‘Self-aware’ fish raises questions about mirror test

Elizabeth Preston writes:

A little blue-and-black fish swims up to a mirror. It maneuvers its body vertically to reflect its belly, along with a brown mark that researchers have placed on its throat. The fish then pivots and dives to strike its throat against the sandy bottom of its tank with a glancing blow. Then it returns to the mirror. Depending on which scientists you ask, this moment represents either a revolution or a red herring.

Alex Jordan, an evolutionary biologist at the Max Planck Institute for Ornithology in Germany, thinks this fish — a cleaner wrasse — has just passed a classic test of self-recognition. Scientists have long thought that being able to recognize oneself in a mirror reveals some sort of self-awareness, and perhaps an awareness of others’ perspectives, too. For almost 50 years, they have been using mirrors to test animals for that capacity. After letting an animal get familiar with a mirror, they put a mark someplace on the animal’s body that it can see only in its reflection. If the animal looks in the mirror and then touches or examines the mark on its body, it passes the test.

Humans don’t usually reach this milestone until we’re toddlers. Very few other species ever pass the test; those that do are mostly or entirely big-brained mammals such as chimpanzees. And yet as reported in a study that appeared on bioRxiv.org earlier this year and that is due for imminent publication in PLOS Biology, Jordan and his co-authors observed this seemingly self-aware behavior in a tiny fish.

Jordan’s findings have consequently inspired strong feelings in the field. “There are researchers who, it seems, do not want fish to be included in this secret club,” he said. “Because then that means that the [primates] are not so special anymore.” [Continue reading…]

An ant colony has memories that its individual members don’t have

By Deborah M Gordon

Like a brain, an ant colony operates without central control. Each is a set of interacting individuals, either neurons or ants, using simple chemical interactions that in the aggregate generate their behaviour. People use their brains to remember. Can ant colonies do that? This question leads to another question: what is memory? For people, memory is the capacity to recall something that happened in the past. We also ask computers to reproduce past actions – the blending of the idea of the computer as brain and brain as computer has lead us to take ‘memory’ to mean something like the information stored on a hard drive. We know that our memory relies on changes in how much a set of linked neurons stimulate each other; that it is reinforced somehow during sleep; and that recent and long-term memory involve different circuits of connected neurons. But there is much we still don’t know about how those neural events come together, whether there are stored representations that we use to talk about something that happened in the past, or how we can keep performing a previously learned task such as reading or riding a bicycle. 

Any living being can exhibit the simplest form of memory, a change due to past events. Look at a tree that has lost a branch. It remembers by how it grows around the wound, leaving traces in the pattern of the bark and the shape of the tree. You might be able to describe the last time you had the flu, or you might not. Either way, in some sense your body ‘remembers’, because some of your cells now have different antibodies, molecular receptors, which fit that particular virus.

Past events can alter the behaviour of both individual ants and ant colonies. Individual carpenter ants offered a sugar treat remembered its location for a few minutes; they were likely to return to where the food had been. Another species, the Sahara Desert ant, meanders around the barren desert, searching for food. It appears that an ant of this species can remember how far it walked, or how many steps it took, since the last time it was at the nest.

[Read more…]

Vast ecosystem beneath the Earth’s surface discovered

The Guardian reports:

The Earth is far more alive than previously thought, according to “deep life” studies that reveal a rich ecosystem beneath our feet that is almost twice the size of that found in all the world’s oceans.

Despite extreme heat, no light, minuscule nutrition and intense pressure, scientists estimate this subterranean biosphere is teeming with between 15bn and 23bn tonnes of micro-organisms, hundreds of times the combined weight of every human on the planet.

Researchers at the Deep Carbon Observatory say the diversity of underworld species bears comparison to the Amazon or the Galápagos Islands, but unlike those places the environment is still largely pristine because people have yet to probe most of the subsurface.

“It’s like finding a whole new reservoir of life on Earth,” said Karen Lloyd, an associate professor at the University of Tennessee in Knoxville. “We are discovering new types of life all the time. So much of life is within the Earth rather than on top of it.” [Continue reading…]

The insect apocalypse is here. What does it mean for the rest of life on Earth?

Brooke Jarvis reports:

Sune Boye Riis was on a bike ride with his youngest son, enjoying the sun slanting over the fields and woodlands near their home north of Copenhagen, when it suddenly occurred to him that something about the experience was amiss. Specifically, something was missing.

It was summer. He was out in the country, moving fast. But strangely, he wasn’t eating any bugs.

For a moment, Riis was transported to his childhood on the Danish island of Lolland, in the Baltic Sea. Back then, summer bike rides meant closing his mouth to cruise through thick clouds of insects, but inevitably he swallowed some anyway. When his parents took him driving, he remembered, the car’s windshield was frequently so smeared with insect carcasses that you almost couldn’t see through it. But all that seemed distant now. He couldn’t recall the last time he needed to wash bugs from his windshield; he even wondered, vaguely, whether car manufacturers had invented some fancy new coating to keep off insects. But this absence, he now realized with some alarm, seemed to be all around him. Where had all those insects gone? And when? And why hadn’t he noticed?

Riis watched his son, flying through the beautiful day, not eating bugs, and was struck by the melancholy thought that his son’s childhood would lack this particular bug-eating experience of his own. It was, he granted, an odd thing to feel nostalgic about. But he couldn’t shake a feeling of loss. “I guess it’s pretty human to think that everything was better when you were a kid,” he said. “Maybe I didn’t like it when I was on my bike and I ate all the bugs, but looking back on it, I think it’s something everybody should experience.”

I met Riis, a lanky high school science and math teacher, on a hot day in June. He was anxious about not having yet written his address for the school’s graduation ceremony that evening, but first, he had a job to do. From his garage, he retrieved a large insect net, drove to a nearby intersection and stopped to strap the net to the car’s roof. Made of white mesh, the net ran the length of his car and was held up by a tent pole at the front, tapering to a small, removable bag in back. Drivers whizzing past twisted their heads to stare. Riis eyed his parking spot nervously as he adjusted the straps of the contraption. “This is not 100 percent legal,” he said, “but I guess, for the sake of science.”

Riis had not been able to stop thinking about the missing bugs. The more he learned, the more his nostalgia gave way to worry. Insects are the vital pollinators and recyclers of ecosystems and the base of food webs everywhere. Riis was not alone in noticing their decline. In the United States, scientists recently found the population of monarch butterflies fell by 90 percent in the last 20 years, a loss of 900 million individuals; the rusty-patched bumblebee, which once lived in 28 states, dropped by 87 percent over the same period. With other, less-studied insect species, one butterfly researcher told me, “all we can do is wave our arms and say, ‘It’s not here anymore!’ ” Still, the most disquieting thing wasn’t the disappearance of certain species of insects; it was the deeper worry, shared by Riis and many others, that a whole insect world might be quietly going missing, a loss of abundance that could alter the planet in unknowable ways. “We notice the losses,” says David Wagner, an entomologist at the University of Connecticut. “It’s the diminishment that we don’t see.”

Because insects are legion, inconspicuous and hard to meaningfully track, the fear that there might be far fewer than before was more felt than documented. People noticed it by canals or in backyards or under streetlights at night — familiar places that had become unfamiliarly empty. The feeling was so common that entomologists developed a shorthand for it, named for the way many people first began to notice that they weren’t seeing as many bugs. They called it the windshield phenomenon. [Continue reading…]

The unexamined inner lives of insects

Lars Chittka and Catherine Wilson write:

René Descartes’s dog, Monsieur Grat (‘Mister Scratch’), used to accompany the 17th-century French philosopher on his ruminative walks, and was the object of his fond attention. Yet, for the most part, Descartes did not think very highly of the inner life of nonhuman animals. ‘[T]he reason why animals do not speak as we do is not that they lack the organs but that they have no thoughts,’ Descartes wrote in a letter in 1646.

Followers of Descartes have argued that consciousness is a uniquely human attribute, perhaps facilitated by language, that allows us to communicate and coordinate our memories, sensations and plans over time. On this view, versions of which persist in some quarters today, nonhuman animals are little more than clever automata with a toolkit of preprogrammed behaviours that respond to specific triggers.

Insects such as bees and ants are often held up as the epitome of the robotically mechanistic approach to animal nature. Scientists have long known that these creatures must possess a large behavioural repertoire in order to construct their elaborate homes, defend against intruders, and provision their young with food. Yet many still find it plausible to look at bees and ants as little more than ‘reflex machines’, lacking an internal representation of the world, or an ability to foresee even the immediate future. In the absence of external stimuli or internal triggers such as hunger, it’s believed that the insect’s mind is dark and its brain is switched off. Insects are close to ‘philosophical zombies’: hypothetical beings that rely entirely on routines and reflexes, without any awareness.

But perhaps the problem is not that insects lack an inner life, but that they don’t have a way to communicate it in terms we can understand. It is hard for us to prise open a window into their minds. So maybe we misdiagnose animal brains as having machine-like properties simply because we understand how machines work – whereas, to date, we have only a fragmentary and imperfect insight into how even the simplest brains process, store and retrieve information.

However, there are now many signs that consciousness-like phenomena might exist not just among humans or even great apes – but that insects might have them, too. Not all of these lines of evidence are from experiments specifically designed to explore consciousness; in fact, some have lain buried in the literature for decades, even centuries, without anyone recognising their hidden significance. [Continue reading…]

Meet the spiders that feed milk to their young

The New York Times reports:

The act of breast-feeding is so fundamental to being a mammal that we named ourselves after it. (“Mammalis” translates to “of the breasts.”) But over time, scientists have discovered that other animals also produce nutrient-rich elixirs to feed their young, including flamingos, cockroaches and male emperor penguins.

The latest addition to the cast of organisms that lactate — or something like it — is a species of jumping spider.

Researchers in China have discovered that females of the Toxeus magnus spider secrete a milk-like fluid to feed their offspring. The study, published Thursday in the journal Science, also found the arachnid mothers continue to provide the fluid, which contains about four times as much protein as cow’s milk, well after their spawn had become young adults.

Though the spiders aren’t using mammary glands to produce the fluid, and hence are “lactating” in name only, the findings should prompt scientists to reconsider what they know about nursing and how it evolved, the researchers said.

“Finding such mammal-like behavior in a spider, or in any invertebrate for that matter, was a surprise,” said Richard Corlett, a conservation biologist at the Chinese Academy of Sciences and an author of the study. [Continue reading…]

Should evolution treat our microbes as part of us?

Jonathan Lambert writes:

Twilight falls on the Tanzanian plain. As the sky turns a deeper purple, a solitary spotted hyena awakens. She trots along the border of her clan’s territory, marking the boundary with a sour paste from under her tail. She sniffs a passing breeze for hints of itinerant males interested in mating, giving little attention to her stomach’s rumbling over the remnants of the previous night’s hunt or the itch on her flank. The lone hyena chooses what she will do next to make her living.

Except she is not alone. That paste she secretes is produced not by her own cells but by billions of bacteria housed within her scent glands. The scents on the breeze from potential mates also come from unique microbial concoctions. A diverse array of bacteria that line her gut are helping to break down her meal. Others assist her immune system in fending off the hordes of parasites and pathogens trying to invade her skin and other tissues.

Who precisely is it, then, trying to survive on the Tanzanian plain? Can we consider the fates of the hyena and the microbes within her independently? Or does their interaction form something new, greater than each part alone?

“We’ve underestimated the potential contribution of microbes to traits we’ve been studying for decades or centuries,” said Kevin Theis, a microbiologist at Wayne State University who studies the paste-making microbes of the hyena. “If the genes for these important traits are actually in the microbiome and not the animal itself, then we need to take a systems-level approach and look at the host-microbe system as a whole.” [Continue reading…]

The health of an ecosystem (including your home) depends on its biodiversity

William Foster writes:

Rob Dunn invites us on a safari in pursuit of the wildlife teeming on our bodies and in every corner of our homes. For him, the creatures that sprawl in the human navel and under the bathroom shower head elicit the kind of wonder most of us would feel only on seeing the denizens of Tanzania’s Ngorongoro Crater or the Great Barrier Reef off Australia. Dunn is more than an informed and entertaining commentator, a David Attenborough of domestic biodiversity. He is a scientist whose research group at North Carolina State University in Raleigh made many of the discoveries described in his fascinating and illuminating book, Never Home Alone.

Dunn and his colleagues have used the concepts and techniques of community ecology to tease apart the functioning of a mostly ignored ecosystem: the human home. Their research enriches our understanding of ecosystem function, and — more grippingly — gives us insight into how our interactions with living things in the domestic habitat affect our health and well-being. The book is structured around sub-habitats in our homes — our bodies, rooms, water supply, pets and food. It considers an awesome range of organisms, from the rich fungal flora on bakers’ hands to the diversity of fly larvae in our drains.

We discover that warm, moist shower heads are ideal for the growth of biofilms containing trillions of bacteria, including Mycobacterium species that are harmful to human health. Dunn and his colleagues invited thousands of volunteers globally to send in samples from their bathrooms. The researchers are finding, for instance, that the more a water supply is treated with chemicals designed to kill microbes, the greater the abundance of pathogenic strains of mycobacteria. We also learn that the numbers of plant and butterfly species in our gardens are correlated with the robustness of the community of microbes on our skin; that some German cockroaches have evolved to perceive glucose as bitter, thus avoiding poisoned bait; and that dogs can give us both heartworm and a top-up of beneficial bacteria from their microbiomes.

The message of Never Home Alone is clear. The health of an ecosystem depends on its biodiversity: this is as true of our homes as of a mangrove swamp. Two factors, notes Dunn, are important. Simply by chance, a home containing more species is more likely to include organisms (especially microbes) that are vital in sparking our immune systems into life. And an ecosystem with niches fully occupied by diverse species is likely to be resilient and resistant to invasion by pests and pathogens. [Continue reading…]

Meet the trillions of viruses that make up your virome

File 20181001 195278 zxp1fb.jpg?ixlib=rb 1.1
Every surface of our body – inside and out – is covered in microorganisms: bacteria, viruses, fungi and many other microscopic life forms.
vrx/Shutterstock.com

By David Pride, University of California San Diego and Chandrabali Ghose, The Rockefeller University

Leer en español.

If you think you don’t have viruses, think again.

It may be hard to fathom, but the human body is occupied by large collections of microorganisms, commonly referred to as our microbiome, that have evolved with us since the early days of man. Scientists have only recently begun to quantify the microbiome, and discovered it is inhabited by at least 38 trillion bacteria. More intriguing, perhaps, is that bacteria are not the most abundant microbes that live in and on our bodies. That award goes to viruses.

Transmission electron micrograph of multiple bacteriophages attached to a bacterial cell wall.
Dr. Graham Beards, CC BY-SA

It has been estimated that there are over 380 trillion viruses inhabiting us, a community collectively known as the human virome. But these viruses are not the dangerous ones you commonly hear about, like those that cause the flu or the common cold, or more sinister infections like Ebola or dengue. Many of these viruses infect the bacteria that live inside you and are known as bacteriophages, or phages for short. The human body is a breeding ground for phages, and despite their abundance, we have very little insight into what all they or any of the other viruses in the body are doing.

I am a physician-scientist studying the human microbiome by focusing on viruses, because I believe that harnessing the power of bacteria’s ultimate natural predators will teach us how to prevent and combat bacterial infections. One might rightly assume that if viruses are the most abundant microbes in the body, they would be the target of the majority of human microbiome studies. But that assumption would be horribly wrong. The study of the human virome lags so far behind the study of bacteria that we are only just now uncovering some of their most basic features. This lag is due to it having taken scientists much longer to recognize the presence of a human virome, and a lack of standardized and sophisticated tools to decipher what’s actually in your virome.

[Read more…]

‘Hyperalarming’ study shows massive insect loss

The Washington Post reports:

Insects around the world are in a crisis, according to a small but growing number of long-term studies showing dramatic declines in invertebrate populations. A new report suggests that the problem is more widespread than scientists realized. Huge numbers of bugs have been lost in a pristine national forest in Puerto Rico, the study found, and the forest’s insect-eating animals have gone missing, too.

In 2014, an international team of biologists estimated that, in the past 35 years, the abundance of invertebrates such as beetles and bees had decreased by 45 percent. In places where long-term insect data are available, mainly in Europe, insect numbers are plummeting. A study last year showed a 76 percent decrease in flying insects in the past few decades in German nature preserves.

The latest report, published Monday in the Proceedings of the National Academy of Sciences, shows that this startling loss of insect abundance extends to the Americas. The study’s authors implicate climate change in the loss of tropical invertebrates.

“This study in PNAS is a real wake-up call — a clarion call — that the phenomenon could be much, much bigger, and across many more ecosystems,” said David Wagner, an expert in invertebrate conservation at the University of Connecticut who was not involved with this research. He added: “This is one of the most disturbing articles I have ever read.” [Continue reading…]