Ancient penguins were giant waddling predators

Carl Zimmer writes: The 57 million-year-old fossil is both fearsome and comical: a long-beaked penguin that stood 5 feet 7 inches tall and weighed about 220 pounds.

“It was as tall as a medium-sized man,” said Gerald Mayr, a paleontologist at the Senckenberg Research Institute in Frankfurt, Germany, and lead author of a report in Nature Communications on Tuesday announcing the discovery.

By comparison, the tallest living species, the emperor penguin, reaches about four feet in height. Kumimanu biceae, as the fossil was named, would have towered above the emperor, and above just about all other known ancient penguins.

(In 2014, another team of researchers estimated that a 34-million-year-old species stood six feet tall, but they based that estimate only on two bone fragments.)

Kumimanu wasn’t just exceptionally big; it also ranks among the oldest penguin fossils yet found. Both its age and its size make Kumimanu important to understanding the astonishing transformation that turned a lineage of flying birds into flightless swimmers.

The 18 modern species of penguin, ranging from the coast of Antarctica to the Galápagos Islands at the Equator, are impressively adapted to aquatic life. Rigid, blade-shaped wings enable them to shoot through the water at up to 22 miles an hour. Record-setting human swimmers don’t even reach six m.p.h.

But their adaptations to water have also left them unable to fly. When penguins haul out to rest or rear their young, they can only waddle about on stumpy legs. “They’re so unbirdlike that many people would not know they are birds,” Dr. Mayr said.

While penguins may look profoundly different from other birds, their DNA points to a close kinship to such species as albatrosses and petrels. These birds all fly over water to hunt for prey, hinting that the ancestors of penguins may have, too. [Continue reading…]

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It’s official: Timeline for human migration gets a rewrite

Gemma Tarlach writes: The great thing about science is supposed to be that you come up with a hypothesis and then you and other researchers try to shoot it down and, if the hypothesis doesn’t hold up, you come up with a new one based on what you learned from destroying the old one. And the scientific method generally works, as long as everyone keeps their egos in check.

Unfortunately, many researchers clung to the idea of a single migration out of Africa, no earlier than 60,000 years ago, for too long. Finds such as a human presence in the Levant 100,000 years ago, for example, were dismissed as a single band of early humans that strayed too far from home and went extinct— in other words, an evolutionary dead end.

Today, however, writing in Science, researchers say that no one can ignore the preponderance of evidence. It’s time, at long last, to revise that tired old timeline of human migration.

The timeline they call for is one of multiple migrations out of Africa beginning perhaps 120,000 years ago. While some of these early explorations certainly failed and became evolutionary dead ends, others, say the authors, survived, not only spreading across Asia but interbreeding with Denisovans and Neanderthals.

Both the archaeological and genetic evidence support a large dispersal from Africa around 60,000 years ago, but it was by no means the first — or the last — to occur. [Continue reading…]

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Young again: How one cell turns back time

Carl Zimmer writes: None of us was made from scratch. Every human being develops from the fusion of two cells, an egg and a sperm, that are the descendants of other cells. The lineage of cells that joins one generation to the next — called the germline — is, in a sense, immortal.

Biologists have puzzled over the resilience of the germline for 130 years, but the phenomenon is still deeply mysterious.

Over time, a cell’s proteins become deformed and clump together. When cells divide, they pass that damage to their descendants. Over millions of years, the germline ought to become too devastated to produce healthy new life.

“You take humans — they age two, three or four decades, and then they have a baby that’s brand new,” said K. Adam Bohnert, a postdoctoral researcher at Calico Life Sciences in South San Francisco, Calif. “There’s some interesting biology there we just don’t understand.”

On Thursday in the journal Nature, Dr. Bohnert and Cynthia Kenyon, vice president for aging research at Calico, reported the discovery of one way in which the germline stays young.

Right before an egg is fertilized, it is swept clean of deformed proteins in a dramatic burst of housecleaning. [Continue reading…]

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Bacteria slow their DNA repair to a crawl in favor of proofreading RNA gene transcripts

Jordana Cepelewicz writes: Evolution is a game of trade-offs. Every trait an organism inherits may have benefits and drawbacks; what matters to natural selection is whether the trait is positive or negative on balance. But in a recent study, researchers described a balancing act that seems more counterintuitive than most: Bacterial cells prioritize transcription — the process of making RNA transcripts of genes as the first step in protein production — over repairing double-strand breaks in their DNA.

“We tend to think of DNA as the brains of the cell,” said Susan Rosenberg, a biologist at Baylor College of Medicine in Houston. “If we push that analogy and think about parts of the cell competing for resources the way the parts of the body do, the brain should be getting whatever it needs at the expense of everything else.”

So when her Baylor colleague Christophe Herman approached her with the hypothesis that transcription might be more important than DNA repair, Rosenberg was ready to bet the other way. “And I was sure I would win,” she said.

But she was proven wrong. Last month, she, Herman and their team published the results of their research in Nature: They found, using a series of experiments and intricate controls, that transcription can trump DNA repair in E. coli. [Continue reading…]

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The surprising forces influencing the complexity of the language we speak and write

Julie Sedivy writes: “[[[When in the course of human events it becomes necessary for one people [to dissolve the political bands [which have connected them with another]] and [to assume among the powers of the earth, the separate and equal station [to which the laws of Nature and of Nature’s God entitle them]]], a decent respect to the opinions of mankind requires [that they should declare the causes [which impel them to the separation]]].”
— Declaration of Independence, opening sentence

An iconic sentence, this. But how did it ever make its way into the world? At 71 words, it is composed of eight separate clauses, each anchored by its own verb, nested within one another in various arrangements. The main clause (a decent respect to the opinions of mankind requires …) hangs suspended above a 50-word subordinate clause that must first be unfurled. Like an intricate equation, the sentence exudes a mathematical sophistication, turning its face toward infinitude.

To some linguists, Noam Chomsky among them, sentences like these illustrate an essential property of human language. These scientists have argued that recursion, a technique that allows chunks of language such as sentences to be embedded inside each other (with no hard limit on the number of nestings) is a universal human ability, perhaps even the one uniquely human ability that supports language. It’s what allows us to create—literally—an infinite variety of novel sentences out of a limited inventory of words.

But that leads to a curious puzzle: Complex sentences are not ubiquitous among the world’s languages. Many languages have little use for them. They prefer to string together simple clauses. They may even lack certain words such as relative pronouns that and which or connectors like if, despite, and although—these words make it possible to link clauses together into larger sentences. Allegedly, the Pirahã language along the Maici River of Brazil lacks recursion altogether. According to linguist Dan Everett, Pirahã speakers avoid linguistic nesting of all kinds, even in structures such as John’s brother’s house. (Instead, they would say something like: Brother’s house. John has a brother. It is the same one.)

This can’t be pinned on biological evolution. All evidence suggests that humans around the world are born with more or less the same brains. Abundant childhood exposure to a language with layered sentences practically guarantees their mastery. Even adult Pirahã speakers, who have remained unusually isolated from European languages, pick up the trick of complex syntax, provided that they spend enough time interacting with speakers of Brazilian Portuguese, a language that offers an adequate diet of embedded structures.

More useful is the notion of linguistic evolution. It’s the languages themselves, rather than the brains, that have evolved along different paths. And just as different species are shaped by adaptations to specific ecological niches, certain linguistic features—like sentence complexity—survive and thrive under some circumstances, whereas other features take hold and spread within very different niches. [Continue reading…]

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A giant insect ecosystem is collapsing due to humans. It’s a catastrophe

Michael McCarthy writes: Thirty-five years ago an American biologist Terry Erwin conducted an experiment to count insect species. Using an insecticide “fog”, he managed to extract all the small living things in the canopies of 19 individuals of one species of tropical tree, Luehea seemannii, in the rainforest of Panama. He recorded about 1,200 separate species, nearly all of them coleoptera (beetles) and many new to science; and he estimated that 163 of these would be found on Luehea seemannii only.

He calculated that as there are about 50,000 species of tropical tree, if that figure of 163 was typical for all the other trees, there would be more than eight million species, just of beetles, in the tropical rainforest canopy; and as beetles make up about 40% of all the arthropods, the grouping that contains the insects and the other creepy-crawlies from spiders to millipedes, the total number of such species in the canopy might be 20 million; and as he estimated the canopy fauna to be separate from, and twice as rich as, the forest floor, for the tropical forest as a whole the number of species might be 30 million.

Yes, 30 million. It was one of those extraordinary calculations, like Edwin Hubble’s of the true size of the universe, which sometimes stop us in our tracks.

Erwin reported that he was shocked by his conclusions and entomologists have argued over them ever since. But about insects, his findings make two things indisputably clear. One is that there are many, many more types than the million or so hitherto described by science, and probably many more than the 10m species sometimes postulated as an uppermost figure; and the second is that this is far and away the most successful group of creatures the Earth has ever seen.

They are multitudinous almost beyond our imagining. They thrive in soil, water, and air; they have triumphed for hundreds of millions of years in every continent bar Antarctica, in every habitat but the ocean. And it is their success – staggering, unparalleled and seemingly endless – which makes all the more alarming the great truth now dawning upon us: insects as a group are in terrible trouble and the remorselessly expanding human enterprise has become too much, even for them.

Does it matter? Oh yes. Most of our fruit crops are insect-pollinated, as are the vast majority of our wild plants
The astonishing report highlighted in the Guardian, that the biomass of flying insects in Germany has dropped by three quarters since 1989, threatening an “ecological Armageddon”, is the starkest warning yet; but it is only the latest in a series of studies which in the last five years have finally brought to public attention the real scale of the problem. [Continue reading…]

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Introducing ‘dark DNA’ – the phenomenon that could change how we think about evolution

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By Adam Hargreaves, University of Oxford

DNA sequencing technology is helping scientists unravel questions that humans have been asking about animals for centuries. By mapping out animal genomes, we now have a better idea of how the giraffe got its huge neck and why snakes are so long. Genome sequencing allows us to compare and contrast the DNA of different animals and work out how they evolved in their own unique ways.

But in some cases we’re faced with a mystery. Some animal genomes seem to be missing certain genes, ones that appear in other similar species and must be present to keep the animals alive. These apparently missing genes have been dubbed “dark DNA”. And its existence could change the way we think about evolution.

My colleagues and I first encountered this phenomenon when sequencing the genome of the sand rat (Psammomys obesus), a species of gerbil that lives in deserts. In particular we wanted to study the gerbil’s genes related to the production of insulin, to understand why this animal is particularly susceptible to type 2 diabetes.

But when we looked for a gene called Pdx1 that controls the secretion of insulin, we found it was missing, as were 87 other genes surrounding it. Some of these missing genes, including Pdx1, are essential and without them an animal cannot survive. So where are they?

The first clue was that, in several of the sand rat’s body tissues, we found the chemical products that the instructions from the “missing” genes would create. This would only be possible if the genes were present somewhere in the genome, indicating that they weren’t really missing but just hidden.

[Read more…]

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Beating the odds for lucky mutations

Jordana Cepelewicz writes: In 1944, a Columbia University doctoral student in genetics named Evelyn Witkin made a fortuitous mistake. During her first experiment in a laboratory at Cold Spring Harbor, in New York, she accidentally irradiated millions of E. coli with a lethal dose of ultraviolet light. When she returned the following day to check on the samples, they were all dead — except for one, in which four bacterial cells had survived and continued to grow. Somehow, those cells were resistant to UV radiation. To Witkin, it seemed like a remarkably lucky coincidence that any cells in the culture had emerged with precisely the mutation they needed to survive — so much so that she questioned whether it was a coincidence at all.

For the next two decades, Witkin sought to understand how and why these mutants had emerged. Her research led her to what is now known as the SOS response, a DNA repair mechanism that bacteria employ when their genomes are damaged, during which dozens of genes become active and the rate of mutation goes up. Those extra mutations are more often detrimental than beneficial, but they enable adaptations, such as the development of resistance to UV or antibiotics.

The question that has tormented some evolutionary biologists ever since is whether nature favored this arrangement. Is the upsurge in mutations merely a secondary consequence of a repair process inherently prone to error? Or, as some researchers claim, is the increase in the mutation rate itself an evolved adaptation, one that helps bacteria evolve advantageous traits more quickly in stressful environments?

The scientific challenge has not just been to demonstrate convincingly that harsh environments cause nonrandom mutations. It has also been to find a plausible mechanism consistent with the rest of molecular biology that could make lucky mutations more likely. Waves of studies in bacteria and more complex organisms have sought those answers for decades. [Continue reading…]

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Here’s what the last common ancestor of apes and humans looked like

Charles Q. Choi writes: The most complete extinct-ape skull ever found reveals what the last common ancestor of all living apes and humans might have looked like, according to a new study.

The 13-million-year-old infant skull, which its discoverers nicknamed “Alesi,” was unearthed in Kenya in 2014. It likely belonged to a fruit-eating, slow-climbing primate that resembled a baby gibbon, the researchers said.

Among the living primates, humans are most closely related to the apes, which include the lesser apes (gibbons) and the great apes (chimpanzees, gorillas and orangutans). These so-called hominoids — that is, the gibbons, great apes and humans — emerged and diversified during the Miocene epoch, approximately 23 million to 5 million years ago. (The last common ancestor that humans had with chimpanzees lived about 6 million to 7 million years ago.)

Much remains unknown about the common ancestors of living apes and humans from the critical time when these branches diverged. Fossil evidence from this part of the primate family tree is scarce, and consists mostly of isolated teeth and broken jaw fragments. As such, researchers were not sure what the last common ancestors of living apes and humans might have looked like, and even whether they originated in Africa or Eurasia. [Continue reading…]

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How to slam dunk creationists when it comes to the theory of evolution

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By Paul Braterman, University of Glasgow

The 2001 discovery of the seven million-year-old Sahelanthropus, the first known upright ape-like creatures, was yet more proof of humanity’s place among the great apes. And yet Mike Pence, then a representative and now US vice president, argues for the opposite conclusion.

For him, our ideas about our ancestors have changed, proving once more that evolution was a theory, and therefore we should be free to teach other theories alongside evolution in our classrooms.

A skull cast of Sahelanthropus, the first upright ape-like creatures which lived seven million years ago.
Didier Descouens, CC BY-SA

How to respond? The usual answer is that we should teach students the meaning of the word “theory” as used in science – that is, a hypothesis (or idea) that has stood up to repeated testing. Pence’s argument will then be exposed to be what philosophers call an equivocation – an argument that only seems to make sense because the same word is being used in two different senses.

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Octopus research shows that consciousness isn’t what makes humans special

Olivia Goldhill writes: Whether or not octopuses should be viewed as charming or terrifying very much depends on your personal perspective. But it’s hard to deny their intelligence.

Octopuses can squirt water at an annoyingly bright bulb until it short-circuits. They can tell humans apart (even those who are wearing the same uniform). And, according to Peter Godfrey-Smith, a philosophy professor at University of Sydney and City University of New York, they are the closest creature to an alien here on earth.

That’s because octopuses are the most complex animal with the most distant common ancestor to humans. There’s some uncertainty about which precise ancestor was most recently shared by octopuses and humans, but, Godfrey-Smith says, “It was probably an animal about the size of a leech or flatworm with neurons numbering perhaps in the thousands, but not more than that.”

This means that octopuses have very little in common with humans, evolution-wise. They have developed eyes, limbs, and brains via a completely separate route, with very different ancestors, from humans. And they seem to have come by their impressive cognitive functioning—and likely consciousness—by different means. [Continue reading…]

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Aliens in our midst

Douglas Fox writes: Leonid Moroz has spent two decades trying to wrap his head around a mind-boggling idea: even as scientists start to look for alien life in other planets, there might already be aliens, with surprisingly different biology and brains, right here on Earth. Those aliens have hidden in plain sight for millennia. They have plenty to teach us about the nature of evolution, and what to expect when we finally discover life on other worlds.

Moroz, a neuroscientist, saw the first hint of his discovery back in the summer of 1995, not long after arriving in the United States from his native Russia. He spent that summer at the Friday Harbor marine laboratory in Washington. The lab sat amid an archipelago of forested islands in Puget Sound – a crossroads of opposing tides and currents that carried hundreds of animal species past the rocky shore: swarms of jellyfish, amphipod crustaceans, undulating sea lilies, nudibranch slugs, flatworms, and the larvae of fish, sea stars and countless other animals. These creatures represented not just the far reaches of Puget Sound, but also the farthest branches of the animal tree of life. Moroz spent hours out on the pier behind the lab, collecting animals so he could study their nerves. He had devoted years to studying nervous systems across the animal kingdom, in hopes of understanding the evolutionary origin of brains and intelligence. But he came to Friday Harbor to find one animal in particular.

He trained his eyes to recognise its bulbous, transparent body in the sunlit water: an iridescent glint and fleeting shards of rainbow light, scattered by the rhythmic beating of thousands of hair-like cilia, propelling it through the water. This type of animal, called a ctenophore (pronounced ‘ten-o-for’ or ‘teen-o-for’), was long considered just another kind of jellyfish. But that summer at Friday Harbor, Moroz made a startling discovery: beneath this animal’s humdrum exterior was a monumental case of mistaken identity. From his very first experiments, he could see that these animals were unrelated to jellyfish. In fact, they were profoundly different from any other animal on Earth.

Moroz reached this conclusion by testing the nerve cells of ctenophores for the neurotransmitters serotonin, dopamine and nitric oxide, chemical messengers considered the universal neural language of all animals. But try as he might, he could not find these molecules. The implications were profound.

The ctenophore was already known for having a relatively advanced nervous system; but these first experiments by Moroz showed that its nerves were constructed from a different set of molecular building blocks – different from any other animal – using ‘a different chemical language’, says Moroz: these animals are ‘aliens of the sea’.

If Moroz is right, then the ctenophore represents an evolutionary experiment of stunning proportions, one that has been running for more than half a billion years. This separate pathway of evolution – a sort of Evolution 2.0 – has invented neurons, muscles and other specialised tissues, independently from the rest of the animal kingdom, using different starting materials. [Continue reading…]

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How to turn a fox into a dog

Lee Dugatkin and Lyudmila Trut: Deep inside my soul,” says Lyudmila Trut, “is a pathological love for animals.” She inherited this from her mother, who was a great dog lover. Lyudmila had grown up with dogs as pets, and even during World War II, when food was horribly scarce, her mother would feed starving stray dogs, telling her, “If we don’t feed them, Lyudmila, how will they survive? They need people.” Following her mother’s example, Lyudmila always carries some kind of treat in a pocket in case she encounters a stray dog. And she’s never forgotten that domesticated animals need people. She knows that this is how we’ve designed them.

In 1958, Lyudmila was just finishing up her studies at Moscow State University, home of Leonid Krushinsky, a pioneering Russian researcher in animal behavior. Dmitri Belyaev was friends with Krushinsky and admired his work. Belyaev had recently accepted a position as vice director of a new research institute in a giant Soviet city of science called Akademgorodok, near Novosibirsk, Siberia. He was searching for someone to lead an experiment he would begin in earnest at Akademgorodok. Dmitri intended to run an experiment domesticating silver foxes, and so the person he sought needed the kind of sophisticated skills in animal behavior that Krushinksy taught.

Belyaev went to visit Krushinsky at his office at Moscow State’s Sparrow Hill campus for advice about who might work with him on this experiment. Ensconced in the grand setting of Krushinsky’s building, with its palatial ceilings, marble floors, ornate columns, and fine art statues, he described his plans for the experiment and explained that he was looking for talented graduates to assist with the work. Krushinsky put the word out, and when Lyudmila heard about the opportunity, she was immediately captivated. Her own undergraduate work had been on the behavior of crabs, and as fascinating as their complex behavior could be, the prospect of working with foxes, so closely related to her beloved dogs, and with such a well-respected scientist as Belyaev, was tantalizing.

In early 1958, Lyudmila went to meet with Belyaev at his office. She was immediately struck by how unusual he was for a male Soviet scientist, especially one of his rank. Many were quite high-handed, and condescending to women. Lyudmila, who has a genial, smiling manner and stands just five feet tall, with her wavy brown hair cropped quite short, looked young for her age, and she hadn’t even finished her undergraduate studies, but Dmitri spoke to her as an equal. She was riveted, she recalls, by his piercing blue eyes, which so strongly communicated his intelligence and drive, but also emanated an extraordinary empathy.

She felt privileged to be invited into the confidence of this extraordinary man, who shared with her so openly about the bold work he was proposing. She had never experienced such a distinctive combination of confidence and warmth in a person. Dmitri told Lyudmila what he had in mind. “He told me that he wanted to make a dog out of a fox,” she recalls. Probing how creative she would be about conducting the experiment, Belyaev asked her, “You are now located on a fox farm that has several hundred foxes, and you need to select the 20 calmest ones for the experiment. How will you do it?” She had no experience whatsoever with foxes, and had only a vague notion of what the fox farms might be like and what sort of welcome she might receive at them. But she was a confident young woman, and she did the best she could to suggest some reasonable possibilities. She would try different methods, she said, talk to people who had worked with foxes, read up on what was known in the literature. Dmitri sat back and listened, gauging how committed she would be to the work and to developing techniques for such a novel study. She must be not only rigorously scientific, but also quite inventive. Was she really ready to go to Novosibirsk, to move to Akademgorodok, he asked her? After all, moving to the heart of Siberia was a life change not to be taken lightly. [Continue reading…]

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In Neanderthal DNA, signs of a mysterious human migration

Carl Zimmer writes: With fossils and DNA, scientists are piecing together a picture of humanity’s beginnings, an origin story with more twists than anything you would find at the movie theater.

The expert consensus now is that Homo sapiens evolved at least 300,000 years ago in Africa. Only much later — roughly 70,000 years ago — did a small group of Africans establish themselves on other continents, giving rise to other populations of people today.

To Johannes Krause, the director of the Max Planck Institute for Human History in Germany, that gap seems peculiar. “Why did people not leave Africa before?” he asked in an interview. After all, he observed, the continent is physically linked to the Near East. “You could have just walked out.”

In a study published Tuesday in Nature Communications, Dr. Krause and his colleagues report that Africans did indeed walk out — over 270,000 years ago.

Based on newly discovered DNA in fossils, the researchers conclude that a wave of early Homo sapiens, or close relatives of our species, made their way from Africa to Europe. There, they interbred with Neanderthals.

Then the ancient African migrants disappeared. But some of their DNA endured in later generations of Neanderthals.

“This is now a comprehensive picture,” Dr. Krause said. “It brings everything together.” [Continue reading…]

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Can microbes encourage altruism?

Elizabeth Svoboda writes: Parasites are among nature’s most skillful manipulators — and one of their specialties is making hosts perform reckless acts of irrational self-harm. There’s Toxoplasma gondii, which drives mice to seek out cats eager to eat them, and the liver fluke Dicrocoelium dendriticum, which motivates ants to climb blades of grass, exposing them to cows and sheep hungry for a snack. There’s Spinochordodes tellinii, the hairworm that compels crickets to drown themselves so the worm can access the water it needs to breed. The hosts’ self-sacrifice gains them nothing but serves the parasites’ hidden agenda, enabling them to complete their own life cycle.

Now researchers are beginning to explore whether parasitic manipulations may spur host behaviors that are selfless rather than suicidal. They are wondering whether microbes might be fundamentally responsible for many of the altruistic behaviors that animals show toward their own kind. Altruism may seem easy to justify ethically or strategically, but explaining how it could have persisted in a survival-of-the-fittest world is surprisingly difficult and has puzzled evolutionary theorists going all the way back to Darwin. If microbes in the gut or other tissues can nudge their hosts toward generosity for selfish reasons of their own, altruism may become less enigmatic.

A recently developed mathematical model and related computer simulations by a trio of researchers at Tel Aviv University appear to validate this theory. The researchers showed that transmissible microbes that promoted altruism in their hosts won the survival battle over microbes that did not — and when this happened, altruism became a stable trait in the host population. The research was published in Nature Communications earlier this year.

“The story is fascinating, because we don’t think of altruism in terms of the host-microbiome relationship,” said John Bienenstock, a biologist at McMaster University in Hamilton, Ontario, and director of the Brain-Body Institute at St. Joseph’s Healthcare Hamilton, who was not involved with the simulation work. “You can’t ignore the possible effect of what your bug population is doing.” [Continue reading…]

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Was the first song a lullaby?

Tom Jacobs writes: Why do humans play, and listen, to music? The question has long baffled evolutionary theorists. Some suggest it had its origins in courtship rituals, while others contend it had (and has) a unique ability to bond people together to work toward a common goal.

Now, a couple of Harvard University researchers have proposed a new concept: They argue that the earliest music  —  and perhaps the prototype for everything from Bach to rap  — may just have been the songs mothers sing to their infants.

Maybe the first musical genre wasn’t the love song, but rather the lullaby.

“The evolution of music must be a complex, multi-step process, with different features developing for different reasons,” says Samuel Mehr, who co-authored the paper with psychologist Max Krasnow. “Our theory raises the possibility that infant-directed song is the starting point for all that.”

Mothers vocalize to their babies “across many, if not all, cultures,” the researches note in the journal Evolution and Human Behavior. Its ubiquity suggests this activity plays a positive role in the parent-child relationship, presumably soothing infants by proving that someone is there and paying attention to them. [Continue reading…]

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New evidence that Lucy, our most famous ancestor, had superstrong arms

The Washington Post reports: In Ethiopia, she is known as “Dinkinesh” — Amharic for “you are marvelous.” It’s an apt name for one of the most complete ancient hominid skeletons ever found, an assemblage of fossilized bones that has given scientists unprecedented insight into the history of humanity.

You probably know her as Lucy.

Discovered in 1974, wedged into a gully in Ethiopia’s Awash Valley, the delicate, diminutive skeleton is both uncannily familiar and alluringly strange. In some ways, the 3.2-million-year-old Australopithecus was a lot like us; her hips, feet and long legs were clearly made for walking. But she also had long arms and dexterous curved fingers, much like modern apes that still swing from the trees.

So, for decades scientists have wondered: Who exactly was Lucy? Was she lumbering and land-bound, like us modern humans? Or did she retain some of the ancient climbing abilities that made her ancestors — and our own — champions of the treetops?

A new study suggests she was a little of both: Though her lower limbs were adapted for bipedalism, she had exceptionally strong arm bones that allowed her to haul herself up branches, researchers reported Wednesday in the journal PLoS One. [Continue reading…]

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Dino-killing asteroid may have punctured Earth’s crust

Live Science reports: After analyzing the crater from the cosmic impact that ended the age of dinosaurs, scientists now say the object that smacked into the planet may have punched nearly all the way through Earth’s crust, according to a new study.

The finding could shed light on how impacts can reshape the faces of planets and how such collisions can generate new habitats for life, the researchers said.

Asteroids and comets occasionally pelt Earth’s surface. Still, for the most part, changes to the planet’s surface result largely from erosion due to rain and wind, “as well as plate tectonics, which generates mountains and ocean trenches,” said study co-author Sean Gulick, a marine geophysicist at the University of Texas at Austin.

In contrast, on the solar system’s other rocky planets, erosion and plate tectonics typically have little, if any, influence on the planetary surfaces. “The key driver of surface changes on those planets is constantly getting hit by stuff from space,” Gulick told Live Science. [Continue reading…]

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