable conditions, small organic molecules and other "biosignatures" that generally could not be formed without life. However, these provide only indirect evidence of life. Moreover, current instruments are relatively large and heavy with high energy requirements. This makes them unsuitable for missions to Europa and Enceladus -- moons of Jupiter and Saturn which, along with Mars, are the primary targets in the search for life in our solar system.

Dr Goordial, together with Professor Lyle Whyte and other scientists from Canada's McGill University, took a different approach: the use of multiple, miniature instruments to directly detect and analyze life. Using existing low-cost and low-weight technology in new ways, the team created a modular "life detection platform" able to culture microorganisms from soil samples, assess microbial activity, and sequence DNA and RNA.

To detect and characterize life on Mars, Europa and Enceladus, the platform would need to work in environments with extreme cold temperatures. The team therefore tested it at a remote site in a close analog on Earth: polar regions.

"Mars is a very cold and dry planet, with a permafrost terrain that looks a lot like what we find in the Canadian high Arctic," says Dr Goordial. "For this reason, we chose a site about 900 km from the North Pole as a Mars analog to take samples and test our methods."

Using a portable, miniature DNA sequencing device (Oxford Nanopore MiniON), the researchers show for the first time that not only can the tool be used for examining environmental samples in extreme and remote settings, but that it can be combined with other methodology to detect active microbial life in the field. The researchers were able to isolate extremophilic microorganisms that have never been cultured before, detect microbial activity, and sequence DNA from the active microbes.

"Successful detection of nucleic acids in Martian permafrost samples would provide unambiguous evidence of life on another world," says Dr Goordial. "However, the presence of DNA alone doesn't tell you much about the state of an organism -- it could be dormant or dead, for example. By using the DNA sequencer with the other methodology in our platform, we were able to first find active life, and then identify it and analyze its genomic potential, that is, the kinds of functional genes it has."

While the team showed that such a platform could theoretically be used to detect life on other planets, it is not ready for a space mission just yet. "Humans were required to carry out much of the experimentation in this study, while life detection missions on other planets will need to be robotic," says Dr Goordial. "The DNA sequencer also needs higher accuracy and durability to withstand the long timescales required for planetary missions."

Nevertheless, Dr Goordial and her team hope this study will act as a starting point for future development of life detection tools.

In the meantime, the platform has potential applications here on Earth. "The types of analyses performed by our platform are typically carried out in the laboratory, after shipping samples back from the field. We show that microbial ecology studies can now be done in real time, directly on site -- including in extreme environments like the Arctic and Antarctic," says Dr Goordial.

Read more at Science Daily

Warming Arctic climate constrains life in cold-adapted mammals

Cold-adapted species, like the muskoxen, are feeling the heat, according to wildlife biologist Joel Berger.
Despite the growth in knowledge about the effects of a warming Arctic on its cold-adapted species, how these changes affect animal populations is poorly understood. Research efforts have been hindered by the area's remoteness and complex logistics required to gain access.

A new study led by Joel Berger, professor in the Department of Fish, Wildlife and Conservation Biology at Colorado State University, has uncovered previously unknown effects of rain-on-snow events, winter precipitation and ice tidal surges on the Arctic's largest land mammal, the muskoxen.

The warmer climate is stressing mothers and young muskoxen, said Berger, also a senior scientist with the Wildlife Conservation Society. Rain-on-snow events occurring in the winter -- when muskoxen gestate -- and unusually dry winter conditions have also led to underdeveloped skeletal growth in juvenile muskoxen. This effect can be traced back to their pregnant mothers.

"When rain-on-snow events occur in the Arctic, due to warming temperatures, and the snow freezes again, this leads to mothers not being able to access food for adequate nutrition," said Berger. "The babies then, unfortunately, pay the price."

The smaller size observed in juvenile and young adult muskoxen is associated with poorer health and fitness, due to delayed puberty, and increased mortality, according to the research team.

In addition, scientists documented a mass mortality event due to a one-time extreme ice event caused by a tidal surge. In February 2011, an historically high tidal surge resulted in at least 52 muskoxen being submerged at the northern coast of Bering Land Bridge peninsula.

Researchers also found historical records documenting deaths due to rapid freezing and thawing during winter at a range of single sites of whales -- 170 Beluga and 150 narwhals -- and sea otters along the Aleutian Islands.

"Unlike polar bears, which are on the world's stage, no one really knows about muskoxen or cares," said Berger. "They roamed with wooly mammoths but still survive. Muskoxen are feeling the heat, just as we humans are feeling the extremes of climate. These wild weather swings have massive impacts on us. Solutions are clear, but we fail to respond by changing our consumptive ways."

Measuring a muskox, tracking temperatures


The research team analyzed head size of juvenile muskoxen using digital photo data over the span of seven years and at three sites in Alaska and Russia. They also compiled winter weather data for the Alaskan sites from the closest weather stations maintained by the National Oceanic and Atmospheric Administration. Data used to calculate rain-on-snow events on Wrangel Island, located in the Arctic Ocean, between the Chukchi Sea and East Siberian Sea, were from the Federal Hydro-meteorological Service of Russia, whose records date back to 1926.

Berger acknowledged the role his research plays "in a challenging political era." His collaborators include Russian scientists in Asia and the Alaskan Arctic. Berger is not only a researcher, but he also serves as a diplomat of sorts, working closely with Russian research counterparts and the government. He praised them for their active engagement and willingness to share data.

Read more at Science Daily

World’s oldest known oxygen oasis discovered

Rock layers in the Pongola Basin, South Africa.
In the Earth's early history, several billion years ago, only traces of oxygen existed in the atmosphere and the oceans. Today's air-breathing organisms could not have existed under those conditions. The change was caused by photosynthesizing bacteria, which created oxygen as a by-product -- in vast amounts. 2.5-billion-year-old rock layers on several continents have yielded indications that the first big increase in the proportion of oxygen in the atmosphere took place then.

Now, working with international colleagues, Dr. Benjamin Eickmann and Professor Ronny Schönberg, isotope geochemists from the University of Tübingen have discovered layers in South Africa's Pongola Basin which bear witness to oxygen production by bacteria as early as 2.97 billion years ago. That makes the Basin the earliest known home to oxygen-producing organisms -- known as an oxygen oasis. The study has been published in the latest Nature Geoscience.

Conditions on Earth some three billion years ago were inhospitible to say the least. The atmosphere contained only one-one hundred thousandth of the oxygen it has today. The primeval oceans contained hardly any sulfate; but they did contain large amounts of ferrous iron. When bacteria started producing oxygen, it could initially bond with other elements, but began to enrich the atmosphere in a massive oxygen emission event around 2.5 billion years ago.

"We can see that in the disappearance of reduced minerals in the sediments on the continents. Certain sulfur signatures which can only be formed in a low-oxygen atmosphere are no longer to be found," says Benjamin Eickmann, the study's lead author. This event, which could be described as global environmental pollution, went down in the Earth's history as the Great Oxygenation Event. It was a disaster for the early bacteria types which had evolved under low-oxygen conditions; the oxygen poisoned them. "However, after the first big rise, the atmosphere only contained 0.2 percent oxygen; today it's around 21 percent," Eickmann explains. Exposed to an atmosphere which contained increasing amounts of oxygen, the continents were subject to enhanced erosion. That led to more trace elements entering the oceans. The improved supply of nutrients in turn led to more life forms in the seas.

Sulfur signatures as an archive of Earth history

In their current study the researchers investigated the 2.97-bilion-year-old sediments deposited in the Pongola Basin in what is now South Africa. From the proportions of sulfur isotopes (particularly the of 34S/32S ratio), in the sediments, the researchers are able to conclude that the bacteria used the sulfate in the primeval seas as a source of energy, reducing it chemically.

"Sulfate is a form of oxidized sulfur. A higher concentration of sulfate in the water indicates that sufficient free oxygen must have been present in the shallow sea of the Pongola Basin," Ronny Schönberg says. This free oxygen must have been produced by other, photosynthesizing bacteria. At the same time, another sulfur isotope signature (the 33S/32S ratio) in these sediments indicates a continued reduced, very low-oxygen atmosphere.

Read more at Science Daily

Ancient DNA results end 4,000-year-old Egyptian mummy mystery

The Two Brothers are the Museum's oldest mummies and amongst the best-known human remains in its Egyptology collection. They are the mummies of two elite men -- Khnum-nakht and Nakht-ankh -- dating to around 1800 BC.
Using 'next generation' DNA sequencing scientists have found that the famous 'Two Brothers' mummies of the Manchester Museum have different fathers so are, in fact, half-brothers.

The Two Brothers are the Museum's oldest mummies and amongst the best-known human remains in its Egyptology collection. They are the mummies of two elite men -- Khnum-nakht and Nakht-ankh -- dating to around 1800 BC.

However, ever since their discovery in 1907 there has been some debate amongst Egyptologists whether the two were actually related at all. So, in 2015, 'ancient DNA' was extracted from their teeth to solve the mystery.

But how did the mystery start? The pair's joint burial site, later dubbed The Tomb of The Two Brothers, was discovered at Deir Rifeh, a village 250 miles south of Cairo.

They were found by Egyptian workmen directed by early 20th century Egyptologists, Flinders Petrie and Ernest Mackay. Hieroglyphic inscriptions on the coffins indicated that both men were the sons of an unnamed local governor and had mothers with the same name, Khnum-aa. It was then the men became known as the Two Brothers.

When the complete contents of the tomb were shipped to Manchester in 1908 and the mummies of both men were unwrapped by the UK's first professional female Egyptologist, Dr Margaret Murray. Her team concluded that the skeletal morphologies were quite different, suggesting an absence of family relationship. Based on contemporary inscriptional evidence, it was proposed that one of the Brothers was adopted.

Therefore, in 2015, the DNA was extracted from the teeth and, following hybridization capture of the mitochondrial and Y chromosome fractions, sequenced by a next generation method. Analysis showed that both Nakht-Ankh and Khnum-Nakht belonged to mitochondrial haplotype M1a1, suggesting a maternal relationship. The Y chromosome sequences were less complete but showed variations between the two mummies, indicating that Nakht-Ankh and Khnum-Nakht had different fathers, and were thus very likely to have been half-brothers.

Dr Konstantina Drosou, of the School of Earth and Environmental Sciences at the University of Manchester who conducted the DNA sequencing, said: "It was a long and exhausting journey to the results but we are finally here. I am very grateful we were able to add a small but very important piece to the big history puzzle and I am sure the brothers would be very proud of us. These moments are what make us believe in ancient DNA. "

The study, which is being published in the Journal of Archaeological Science, is the first to successfully use the typing of both mitochondrial and Y chromosomal DNA in Egyptian mummies.

Read more at Science Daily

Jan 17, 2018

Not just for Christmas: Study sheds new light on ancient human-turkey relationship

Wild turkey.
For the first time, research has uncovered the origins of the earliest domestic turkeys in ancient Mexico.

The study also suggests turkeys weren't only prized for their meat -- with demand for the birds soaring with the Mayans and Aztecs because of their cultural significance in rituals and sacrifices.

In an international collaboration, researchers from the University of York, the Institute of Anthropology and History in Mexico, Washington State University and Simon Fraser University, studied the remains of 55 turkeys which lived between 300BC and 1500 AD and had been discovered in Mesoamerica- an area stretching from central Mexico to Northern Costa Rica within which pre-Columbian societies such as the Mayans and Aztecs flourished.

Analysing the ancient DNA of the birds, the researchers were able to confirm that modern European turkeys are descended from Mexican ancestors.

The team also measured the carbon isotope ratios in the turkey bones to reconstruct their diets. They found that the turkeys were gobbling crops cultivated by humans such as corn in increasing amounts, particularly in the centuries leading up to Spanish exploration, implying more intensive farming of the birds.

Interestingly, the gradual intensification of turkey farming does not directly correlate to an increase in human population size, a link you would expect to see if turkeys were reared simply as a source of nutrition.

Lead author of the paper and Marie Sk?odowska-Curie Fellow in the Department of Archaeology at the University of York, Dr Aurélie Manin, said: "Turkey bones are rarely found in domestic refuse in Mesoamerica and most of the turkeys we studied had not been eaten -- some were found buried in temples and human graves, perhaps as companions for the afterlife. This fits with what we know about the iconography of the period, where we see turkeys depicted as gods and appearing as symbols in the calendar.

"The archaeological evidence suggests that meat from deer and rabbit was a more popular meal choice for people in pre-Columbian societies; turkeys are likely to have also been kept for their increasingly important symbolic and cultural role."

The fact that some of the turkey bones were uncovered outside of the natural range of the species also suggests that there was a thriving turkey trade in live birds along Mesoamerica's expanding trade routes.

Senior author of the paper from the Department of Archaeology at the University of York, Dr Camilla Speller, said: "Even though humans in this part of the word had been practicing agriculture for around 10,000 years, the turkey was the first animal, other than the dog, people in Mesoamerica started to take under their control.

"Turkeys would have made a good choice for domestication as there were not many other animals of suitable temperament available and turkeys would have been drawn to human settlements searching for scraps"

Some of the remains the researchers analysed were from a cousin of the common turkey -- the brightly plumed Ocellated turkey. In a strange twist the researchers found that the diets of these more ornate birds remained largely composed of wild plants and insects, suggesting that they were left to roam free and never domesticated.

Read more at Science Daily