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Category: Evolution

Ancient microbial life used arsenic to thrive in a world without oxygen

Ancient microbial life used arsenic to thrive in a world without oxygen

Purple microbial mats offer clues to how ancient life functioned. Pieter Visscher, CC BY-ND By Pieter Visscher, University of Connecticut; Brendan Paul Burns, UNSW, and Kimberley L. Gallagher, Quinnipiac University Billions of years ago, life on Earth was mostly just large slimy mats of microbes living in shallow water. Sometimes, these microbial communities made carbonate minerals that over many years cemented together to become layered limestone rocks called stromatolites. They are the oldest evidence of life on Earth. But the…

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Humans aren’t inherently selfish – we’re actually hardwired to work together

Humans aren’t inherently selfish – we’re actually hardwired to work together

Franzi/Shutterstock By Steve Taylor, Leeds Beckett University There has long been a general assumption that human beings are essentially selfish. We’re apparently ruthless, with strong impulses to compete against each other for resources and to accumulate power and possessions. If we are kind to one another, it’s usually because we have ulterior motives. If we are good, it’s only because we have managed to control and transcend our innate selfishness and brutality. This bleak view of human nature is closely…

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‘Zombie’ microbes redefine life’s energy limits

‘Zombie’ microbes redefine life’s energy limits

Jordana Cepelewicz writes: Energy drives the planet; it’s the currency that all living things use to grow, develop and function. But just how little energy do cells need to get by? Sediment-dwelling microbes below the seafloor — which may outnumber the microbial cells found in the oceans themselves — are providing some surprising answers. The organisms not only challenge what scientists thought they knew about life’s energy needs, but hint at new ways of defining what life is and where…

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On the origin of an interstellar species

On the origin of an interstellar species

Caleb Scharf writes: Once upon a time there was a molecule. That molecule, when it reacted with other molecules, set in motion a story that would result in the universe making another molecule almost exactly like that first one. Then that new molecule, when it reacted with other molecules, set in motion a story that would result in another molecule almost exactly like it. And all across the galaxy there were molecules setting stories in motion. A fundamental property of…

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Catastrophe drives evolution but life resides in the pauses

Catastrophe drives evolution but life resides in the pauses

Renée A Duckworth writes: In certain places around the world – in the Badlands near Drumheller in Alberta, Canada, in the Geulhemmergroeve tunnels in the Netherlands, or in the Hell Creek formation in eastern Montana – you can touch a thin line of rock, and know you are touching the most famous mass extinction event on Earth. This Cretaceous-Paleogene (K-Pg) boundary layer is a seam of clay found all over the world, enriched with iridium – an element that appears…

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Why plants are green

Why plants are green

Rodrigo Pérez Ortega writes: From large trees in the Amazon jungle to houseplants to seaweed in the ocean, green is the color that reigns over the plant kingdom. Why green, and not blue or magenta or gray? The simple answer is that although plants absorb almost all the photons in the red and blue regions of the light spectrum, they absorb only about 90% of the green photons. If they absorbed more, they would look black to our eyes. Plants…

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Ancient microbial arms race sharpened our immune system — but also left us vulnerable

Ancient microbial arms race sharpened our immune system — but also left us vulnerable

Ann Gibbons writes: At a recent symposium on the evolution of infectious diseases, University of California, San Diego (UCSD), pathologist Nissi Varki noted that humans suffer from a long list of deadly diseases—including typhoid fever, cholera, mumps, whooping cough, measles, smallpox, polio, and gonorrhea—that don’t afflict apes and most other mammals. All of those pathogens follow the same well-trodden pathway to break into our cells: They manipulate sugar molecules called sialic acids. Hundreds of millions of these sugars stud the…

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DNA linked to severe Covid-19 was inherited from Neanderthals, study finds

DNA linked to severe Covid-19 was inherited from Neanderthals, study finds

The New York Times reports: A stretch of DNA linked to Covid-19 was passed down from Neanderthals 60,000 years ago, according to a new study. Scientists don’t yet know why this particular segment increases the risk of severe illness from the coronavirus. But the new findings, which were posted online on Friday and have not yet been published in a scientific journal, show how some clues to modern health stem from ancient history. “This interbreeding effect that happened 60,000 years…

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Halos of clay can preserve billion-year-old microbes

Halos of clay can preserve billion-year-old microbes

Meredith Fore writes: Putting together the history of life on Earth has a major stumbling block: Prior to about 540 million years ago, most life was squishy and microbial, which meant it rarely fossilized. This major blind spot makes it difficult for researchers to study ancient life at a key point in Earth’s evolutionary history, and even more difficult to potentially find evidence of ancient microbial life on Mars. But a recent study of kaolinite, an aluminum-rich clay, gives researchers…

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Why are there so many humans?

Why are there so many humans?

By Karen L. Kramer, Sapiens, June 9, 2020 Something curious happened in human population history over the last 1 million years. First, our numbers fell to as low as 18,500, and our ancestors were more endangered than chimpanzees and gorillas. Then we bounced back to extraordinary levels, far surpassing the other great apes. Today the total population of gorillas, chimpanzees, bonobos, and orangutans is estimated to be only around 500,000, according to the World Wildlife Fund. Many species are critically…

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Are viruses alive? Perhaps we’re asking the wrong question

Are viruses alive? Perhaps we’re asking the wrong question

Axel_Kock/Shutterstock Hugh Harris, University College Cork Viruses are an inescapable part of life, especially in a global viral pandemic. Yet ask a roomful of scientists if viruses are alive and you’ll get a very mixed response. The truth is, we don’t fully understand viruses, and we’re still trying to understand life. Some properties of living things are absent from viruses, such as cellular structure, metabolism (the chemical reactions that take place in cells) and homeostasis (keeping a stable internal environment)….

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Out-of-sync ‘loners’ may secretly protect orderly swarms

Out-of-sync ‘loners’ may secretly protect orderly swarms

Jordana Cepelewicz writes: Dense clouds of starlings dip and soar, congregating in undulating curtains that darken the sky; hundreds of thousands of wildebeests thunder together across the plains of Africa in a coordinated, seemingly never-ending migratory loop; fireflies blink in unison; entire forests of bamboo blossom at once. Scientists have studied these mesmerizing feats of synchronization for decades, trying to tease apart the factors that enable such cooperation and complexity. Yet there are always individuals that don’t participate in the…

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How staying indoors affects your immune system

How staying indoors affects your immune system

Linda Geddes writes: For the past two months, a sizable chunk of the world’s population has been shuttered inside their homes, only stepping out for essential supplies. Although this may have reduced our chances of being exposed to coronavirus, it may have had a less obvious effect on our immune systems by leaving us more vulnerable to other infections. Humans evolved on a planet with a 24-hour cycle of light and dark, and our bodies are set up to work…

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The coronavirus is mutating, but that’s not necessarily good or bad

The coronavirus is mutating, but that’s not necessarily good or bad

Jeremy Draghi and C. Brandon Ogbunu write: In early March, the Chinese Academy of Sciences’ National Science Review published a peer-reviewed study titled “On the Origin and Continuing Evolution of SARS-CoV-2.” The authors argued that the various strains of SARS-CoV-2, the coronavirus that causes Covid-19, could be grouped into two clusters: An “L” type, which was predominant during the early weeks of the outbreak in Wuhan, and an “S” type, which could be distinguished from the L type by only…

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The coronavirus genome is like a shipping label that lets epidemiologists track where it’s been

The coronavirus genome is like a shipping label that lets epidemiologists track where it’s been

The steady rate of genetic changes lets researchers recreate how a virus has travelled. nextstrain.org, CC BY By Bert Ely, University of South Carolina and Taylor Carter, University of South Carolina Following the coronavirus’s spread through the population – and anticipating its next move – is an important part of the public health response to the new disease, especially since containment is our only defense so far. Just looking at an infected person doesn’t tell you where their version of…

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Why mammalian brains are geared toward kindness

Why mammalian brains are geared toward kindness

Patricia Churchland writes: Three myths about morality remain alluring: only humans act on moral emotions, moral precepts are divine in origin, and learning to behave morally goes against our thoroughly selfish nature. Converging data from many sciences, including ethology, anthropology, genetics, and neuroscience, have challenged all three of these myths. First, self-sacrifice, given the pressing needs of close kin or conspecifics to whom they are attached, has been documented in many mammalian species—wolves, marmosets, dolphins, and even rodents. Birds display…

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