Africa’s deadliest rapids give birth to new fish species

The world’s largest and deadliest rapids are also crucibles of life. According to a new study, the final stretch of Africa’s Congo River—which packs five times the water flow of the Mississippi River into just 320 kilometers—has likely given birth to several new fish species since it formed some 5 million years ago. That’s impressive, because even though scientists have long known that geographical features like mountains and rivers can isolate animal populations—eventually giving rise to new species—rushing water is typically not thought to be the culprit. To find out just how different the fish of Congo’s Inga Rapids and nearby waters were, evolutionary biologists captured about 50 rock-dwelling fish known as cichlids from the genus Teleogramma. They then examined them for morphological differences and sequenced about 2% of their DNA. What they found surprised them: Just as these waters have been so deadly to people—no one had successfully run the rapids until 6 years ago—they can also be deadly to fish that try to navigate through them. Because the tumultuous currents cut groups of fish off from one another, they evolve independently and, eventually, become new species. In the new study, all known and potentially new species were separated by rapids or other hydrological features, the scientists report this month in Molecular Ecology. Two of the species live just across the river from each other, a mere 1.5 kilometers. Altogether, researchers have used DNA differences to confirm the existence of four species, including a new one they named after former U.S. President Barack Obama. But there seem to be at least two other species there as well, swimming in the eddies.

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Einstein’s Lost Theory Describes a Universe Without a Big Bang

Einstein with Edwin Hubble, in 1931, at the Mount Wilson Observatory in California, looking through the lens of the 100-inch telescope through which Hubble discovered the expansion of the universe in 1929. Courtesy of the Archives, Calif Inst of Technology. In 1917, a year after Albert Einstein’s general theory of relativity was published—but still two years before he would become the international celebrity we know—Einstein chose to tackle the entire universe . For anyone else, this might seem an exceedingly ambitious task—but this was Einstein. Einstein began by applying his field equations of gravitation to what he considered to be the entire universe. The field equations were the mathematical essence of his general theory of relativity, which extended Newton’s theory of gravity to realms where speeds approach that of light and masses are very large. But his math was better than he wanted to believe—...

There’s a Previously Undiscovered Organ in Your Body, And It Could Explain How Cancer Spreads

Ever heard of the interstitium? No? That’s OK, you’re not alone — scientists hadn’t either. Until recently. And, hey, guess what — you’ve got one! The interstitium is your newest organ. Scientists identified it for the first time because they are better able to observe living tissues at a microscopic scale, according to a recent study published in Scientific Reports , Scientists had long believed that connective tissue surrounding our organs was a thick, compact layer. That’s what they saw when they looked at it in the lab, outside the body, at least. But in a routine endoscopy (exploration of the gastrointestinal tract), a micro camera revealed something unexpected: When observed in a living body, the connective tissue turned out to be “an open, fluid-filled space supported by a lattice made of thick collagen bundles,” pathologist and study author Neil Theise told Research Gate . This network of channels is present throughout ...

First light-bending calculator designed with metamaterials

Exotic materials that bend light in extreme ways could be used to perform complex mathematical operations, creating a new kind of analogue computer. Tools for manipulating light waves have taken off in recent years thanks to the development of metamaterials . These materials have complex internal structures on scales smaller than the wavelength of the light they interact with, and so they produce unusual effects. Most famously, metamaterials promise to deliver " invisibility cloaks " that can route light around an object, making it seem to disappear. Nader Engheta at the University of Pennsylvania, Philadelphia, and his colleagues decided to explore a different use for metamaterials, one that adapts the old idea of analogue computing . Today's digital computers are based on electrical switches that are either on or off. But before these machines were analogue computers based on varying electrical or mechanical properties. The slide rule is one example...

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