Category Archives: Biology

Devasting consequences of losing ‘knowledgeable elders’ in non-human cultures

bluefin-tuna

Culture — something we generally associate with its expressions through art, music, literature and so forth — is commonly viewed as one of the defining attributes of humanity. We supposedly rose above animal instinct when we started creating bodies of knowledge, held collectively and passed down from generation to generation.

But it increasingly appears that this perspective has less to do with an appreciation of what makes us human than it has with our ignorance about non-human cultures.

Although non-human cultures don’t produce the kind of artifacts we create, the role of knowledge-sharing seems to be just as vital to the success of these societies as it is to ours. In other words, what makes these creatures what they are cannot be reduced to the structure of their DNA — it also involves a dynamic and learned element: the transmission of collective knowledge.

The survival of some species doesn’t simply depend on their capacity to replicate their DNA; it depends on their ability to pass on what they know.

Scuola Internazionale Superiore di Studi Avanzati: Small changes in a population may lead to dramatic consequences, like the disappearance of the migratory route of a species. A study carried out in collaboration with the SISSA has created a model of the behaviour of a group of individuals on the move (like a school of fish, a herd of sheep or a flock of birds, etc.) which, by changing a few simple parameters, reproduces the collective behaviour patterns observed in the wild. The model shows that small quantitative changes in the number of knowledgeable individuals and availability of food can lead to radical qualitative changes in the group’s behaviour.

Until the ’50s, bluefin tuna fishing was a thriving industry in Norway, second only to sardine fishing. Every year, bluefin tuna used to migrate from the eastern Mediterranean up to the Norwegian coasts. Suddenly, however, over no more than 4-5 years, the tuna never went back to Norway. In an attempt to solve this problem, Giancarlo De Luca from SISSA (the International School for Advanced Studies of Trieste) together with an international team of researchers (from the Centre for Theoretical Physics — ICTP — of Trieste and the Technical University of Denmark) started to devise a model based on an “adaptive stochastic network.” The physicists wanted to simulate, simplifying it, the collective behaviour of animal groups. Their findings, published in the journal Interface, show that the number of “informed individuals” in a group, sociality and the strength of the decision of the informed individuals are “critical” variables, such that even minimal fluctuations in these variables can result in catastrophic changes to the system.

“We started out by taking inspiration from the phenomenon that affected the bluefin tuna, but in actual fact we then developed a general model that can be applied to many situations of groups “on the move,” explains De Luca.

The collective behaviour of a group can be treated as an “emerging property,” that is, the result of the self-organization of each individual’s behaviour. “The majority of individuals in a group may not possess adequate knowledge, for example, about where to find rich feeding grounds” explains De Luca. “However, for the group to function, it is enough that only a minority of individuals possess that information. The others, the ones who don’t, will obey simple social rules, for example by following their neighbours.”

The tendency to comply with the norm, the number of knowledgeable individuals and the determination with which they follow their preferred route (which the researchers interpreted as being directly related to the appeal, or abundance, of the resource) are critical variables. “When the number of informed individuals falls below a certain level, or the strength of their determination to go in a certain direction falls below a certain threshold, the migratory pathway disappears abruptly.”

“In our networks the individuals are “points,” with interconnections that form and disappear in the course of the process, following some established rules. It’s a simple and general way to model the system which has the advantage of being able to be solved analytically,” comments De Luca.

So what ever happened to the Norwegian tuna? “Based on our results we formulated some hypotheses which will, however, have to be tested experimentally,” says De Luca. In the’50s Norway experienced a reduction in biomass and in the quantity of herrings, the main prey of tuna, which might have played a role in their disappearance. “This is consistent with our model, but there’s more to the story. In a short time the herring population returned to normal levels, whereas the tuna never came back. Why?”

One hypothesis is that, although the overall number of Mediterranean tuna has not changed, what has changed is the composition of the population: “The most desirable tuna specimens for the fishing industry are the larger, older individuals, which are presumably also those with the greater amount of knowledge, in other words the knowledgeable elders.” concludes De Luca.

Another curious fact: what happens if there are too many knowledgeable elders? “Too many know-alls are useless,” jokes De Luca. “In fact, above a certain number of informed individuals, the group performance does not improve so much as to justify the “cost” of their training. The best cost-benefit ratio is obtained by keeping the number of informed individuals above a certain level, provided they remain a minority of the whole population.”

Facebooktwittermail

A Siberian giant virus and the butterfly effect

Omulyakhskaya and Khromskaya Bays lie along the northern Siberian coast, where permafrost blankets the land around the bays. Photo: NASA Earth Observatory

Omulyakhskaya and Khromskaya Bays lie along the northern Siberian coast, where permafrost blankets the land around the bays. Photo: NASA Earth Observatory

Embedded in the mud, glistening green and gold and black, was a butterfly, very beautiful and very dead.

“Not a little thing like that! Not a butterfly!” cried Eckels.

It fell to the floor, an exquisite thing, a small thing that could upset balances and knock down a line of small dominoes and then big dominoes and then gigantic dominoes, all down the years across Time. Eckels’ mind whirled. It couldn’t change things. Killing one butterfly couldn’t be that important! Could it? — Ray Bradbury, A Sound of Thunder, 1952

As one of the massive and probably irreversible consequences of climate change, the melting of the Northern Hemisphere’s permafrost is not an example of the butterfly effect. Yet the discovery of a giant virus which has come back to life after 30,000 years of frozen dormancy, suggests many possibilities including some akin to those envisaged by Ray Bradbury is his famous science fiction story.

Whereas his narrative required that the reader suspend disbelief by entertaining the idea of time travel, the thawing tundra may produce a very real kind of time travel if any viruses or other microbes were to emerge as new invasive species.

Rather than being transported geographically as a result of human activity, these will spring suddenly from a distant past into an environment that may lack necessary evolutionary adaptations to accommodate their presence.

We are assured that Pithovirus sibericum poses no threat to humans — it just attacks amoebas. But our concern shouldn’t be limited to fears about the reemergence of something like an ancient strain of smallpox.

The rebirth of a pathogen that could strike phytoplankton — producers of half the world’s oxygen — would have a devastating impact on the planet.

BBC News reports: The ancient pathogen was discovered buried 30m (100ft) down in the frozen ground.

Called Pithovirus sibericum, it belongs to a class of giant viruses that were discovered 10 years ago.

These are all so large that, unlike other viruses, they can be seen under a microscope. And this one, measuring 1.5 micrometres in length, is the biggest that has ever been found.

The last time it infected anything was more than 30,000 years ago, but in the laboratory it has sprung to life once again.

Tests show that it attacks amoebas, which are single-celled organisms, but does not infect humans or other animals.

Co-author Dr Chantal Abergel, also from the CNRS, said: “It comes into the cell, multiplies and finally kills the cell. It is able to kill the amoeba – but it won’t infect a human cell.”

However, the researchers believe that other more deadly pathogens could be locked in Siberia’s permafrost.

“We are addressing this issue by sequencing the DNA that is present in those layers,” said Dr Abergel.

“This would be the best way to work out what is dangerous in there.”

The researchers say this region is under threat. Since the 1970s, the permafrost has retreated and reduced in thickness, and climate change projections suggest it will decrease further.

It has also become more accessible, and is being eyed for its natural resources.

Prof Claverie warns that exposing the deep layers could expose new viral threats.

He said: “It is a recipe for disaster. If you start having industrial explorations, people will start to move around the deep permafrost layers. Through mining and drilling, those old layers will be penetrated and this is where the danger is coming from.”

He told BBC News that ancient strains of the smallpox virus, which was declared eradicated 30 years ago, could pose a risk. [Continue reading…]

Facebooktwittermail

Can plants make choices?

a13-iconHelmholtz Centre for Environmental Research: Plants are also able to make complex decisions. At least this is what scientists from the Helmholtz Center for Environmental Research (UFZ) and the University of Göttingen have concluded from their investigations on Barberry (Berberis vulgaris), which is able to abort its own seeds to prevent parasite infestation. The results are the first ecological evidence of complex behaviour in plants. They indicate that this species has a structural memory, is able to differentiate between inner and outer conditions as well as anticipate future risks, scientists write in the renowned journal American Naturalist — the premier peer-reviewed American journal for theoretical ecology.

The European barberry or simply Barberry (Berberis vulgaris) is a species of shrub distributed throughout Europe. It is related to the Oregon grape (Mahonia aquifolium) that is native to North America and that has been spreading through Europe for years. Scientists compared both species to find a marked difference in parasite infestation: “a highly specialized species of tephritid fruit fly, whose larvae actually feed on the seeds of the native Barberry, was found to have a tenfold higher population density on its new host plant, the Oregon grape”, reports Dr. Harald Auge, a biologist at the UFZ.

This led scientists to examine the seeds of the Barberry more closely. Approximately 2000 berries were collected from different regions of Germany, examined for signs of piercing and then cut open to examine any infestation by the larvae of the tephritid fruit fly (Rhagoletis meigenii). This parasite punctures the berries in order to lay its eggs inside them. If the larva is able to develop, it will often feed on all of the seeds in the berry. A special characteristic of the Barberry is that each berry usually has two seeds and that the plant is able to stop the development of its seeds in order to save its resources. This mechanism is also employed to defend it from the tephritid fruit fly. If a seed is infested with the parasite, later on the developing larva will feed on both seeds. If however the plant aborts the infested seed, then the parasite in that seed will also die and the second seed in the berry is saved. Continue reading →

Facebooktwittermail

Searching for the elephant’s genius inside the largest brain on land

elephant

Ferris Jabr writes: Many years ago, while wandering through Amboseli National Park in Kenya, an elephant matriarch named Echo came upon the bones of her former companion Emily. Echo and her family slowed down and began to inspect the remains. They stroked Emily’s skull with their trunks, investigating every crevice; they touched her skeleton gingerly with their padded hind feet; they carried around her tusks. Elephants consistently react this way to other dead elephants, but do not show much interest in deceased rhinos, buffalo or other species. Sometimes elephants will even cover their dead with soil and leaves.

What is going through an elephant’s mind in these moments? We cannot explain their behavior as an instinctual and immediate reaction to a dying or recently perished compatriot. Rather, they seem to understand—even years and years after a friend or relative’s death—that an irreversible change has taken place, that, here on the ground, is an elephant who used to be alive, but no longer is. In other words, elephants grieve.

Such grief is but one of many indications that elephants are exceptionally intelligent, social and empathic creatures. After decades of observing wild elephants—and a series of carefully controlled experiments in the last eight years—scientists now agree that elephants form lifelong kinships, talk to one another with a large vocabulary of rumbles and trumpets and make group decisions; elephants play, mimic their parents and cooperate to solve problems; they use tools, console one another when distressed, and probably have a sense of self (See: The Science Is In: Elephants Are Even Smarter Than We Realized)

All this intellect must emerge, in one way or another, from the elephant brain—the largest of any land animal, three times as big as the human brain with individual neurons that seem to be three to five times the size of human brain cells. [Continue reading…]

Facebooktwittermail

The emotional intelligence of dogs

f13-iconThe ability to discern the emotions of others provides the foundation for emotional intelligence. How well-developed this faculty is seems to have little to do with the strength of other markers of intelligence, indeed, as a new study seems to imply, there may be little reason to see in emotional intelligence much that is uniquely human.

Scientific American: [A]lthough dogs have the capacity to understand more than 100 words, studies have demonstrated Fido can’t really speak human languages or comprehend them with the same complexity that we do. Yet researchers have now discovered that dog and human brains process the vocalizations and emotions of others more similarly than previously thought. The findings suggest that although dogs cannot discuss relativity theory with us, they do seem to be wired in a way that helps them to grasp what we feel by attending to the sounds we make.

To compare active human and dog brains, postdoctoral researcher Attila Andics and his team from MTA-ELTE Comparative Ethology Research Group in Hungary trained 11 dogs to lie still in an fMRI brain scanner for several six minute intervals so that the researchers could perform the same experiment on both human and canine participants. Both groups listened to almost two hundred dog and human sounds — from whining and crying to laughter and playful barking — while the team scanned their brain activity.

The resulting study, published in Current Biology today, reveals both that dog brains have voice-sensitive regions and that these neurological areas resemble those of humans. Sharing similar locations in both species, they process voices and emotions of other individuals similarly. Both groups respond with greater neural activity when they listen to voices reflecting positive emotions such as laughing than to negative sounds that include crying or whining. Dogs and people, however, respond more strongly to the sounds made by their own species. “Dogs and humans meet in a very similar social environment but we didn’t know before just how similar the brain mechanisms are to process this social information,” Andics says. [Continue reading…]

Facebooktwittermail

Climate change is threatening the entire marine food chain

f13-iconPeter Brannen writes: At the Woods Hole Oceanographic Institution on Cape Cod, Massachusetts, snowdrifts piled up outside shuttered T-shirt shops, and wind and whitecaps lashed vessels tethered to empty piers in the harbour. The flood of sun-tanned tourists and research students that descends on this place in summer was still months away. The only visitor was a winter storm that hung over the coast, making travel in and out of the cedar-shingled town impossible. In a research building downtown, at the end of a dimly lit hallway, Peter Wiebe sat with a stack of yellowed composition notebooks, reliving a lifetime spent on the ocean. Wiebe, a grizzled scientist emeritus, is transcribing his research cruise logs, which go back to 1962. His handwritten notes archive a half-century of twilit cruises in the Antarctic and languorous equatorial days surrounded by marine life.

‘It’s quite clear to me things are changing,’ he told me, after I asked him to think back on his decades on the ocean. ‘As a graduate student on one cruise, my logs talk about a hammerhead and two whitetips following the ship the whole time. On other cruises, we would fish for mahimahi and tuna, and occasionally catch a shark. Now we hardly ever see any big fish or sharks at all.’

Indeed, in oceanography, the big story over the past half century – the span of Wiebe’s career – has been the wholesale removal of the seas’ top predators through overfishing. But the story of the oceans for the coming century may be a revolution that starts from the bottom of the food chain, not the top.

‘I won’t be around to see it,’ Wiebe told me. ‘I wish I were.’

Plankton (taken from the Greek word for wanderer) are the plants, animals and microbes that are unable to overcome the influence of ocean currents, either because they’re too small, like bacteria, or because, as in the case of the indifferent jellyfish, they can’t be bothered. Wiebe’s speciality is zooplankton, the kaleidoscopic, translucent animal world in miniature, much of which feeds on even smaller photosynthetic life called phytoplankton. To make the jump from photosynthesis to fish, birds and whales, you have to go through zooplankton first.

Wiebe is part of a body of researchers worldwide working feverishly to find out how these grazers will be affected by an increasingly unfamiliar ocean, an ocean that absorbs 300,000 Hiroshimas of excess heat every day, and whose surface waters have already become 30 per cent more acidic since the dawn of the Industrial Revolution.

‘When I first started, the idea that you could actually change the pH of the ocean just wasn’t there – no one expected us to be able to do it,’ Wiebe told me. ‘Certainly, no one expected us to be able to do it at the pace we’re doing it, at a pace that far surpasses anything natural that has ever happened.’ [Continue reading…]

Facebooktwittermail

The secret language of plants

f13-iconKat McGowan writes: Up in the northern Sierra Nevada, the ecologist Richard Karban is trying to learn an alien language. The sagebrush plants that dot these slopes speak to one another, using words no human knows. Karban, who teaches at the University of California, Davis, is listening in, and he’s beginning to understand what they say.

The evidence for plant communication is only a few decades old, but in that short time it has leapfrogged from electrifying discovery to decisive debunking to resurrection. Two studies published in 1983 demonstrated that willow trees, poplars and sugar maples can warn each other about insect attacks: Intact, undamaged trees near ones that are infested with hungry bugs begin pumping out bug-repelling chemicals to ward off attack. They somehow know what their neighbors are experiencing, and react to it. The mind-bending implication was that brainless trees could send, receive and interpret messages.

The first few “talking tree” papers quickly were shot down as statistically flawed or too artificial, irrelevant to the real-world war between plants and bugs. Research ground to a halt. But the science of plant communication is now staging a comeback. Rigorous, carefully controlled experiments are overcoming those early criticisms with repeated testing in labs, forests and fields. It’s now well established that when bugs chew leaves, plants respond by releasing volatile organic compounds into the air. By Karban’s last count, 40 out of 48 studies of plant communication confirm that other plants detect these airborne signals and ramp up their production of chemical weapons or other defense mechanisms in response. “The evidence that plants release volatiles when damaged by herbivores is as sure as something in science can be,” said Martin Heil, an ecologist at the Mexican research institute Cinvestav Irapuato. “The evidence that plants can somehow perceive these volatiles and respond with a defense response is also very good.”

Plant communication may still be a tiny field, but the people who study it are no longer seen as a lunatic fringe. “It used to be that people wouldn’t even talk to you: ‘Why are you wasting my time with something we’ve already debunked?’” said Karban. “That’s now better for sure.” The debate is no longer whether plants can sense one another’s biochemical messages — they can — but about why and how they do it. [Continue reading…]

Facebooktwittermail

Bees translate polarized light into a navigational dance

bee

Queensland Brain Institute: QBI scientists at The University of Queensland have found that honeybees use the pattern of polarised light in the sky invisible to humans to direct one another to a honey source.

The study, conducted in Professor Mandyam Srinivasan’s laboratory at the Queensland Brain Institute, a member of the Australian Research Council Centre of Excellence in Vision Science (ACEVS), demonstrated that bees navigate to and from honey sources by reading the pattern of polarised light in the sky.

“The bees tell each other where the nectar is by converting their polarised ‘light map’ into dance movements,” Professor Srinivasan said.

“The more we find out how honeybees make their way around the landscape, the more awed we feel at the elegant way they solve very complicated problems of navigation that would floor most people – and then communicate them to other bees,” he said.

The discovery shines new light on the astonishing navigational and communication skills of an insect with a brain the size of a pinhead.

The researchers allowed bees to fly down a tunnel to a sugar source, shining only polarised light from above, either aligned with the tunnel or at right angles to the tunnel.

They then filmed what the bees ‘told’ their peers, by waggling their bodies when they got back to the hive.

“It is well known that bees steer by the sun, adjusting their compass as it moves across the sky, and then convert that information into instructions for other bees by waggling their body to signal the direction of the honey,” Professor Srinivasan said.

“Other laboratories have shown from studying their eyes that bees can see a pattern of polarised light in the sky even when the sun isn’t shining: the big question was could they translate the navigational information it provides into their waggle dance.”

The researchers conclude that even when the sun is not shining, bees can tell one another where to find food by reading and dancing to their polarised sky map.

In addition to revealing how bees perform their remarkable tasks, Professor Srinivasan says it also adds to our understanding of some of the most basic machinery of the brain itself.

Professor Srinivasan’s team conjectures that flight under polarised illumination activates discrete populations of cells in the insect’s brain.

When the polarised light was aligned with the tunnel, one pair of ‘place cells’ – neurons important for spatial navigation – became activated, whereas when the light was oriented across the tunnel a different pair of place cells was activated.

The researchers suggest that depending on which set of cells is activated, the bee can work out if the food source lies in a direction toward or opposite the direction of the sun, or in a direction ninety degrees to the left or right of it.

The study, “Honeybee navigation: critically examining the role of polarization compass”, is published in the 6 January 2014 issue of the Philosophical Transactions of the Royal Society B.

Facebooktwittermail

The intelligent plant

Michael Pollan writes: In 1973, a book claiming that plants were sentient beings that feel emotions, prefer classical music to rock and roll, and can respond to the unspoken thoughts of humans hundreds of miles away landed on the New York Times best-seller list for nonfiction. “The Secret Life of Plants,” by Peter Tompkins and Christopher Bird, presented a beguiling mashup of legitimate plant science, quack experiments, and mystical nature worship that captured the public imagination at a time when New Age thinking was seeping into the mainstream. The most memorable passages described the experiments of a former C.I.A. polygraph expert named Cleve Backster, who, in 1966, on a whim, hooked up a galvanometer to the leaf of a dracaena, a houseplant that he kept in his office. To his astonishment, Backster found that simply by imagining the dracaena being set on fire he could make it rouse the needle of the polygraph machine, registering a surge of electrical activity suggesting that the plant felt stress. “Could the plant have been reading his mind?” the authors ask. “Backster felt like running into the street and shouting to the world, ‘Plants can think!’ ”

Backster and his collaborators went on to hook up polygraph machines to dozens of plants, including lettuces, onions, oranges, and bananas. He claimed that plants reacted to the thoughts (good or ill) of humans in close proximity and, in the case of humans familiar to them, over a great distance. In one experiment designed to test plant memory, Backster found that a plant that had witnessed the murder (by stomping) of another plant could pick out the killer from a lineup of six suspects, registering a surge of electrical activity when the murderer was brought before it. Backster’s plants also displayed a strong aversion to interspecies violence. Some had a stressful response when an egg was cracked in their presence, or when live shrimp were dropped into boiling water, an experiment that Backster wrote up for the International Journal of Parapsychology, in 1968.

In the ensuing years, several legitimate plant scientists tried to reproduce the “Backster effect” without success. Much of the science in “The Secret Life of Plants” has been discredited. But the book had made its mark on the culture. Americans began talking to their plants and playing Mozart for them, and no doubt many still do. This might seem harmless enough; there will probably always be a strain of romanticism running through our thinking about plants. (Luther Burbank and George Washington Carver both reputedly talked to, and listened to, the plants they did such brilliant work with.) But in the view of many plant scientists “The Secret Life of Plants” has done lasting damage to their field. According to Daniel Chamovitz, an Israeli biologist who is the author of the recent book “What a Plant Knows,” Tompkins and Bird “stymied important research on plant behavior as scientists became wary of any studies that hinted at parallels between animal senses and plant senses.” Others contend that “The Secret Life of Plants” led to “self-censorship” among researchers seeking to explore the “possible homologies between neurobiology and phytobiology”; that is, the possibility that plants are much more intelligent and much more like us than most people think—capable of cognition, communication, information processing, computation, learning, and memory.

The quotation about self-censorship appeared in a controversial 2006 article in Trends in Plant Science proposing a new field of inquiry that the authors, perhaps somewhat recklessly, elected to call “plant neurobiology.” The six authors—among them Eric D. Brenner, an American plant molecular biologist; Stefano Mancuso, an Italian plant physiologist; František Baluška, a Slovak cell biologist; and Elizabeth Van Volkenburgh, an American plant biologist—argued that the sophisticated behaviors observed in plants cannot at present be completely explained by familiar genetic and biochemical mechanisms. Plants are able to sense and optimally respond to so many environmental variables—light, water, gravity, temperature, soil structure, nutrients, toxins, microbes, herbivores, chemical signals from other plants—that there may exist some brainlike information-processing system to integrate the data and coördinate a plant’s behavioral response. The authors pointed out that electrical and chemical signalling systems have been identified in plants which are homologous to those found in the nervous systems of animals. They also noted that neurotransmitters such as serotonin, dopamine, and glutamate have been found in plants, though their role remains unclear.

Hence the need for plant neurobiology, a new field “aimed at understanding how plants perceive their circumstances and respond to environmental input in an integrated fashion.” The article argued that plants exhibit intelligence, defined by the authors as “an intrinsic ability to process information from both abiotic and biotic stimuli that allows optimal decisions about future activities in a given environment.” Shortly before the article’s publication, the Society for Plant Neurobiology held its first meeting, in Florence, in 2005. A new scientific journal, with the less tendentious title Plant Signaling & Behavior, appeared the following year.

Depending on whom you talk to in the plant sciences today, the field of plant neurobiology represents either a radical new paradigm in our understanding of life or a slide back down into the murky scientific waters last stirred up by “The Secret Life of Plants.” Its proponents believe that we must stop regarding plants as passive objects—the mute, immobile furniture of our world—and begin to treat them as protagonists in their own dramas, highly skilled in the ways of contending in nature. They would challenge contemporary biology’s reductive focus on cells and genes and return our attention to the organism and its behavior in the environment. It is only human arrogance, and the fact that the lives of plants unfold in what amounts to a much slower dimension of time, that keep us from appreciating their intelligence and consequent success. Plants dominate every terrestrial environment, composing ninety-nine per cent of the biomass on earth. By comparison, humans and all the other animals are, in the words of one plant neurobiologist, “just traces.” [Continue reading…]

Facebooktwittermail

Christmas food for thought

Shelly Fan writes: The morning before Christmas eve, I’m sitting here in the dining room munching happily on the bits and pieces of what’s left of our gingerbread house that was only erected to its full glory the night before. I have not consumed this amount of carbohydrates in over a year.

Inside, a few species of my extensive gut microbe community are screaming bloody murder.

When you eat, you’re not only feeding your own fleshy vessel, but also the 100 trillion of microbugs that thrive in your intestines. Hardly “along for the ride”, these bugs not only help us digest foodstuff, ferment carbohydrates and proteins but also heavily impact our metabolism and general health. Depending on their composition, they tweak our risk of cardiovascular diseases, Type II diabetes and may even cause obesity in humans. There’s tantalizing evidence that their reach extends to the brain, influencing mood, anxiety and cognition in mice.

However, the gut microbiota* is a fluid, ever-changing beast. In one previous study, researchers transplanted gut-free mice with fresh or frozen human poop to inoculate them with a microbiome of known composition. When researchers switched these mice’s plant-based diet to a high-fat, high-sugar one, the structure of the established microbiome changed within a single day: some species dwindled in number, while others exploded onto the intestinal stage, bringing with them their particular metabolic tricks. (*The word “microbiome” refers to the set of genes in the gut bugs).

Similar diet-induced changes have been found in humans. When babies are weaned from their mothers’ milk and switch to solid food, their gut bug community simultaneously go through tumultuous changes. The gut bugs of African hunter-gatherers vastly differ from those in people grown on a Western diet. But these changes take weeks, even lifetimes. Just how fast can the microbiome adapt and change to a new diet? [Continue reading…]

Facebooktwittermail

The society of microbes that make us what we are

Earth Island Journal: In your new book, Cooked, you explore the art of cooking through the elements of Fire, Water, Air, and Earth. I’m sure you love all your children equally, but of those four, which taught you the most?

Michael Pollan: Fermentation – without a doubt. I began this education about microbiology. I’ve always been interested in nature and other species, and this symbiotic relationship we have with them, and I have mostly paid attention to it in the plant world. I just had no idea of how rich our engagement with microbes was, and how invisible it is to us. I began it when I was doing the Air section and learning about sourdough cultures. But then I got into that last chapter and started learning about fermentation: how much of our food is fermented, the fact that you could cook without the use of any heat, and the fact that we are dependent on these microbes. They’re using us; we’re using them. For me that was most fascinating.

You point out that our feelings about microbes are an expression of our attitude toward the natural world.

Yeah, and our drive for control, at all costs. Microbes are frightening for a couple reasons. One is, they’re invisible. They’re an unseen enemy. And they are pathogens, I mean some of them. You know, conquering infectious disease was a tremendous achievement for our civilization. But as so often happens, we cast things in black and white. So microbes are all bad because some microbes cause disease, and we fail to realize how dependent we are on them for our health. I think we’re going to get to a point where we will discover the unit in evolution and natural selection is not the species as an individual, but what is called the “holobiont,” the group of species that travel together. And that’s what selection is acting on very often, is the super-organism of humans or cats or plants.

Plants, you know, they, too, have their own microbiome; I didn’t talk about this in the piece, but their microbiome is outside their bodies. It surrounds their roots. It’s in what’s called the rhizosphere. There’s a little ecosystem around the root of every plant, and I think we’re going to come to learn that it’s as important to plant health as our flora is to us. I think we’re going to start looking at all species as collectivities, and microbes will be the part of that. And that changes a lot. It changes how you approach agriculture. It certainly changes how you approach health. So I think we’re really on the verge of a paradigm shift around that. [Continue reading…]

Facebooktwittermail

Worried about terrorism? You should be more afraid of bread!

David Perlmutter, MD writes: While gluten makes up the lion’s share of protein in wheat, research reveals that modern wheat is capable of producing more than 23,000 different proteins, any one of which could trigger a potentially damaging inflammatory response. One protein in particular is wheat germ agglutinin (WGA). WGA is classified as a lectin — a term for a protein produced by an organism to protect itself from predation.

All grains produce lectins, which selectively bind to unique proteins on the surfaces of bacteria, fungi, and insects. These proteins are found throughout the animal kingdom. One protein in particular for which WGA has an extremely high affinity is N-Acetylglucosamine. N-Acetylglucosamine richly adorns the casing of insects and plays an important role in the structure of the cellular walls of bacteria. More importantly, it is a key structural component in humans in a variety of tissues, including tendons, joint surfaces, cartilage, the lining of the entire digestive tract, and even the lining of the hundreds of miles of blood vessels found within each of us.

It is precisely the ability of WGA to bind to proteins lining the gut that raises concern amongst medical researchers. When WGA binds to these proteins, it may leave these cells less well protected against the harmful effects of the gut contents.

WGA may also have direct toxic effects on the heart, endocrine, and immune systems, and even the brain. In fact, so readily does WGA make its way into the brain that scientists are actually testing it as a possible means of delivering medicines in an attempt to treat Alzheimer’s disease.

And again, the concern here is not just for a small segment of the population who happened to inherit susceptibility for sensitivity to gluten. This is a concern as it relates to all humans. As medical researcher Sayer Ji stated, “What is unique about WGA is that it can do direct damage to the majority of tissues in the human body without requiring a specific set of genetic susceptibilities and/or immune-mediated articulations. This may explain why chronic inflammatory and degenerative conditions are endemic to wheat-consuming populations even when overt allergies or intolerances to wheat gluten appear exceedingly rare.”

The gluten issue is indeed very real and threatening. But it now seems clear that lectin proteins found in wheat may harbor the potential for even more detrimental effects on human health. It is particularly alarming to consider the fact that there is a move to actually genetically modify wheat to enhance its WGA content.

Scientific research is now giving us yet another reason to reconsider the merits of our daily bread. The story of WGA’s potential destructive effects on human health is just beginning to be told. We should embrace the notion that low levels of exposure to any toxin over an extended period can lead to serious health issues. And this may well characterize the under-recognized threat of wheat consumption for all humans.

Facebooktwittermail

The misleading metaphor of the selfish gene

David Dobbs writes: A couple of years ago, at a massive conference of neuroscientists — 35,000 attendees, scores of sessions going at any given time — I wandered into a talk that I thought would be about consciousness but proved (wrong room) to be about grasshoppers and locusts. At the front of the room, a bug-obsessed neuroscientist named Steve Rogers was describing these two creatures — one elegant, modest, and well-mannered, the other a soccer hooligan.

The grasshopper, he noted, sports long legs and wings, walks low and slow, and dines discreetly in solitude. The locust scurries hurriedly and hoggishly on short, crooked legs and joins hungrily with others to form swarms that darken the sky and descend to chew the farmer’s fields bare.

Related, yes, just as grasshoppers and crickets are. But even someone as insect-ignorant as I could see that the hopper and the locust were wildly different animals — different species, doubtless, possibly different genera. So I was quite amazed when Rogers told us that grasshopper and locust are in fact the same species, even the same animal, and that, as Jekyll is Hyde, one can morph into the other at alarmingly short notice.

Not all grasshopper species, he explained (there are some 11,000), possess this morphing power; some always remain grasshoppers. But every locust was, and technically still is, a grasshopper — not a different species or subspecies, but a sort of hopper gone mad. If faced with clues that food might be scarce, such as hunger or crowding, certain grasshopper species can transform within days or even hours from their solitudinous hopper states to become part of a maniacally social locust scourge. They can also return quickly to their original form.

In the most infamous species, Schistocerca gregaria, the desert locust of Africa, the Middle East and Asia, these phase changes (as this morphing process is called) occur when crowding spurs a temporary spike in serotonin levels, which causes changes in gene expression so widespread and powerful they alter not just the hopper’s behaviour but its appearance and form. Legs and wings shrink. Subtle camo colouring turns conspicuously garish. The brain grows to manage the animal’s newly complicated social world, which includes the fact that, if a locust moves too slowly amid its million cousins, the cousins directly behind might eat it.

How does this happen? Does something happen to their genes? Yes, but — and here was the point of Rogers’s talk — their genes don’t actually change. That is, they don’t mutate or in any way alter the genetic sequence or DNA. Nothing gets rewritten. Instead, this bug’s DNA — the genetic book with millions of letters that form the instructions for building and operating a grasshopper — gets reread so that the very same book becomes the instructions for operating a locust. Even as one animal becomes the other, as Jekyll becomes Hyde, its genome stays unchanged. Same genome, same individual, but, I think we can all agree, quite a different beast.

Why?

Transforming the hopper is gene expression — a change in how the hopper’s genes are ‘expressed’, or read out. Gene expression is what makes a gene meaningful, and it’s vital for distinguishing one species from another. We humans, for instance, share more than half our genomes with flatworms; about 60 per cent with fruit flies and chickens; 80 per cent with cows; and 99 per cent with chimps. Those genetic distinctions aren’t enough to create all our differences from those animals — what biologists call our particular phenotype, which is essentially the recognisable thing a genotype builds. This means that we are human, rather than wormlike, flylike, chickenlike, feline, bovine, or excessively simian, less because we carry different genes from those other species than because our cells read differently our remarkably similar genomes as we develop from zygote to adult. The writing varies — but hardly as much as the reading.

This raises a question: if merely reading a genome differently can change organisms so wildly, why bother rewriting the genome to evolve? How vital, really, are actual changes in the genetic code? Do we even need DNA changes to adapt to new environments? Is the importance of the gene as the driver of evolution being overplayed?

You’ve probably noticed that these questions are not gracing the cover of Time or haunting Oprah, Letterman, or even TED talks. Yet for more than two decades they have been stirring a heated argument among geneticists and evolutionary theorists. As evidence of the power of rapid gene expression mounts, these questions might (or might not, for pesky reasons we’ll get to) begin to change not only mainstream evolutionary theory but our more everyday understanding of evolution. [Continue reading…]

Facebooktwittermail

It’s not just the genes

Eric E. Schadt writes: It’s been 10 years since an international consortium of scientists successfully completed the mapping of the human genome — a world-changing project that couldn’t have happened without public and private support. The feat neatly coincided with the 50th anniversary of the description of DNA’s double helix by Nobel laureates James Watson and Francis Crick. These are incredible achievements, and today, we couldn’t conceive of the future of medicine without them.

Equally unfathomable is a view of medicine that doesn’t take into account the trove of clinically relevant information available for any individual person, and for all people more generally. DNA holds (among other things) your personal architectural blueprint, but unto itself, it is a fairly static factor, the genome in your normal, healthy cells changing very little over the course of your life. We know with certainty that DNA alone is not a categorical predictor of disease. The BRCA1 or BRCA2 gene mutation, for example, signals significantly higher risk for breast cancer in women, but people with the same defective gene often have remarkably different outcomes. Researchers and the public are asking: why is that?

Whether disease manifests, the age at which it manifests, and how severe it becomes, all depend on a multitude of other factors and the dynamic interplay between them: RNA, metabolites, proteins, healthy and diseased tissues, insulin and cholesterol levels, weight, age, gender, tobacco use, and toxic exposures — to name just a few. To achieve a comprehensive understanding of disease so that we can better diagnose and treat it, researchers must examine a hierarchy of levels — multiple scales — of all observable characteristics. Each element — from molecules, to cells, to tissues, to organs, to the person, and then to the community at large — and the flow of information between these elements, is a biological data point at a particular point in time, and the observation of many millions of these elements in a given individual and population of time is where “big data” meets medicine. [Continue reading…]

Facebooktwittermail

Slow-motion world for small animals

chipmunk

BBC News reports: Smaller animals tend to perceive time as if it is passing in slow motion, a new study has shown.

This means that they can observe movement on a finer timescale than bigger creatures, allowing them to escape from larger predators.

Insects and small birds, for example, can see more information in one second than a larger animal such as an elephant.

The work is published in the journal Animal Behaviour.

“The ability to perceive time on very small scales may be the difference between life and death for fast-moving organisms such as predators and their prey,” said lead author Kevin Healy, at Trinity College Dublin (TCD), Ireland.

The reverse was found in bigger animals, which may miss things that smaller creatures can rapidly spot. [Continue reading…]

Facebooktwittermail

The global land crisis and the very real threat of famine

Ambrose Evans-Pritchard writes: American scientists have made an unsettling discovery. Crop farming across the Prairies since the late 19th Century has caused a collapse of the soil microbia that holds the ecosystem together.

They do not know exactly what role is played by the bacteria. It is a new research field. Nor do they know where the tipping point lies, or how easily this can be reversed. Nobody yet knows whether this is happening in other parts of the world.

A team at the University of Colorado under Noah Fierer used DNA gene technology to test the ‘verrucomicrobia’ in Prairie soil, contrasting tilled land with the rare pockets of ancient tallgrass found in cemeteries and reservations. The paper published in the US journal Science found that crop agriculture has “drastically altered” the biology of the land. “The soils currently found throughout the region bear little resemblance to their pre-agricultural state,” it concluded.

You might say we already knew this. In fact we did not. There has never before been a metagenomic analysis of this kind and on this scale. Professor Fierer said mankind needs to watch its step. “We really know very little about one of the most productive soils on the planet, but we do know that soil microbes play a key role and we can’t just keep adding fertilizers,” he said.

The Colorado study has caused a stir in the soil world. It was accompanied by a sobering analysis in Science by academics from South Africa’s Witwatersrand University. They fear that we are repeating the mistakes of past civilisations, over-exploiting the land until it goes beyond the point of no return, and leads to a vicious circle of famine, and then social disintegration.

Entitled “Dust to Dust“, the paper argues that the erosion of soil fertility has been masked by a “soup of nutrients” poured over crop lands, giving us a false sense of security. It said 1pc of global land is being degraded each year, defined as a 70pc loss of the top soil.

Once the top soil crosses a crucial threshold, the recovery rate plunges. Chemicals can keep crop yields high for a while but the complex ecology beneath is being abused further. Yields have already fallen 8pc across Africa as a whole. The paper calls for a complete change of course as the “only viable route to feeding the world and keeping it habitable.” [Continue reading…]

Facebooktwittermail