How Lyme disease the first epidemic of climate change

Mary Beth Pfeiffer writes:

In the tally of species that will evolve or perish as temperatures rise, now consider the moose. The lumbering king of the deer family, known for antlers that can span six feet like giant outstretched fingers, the moose faces a litany of survival threats, from wolves and bears to brain worms and liver fluke parasites. But in the late 1990s in many northern states and Canada, something else began to claim adult cows and bull moose and, in even greater numbers, their single or twin calves.

Lee Kantar is the moose biologist for the state of Maine, which means that he makes a living climbing the rugged terrain of north-central Maine when a GPS collar indicates a moose has died. A lean man with a prominent salt-and-pepper moustache who wears flannel shirts and jeans to work, Kantar tagged 60 moose in January of 2014 around Moosehead Lake in the Maine Highlands. By the end of that year, 12 adults and 22 calves were dead – 57 per cent of the group. When biologists examined the carcasses, they found what they thought was the cause. Calves not even a year old harboured up to 60,000 blood-sucking arthropods known as winter ticks. In Vermont, dead moose were turning up with 100,000 ticks – each. In New Hampshire, the moose population had dropped from 7,500 to 4,500 from the 1990s to 2014, the emaciated bodies of cows, bulls and calves bearing similar infestations of ticks. These magnificent animals were literally being bled to death. [Continue reading…]

The interstitium, the largest organ we never knew we had

Tanya Basu writes:

What is an organ? Anatomy textbooks are rather fuzzy about what defines an “organ,” requiring one to have primary tissue—parenchyma—and “sporadic” tissue, called stroma, which can be nerves, vessels, and other connective tissue. Organs are the necessary building blocks of organisms (hence, the name), and can be gigantic or microscopic. So long as cells clump together to form tissues, and these tissues organize themselves into organs that perform specific functions in the survival of an organism, that mass of tissues and cells can be called an organ.

Theise, Carr-Locke, and Benias weren’t sure what to call this space with its collagen bundles and fluid. The fluid itself appeared rich in proteins typical of lymphatics and serum, but the space was neither lymphatic nor vascular (meaning that it contained neither veins nor arteries), so what could it be?

That’s when it dawned on them that what they’d stumbled upon was actually talked about in medical textbooks, but that they were the first to actually define it.

This thing they were looking at, struggling to understand with its bizarre structure and rule-breaking form, was the interstitium, a space vaguely described in textbooks as where “extracellular fluid” is found, the fluid that isn’t contained within cells. What doctors had defined as “dense connective tissue” wasn’t dense connective tissue at all. In fact, they were all fluid-filled structures that only appeared to be densely compacted when tissues were made into slides, the fluid draining away, the collagen lattice collapsing onto itself.

They had a theory—that the space was the interstitium—and a way to prove it. They were on to something.

So far they had only recognized this in the bile duct. But Theise began to recognize through his daily lot of diagnostic slides from surgical resections and biopsies of all sorts of tissues and tumors that the dense connective tissue layers of other parts of the body also had the same appearance as this layer in the bile duct. He noticed it in stomach and intestine and esophageal specimens, then he saw it in fascia around muscles and in fat. And then he noticed it around veins and arteries. Then skin.

It seemed to be everywhere, and Theise realized the potential enormity of what they’d discovered, calculating that it was largest organ of the body by volume—larger even than that of skin due to its wrapping around every organ, including the skin. At about 20 percent of all the fluid of the body, and about 10 liters, it was gigantic despite the fact that it could only be seen by peering through a microscope: The cardiovascular system (heart, veins, arteries, and capillaries) weighed in at about a third of that volume, the cerebrospinal fluid 20 times smaller. [Continue reading…]

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How new data is transforming our understanding of place cells — the brain’s GPS


Adithya Rajagopalan writes:

The first pieces of the brain’s “inner GPS” started coming to light in 1970. In the laboratories of University College London, John O’Keefe and his student Jonathan Dostrovsky recorded the electrical activity of neurons in the hippocampus of freely moving rats. They found a group of neurons that increased their activity only when a rat found itself in a particular location. They called them “place cells.”

Building on these early findings, O’Keefe and his colleague Lynn Nadel proposed that the hippocampus contains an invariant representation of space that does not depend on mood or desire. They called this representation the “cognitive map.” In their view, all of the brain’s place cells together represent the entirety of an animal’s environment, and whichever place cell is active indicates its current location. In other words, the hippocampus is like a GPS. It tells you where you are on a map and that map remains the same whether you are hungry and looking for food or sleepy and looking for a bed. O’Keefe and Nadel suggested that the absolute position represented in the hippocampal place cells provides a mental framework that can be used by an animal to find its way in any situation—be that to find food or a bed.

Over the next 40 years, other researchers—including the husband and wife duo of Edvard and May-Britt Moser—produced support for the idea that the brain’s hippocampal circuitry acts like an inner GPS. In recognition of their pioneering work, O’Keefe and the Mosers were awarded the 2014 Nobel Prize in physiology or medicine. You’d think that this would mean that the role of the hippocampus in guiding an animal through space was solved.

But studying the brain is never that straightforward. Like a match lighting a fuse, the 2014 Nobel Prize set off an explosion of experiments and ideas, some of which have pushed back against O’Keefe and Nadel’s early interpretation. This new work has suggested that when it comes to spatial navigation, the hippocampal circuit represents location information that is relative and malleable by experience rather than absolute. The study of the hippocampus seems to have stumbled into an age-old philosophical argument. [Continue reading…]

3.5 billion-year-old fossils challenge ideas about early life on Earth

Rebecca Boyle writes:

In the arid, sun-soaked northwest corner of Australia, along the Tropic of Capricorn, the oldest face of Earth is exposed to the sky. Drive through the northern outback for a while, south of Port Hedlund on the coast, and you will come upon hills softened by time. They are part of a region called the Pilbara Craton, which formed about 3.5 billion years ago, when Earth was in its youth.

Look closer. From a seam in one of these hills, a jumble of ancient, orange-Creamsicle rock spills forth: a deposit called the Apex Chert. Within this rock, viewable only through a microscope, there are tiny tubes. Some look like petroglyphs depicting a tornado; others resemble flattened worms. They are among the most controversial rock samples ever collected on this planet, and they might represent some of the oldest forms of life ever found.

In December, researchers lobbed another salvo in the decades-long debate about the nature of these forms. They are indeed fossil life, and they date to 3.465 billion years ago, according to John Valley, a geochemist at the University of Wisconsin. If Valley and his team are right, the fossils imply that life diversified remarkably early in the planet’s tumultuous youth.

The fossils add to a wave of discoveries that point to a new story of ancient Earth. In the past year, separate teams of researchers have dug up, pulverized and laser-blasted pieces of rock that may contain life dating to 3.7, 3.95 and maybe even 4.28 billion years ago. All of these microfossils — or the chemical evidence associated with them — are hotly debated. But they all cast doubt on the traditional tale. [Continue reading…]

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Land degradation by human activities pushing Earth into sixth mass extinction and undermining well-being of 3.2 billion people

 

Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES): Worsening land degradation caused by human activities is undermining the well-being of two fifths of humanity, driving species extinctions and intensifying climate change. It is also a major contributor to mass human migration and increased conflict, according to the world’s first comprehensive evidence-based assessment of land degradation and restoration.

The dangers of land degradation, which cost the equivalent of about 10% of the world’s annual gross product in 2010 through the loss of biodiversity and ecosystem services, are detailed for policymakers, together with a catalogue of corrective options, in the three-year assessment report by more than 100 leading experts from 45 countries, launched today.

Produced by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), the report was approved at the 6th session of the IPBES Plenary in Medellín, Colombia. IPBES has 129 State Members.

Providing the best-available evidence for policymakers to make better-informed decisions, the report draws on more than 3,000 scientific, Government, indigenous and local knowledge sources. Extensively peer-reviewed, it was improved by more than 7,300 comments, received from over 200 external reviewers.

Serious Danger to Human Well-being

Rapid expansion and unsustainable management of croplands and grazing lands is the most extensive global direct driver of land degradation, causing significant loss of biodiversity and ecosystem services – food security, water purification, the provision of energy and other contributions of nature essential to people. This has reached ‘critical’ levels in many parts of the world, the report says.

“With negative impacts on the well-being of at least 3.2 billion people, the degradation of the Earth’s land surface through human activities is pushing the planet towards a sixth mass species extinction,” said Prof. Robert Scholes (South Africa), co-chair of the assessment with Dr. Luca Montanarella (Italy). “Avoiding, reducing and reversing this problem, and restoring degraded land, is an urgent priority to protect the biodiversity and ecosystem services vital to all life on Earth and to ensure human well-being.”

“Wetlands have been particularly hard hit,” said Dr. Montanarella. “We have seen losses of 87% in wetland areas since the start of the modern era – with 54% lost since 1900.”

According to the authors, land degradation manifests in many ways: land abandonment, declining populations of wild species, loss of soil and soil health, rangelands and fresh water, as well as deforestation.

Underlying drivers of land degradation, says the report, are the high-consumption lifestyles in the most developed economies, combined with rising consumption in developing and emerging economies. High and rising per capita consumption, amplified by continued population growth in many parts of the world, can drive unsustainable levels of agricultural expansion, natural resource and mineral extraction, and urbanization – typically leading to greater levels of land degradation.

By 2014, more than 1.5 billion hectares of natural ecosystems had been converted to croplands. Less than 25% of the Earth’s land surface has escaped substantial impacts of human activity – and by 2050, the IPBES experts estimate this will have fallen to less than 10%.

Crop and grazing lands now cover more than one third of the Earth´s land surface, with recent clearance of native habitats, including forests, grasslands and wetlands, being concentrated in some of the most species-rich ecosystems on the planet.

The report says increasing demand for food and biofuels will likely lead to continued increase in nutrient and chemical inputs and a shift towards industrialized livestock production systems, with pesticide and fertilizer use expected to double by 2050.

Avoidance of further agricultural expansion into native habitats can be achieved through yield increases on the existing farmlands, shifts towards less land degrading diets, such as those with more plant-based foods and less animal protein from unsustainable sources, and reductions in food loss and waste.

Strong Links to Climate Change

“Through this report, the global community of experts has delivered a frank and urgent warning, with clear options to address dire environmental damage,” said Sir Robert Watson, Chair of IPBES.

“Land degradation, biodiversity loss and climate change are three different faces of the same central challenge: the increasingly dangerous impact of our choices on the health of our natural environment. We cannot afford to tackle any one of these three threats in isolation – they each deserve the highest policy priority and must be addressed together.”

The IPBES report finds that land degradation is a major contributor to climate change, with deforestation alone contributing about 10% of all human-induced greenhouse gas emissions. Another major driver of the changing climate has been the release of carbon previously stored in the soil, with land degradation between 2000 and 2009 responsible for annual global emissions of up to 4.4 billion tonnes of CO2.

Given the importance of soil’s carbon absorption and storage functions, the avoidance, reduction and reversal of land degradation could provide more than a third of the most cost-effective greenhouse gas mitigation activities needed by 2030 to keep global warming under the 2°C threshold targeted in the Paris Agreement on climate change, increase food and water security, and contribute to the avoidance of conflict and migration.

Projections to 2050

“In just over three decades from now, an estimated 4 billion people will live in drylands,” said Prof. Scholes. “By then it is likely that land degradation, together with the closely related problems of climate change, will have forced 50-700 million people to migrate. Decreasing land productivity also makes societies more vulnerable to social instability – particularly in dryland areas, where years with extremely low rainfall have been associated with an increase of up to 45% in violent conflict.”

Dr. Montanarella added: “By 2050, the combination of land degradation and climate change is predicted to reduce global crop yields by an average of 10%, and by up to 50% in some regions. In the future, most degradation will occur in Central and South America, sub-Saharan Africa and Asia – the areas with the most land still remaining that is suitable for agriculture.”

The report also underlines the challenges that land degradation poses, and the importance of restoration, for key international development objectives, including the United Nations Sustainable Development Goals and the Aichi Biodiversity Targets. “The greatest value of the assessment is the evidence that it provides to decision makers in Government, business, academia and even at the level of local communities,” said Dr. Anne Larigauderie, Executive Secretary of IPBES. “With better information, backed by the consensus of the world’s leading experts, we can all make better choices for more effective action.”

Options for Land Restoration

The report notes that successful examples of land restoration are found in every ecosystem, and that many well-tested practices and techniques, both traditional and modern, can avoid or reverse degradation.

In croplands, for instance, some of these include reducing soil loss and improving soil health, the use of salt tolerant crops, conservation agriculture and integrated crop, livestock and forestry systems.

In rangelands with traditional grazing, maintenance of appropriate fire regimes, and the reinstatement or development of local livestock management practices and institutions have proven effective.

Successful responses in wetlands have included control over pollution sources, managing the wetlands as part of the landscape, and reflooding wetlands damaged by draining.

In urban areas, urban spatial planning, replanting with native species, the development of ‘green infrastructure’ such as parks and riverways, remediation of contaminated and sealed soils (e.g. under asphalt), wastewater treatment and river channel restoration are identified as key options for action.

Opportunities to accelerate action identified in the report include:

  • Improving monitoring, verification systems and baseline data;
  • Coordinating policy between different ministries to simultaneously encourage more sustainable production and consumption practices of land-based commodities;
  • Eliminating ‘perverse incentives’ that promote land degradation and promoting positive incentives that reward sustainable land management; and
  • Integrating the agricultural, forestry, energy, water, infrastructure and service agendas.

Making the point that existing multilateral environmental agreements provide a good platform for action to avoid, reduce and reverse land degradation and promote restoration, the authors observe, however, that greater commitment and more effective cooperation is needed at the national and local levels to achieve the goals of zero net land degradation, no loss of biodiversity and improved human well-being.

Knowledge Gaps

Among the areas identified by the report as opportunities for further research are:

  • The consequences of land degradation on freshwater and coastal ecosystems, physical and mental health and spiritual well-being, and infectious disease prevalence and transmission;
  • The potential for land degradation to exacerbate climate change, and land restoration to help both mitigation and adaptation;
  • The linkages between land degradation and restoration and social, economic and political processes in far-off places; and
  • Interactions among land degradation, poverty, climate change, and the risk of conflict and of involuntary migration.

Environmental and Economic Sense

The report found that higher employment and other benefits of land restoration often exceed by far the costs involved. On average, the benefits of restoration are 10 times higher than the costs (estimated across nine different biomes), and, for regions like Asia and Africa, the cost of inaction in the face of land degradation is at least three times higher than the cost of action.

“Fully deploying the toolbox of proven ways to stop and reverse land degradation is not only vital to ensure food security, reduce climate change and protect biodiversity,” said Dr. Montanarella, “It’s also economically prudent and increasingly urgent.”

Echoing this message, Sir Robert Watson, said: “Of the many valuable messages in the report, this ranks among the most important: implementing the right actions to combat land degradation can transform the lives of millions of people across the planet, but this will become more difficult and more costly the longer we take to act.”

 

DNA from more than 900 ancient people trace the prehistoric migrations of our species

Carl Zimmer writes:

David Reich wore a hooded, white suit, cream-colored clogs, and a blue surgical mask. Only his eyes were visible as he inspected the bone fragments on the counter.

Dr. Reich, a geneticist at Harvard Medical School, pointed out a strawberry-sized chunk: “This is from a 4,000-year-old site in Central Asia — from Uzbekistan, I think.”

He moved down the row. “This is a 2,500-year-old sample from a site in Britain. This is Bronze Age Russian, and these are Arabian samples. These people would have never met each other in time or space.”

Dr. Reich hopes that his team of scientists and technicians can find DNA in these bones. Odds are good that they will.

In less than three years, Dr. Reich’s laboratory has published DNA from the genomes of 938 ancient humans — more than all other research teams working in this field combined. The work in his lab has reshaped our understanding of human prehistory.

“They often answer age-old questions and sometimes provide astonishing unanticipated insights,” said Svante Paabo, the director of the Max Planck Institute of Paleoanthropology in Leipzig, Germany.

Dr. Reich, Dr. Paabo and other experts in ancient DNA are putting together a new history of humanity, one that runs in parallel with the narratives gleaned from fossils and written records. In Dr. Reich’s research, he and his colleagues have shed light on the peopling of the planet and the spread of agriculture, among other momentous events.

In a book to be published next week, “Who We Are and How We Got Here,” Dr. Reich, 43, explains how advances in DNA sequencing and analysis have helped this new field take off. [Continue reading…]

Are we smart enough to know how smart animals are?


Frans de Waal asks: are we smart enough to know how smart animals are?

Just as attitudes of superiority within segments of human culture are often expressions of ignorance, humans collectively — especially when subject to the dislocating effects of technological dependence — tend to underestimate the levels of awareness and cognitive skills of creatures who live mostly outside our sight. This tendency translates into presuppositions that need to be challenged by what de Waal calls his “cognitive ripple rule”:

Every cognitive capacity that we discover is going to be older and more widespread than initially thought.

In a review of de Waal’s book, Are We Smart Enough to Know How Smart Animals Are?, Ludwig Huber notes that there are a multitude of illustrations of the fact that brain size does not correlate with cognitive capacities.

Whereas we once thought of humans as having unique capabilities in learning and the use of tools, we now know these attributes place us in a set of species that also includes bees. Our prior assumptions about seemingly robotic behavior in such creatures turns out to have been an expression of our own anthropocentric prejudices.

Huber writes:

Various doctrines of human cognitive superiority are made plausible by a comparison of human beings and the chimpanzees. For questions of evolutionary cognition, this focus is one-sided. Consider the evolution of cooperation in social insects, such as the Matabele ant (Megaponera analis). After a termite attack, these ants provide medical services. Having called for help by means of a chemical signal, injured ants are brought back to the nest. Their increased chance of recovery benefits the entire colony. Red forest ants (Myrmica rubra) have the ability to perform simple arithmetic operations and to convey the results to other ants.

When it comes to adaptations in animals that require sophisticated neural control, evolution offers other spectacular examples. The banded archerfish (Toxotes jaculatrix) is able to spit a stream of water at its prey, compensating for refraction at the boundary between air and water. It can also track the distance of its prey, so that the jet develops its greatest force just before impact. Laboratory experiments show that the banded archerfish spits on target even when the trajectory of its prey varies. Spit hunting is a technique that requires the same timing used in throwing, an activity otherwise regarded as unique in the animal kingdom. In human beings, the development of throwing has led to an enormous further development of the brain. And the archerfish? The calculations required for its extraordinary hunting technique are based on the interplay of about six neurons. Neural mini-networks could therefore be much more widespread in the animal kingdom than previously thought.

Research on honeybees (Apis mellifera) has brought to light the cognitive capabilities of minibrains. Honeybees have no brains in the real sense. Their neuronal density, however, is among the highest in insects, with roughly 960 thousand neurons—far fewer than any vertebrate. Even if the brain size of honeybees is normalized to their body size, their relative brain size is lower than most vertebrates. Insect behavior should be less complex, less flexible, and less modifiable than vertebrate behavior. But honeybees learn quickly how to extract pollen and nectar from a large number of different flowers. They care for their young, organize the distribution of tasks, and, with the help of the waggle dance, they inform each other about the location and quality of distant food and water.

Early research by Karl von Frisch suggested that such abilities cannot be the result of inflexible information processing and rigid behavioral programs. Honeybees learn and they remember. The most recent experimental research has, in confirming this conclusion, created an astonishing picture of the honeybee’s cognitive competence. Their representation of the world does not consist entirely of associative chains. It is far more complex, flexible, and integrative. Honeybees show configural conditioning, biconditional discrimination, context-dependent learning and remembering, and even some forms of concept formation. Bees are able to classify images based on such abstract features as bilateral symmetry and radial symmetry; they can comprehend landscapes in a general way, and spontaneously come to classify new images. They have recently been promoted to the set of species capable of social learning and tool use.

In any case, the much smaller brain of the bee does not appear to be a fundamental limitation for comparable cognitive processes, or at least their performance. Jumping spiders and cephalopods are similarly instructive. The similarities between mammals and bees are astonishing, but they cannot be traced to homologous neurological developments. As long as the animal’s neural architecture remains unknown, we cannot determine the cause of their similarity. [Continue reading…]

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Why moths learn so much faster than machines


Technology Review reports:

One of the curious features of the deep neural networks behind machine learning is that they are surprisingly different from the neural networks in biological systems. While there are similarities, some critical machine-learning mechanisms have no analogue in the natural world, where learning seems to occur in a different way.

These differences probably account for why machine-learning systems lag so far behind natural ones in some aspects of performance. Insects, for example, can recognize odors after just a handful of exposures. Machines, on the other hand, need huge training data sets to learn. Computer scientists hope that understanding more about natural forms of learning will help them close the gap.

Enter Charles Delahunt and colleagues at the University of Washington in Seattle, who have created an artificial neural network that mimics the structure and behavior of the olfactory learning system in Manduca sexta moths. They say their system provides some important insights into the way natural networks learn, with potential implications for machines. [Continue reading…]

Pistachio trees ‘talk’ to their neighbours, reveals statistical physics


Philip Ball writes:

The number of nuts on pistachio trees in any given year could be explained with a model from statistical physics that is normally used to study magnetic materials. That is according to researchers led by Alan Hastings, a mathematical ecologist from the University of California, Davis, who have used the “Ising model” to analyse the yields of pistachio trees in one particular orchard in California. Their work explains why the orchard does not always have a uniformly good crop one year followed by a uniformly bad crop the next, arguing that the patchiness in nut production in certain years is due to interactions between neighbouring trees.

It might seem odd there should be a link between pistachio trees and magnetic materials. But the statistical physics developed to understand systems like magnets or liquid–vapour transitions has been found to apply to a wide range of biological systems, from the flocking of birds to patterns of neural activity in the brain. In particular, various biological systems seem to operate close to a critical phase transition like that in iron when the spin magnetic moments switch from a disordered to an ordered orientation as it is cooled below the Curie temperature.

Close to the magnetic critical phase transition, each spin in the material becomes acutely sensitive to the orientation of the others, with their alignment exhibiting long-range correlations. Patches of aligned spins can therefore develop on all length scales from just a few neighbours to the entire system, making the patches “scale-invariant”.

Critical behaviour might be useful in biological systems because it leads to extreme sensitivity to external influences, with the long-range correlations meaning that a small disturbance can spread rapidly through a system. The system therefore has access to many different configurations and will not get trapped in a particular arrangement. Indeed, biological systems might deliberately sit close to critical points to benefit from this responsiveness – a flock of animals, for example, could then quickly adapt to the presence of a predator. [Continue reading…]

We’re killing our lakes and oceans

Eelco Rohling and Joseph Ortiz write:

On January 5, 2018, a paper published in the journal Science delivered a sobering message: The oxygenation of open oceans and coastal seas has been steadily declining during the past half century. The volume of ocean with no oxygen at all has quadrupled, and the volume where oxygen levels are falling dangerously low has increased even more.

We’re seeing the same thing happen in major lakes.

The main culprits are warming and — especially in coastal seas and lakes — eutrophication caused by enhanced nutrient loads in runoff. The findings reaffirm that we urgently need to address global warming, and that we are in need of an updated Clean Water Act. We only need to look to the Mediterranean Sea and, more recently, the North American Great Lakes region for dramatic illustrations of what lies in store if we don’t act now.

Around 8,000 years ago, the entire eastern half of the Mediterranean Sea became severely oxygen-starved between 300 and 1,500 meters, and lost all oxygen, or became ‘anoxic,’ below that. It wasn’t warming that caused the oxygen decline then, as is happening in today’s oceans, but the amplification of the African monsoon, which drove intense flooding of the Nile River, full of nutrients from decomposing organic matter. The freshwater itself inhibited deep-water formation, while its nutrient-load led to wild-growth of algae, cyanobacteria, and animals grazing on them. Upon their death, decomposition sapped oxygen from the water, rapidly turning it oxygen-starved, anoxic, and in extreme cases rendered it ‘euxinic’ (containing hydrogen sulfide, infamous for its rotten-eggs smell).

The conditions wiped out virtually the entire ecosystem from a few hundred meters below the surface of the water to the seafloor. A devastating 4,000-year period of anoxic ‘dead zone’ conditions ensued, which all started within a century of the flooding. [Continue reading…]