Category Archives: Biology

Revealed: Honeybees are being killed off by a manmade pandemic

By Stephen John Martin, University of Salford

We live in a world where large numbers of people are connected by just a few degrees of separation. But while having friends of friends all over the globe can be great for holidays, trade and networking, travel also allows viruses to move like never before.

Zika is the latest “explosive pandemic” to be declared a global emergency by the World Health Organisation. But viruses don’t just target humans – they can infect all forms of life from bacteria to bananas, horses to honeybees.

A lethal combination of the Varroa mite and the deformed wing virus has resulted in the death of billions of bees over the past half century. In a study published in the journal Science, colleagues from the Universities of Exeter, Sheffield and I report how the virus has spread across the globe.

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Race is a social construct, scientists argue

Scientific American: More than 100 years ago, American sociologist W.E.B. Du Bois was concerned that race was being used as a biological explanation for what he understood to be social and cultural differences between different populations of people. He spoke out against the idea of “white” and “black” as discrete groups, claiming that these distinctions ignored the scope of human diversity.

Science would favor Du Bois. Today, the mainstream belief among scientists is that race is a social construct without biological meaning. And yet, you might still open a study on genetics in a major scientific journal and find categories like “white” and “black” being used as biological variables.

In an article published today (Feb. 4) in the journal Science, four scholars say racial categories are weak proxies for genetic diversity and need to be phased out. [Continue reading…]

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Keen to be healthier in old age? Tend your inner garden

By Claire Steves, King’s College London and Tim Spector, King’s College London

The world’s oldest man, Yasutaro Koide recently died at the age of 112. Commentators as usual, focused on his reported “secret to longevity”: not smoking, drinking or overdoing it. No surprises there. But speculation on the basis of one individual is not necessarily the most helpful way of addressing this human quest for the Philosopher’s Stone.

The “very old” do spark our interest – but is our search for a secret to longevity actually misguided? Wouldn’t you rather live healthier than live longer in poor health? Surely, what we really want to know is how do we live well in old age.

Clearly as scientists we try to illuminate these questions using populations of people not just odd individuals. Many previous attempts have approached this question by looking for differences between young and old people, but this approach is often biased by the many social and cultural developments that happen between generations, including diet changes. Time itself should not be the focus – at least, in part, because time is one thing we are unlikely to be able to stop.

Yasutaro Koide made 112.
Kyodo/Reuters

The real question behind our interest in people who survive into old age is how some manage to stay robust and fit while others become debilitated and dependent. To this end, recent scientific interest has turned to investigating the predictors of frailty within populations of roughly the same age. Frailty is a measure of how physically and mentally healthy an individual is. Studies show frailer older adults have an increased levels of low grade inflammation – so-called “inflammaging”.

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How plants rely on friendly fungal bodyguards

By Alan Gange, Royal Holloway

Two plants of the same species grow side by side. One is attacked by insects, one not. On an individual plant, some leaves get eaten, some not. This doesn’t happen at random, but is caused by the fungi that live within the leaves and roots of the plant.

Imagine you are holding a shoot of the dahlia plant, pictured below. How many species do you have in your hand? The answer is most certainly not one, but probably somewhere between 20 and 30. This is because every plant has fungi and bacteria that live on its surface (called epiphytes) and within its tissues (called endophytes).

If the stem is still attached to its roots then the number of species would easily double. The roots contain lots of endophytes and a separate group of fungi, called mycorrhizas. These fungi grow into plant roots and form a symbiotic relationship in which the fungus donates nutrients (principally phosphate and nitrate) to the plant, in return for a supply of carbon.

Dahlia is full of fungi.
Alan Gange, Author provided

There has been a recent surge of interest in these fungi, as their presence can affect the growth of insects that attack plants. Research at Royal Holloway has shown that mycorrhizal fungi reduce the growth of many insects, by increasing the plant’s chemical defences. Our most recent work shows that endophyte fungi, the ones that live within plant tissue, can also cause plants to produce novel chemicals.

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Human sounds convey emotions clearer and faster than words

McGill University: It takes just one-tenth of a second for our brains to begin to recognize emotions conveyed by vocalizations, according to researchers from McGill. It doesn’t matter whether the non-verbal sounds are growls of anger, the laughter of happiness or cries of sadness. More importantly, the researchers have also discovered that we pay more attention when an emotion (such as happiness, sadness or anger) is expressed through vocalizations than we do when the same emotion is expressed in speech.

The researchers believe that the speed with which the brain ‘tags’ these vocalizations and the preference given to them compared to language, is due to the potentially crucial role that decoding vocal sounds has played in human survival.

“The identification of emotional vocalizations depends on systems in the brain that are older in evolutionary terms,” says Marc Pell, Director of McGill’s School of Communication Sciences and Disorders and the lead author on the study that was recently published in Biological Psychology. ”Understanding emotions expressed in spoken language, on the other hand, involves more recent brain systems that have evolved as human language developed.” [Continue reading…]

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The new atheists’ faith in demons

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John Gray writes: An American scientist visiting the home of Niels Bohr, the Nobel Prize-winning Danish physicist and refugee from Nazism who was a leading figure in the Manhattan Project, which produced the atomic bomb, was surprised to discover a horseshoe hanging over Bohr’s desk: “Surely you don’t believe the horseshoe will bring you good luck, Professor Bohr?” he asked. “After all, as a scientist . . .”

Bohr laughed. “I believe no such thing, my good friend. Not at all. I am scarcely likely to believe such foolish nonsense. However, I am told that a horseshoe will bring one good luck whether you believe it or not.”

Dominic Johnson, who tells this story, acknowledges that Bohr might have been joking. But the physicist’s response captured an important truth. Human beings never cease looking for a pattern in events that transcends the workings of cause and effect. No matter how much they may think their view of the world has been shaped by science, they cannot avoid thinking and acting as if their lives are subject to some kind of non-human oversight. As Johnson puts it, “Humans the world over find themselves, consciously or subconsciously, believing that we live in a just world or a moral universe, where people are supposed to get what they deserve. Our brains are wired such that we cannot help but search for meaning in the randomness of life.”

An evolutionary biologist trained at Oxford who also holds a doctorate in political science, Johnson believes that the need to find a more-than-natural meaning in natural events is universal – “a ubiquitous phenomenon of human nature” – and performs a vital role in maintaining order in society. Extending far beyond cultures shaped by monotheism, it “spans cultures across the globe and every historical period, from indigenous tribal societies . . . to modern world religions – and includes atheists, too”.

Reward and punishment may not emanate from a single omnipotent deity, as imagined in Western societies. Justice may be dispensed by a vast unseen army of gods, angels, demons and ghosts, or else by an impersonal cosmic process that rewards good deeds and punishes wrongdoing, as in the Hindu and Buddhist conception of karma. But some kind of moral order beyond any human agency seems to be demanded by the human mind, and this sense that our actions are overseen and judged from beyond the natural world serves a definite evolutionary role. Belief in supernatural reward and punishment promotes social co-operation in a way nothing else can match. The belief that we live under some kind of supernatural guidance is not a relic of superstition that might some day be left behind but an evolutionary adaptation that goes with being human.

It’s a conclusion that is anathema to the current generation of atheists – Richard Dawkins, Daniel Dennett, Sam Harris and others – for whom religion is a poisonous concoction of lies and delusion. These “new atheists” are simple souls. In their view, which derives from rationalist philosophy and not from evolutionary theory, the human mind is a faculty that seeks an accurate representation of the world. This leaves them with something of a problem. Why are most human beings, everywhere and at all times, so wedded to some version of religion? It can only be that their minds have been deformed by malignant priests and devilish power elites. Atheists have always been drawn to demonology of this kind; otherwise, they cannot account for the ­persistence of the beliefs they denounce as poisonously irrational. The inveterate human inclination to religion is, in effect, the atheist problem of evil. [Continue reading…]

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The magic of the Amazon — a river that flows invisibly all around us

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Dan Kedmey writes: On a typical sunny day in the Amazon, 20 billion metric tons of water flow upward through the trees and pour into the air, an invisible river that flows through the sky across a continent.

“This river of vapor that comes up from the forest and goes into the atmosphere is greater than the Amazon River,” says Antonio Donato Nobre (TED Talk: The magic of the Amazon: A river that flows invisibly all around us). Nobre is a senior researcher at Brazil’s National Institute of Amazonian Research. And in his opinion, the most remarkable thing about the Amazon — even more than its 4,000 miles of river or its hundreds of billions of trees — is that it’s essentially a massive, solar-powered sprinkler system, spritzing water across a continent. If this were a man-made system, Nobre says, it would be the envy of the world. Here’s why Nature is the most badass engineer of all.

Every tree is a silent geyser. Through a process called transpiration, a large tree in the Amazon can release 1,000 liters of water into the atmosphere in a single day. “There is a frantic evaporation taking place here,” Nobre says. He likens the force to a geyser spouting water into the air, but “with much more elegance.” After all, geysers draw their power from the scalding heat of magma, while trees only need to bask in the sunlight to release their invisible steam. Plus, they have the sheer force of numbers; hundreds of billions of trees in the jungle release as many as 20 billion metric tons of water into the atmosphere every day. That means that while the Amazon, which pours 17 billion tons of water into the Atlantic Ocean a day, may be the largest river on earth — it’s still exceeded by the airborne river drifting above the canopy of the trees. [Continue reading…]

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Pathogens found in Otzi’s stomach reveal unexpected insights into the coexistence of humans and bacterium

The European Academy of Bozen/Bolzano (EURAC) reports: Scientists are continually unearthing new facts about Homo sapiens from the mummified remains of Ötzi, the Copper Age man, who was discovered in a glacier in 1991. Five years ago, after Ötzi’s genome was completely deciphered, it seemed that the wellspring of spectacular discoveries about the past would soon dry up. An international team of scientists working with paleopathologist Albert Zink and microbiologist Frank Maixner from the European Academy (EURAC) in Bozen/Bolzano have now succeeded in demonstrating the presence of Helicobacter pylori in Ötzi’s stomach contents, a bacterium found in half of all humans today. The theory that humans were already infected with this stomach bacterium at the very beginning of their history could well be true. The scientists succeeded in decoding the complete genome of the bacterium.

When EURAC’s Zink and Maixner first placed samples from the Iceman’s stomach under the microscope in their ancient DNA Lab at EURAC, almost three years ago, they were initially sceptical.

“Evidence for the presence of the bacterium Helicobacter pylori is found in the stomach tissue of patients today, so we thought it was extremely unlikely that we would find anything because Ötzi’s stomach mucosa is no longer there,” explains Zink. Together with colleagues from the Universities of Kiel, Vienna and Venda in South Africa as well as the Max Planck Institute for the Science of Human History in Jena, the scientists tried to find a new way to proceed. “We were able to solve the problem once we hit upon the idea of extracting the entire DNA of the stomach contents,” reports Maixner. “After this was successfully done, we were able to tease out the individual Helicobacter sequences and reconstruct a 5,300 year old Helicobacter pylori genome.” Continue reading →

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Does our microbiome control us or do we control it?

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Dina Fine Maron writes: We may be able to keep our gut in check after all. That’s the tantalizing finding from a new study published today that reveals a way that mice—and potentially humans—can control the makeup and behavior of their gut microbiome. Such a prospect upends the popular notion that the complex ecosystem of germs residing in our guts essentially acts as our puppet master, altering brain biochemistry even as it tends to our immune system, wards off infection and helps us break down our supersized burger and fries.

In a series of elaborate experiments researchers from Harvard Medical School and Brigham and Women’s Hospital discovered that mouse poop is chock full of tiny, noncoding RNAs called microRNAs from their gastrointestinal (GI) tracts and that these biomolecules appear to shape and regulate the microbiome. “We’ve known about how microbes can influence your health for a few years now and in a way we’ve always suspected it’s a two-way process, but never really pinned it down that well,” says Tim Spector, a professor of genetic epidemiology at King’s College London, not involved with the new study. “This [new work] explains quite nicely the two-way interaction between microbes and us, and it shows the relationship going the other way—which is fascinating,” says Spector, author of The Diet Myth: Why the Secret to Health and Weight Loss Is Already in Your Gut. [Continue reading…]

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America is a constipated nation

Ed Wong writes: In the decades after World War II, a one-eyed Irish missionary-surgeon named Denis Burkitt moved to Uganda, where he noted that the villagers there ate far more fiber than Westerners did. This didn’t just bulk up their stools, Burkitt reasoned; it also explained their low rates of heart disease, colon cancer, and other chronic illnesses. “America is a constipated nation,” he once said. “If you pass small stools, you have big hospitals.”

“Burkitt really nailed it,” says Justin Sonnenburg, a microbiologist at Stanford University. Sure, some of the man’s claims were far-fetched, but he was right about the value of fiber and the consequences of avoiding it. And Sonnenburg thinks he knows why: Fiber doesn’t just feed us—it also feeds the trillions of microbes in our guts.

Fiber is a broad term that includes many kinds of plant carbohydrates that we cannot digest. Our microbes can, though, and they break fiber into chemicals that nourish our cells and reduce inflammation. But no single microbe can tackle every kind of fiber. They specialize, just as every antelope in the African savannah munches on its own favored type of grass or shoot. This means that a fiber-rich diet can nourish a wide variety of gut microbes and, conversely, that a low-fiber diet can only sustain a narrower community. [Continue reading…]

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Why we should learn to love all insects – not just the ones that work for us

By Paul Manning, University of Oxford

Insects, which include more than a million described species, represent roughly two-thirds of the biodiversity on Earth. But they have a big PR problem – many think of insects as little more than crop-eating, disease-carrying jumper-munchers. But in reality, species fitting this bill are but a tiny part of an enormous picture.

A dominant narrative has emerged in an effort to clear the good name of our six-legged friends. Insects are the unsung heroes, the little things that run the world. This fact is undeniable. Insects are critical to the existence of the world as we know it, whether through pollinating plants, controlling populations of agricultural pests, or helping with the decomposition of animal waste.

These numerous benefits provided by our environment are known as ecosystem services. A widely cited paper from 2006 estimates that these insect services are worth an annual US$57 billion to the US economy alone. These valuations are an important step in starting conversations about the importance of insect conservation.

However economic arguments can only take us so far.

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Why life is not a thing but a restless manner of being

Tim Requarth writes: Mike Russell found his moment of inspiration on a warm spring evening in Glasgow in 1983, when his 11-year-old son broke a new toy. The toy in question was a chemical garden, a small plastic tank in which stalactite-like tendrils grew out of seed crystals placed in a mineral solution. Although the tendrils appeared solid from the outside, when shattered they revealed their true nature: each one was actually a network of hollow tubes, like bundles of tiny cocktail straws.

At the time, Russell, a geologist, was struggling to understand an unusual rock he had recently found. It, too, was solid on the outside but inside was full of hollow tubes, their thin walls riddled with microscopic compartments. It dawned on him then that this rock – like the formations in his son’s toy – must have formed in some unusual kind of liquid solution. Russell posited a whole new geological phenomenon to explain it: undersea hydrothermal hotspots where mineral-rich water spewed from Earth’s interior and then precipitated in the cool surrounding water, creating chemical gardens of towering, hollow rocks growing up from the ocean floor.

That was a huge intuitive leap, but it soon led Russell to an even more outlandish thought. ‘I had the epiphany that life emerged from those rocks,’ he said. ‘Many years later, people would tell me the idea was amazing, but it wasn’t to me. I was just thinking in a different realm, in the light of what I knew as a geologist. I didn’t set out to study the origin of life, but it just seemed so obvious.’

What seemed obvious to Russell was that his hypothetical chemical gardens could solve one of the deepest riddles of life’s origin: the energy problem. Then as now, many leading theories of life’s origins had their roots in Charles Darwin’s speculation of a ‘warm little pond’, in which inanimate matter, energised by heat, sunlight or lightning, formed complex molecules that eventually began reproducing themselves. For decades, most origin-of-life research has focused on how such self-replicating chemistry could have arisen. They largely brushed aside the other key question, how the first living things obtained the energy to grow, reproduce and evolve to greater complexity.

But in Russell’s mind, the origin of life and the source of the energy it needed were a single issue, the two parts inextricably intertwined. As a geologist (now working at NASA’s Jet Propulsion Laboratory in California), he came at the problem with a very different perspective from his biology-trained colleagues. Undersea chemical gardens, Russell realised, would have provided an abundant flux of matter and energy in the same place – a setting conducive for self-replicating reactions, and also a free lunch for fledgling creatures. It has long troubled researchers that the emergence of life seems to rely on highly improbable chemical events that lead toward greater complexity. By considering energy first, Russell believed he could address that. In his view, the emergence of biological complexity was not improbable but inevitable. [Continue reading…]

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Why wealth hasn’t brought health: The body isn’t built to be an exclusive neighborhood

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Matt Ridley writes: As Stewart Brand acutely says, most of the things that dominate the news are not really new: love, scandal, crime, and war come round again and again. Only science and invention deliver truly new stuff, like double helixes and search engines. In this respect, the new news from recent science that most intrigues me is that we may have a way to explain why certain diseases are getting worse as we get richer. We are defeating infectious diseases, slowing or managing many diseases of ageing like heart disease and cancer, but we are faced with a growing epidemic of allergy, auto-immunity, and things like autism. Some of it is due to more diagnosis, some of it is no doubt hypochondria, but there does seem to be a real increase in these kinds of problems.

Take hay fever. It is plainly a modern disease, far more common in urban, middle-class people than it used to be in peasants in the past, or still is in subsistence farmers in Africa today. There’s really good timeline data on this, chronicling the appearance of allergies as civilization advances, province by province or village by village. And there’s really good evidence that what causes this is the suppression of parasites. You can see this happen in eastern Europe and in Africa in real time: get rid of worms and a few years later children start getting hay fever. Moises Velasquez-Manoff chronicles this in glorious detail in his fine book An Epidemic of Absence.

This makes perfect sense. In the arms race with parasites, immune systems evolved to “expect” to be down-regulated by parasites, so they over-react in their absence. A good balance is reached when parasites try down-regulating the immune system, but it turns rogue when there are no parasites. [Continue reading…]

Nina Jablonski writes: The taxonomic diversity and census of our resident bacteria are more than just subjects of scientific curiosity; they matter greatly to our health. The normal bacteria on our skin, for instance, are essential to maintaining the integrity of the skin’s barrier functions. Many diseases, from psoriasis to obesity, inflammatory bowel disease, some cancers, and even cardiovascular disease, are associated with shifts in our microbiota.

While it’s too early to tell if the changing bacteria are the cause or the result of these problems, the discovery of robust associations between bacterial profiles and disease states opens the door for new treatments and targeted preventive measures. The body’s microbiota also affects and is affected by the body’s epigenome, the chemical factors influencing gene expression. Thus, the bugs on us and in us are controlling the normal action of genes in the cells of our bodies, and changes in the proportions or overall numbers of bacterial affect how our cells work and respond to stress.

Let’s stop thinking about our bodies as temples of sinew and cerebrum, and instead as evolving and sloshing ecosystems full of bacteria, which are regulating our health in more ways than we could ever imagine. As we learn more about our single-celled companions in the coming years, we will take probiotics for curing acute and chronic diseases, we’ll undertake affirmative action to maintain diversity of our gut microflora as we age, and we’ll receive prescriptions for increasingly narrow-spectrum antibiotics to exterminate only the nastiest of the nasties when we have a serious acute infection. Hand sanitizers and colon cleansing will probably be with us for some time, but it’s best just to get used to it now: Bugs R us. [Continue reading…]

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How plants fight to stay alive

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Mike Newland writes: Compared to the hectic rush of our bipedal world, a plant’s life may appear an oasis of tranquility. But look a little closer. The voracious appetites of pests put plants under constant stress: They have to fight just to stay alive.

And fight they do. Far from being passive victims, plants have evolved potent defenses: chemical compounds that serve as toxins, signal an escalating attack, and solicit help from unlikely allies.

However, all of this security comes at a cost: energy and other resources that plants could otherwise use for growth and repair. So to balance the budget, plants have to be selective about how and when to deploy their chemical arsenal. Here are five tactics they’ve developed to ward off their insect foes without sacrificing their own wellbeing. [Continue reading…]

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‘Critical slowing down’ — nature’s early warning signal of system failure

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Natalie Wolchover writes: Nestled in the northern Wisconsin woods, Peter Lake once brimmed with golden shiners, fatheads, and other minnows, which plucked algae-eating fleas from the murky water. Then, seven years ago, a crew of ecologists began stepping up the lake’s population of predatory largemouth bass. To the 39 bass already present, they added 12, then 15 more a year later, and another 15 a month after that. The bass hunted down the minnows and drove survivors to the rocky shoreline, which gave fleas free rein to multiply and pick the water clean. Meanwhile, bass hatchlings — formerly gobbled up by the minnows — flourished, and in 2010, the bass population exploded to more than 1,000. The original algae-laced, minnow-dominated ecosystem was gone, and the reign of bass in clear water began.

Today, largemouth bass still swim rampant. “Once that top predator is dominant, it’s very hard to dislodge,” said Stephen Carpenter, an ecologist at the University of Wisconsin, Madison, who led the experiment. “You could do it, but it’s gonna cost you.”

The Peter Lake experiment demonstrated a well-known problem with complex systems: They are sensitive beasts. Just as when the Earth periodically plunges into an ice age, or when grasslands turn to desert, fisheries suddenly collapse, or a person slumps into a deep depression, systems can drift toward an invisible edge, where only a small change is needed to touch off a dramatic and often disastrous transformation. But systems that exhibit such “critical transitions” tend to be so complicated and riddled with feedback loops that experts cannot hope to calculate in advance where their tipping points lie — or how much additional tampering they can withstand before snapping irrevocably into a new state.

At Peter Lake, though, Carpenter and his team saw the critical transition coming. Rowing from trap to trap counting wriggling minnows and harvesting other data every day for three summers, the researchers captured the first field evidence of an early-warning signal that is theorized to arise in many complex systems as they drift toward their unknown points of no return.

The signal, a phenomenon called “critical slowing down,” is a lengthening of the time that a system takes to recover from small disturbances, such as a disease that reduces the minnow population, in the vicinity of a critical transition. It occurs because a system’s internal stabilizing forces — whatever they might be — become weaker near the point at which they suddenly propel the system toward a different state. [Continue reading…]

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How noise pollution is changing animal behaviour

By Graeme Shannon, Bangor University

Noise pollution, generally an unintended byproduct of urbanisation, transport and industry, is a key characteristic of human development and population growth. In some cases, it is produced intentionally, for example when seismic surveys are being carried out using powerful airgun arrays to explore and map the seafloor, or active sonar, which uses sound waves to detect objects in the ocean.

All of this noise – whether intentional or not – has the ability to alter the acoustic environment of aquatic and terrestrial habitats. This can have a dramatic effect on the animals that live in them, perhaps even driving evolutionary change as species adapt to or avoid noisy environments.

Rising noise levels

The dramatic and comparatively recent rise in noise levels is marked in both magnitude and extent, with an estimated 30% of the European population exposed to road traffic noise levels greater than 55dB (decibels) at night, well above the 40dB target recommended by the World Health Organisation. Even remote natural areas do not escape the reach of anthropogenic, or manmade, noise. One study across 22 US national parks demonstrated that this kind of noise was, on average, audible more than 28% of the time.

Noise is not just irritating; we have known for some time that it can have direct human health impacts. Indeed, chronic exposure to noise levels above 55dB dramatically increases the risks of heart disease and stroke, while aircraft noise has been shown to impact the development of reading skills in children attending schools close to busy airports. The WHO estimates that in Europe at least a million healthy life years are lost every year due to traffic noise.

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6,000 years ago humans upturned 300 million years of evolution

Smithsonian.com reports: It’s hard to imagine a global force strong enough to change natural patterns that have persisted on Earth for more than 300 million years, but a new study shows that human beings have been doing exactly that for about 6,000 years.

The increase in human activity, perhaps tied to population growth and the spread of agriculture, seems to have upended the way plants and animals distribute themselves across the land, so that species today are far more segregated than they’ve been at any other time.

That’s the conclusion of a study appearing this week in the journal Nature, and the ramifications could be huge, heralding a new stage in global evolution as dramatic as the shift from single-celled microbes to complex organisms.

A team of researchers led by S. Kathleen Lyons, a paleobiologist at the Evolution of Terrestrial Ecosystems (ETE) program in the Smithsonian’s National Museum of Natural History, examined the distribution of plants and animals across landscapes in the present and back through the fossil record in search of patterns.

Mostly they found randomness, but throughout time, there was always a small subset of plants and animals that showed up in relationship to one another more often than can be attributed to chance. That relationship either meant that pairs of species occur together, so when you find one, you usually find the other. Or it meant the opposite: when you find one, the other is usually not present, in which case they’re considered segregated. [Continue reading…]

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Local ecological disasters are too easily obscured by the lofty discourse of climate change

Brandon Keim writes: In the Great Basin desert of the western United States, not far from the Great Salt Lake, is a kind of time machine. Homestead Cave has been inhabited for the past 13,000 years by successive generations of owls, beneath whose roosts accumulated millennia-deep piles of undigested fur and bone. By examining these piles, researchers have been able to reconstruct the region’s ecological history. It contains a very timely lesson.

Those 13,000 years spanned some profound environmental upheavals. Indeed, the cave opened when Lake Bonneville, a vast prehistoric water body that covered much of the region, receded at the last ice age’s end, and the Great Basin shifted from rainfall-rich coolness to its present hot, dry state. Yet despite these changes, life was pretty stable. Different species flourished at different times, but the total amount of biological energy – a metric used by ecologists to describe all the metabolic activity in an ecosystem – remained steady.

About a century ago, though, all that changed. There’s now about 20 per cent less biological energy flowing through the Great Basin than at the 20th century’s beginning. To put it another way: life’s richness contracted by one-fifth in an eyeblink of geological time. The culprit? Not climate change, as one might expect, but human activity, in particular the spread of invasive non-native grasses that flourish in disturbed areas and have little nutritional value, sustaining less life than would the native plants they’ve displaced.

I find myself thinking often of the parable of Homestead Cave, as I’ve come to call it. It underscores how resilient nature can be, and also the enormity of human impacts, which in this case dwarfed the transition to an entirely new climate state. The latter point, I fear, is too often overlooked these days, obscured by a fixation on climate change as Earth’s great ecological problem.

Make no mistake: climate change is a huge, desperately important issue. And it feels strange, if not downright traitorous, to raise concerns about the attention it receives. The parable of Homestead Cave is no licence to shirk climate duties on the assumption that nature will adapt, or to imagine that a rapidly warming, weather-extremed Earth won’t be calamitous for non‑human life. It will be. But so is a great deal else that we do. Paying attention to climate change and to other human impacts shouldn’t be a zero-sum game, but it too often seems that way. [Continue reading…]

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