Monday, January 20, 2020

Here's What Scientists Know About 'Screen Time' and Your Health

By , , '
 
 
Humans are bombarded by digital media 24/7. Is that a problem?
(Image: © Bruce Rolff/Shutterstock)
There's a lot of talk about digital media. Increasing screen time has created worries about media's impacts on democracy, addiction, depression, relationships, learning, health, privacy and much more. The effects are frequently assumed to be huge, even apocalyptic.
Scientific data, however, often fail to confirm what seems true based on everyday experiences. In study after study, screen time is often not correlated with important effects at a magnitude that matches the concerns and expectations of media consumers, critics, teachers, parents, pediatricians and even the researchers themselves. For example, a recent review of over 200 studies about social media concluded there was almost no effect of greater screen time on psychological well-being. A comprehensive study of adolescents reported small effects of screen time on brain development, and no relationship between media use and cognitive performance. A review of 20 studies about the effects of multitasking with media — that is, using two or more screens at the same time — showed small declines in cognitive performance because of multitasking but also pointed out new studies that showed the opposite.
As communication, psychological and medical researchers interested in media effects, we are interested in how individuals' engagement with digital technology influences peoples' thoughts, emotions, behaviors, health and well-being.

Moving beyond 'screen time'

Has the power of media over modern life been overstated? Probably not, but no one knows, because there is a severe lack of knowledge about what people are actually seeing and doing on their screensIndividuals all around the world are now all looking at pretty much the same screens and spending a lot of time with them. However, the similarities between us end there. Many different kinds of applications, games and messages flow across people's screens. And, because it is so easy to create customized personal threads of experiences, each person ends up viewing very different material at different times. No two people share the same media experiences.
To determine the effects of media on people's lives, whether beneficial or harmful, requires knowledge of what people are actually seeing and doing on those screens. But researchers often mistakenly depend on a rather blunt metric — screen time.
Reports of screen time, the most common way to assess media use, are known to be terribly inaccurate and describe only total viewing time. Today, on a single screen, you can switch instantly between messaging a neighbor, watching the news, parenting a child, arranging for dinner delivery, planning a weekend trip, talking on an office video conference and even monitoring your car, home irrigation and lighting. Add to that more troublesome uses — bullying a classmate, hate speech or reading fabricated news. Knowing someone's screen time — their total dose of media — will not diagnose problems with any of that content.
A media solution based only on screen time is like medical advice to someone taking multiple prescription medications to reduce their total number of pills by half. Which medications and when?

Complex and unique nature of media use

What would be a better gauge of media consumption than screen time? Something that better captures the complexities of how individuals engage with media. Perhaps the details about specific categories of content — the names of the programs, software and websites - would be more informative. Sometimes that may be enough to highlight problems — playing a popular game more than intended, frequent visits to a suspicious political website or too much social time on Facebook.
Tracking big categories of content, however, is still not that helpful. My one hour of Facebook, for example, could be spent on self-expression and social comparison; yours could be filled with news, shopping, classes, games and videos. Further, our research finds that people now switch between content on their smartphones and laptops every 10 to 20 seconds on average. Many people average several hundred different smartphone sessions per day. The fast cadence certainly influences how people converse with each other and how engaged we are with information. And each bit of content is surrounded by other kinds of material. News read on Facebook sandwiches political content between social relationships, each one changing the interpretation of the other.

A call for a Human Screenome Project

In this era of technology and big data, we need a DVR for digital life that records the entirety of individuals' screen media experiences - what we call the screenome, analogous to the genome, microbiome and other "omes" that define an individual's unique characteristics and exposures.
An individual's screenome includes apps and websites, the specific content observed and created, all of the words, images and sounds on the screens, and their time of day, duration and sequencing. It includes whether the content is produced by the user or sent from others. And it includes characteristics of use, such as variations in how much one interacts with a screen, how quickly one switches between content, scrolls through screens, and turns the screen on and off.
Without knowledge of the whole screenome, no one — including researchers, critics, educators, journalists or policymakers — can accurately describe the new media chaos. People need much better data — for science, policy, parenting and more. And it needs to be collected and supported by individuals and organizations who are motivated to share the information for all to analyze and apply.
The benefits from studying the human genome required developing the field of genomics. The same will be true for the human screenome, the unique individual record of experiences that constitute psychological and social life on digital devices. Researchers now have the technologies to begin a serious study of screenomics, which we describe in the journal Nature. Now we need the data — a collective effort to produce, map and analyze a large and informative set of screenomes. A Human Screenome Project could inform academics, health professionals, educators, parents, advocacy groups, tech companies and policymakers about how to maximize the potential of media and remedy its most pernicious effects.
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This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.
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Ancient Australian Crystals Unlock History of Earth's First Magnetic Field


By Rafi Letzter - Staff Writer

It was a lot more powerful than anyone believed.

An image shows one of the tiny zircon crystals
found in Australia on a US dime. Even smaller 
particles within the zircon encode data about the 
state of the Earth's magnetic field at the time the crystal formed.
(Image: © University of Rochester / John Tarduno)


Tiny Crystals in Australia are helping scientists unlock the ancient history of our planet's first magnetic field, which disappeared hundreds of millions of years ago. And the crystals show that this field was a lot more powerful than anyone believed. That, in turn, could help answer a question about why life emerged on Earth.

Those tiny, old crystals are locked in rocks that date to well over half a billion years ago. At the time, tiny magnetic particles floated in the molten rock. But as that rock cooled, the particles, which aligned to the magnetic field orientation at the time, locked into place. And those particles still sit in a pose suggesting that they were influenced by a much more powerful magnetic field than scientists had assumed, a new study reveals.

Earth's magnetic field is generated by the planet's solid iron inner core spinning in a liquid-iron outer core. Extending far beyond our atmosphere, this field protects the planet from dangerous particles blasting through space, such as solar wind and cosmic rays. But because its visible effects on the planet's surface are so minimal, studying the field's long history is difficult. However, this history is important for understanding the future of our own planet and other planets in the universe. We know our planet has had a strong magnetic shield for a long time, because it kept its surface water and sprouted life. Otherwise, cosmic radiation would have blasted both life and water off the surface long ago. In that scenario, Earth would look a lot like Mars, where the old magnetic field collapsed as the planet cooled and its core stopped spinning, according to a statement from the researchers.

Earth has had a magnetic core for 4.2 billion years, according to the new study. But until 565 million years ago, long before the dinosaurs arrived and a bit before complex life emerged in the Cambrian explosion, that magnetic core worked completely differently. At that point, there was no inner core. But magnesium oxide, which had dissolved into the all-liquid core during the same giant impact that created Earth's moon, was slowly moving out of the core and into the mantle. That movement of magnesium generated movement in the liquid core that created Earth's early magnetic field.

When the magnesium oxide ran out, the field almost collapsed, researchers believe. But the solid inner core formed at around the same time and saved life on Earth.

Conventional wisdom held that the field produced by the old, magnesium-oxide magnet was a lot weaker than the one we have now. But studying those ancient ancient zircon crystals, which formed when the old magnetic field still suffused the planet, indicates that this was wrong.

"This research is telling us something about the formation of a habitable planet," John Tarduno, an Earth scientist at the University of Rochester and author of the new paper, said in the statement. "One of the questions we want to answer is why Earth evolved as it did, and this gives us even more evidence that the magnetic shielding was recorded very early on the planet."

The paper was published today (Jan. 20) in the journal Proceedings of the National Academy of Sciences.

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Are Birds Dinosaurs?

By Mindy Weisberger - Senior Writer

Modern birds can trace their origins to theropods, a branch of mostly meat-eaters on the dinosaur family tree.

In some birds, like this cassowary, the resemblance to extinct
 theropod dinosaurs is easy to see. (Image: © Shutterstock)

What do sparros, geese and owls have in common with a velociraptor or the mighty Tyrannosaurus rex? All can trace their origins to a bipedal, mostly meat-eating group of dinosaurs called theropods ("beast-footed") that first appeared around 231 million years ago, during the late Triassic Period.

The earliest birds shared much in common with their theropod relatives, including feathers and egg-laying. However, certain traits – such as sustained, powered flight – distinguished ancient birds from other theropods, and eventually came to define modern-bird lineage (even though not all modern birds fly).

Today, all non-avian dinosaurs are long extinct. But are birds still considered to be true dinosaurs?
In a word: Yes.

"Birds are living dinosaurs, just as we are mammals," said Julia Clarke, a paleontologist studying the evolution of flight and a professor with the Department of Geological Sciences at the University of Texas at Austin.

In spite of the physical differences that distinguish all mammals from other species, every animal in that group — living and extinct — can trace certain anatomical characteristics to a common ancestor. And the same is true for birds, Clarke told Live Science.

"They're firmly nested in that one part of the dinosaur tree," she said. "All of the species of birds we have today are descendants of one lineage of dinosaur: the theropod dinosaurs."
What makes a bird, a bird?

Modern birds have feathered tails and bodies, unfused shoulder bones, toothless beaks and forelimbs that are longer than their hind limbs. They also have a bony plate near their tails called a pygostyle. Other types of extinct theropods had one or more of these features, but only modern birds have all of them, according to Takuya Imai, an assistant professor with the Dinosaur Research Institute at Fukui Prefectural University in Fukui, Japan.

In a primitive bird from Japan called Fukuipteryx — a 120-million-year-old avian that Imai described in November 2019 and the earliest known bird with a pygostyle — the preserved structure closely resembled the pygostyle of a modern chicken, Imai previously told Live Science. In other words, some structures in modern birds can be traced back to some of their earliest ancestors.

However, primitive birds still had much in common with non-avian theropods, said Jingmai O'Connor, a paleontologist specializing in dinosaur-era birds and the transition from non-avian dinosaurs, at the Institute of Vertebrate Paleontology and Paleoanthroplogy in Beijing, China.

In fact, early birds were "very dinosaur-like" compared to modern birds, O'Connor told Live Science in an email. "Some had long, reptilian tails, teeth and claws on their hands," she said. And many theropod dinosaurs that were not birds had true feathers, "which are feathers that have a central part down the middle and branching barbs," according to Clarke.

Paleontologists distinguish between animal groups through precise measurements of subtle variations in bones and other fossilized body tissues, including "little bumps and tubercles [a rounded bulge on a bone] that are related to reorganizing different muscle groups," Clarke said. This morphological data is translated into numbers that are then processed by algorithms to pinpoint how animals are related, O'Connor explained. By using these algorithms in a system known as cladistics, experts can differentiate ancient birds from their theropod relatives.



Early birds

The earliest known bird is Archaeopteryx ("ancient wing"), which lived around 150 million years ago in what is now southern Germany. The creature weighed around 2 pounds(1 kilogram) and measured about 20 inches (50 centimeters) in length; fossil evidence shows that it sported plumage on its tail and body. The shape of its forelimbs and feathers also suggests that Archaeopteryx was capable of powered flight, a trait associated with most modern birds. However, unlike birds today, Archaeopteryx retained individual, clawlike fingers at the tips of its wings.

Fossils of birds from the early Cretaceous Period (145.5 million to 65.5 million years ago) have been found in northeastern China, such as Confuciusornis, which lived around 125 million years ago, and had a beak and long tail-feathers. Some Confuciusornis fossils, described in 2013, even included medullary bone, a spongy tissue found in female birds that are sexually mature, Live Science previously reported.

Another piece of fossil evidence links ancient birds to their modern relatives through their digestion, in the form of the earliest known bird pellet — a mass of indigestible fish bones coughed up by a Cretaceous avian in China around 120 million years ago.
Fly, robin, fly

One defining feature of birds is their ability to fly, requiring large forelimbs covered with asymmetrically-shaped feathers and roped in powerful muscles, O'Connor said.

"In the lineage evolving towards birds, most likely a lineage within the Troodontidae [a family of birdlike theropods], flight is what separates birds from their closest non-avian dinosaur (probable troodontid) kin," said O'Connor.

Then, after the evolution of flight, the small bones in birds' hands "become reduced and fused up to create this kind of stiffened structure that supports the feathers of the wing," Clarke said.

After the extinction of the non-avian dinosaurs at the end of the Cretaceous period, birds continued to evolve and diversify, developing more specialized features related to flight, such as an elongated structure in their breastbones (called a keel), and powerful pectoralis muscles to power the downstroke during flight, Clarke said.

"You see bigger and bigger pectoralis that are associated with this deep keel. And that evolved after the origin of flight and is present in living birds," she said.

Today, there are approximately 10,000 bird species worldwide. Birds might be as tiny as a hummingbird or as big as an ostrich; they might soar like an eagle or dive like a penguin. Nevertheless, they still belong to the same group of theropod dinosaurs that hatched Archaeopteryx 150 million years ago.

So, the next time you wonder what dinosaurs may have looked like when they walked the Earth, look no farther than the seagull eyeing your french fries at the beach, the crow scolding you from a fence, or the nearest pigeon pecking at crumbs on the sidewalk.



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