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Category: Evolution

A billion years before sex, ancient cells were equipped for it

A billion years before sex, ancient cells were equipped for it

Jake Buehler writes: Most complex organisms engage in a strange bit of genomic math at some point in their lives: To multiply, they subtract and then add. That is, to reproduce through the process of meiosis they create specialized sex cells, or gametes, with half the usual number of chromosomes; they then merge pairs of those gametes to create new individuals with a full, unique genome. Sexual reproduction is nearly ubiquitous among eukaryotes — organisms from kelp to koalas that…

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An ancient link between heart and head — as seen in the blobby, headless sea squirt

An ancient link between heart and head — as seen in the blobby, headless sea squirt

Nature reports: The head is stately, calm, and wise, And bears a princely part; And down below in secret lies The warm, impulsive heart. — John Godfrey Saxe, 1898 For centuries, writers have mused on the heart as the core of humanity’s passion, its morals, its valour. The head, by contrast, was the seat of cold, hard rationality. In 1898, US poet John Godfrey Saxe wrote of such differences, but concluded his verses arguing that the heart and head are…

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New database reveals impact humans are having on evolution

New database reveals impact humans are having on evolution

Wired reports: Charles Darwin thought of evolution as an incremental process, like the patient creep of glaciers or the march of continental plates. “We see nothing of these slow changes in progress until the hand of time has marked the long lapse of ages,” he wrote in On the Origin of Species, his famous 1859 treatise on natural selection. But by the 1970s, scientists were finding evidence that Darwin might be wrong—at least about the timescale. Peppered moths living in…

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Secrets of early animal evolution revealed by chromosome ‘tectonics’

Secrets of early animal evolution revealed by chromosome ‘tectonics’

Viviane Callier writes: Chromosomes, the bundles of DNA that star in the mitotic ballet of cell division, play a leading role in complex life. But the question of how chromosomes came to exist and evolve has long been discouragingly hard to answer. This is due partly to the lack of chromosome-level genomic information and partly to the suspicion that eons of evolutionary change have washed away any clues about that ancient history. Now, in a paper appearing today in Science…

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Scientists find hints of a hidden mass extinction 30 million years ago

Scientists find hints of a hidden mass extinction 30 million years ago

Inside Science reports: Nearly two-thirds of mammal species in Africa and the Arabian Peninsula may have died off about 30 million years ago, a mass extinction that escaped detection for decades until now, a new study finds. During a time span known as the Eocene-Oligocene transition between 40 million and 34 million years ago, Earth’s climate shifted dramatically, with the planet growing cooler, ice sheets expanding and sea levels dropping worldwide. During the Eocene, Antarctica was covered by lush forests,…

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Humans have evolved to stay active even in old age, new hypothesis claims

Humans have evolved to stay active even in old age, new hypothesis claims

Science Alert reports: In the modern western world, people tend to reduce their levels of physical activity as they get older. But with this inactivity comes a raft of adverse health effects, so why didn’t evolution engineer us so that people could maintain a decent quality of life as they inevitably slow down? In a newly published paper, researchers argue it is because we aren’t meant to reduce our physical activity as we age at all. Enter the ‘active grandparent…

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At the dawn of life, heat may have driven cell division

At the dawn of life, heat may have driven cell division

Carrie Arnold writes: An elegant ballet of proteins enables modern cells to replicate themselves. During cell division, structural proteins and enzymes coordinate the duplication of DNA, the division of a cell’s cytoplasmic contents, and the cinching of the membrane that cleaves the cell. Getting these processes right is crucial because errors can lead to daughter cells that are abnormal or unviable. Billions of years ago, the same challenge must have faced the first self-organizing membranous bundles of chemicals arising spontaneously…

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How the Western diet has derailed our evolution

How the Western diet has derailed our evolution

Moises Velesquez-Manoff writes: For the microbiologist Justin Sonnenburg, that career-defining moment—the discovery that changed the trajectory of his research, inspiring him to study how diet and native microbes shape our risk for disease—came from a village in the African hinterlands. A group of Italian microbiologists had compared the intestinal microbes of young villagers in Burkina Faso with those of children in Florence, Italy. The villagers, who subsisted on a diet of mostly millet and sorghum, harbored far more microbial diversity…

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Mass extinctions don’t drive evolutionary change — life does

Mass extinctions don’t drive evolutionary change — life does

Riley Black writes: Of all the species that have ever lived on our planet, more than 99 per cent are extinct. Most of these organisms disappeared through the constant shuffle of ecological and evolutionary change. But not all. Many species have vanished in a geological snap during mass extinctions – truly catastrophic events where the rate of extinction vastly outpaces the origin of new species. For a time, these ecological disasters were thought to drive a great flourish of new…

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Imagination: It might be the core of what human brains evolved to do

Imagination: It might be the core of what human brains evolved to do

Philip Ball writes: ‘To me,’ wrote William Blake in 1799, ‘this world is all one continued vision of fancy or imagination.’ The imagination, he later added, ‘is not a state: it is the human existence itself.’ Blake, a painter as well as a poet, created images that acquire their power not only from a certain naive artistic technique, but because they are striving to transcend it – to convey a vision of the world beyond superficial appearances, which only imagination…

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Why I still believe Covid-19 could not have originated in a lab

Why I still believe Covid-19 could not have originated in a lab

By Wendy Orent Where did the Covid-19 pandemic come from? Almost since the beginning of the outbreak, a bitter and explosive controversy has raged over the origins of the novel coronavirus known as SARS-CoV-2. The rapid shut-down of the Huanan Seafood Wholesale Market in Wuhan immediately suggested to Western observers that the Chinese government itself thought that the market was the source, especially since 26 out of 47 of the original cases could be linked to it. An article published…

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The study of the mind needs a Copernican shift in perspective

The study of the mind needs a Copernican shift in perspective

Pamela Lyon writes: In On the Origin of Species (1859), Charles Darwin draws a picture of the long sweep of evolution, from the beginning of life, playing out along two fundamental axes: physical and mental. Body and mind. All living beings, not just some, evolve by natural selection in both ‘corporeal and mental endowments’, he writes. When psychology has accepted this view of nature, Darwin predicts, the science of mind ‘will be based on a new foundation’, the necessarily gradual…

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Ants could help explain why human brains mysteriously shrank thousands of years ago

Ants could help explain why human brains mysteriously shrank thousands of years ago

Science Alert reports: In the 6 million years since our ancestors first branched off from our ancient primate relatives, the volume of the human brain has nearly quadrupled. What many people don’t realize, however, is that sometime after the last ice age, that very brain actually began to shrink. The result is that today, our brains are slightly smaller than those of early humans living 100,000 years ago, and yet no one really knows when or why this happened. Now,…

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Flatworms can reproduce ripping themselves in half

Flatworms can reproduce ripping themselves in half

Ed Yong writes: When planarian flatworms want to reproduce, some have sex. Others, more straightforwardly, tear themselves in two. The latter option is fast and violent. The planarian begins as a small, flattened, sluglike creature with a spade-shaped head and two googly eyes. After a few minutes of stretching and ripping, it separates into two halves—a head and a tail. Within days, the head piece grows a tail. And even more miraculously, the tail regrows its head. “It’s just mind-blowing,”…

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The complex truth about ‘junk DNA’

The complex truth about ‘junk DNA’

Jake Buehler writes: Imagine the human genome as a string stretching out for the length of a football field, with all the genes that encode proteins clustered at the end near your feet. Take two big steps forward; all the protein information is now behind you. The human genome has three billion base pairs in its DNA, but only about 2% of them encode proteins. The rest seems like pointless bloat, a profusion of sequence duplications and genomic dead ends…

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Why the coronavirus has changed as it has, and what it means going forward

Why the coronavirus has changed as it has, and what it means going forward

STAT reports: It’s impossible to say how the coronavirus will continue to evolve. Those changes, after all, are a result of random mutations. But there are some fundamental principles that explain why the virus has morphed as it has, principles that could guide our understanding of its ongoing evolution — and what that means for our future with the pathogen. The great fear is that nature could spit out some new variant that completely saps the power of vaccines and…

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