Category Archives: Evolution

In a society where everyone is ready to defend the common good, corruption doesn’t pay

Suzanne Sadedin writes: By making a few alterations to the composition of the justice system, corrupt societies could be made to transition to a state called ‘righteousness’. In righteous societies, police were not a separate, elite order. They were everybody. When virtually all of society stood ready to defend the common good, corruption didn’t pay.

Among honeybees and several ant species, this seems to be the status quo: all the workers police one another, making corruption an unappealing choice. In fact, the study showed that even if power inequalities later re-appeared, corruption would not return. The righteous community was extraordinarily stable.

Not all societies could make the transition. But those that did would reap the benefits of true, lasting harmony. An early tribe that made the transition to righteousness might out-compete more corrupt rivals, allowing righteousness to spread throughout the species. Such tribal selection is uncommon among animals other than eusocial insects, but many researchers think it could have played a role in human evolution. Hunter-gatherer societies commonly tend toward egalitarianism, with social norms enforced by the whole group rather than any specially empowered individuals. [Continue reading…]

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How did complex creatures evolve from simple single-celled organisms?

Emily Singer writes: In September 2014, Christa Schleper embarked on an unusual hunting expedition in Slovenia. Instead of seeking the standard quarry of deer or wild boar, Schleper was in search of Lokiarchaeota, or Loki, a newly discovered group of organisms first identified near deep-sea vents off the coast of Norway. The simple, single-celled creatures have captured scientists’ interest because they are unlike any other organism known to science. They belong to an ancient group of creatures known as archaea, but they seem to share some features with more complex life-forms, including us.

Though little is known about Loki, scientists hope that it will help to resolve one of biology’s biggest mysteries: how life transformed from simple single-celled organisms to the menagerie of complex life known as eukaryotes — a category that includes everything from yeast to azaleas to elephants. “Next to the origins of life, there’s probably no bigger mystery in the history of life,” said John Archibald, an evolutionary biologist at Dalhousie University in Nova Scotia.

The jump from single cells to complex creatures is so puzzling because it represents an enormous evolutionary gulf. “How do you make a eukaryote, that’s a big question,” said Schleper, a microbiologist at the University of Vienna in Austria. “It’s a huge transition.”

Though single-celled organisms blanket the Earth and are capable of impressive biochemistry — some can eat nuclear waste, for example — their structure and shape remain simple. Cells from animals, plants and fungi, which make up the eukaryotes, are much more sophisticated. They possess a suite of features lacking in their simpler brethren: a nucleus that houses DNA; an energy-producing device known as the mitochondrion; and molecular architecture, known as the cytoskeleton, that controls cell shape and movement.

Most biologists agree that at some point around two billion years ago, one featureless cell swallowed another, and the two began to work together as one. But the details of this process — whether this symbiosis jump-started an evolutionary process, or whether it happened midway along the path to eukaryotes — continue to drive huge disputes in the field. [Continue reading…]

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Competition in Cambrian seas 542 million years ago helped cause an explosion in animal diversity

Brooke Borel writes: Battles fought 542 million years before today helped fuel a blast that brought humans and most animals into existence. The great Cambrian Explosion was a period of unprecedented one-upmanship. Beastly claws crushed through thin skin, and soft-bodied creatures evolved shells shaped like scythes, sickles, and shields.

For about a billion years prior, the cells and genes that would later create animals were evolving in microscopic organisms who inhabited the oceans of Earth. These essential molecular changes may only be inferred today because they’re not preserved in fossils. The earliest traces of animals, about 580 million years old, appear soft, with no sign of claws, teeth, limbs, or brains. Then, within 54 million years (a relative blink but still, 270 times the duration of humans’ existence thus far), most of the main animal groups around today originated. This rapid rate of increase in animal architectures has never since been repeated.

A simple species count does not do justice to the power of the Cambrian Explosion. Species have continuously formed over time. A new type of moth may have antennae that are furrier than its sisters; a new species of dinosaur may be distinguished by clawed wings and vicious front fangs. But a new phylum — a major branch on the tree of life, the upper-level ranking that separates an insect from a pterodactyl — is rarely born.

Most of today’s 30 to 40 animal phyla originated in the Cambrian, and have persisted through time with hundreds of variations on a theme. [Continue reading…]

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Long before going to Europe, humans ventured east to Asia

LiveScience reports: Teeth from a cave in China suggest that modern humans lived in Asia much earlier than previously thought, and tens of thousands of years before they reached Europe, researchers say.

This discovery yields new information about the dispersal of modern humans from Africa to the rest of the world, and could shed light on how modern humans and Neanderthals interacted, the scientists added.

Modern humans first originated about 200,000 years ago in Africa. When and how the modern human lineage dispersed from Africa has long been controversial.

Previous research suggested the exodus from Africa began between 70,000 and 40,000 years ago. However, recent research hinted that modern humans might have begun their march across the globe as early as 130,000 years ago. [Continue reading…]

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Human Genome Project: Twenty-five years of big biology

Eric D. Green, James D. Watson& Francis S. Collins write: Twenty-five years ago, the newly created US National Center for Human Genome Research (now the National Human Genome Research Institute; NHGRI), which the three of us have each directed, joined forces with US and international partners to launch the Human Genome Project (HGP). What happened next represents one of the most historically significant scientific endeavours: a 13-year quest to sequence all three billion base pairs of the human genome.

Even just a few years ago, discussions surrounding the HGP focused mainly on what insights the project had brought or would bring to our understanding of human disease. Only now is it clear that, as well as dramatically accelerating biomedical research, the HGP initiated a new way of doing science.

As biology’s first large-scale project, the HGP paved the way for numerous consortium-based research ventures. The NHGRI alone has been involved in launching more than 25 such projects since 2000. These have presented new challenges to biomedical research — demanding, for instance, that diverse groups from different countries and disciplines come together to share and analyse vast data sets. [Continue reading…]

The Independent reports: The most comprehensive study of the human genome has discovered that a sizeable minority of people are walking around with some of their genes missing without any apparent ill-effects, scientists have found.

A project to sequence and analyse the entire genetic code of more than 2,500 people drawn from 26 different ethnic populations from around the world has revealed that some genes do not seem to be as essential for health and life as previously believed.

The finding is just one to have emerged from the 1,000 Genomes Project set up in 2008 to study the genetic variation in at least this number of people in order to understand the variety of DNA types within the human population, the researchers said. [Continue reading…]

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Imagining strange new lifeforms could help us discover our own origins

By Michael Page, University of Huddersfield

From the earliest of times, philosophers and scientists have tried to understand the relationship between animate and inanimate matter. But the origin of life remains one of the major scientific riddles to be solved.

The building blocks of life as we know it essentially consist of four groups of chemicals: proteins, nucleic acids, lipids (fats) and carbohydrates. There was much excitement about the possibility of finding amino acids (the ingredients for proteins) on comets or distant planets because some scientists believe that life on Earth, or at least its building blocks, may have originally come from outer space and been deposited by meteorites.

But there are now extensive examples of how natural processes on Earth can convert simple molecules into these building blocks. Scientists have demonstrated in the lab how to make amino acids, simple sugars, lipids and even nucleotides – the basic units of DNA – from very simple chemicals, under conditions that could have existed on early earth. What still eludes them is the point in the process when a chemical stew becomes an organism. How did the first lifeforms become alive?

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Which species will survive the Earth’s sixth mass extinction?

By Matthew Wills, University of Bath

Scientists recently suggested that the Earth’s sixth mass extinction has begun. As terrifying as that sounds, surely humans are too smart and too important to get wiped out? Palaeontologists have long tried to shed light on this question by looking for general rules that might predict the survival of a species.

While this is not exactly a straightforward exercise, research so far indicates that the odds are not in our favour.

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In defence of bats: Beautifully designed mammals that should be left in peace

By Daniel Horton, University of Surrey

As a wildlife veterinarian, I often get asked about bats. I like bats, and I am always eager to talk about how interesting they are. Unfortunately the question is often not about biology but instead “what should I do about the ones in my roof?”.

With some unique talents and remarkable sex lives, bats are actually one of the most interesting, diverse and misunderstood groups of animals. Contrary to popular belief, they are beautiful creatures. Not necessarily in the cuddly, human-like sense – although some fruit bats with doey brown eyes and button noses could be considered so – but they are beautifully designed.

This couldn’t be illustrated better than by the discovery of the oldest known complete bat fossil, more than 53 million-years-old yet with a similar wing design to those flying around today. To put it in perspective, 50m years ago our ancestors were still swinging from the trees and would certainly not be recognised as human. But even then bats already had the combination of thin, long forearms and fingers covered by an extremely thin, strong membrane, which allowed them to master the art of powered, agile flight.

A flying fox shows off its 50 million-year-old wing design.
Duncan PJ, CC BY-SA

Soon afterwards, fossils record another game-changing adaptation in the evolution of most bats, and that is the ability to accurately locate prey using sound (what we call echolocation). These two adaptations early in their history gave bats an evolutionary edge compared to some other mammals, and allowed them to diversify into almost all habitats, on every continent except Antarctica.

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Mysterious new genes may arise from ‘junk’ DNA

Emily Singer writes: Genes, like people, have families — lineages that stretch back through time, all the way to a founding member. That ancestor multiplied and spread, morphing a bit with each new iteration.

For most of the last 40 years, scientists thought that this was the primary way new genes were born — they simply arose from copies of existing genes. The old version went on doing its job, and the new copy became free to evolve novel functions.

Certain genes, however, seem to defy that origin story. They have no known relatives, and they bear no resemblance to any other gene. They’re the molecular equivalent of a mysterious beast discovered in the depths of a remote rainforest, a biological enigma seemingly unrelated to anything else on earth.

The mystery of where these orphan genes came from has puzzled scientists for decades. But in the past few years, a once-heretical explanation has quickly gained momentum — that many of these orphans arose out of so-called junk DNA, or non-coding DNA, the mysterious stretches of DNA between genes. “Genetic function somehow springs into existence,” said David Begun, a biologist at the University of California, Davis. [Continue reading…]

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The difference between Americans who do or don’t believe in evolution

Dan Kahan writes: It’s well established that there is no meaningful correlation between what a person says he or she “believes” about evolution and having the rudimentary understanding of natural selection, random mutation, and genetic variance necessary to pass a high school biology exam (Bishop & Anderson 1990; Shtulman 2006).

There is a correlation between “belief” in evolution and possession of the kinds of substantive knowledge and reasoning skills essential to science comprehension generally.

But what the correlation is depends on religiosity: a relatively nonreligious person is more likely to say he or she “believes in” evolution, but a relatively religious person less likely to do so, as their science comprehension capacity goes up (Kahan 2015).

That’s what “belief in” evolution of the sort measured in a survey item signifies: who one is, not what one knows.

Americans don’t disagree about evolution because they have different understandings of or commitments to science. They disagree because they subscribe to competing cultural worldviews that invest positions on evolution with identity-expressive significance. [Continue reading…]

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Everything we thought we knew about the genome is turning out to be wrong

Claire Ainsworth writes: Ask me what a genome is, and I, like many science writers, might mutter about it being the genetic blueprint of a living creature. But then I’ll confess that “blueprint” is a lousy metaphor since it implies that the genome is two-dimensional, prescriptive and unresponsive.

Now two new books about the genome show the limitation of that metaphor for something so intricate, complex, multilayered and dynamic. Both underscore the risks of taking metaphors too literally, not just in undermining popular understanding of science, but also in trammelling scientific enquiry. They are for anyone interested in how new discoveries and controversies will transform our understanding of biology and of ourselves.

John Parrington is an associate professor in molecular and cellular pharmacology at the University of Oxford. In The Deeper Genome, he provides an elegant, accessible account of the profound and unexpected complexities of the human genome, and shows how many ideas developed in the 20th century are being overturned.

Take DNA. It’s no simple linear code, but an intricately wound, 3D structure that coils and uncoils as its genes are read and spliced in myriad ways. Forget genes as discrete, protein-coding “beads on a string”: only a tiny fraction of the genome codes for proteins, and anyway, no one knows exactly what a gene is any more.[Continue reading…]

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The dysevolution of humanity

Jeff Wheelwright writes: I sat in my padded desk chair, hunched over, alternately entering notes on my computer and reading a book called The Story of the Human Body. It was the sort of book guaranteed to make me increasingly, uncomfortably aware of my own body. I squirmed to relieve an ache in my lower back. When I glanced out the window, the garden looked fuzzy. Where were my glasses? My toes felt hot and itchy: My athlete’s foot was flaring up again.

I returned to the book. “This chapter focuses on just three behaviors … that you are probably doing right now: wearing shoes, reading, and sitting.” OK, I was. What could be more normal?

According to the author, a human evolutionary biologist at Harvard named Daniel Lieberman, shoes, books and padded chairs are not normal at all. My body had good reason to complain because it wasn’t designed for these accessories. Too much sitting caused back pain. Too much focusing on books and computer screens at a young age fostered myopia. Enclosed, cushioned shoes could lead to foot problems, including bunions, fungus between the toes and plantar fasciitis, an inflammation of the tissue below weakened arches.

Those are small potatoes compared with obesity, Type 2 diabetes, osteoporosis, heart disease and many cancers also on the rise in the developed and developing parts of the world. These serious disorders share several characteristics: They’re chronic, noninfectious, aggravated by aging and strongly influenced by affluence and culture. Modern medicine has come up with treatments for them, but not solutions; the deaths and disabilities continue to climb.
lieberman

An evolutionary perspective is critical to understanding the body’s pitfalls in a time of plenty, Lieberman suggests. [Continue reading…]

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Were we happier in the Stone Age?

Yuval Noah Harari writes: Over the last decade, I have been writing a history of humankind, tracking down the transformation of our species from an insignificant African ape into the master of the planet. It was not easy to understand what turned Homo sapiens into an ecological serial killer; why men dominated women in most human societies; or why capitalism became the most successful religion ever. It wasn’t easy to address such questions because scholars have offered so many different and conflicting answers. In contrast, when it came to assessing the bottom line – whether thousands of years of inventions and discoveries have made us happier – it was surprising to realise that scholars have neglected even to ask the question. This is the largest lacuna in our understanding of history.

Though few scholars have studied the long-term history of happiness, almost everybody has some idea about it. One common preconception – often termed “the Whig view of history” – sees history as the triumphal march of progress. Each passing millennium witnessed new discoveries: agriculture, the wheel, writing, print, steam engines, antibiotics. Humans generally use newly found powers to alleviate miseries and fulfil aspirations. It follows that the exponential growth in human power must have resulted in an exponential growth in happiness. Modern people are happier than medieval people, and medieval people were happier than stone age people.

But this progressive view is highly controversial. Though few would dispute the fact that human power has been growing since the dawn of history, it is far less clear that power correlates with happiness. The advent of agriculture, for example, increased the collective power of humankind by several orders of magnitude. Yet it did not necessarily improve the lot of the individual. For millions of years, human bodies and minds were adapted to running after gazelles, climbing trees to pick apples, and sniffing here and there in search of mushrooms. Peasant life, in contrast, included long hours of agricultural drudgery: ploughing, weeding, harvesting and carrying water buckets from the river. Such a lifestyle was harmful to human backs, knees and joints, and numbing to the human mind.

In return for all this hard work, peasants usually had a worse diet than hunter-gatherers, and suffered more from malnutrition and starvation. Their crowded settlements became hotbeds for new infectious diseases, most of which originated in domesticated farm animals. Agriculture also opened the way for social stratification, exploitation and possibly patriarchy. From the viewpoint of individual happiness, the “agricultural revolution” was, in the words of the scientist Jared Diamond, “the worst mistake in the history of the human race”.

The case of the agricultural revolution is not a single aberration, however. Themarch of progress from the first Sumerian city-states to the empires of Assyria and Babylonia was accompanied by a steady deterioration in the social status and economic freedom of women. The European Renaissance, for all its marvellous discoveries and inventions, benefited few people outside the circle of male elites. The spread of European empires fostered the exchange of technologies, ideas and products, yet this was hardly good news for millions of Native Americans, Africans and Aboriginal Australians.

The point need not be elaborated further. Scholars have thrashed the Whig view of history so thoroughly, that the only question left is: why do so many people still believe in it? [Continue reading…]

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Resurrecting ancient proteins to illuminate the origins of life

Emily Singer writes: About 4 billion years ago, molecules began to make copies of themselves, an event that marked the beginning of life on Earth. A few hundred million years later, primitive organisms began to split into the different branches that make up the tree of life. In between those two seminal events, some of the greatest innovations in existence emerged: the cell, the genetic code and an energy system to fuel it all. All three of these are essential to life as we know it, yet scientists know disappointingly little about how any of these remarkable biological innovations came about.

“It’s very hard to infer even the relative ordering of evolutionary events before the last common ancestor,” said Greg Fournier, a geobiologist at the Massachusetts Institute of Technology. Cells may have appeared before energy metabolism, or perhaps it was the other way around. Without fossils or DNA preserved from organisms living during this period, scientists have had little data to work from.

Fournier is leading an attempt to reconstruct the history of life in those evolutionary dark ages — the hundreds of millions of years between the time when life first emerged and when it split into what would become the endless tangle of existence.

He is using genomic data from living organisms to infer the DNA sequence of ancient genes as part of a growing field known as paleogenomics. In research published online in March in the Journal of Molecular Evolution, Fournier showed that the last chemical letter added to the code was a molecule called tryptophan — an amino acid most famous for its presence in turkey dinners. The work supports the idea that the genetic code evolved gradually. [Continue reading…]

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The man who drank cholera and launched the yogurt craze

Lina Zeldovich writes: What do Jamie Lee Curtis, gut bacteria, and a long forgotten Russian scientist have in common? Why, yogurt, of course. But wait, the answer is not that easy. Behind it stretches a tale that shows you can never predict cultural influence. It wends its way through the Pasteur Institute, the Nobel Prize, one of the hottest fields of scientific research today, the microbiome, and one of the trendiest avenues in nutrition, probiotics. It all began in the 19th century with a hyperactive kid in Russia who had a preternatural ability to connect dots where nobody saw dots at all.

When Ilya Metchnikoff was 8 and running around on his parents’ Panassovka estate in Little Russia, now Ukraine, he was making notes on the local flora like a junior botanist. He gave science lectures to his older brothers and local kids whose attendance he assured by paying them from his pocket money. Metchnikoff earned the nickname “Quicksilver” because he was in constant motion, always wanting to see, taste, and try everything, from studying how his father played card games to learning to sew and embroider with the maids. His wife later wrote in The Life of Ellie Metchnikoff that Metchnikoff asked the “queerest” questions, often exasperating his caretakers. “He could only be kept quiet when his curiosity was awakened by observation of some natural objects such as an insect or a butterfly.”

At 16, Metchnikoff borrowed a microscope from a university professor to study the lower organisms. Darwin’s On the Origin of Species shaped his comparative approach to science during his university years — he viewed all organisms, and physiological processes that took place in them, as interconnected and related.

That ability led him to the discovery of a particular cell and enabled him to link digestive processes in primitive creatures to the human body’s immune defenses. In lower organisms, which lack the abdominal cavity and intestines, digestion is accomplished by a particular type of cells — mobile mesodermal cells — that move around engulfing and dissolving food particles. While staring at mesodermal cells inside transparent starfish larvae, Metchnikoff, 37 at the time, had a thought. “It struck me that similar cells might serve in the defense of the organisms against intruders,” he wrote. He fetched a few rose thorns from the garden and stuck them into the larvae. If his hypothesis was correct, the larva’s body would recognize thorns as intruders and mesodermal cells would aggregate around the thorns in an attempt to gobble them up. As Metchnikoff expected, the mesodermal cells surrounded the thorns, proving his theory. He named his cells phagocytes, which in Greek means “devouring cells,” and likened them to an “army hurling itself upon the enemy.” [Continue reading…]

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Inside the new social science of genetics

David Dobbs writes: A few years ago, Gene Robinson, of Urbana, Illinois, asked some associates in southern Mexico to help him kidnap some 1,000 newborns. For their victims they chose bees. Half were European honeybees, Apis mellifera ligustica, the sweet-tempered kind most beekeepers raise. The other half were ligustica’s genetically close cousins, Apis mellifera scutellata, the African strain better known as killer bees. Though the two subspecies are nearly indistinguishable, the latter defend territory far more aggressively. Kick a European honeybee hive and perhaps a hundred bees will attack you. Kick a killer bee hive and you may suffer a thousand stings or more. Two thousand will kill you.

Working carefully, Robinson’s conspirators — researchers at Mexico’s National Center for Research in Animal Physiology, in the high resort town of Ixtapan de la Sal — jiggled loose the lids from two African hives and two European hives, pulled free a few honeycomb racks, plucked off about 250 of the youngest bees from each hive, and painted marks on the bees’ tiny backs. Then they switched each set of newborns into the hive of the other subspecies.

Robinson, back in his office at the University of Illinois at Urbana-Champaign’s Department of Entomology, did not fret about the bees’ safety. He knew that if you move bees to a new colony in their first day, the colony accepts them as its own. Nevertheless, Robinson did expect the bees would be changed by their adoptive homes: He expected the killer bees to take on the European bees’ moderate ways and the European bees to assume the killer bees’ more violent temperament. Robinson had discovered this in prior experiments. But he hadn’t yet figured out how it happened.

He suspected the answer lay in the bees’ genes. He didn’t expect the bees’ actual DNA to change: Random mutations aside, genes generally don’t change during an organism’s lifetime. Rather, he suspected the bees’ genes would behave differently in their new homes — wildly differently.

This notion was both reasonable and radical. Scientists have known for decades that genes can vary their level of activity, as if controlled by dimmer switches. Most cells in your body contain every one of your 22,000 or so genes. But in any given cell at any given time, only a tiny percentage of those genes is active, sending out chemical messages that affect the activity of the cell. This variable gene activity, called gene expression, is how your body does most of its work. [Continue reading…]

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The genetic code is less like a blueprint than a first draft

Nessa Carey writes: When President Obama delivered a speech at MIT in 2009, he used a common science metaphor: “We have always been about innovation,” he said. “We have always been about discovery. That’s in our DNA.” Deoxyribonucleic acid, the chemical into which our genes are encoded, has become the metaphor of choice for a whole constellation of ideas about essence and identity. A certain mystique surrounds it. As Evelyn Fox Keller argues in her book The Century of the Gene, the genome is, in the popular imagination at least, the secret of life, the holy grail. It is a master builder, the ultimate computer program, and a modern-day echo of the soul, all wrapped up in one. This fantasy does not sit easily, however, with geneticists who have grown more aware over the last several decades that the relationship between genes and biological traits is much less than certain.

The popular understanding of DNA as a blueprint for organisms, with a one-to-one correspondence between genes and traits (called phenotypes), is the legacy of the early history of genetics. The term “gene” was coined in 1909 to refer to abstract units of inheritance, predating the discovery of DNA by forty years. Biologists came to think of genes like beads on a string that lined up neatly into chromosomes, with each gene determining a single phenotype. But, while some genes do correspond to traits in a straightforward way, as in eye color or blood group, most phenotypes are far more complex, set in motion by many different genes as well as by the environment in which the organism lives.

It turns out that the genetic code is less like a blueprint and more like a movie script, subject to revision and reinterpretation by a director. This process is called epigenetic modification (“epi” meaning “above” or “in addition to”). Just as a script can be altered with crossed-out words, sentences or scenes, epigenetic editing allows entire sections of DNA to be activated or de-activated. Genes can be as finely tuned as actors responding to stage directions to shout, whisper, or cackle. [Continue reading…]

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