It's one of the big mysteries of cell biology. Why do mitochondria—the oval-shaped structures that power our cells—have their own DNA, and why have they kept it when the cell itself has plenty of its own genetic material? A new study may have found an answer.

Scientists think that mitochondria were once independent single-celled organisms until, more than a billion years ago, they were swallowed by larger cells. Instead of being digested, they settled down and developed a mutually beneficial relationship developed with their hosts that eventually enabled the rise of more complex life, like today's plants and animals.

Over the years, the mitochondrial genome has shrunk. The nucleus now harbors the vast majority of the cell's genetic material—even genes that help the mitochondria function. In humans, for instance, the mitochondrial genome contains just 37 genes, versus the nucleus's 20,000-plus. Over time, most mitochondrial genes have jumped into the nucleus. But if those genes are mobile, why have mitochondria retained any genes at all, especially considering that mutations in some of those genes can cause rare but crippling diseases that gradually destroy patients' brains, livers, hearts, and other key organs.

Scientists have tossed around some ideas, but there haven't been hard data to pick one over another.

Rapid reversals of Earth's magnetic field 550 million years ago destroyed a large part of the ozone layer and let in a flood of ultraviolet radiation, devastating the unusual creatures of the so-called Ediacaran Period and triggering an evolutionary flight from light that led to the Cambrian explosion of animal groups. That's the conclusion of a new study, which proposes a connection between hyperactive field reversals and this crucial moment in the evolution of life.

The Kotlinian Crisis, as it is known, saw widespread extinction and put an end to the Ediacaran Period. During this time, large (up to meter-sized) soft-bodied organisms, often shaped like discs or fronds, had lived on or in shallow horizontal burrows beneath thick mats of bacteria which, unlike today, coated the sea floor. The slimy mats acted as a barrier between the water above and the sediments below, preventing oxygen from reaching under the sea floor and making it largely uninhabitable.

The Ediacaran gave way to the Cambrian explosion, 542 million years ago: the rapid emergence of new species with complex body plans, hard parts for defense, and sophisticated eyes. Burrowing also became more common and varied, which broke down the once-widespread bacterial mats, allowing oxygen into the sea floor to form a newly hospitable space for living.

The world's oldest known wild bird just added a new chick to the family — her 40th one, experts say.

The Laysan albatross (Phoebastria immutabilis), named Wisdom, is at least 65 years old but shows no signs of slowing down. Wildlife officials at the Midway Atoll National Wildlife Refuge in Hawaii saw her lay an egg on Nov. 28, 2015, and incubate it for several weeks.

A fuzzy, gray chick cracked out of its shell on Feb. 1. But Wisdom wasn't there when the baby chick hatched: She had headed out to sea on Jan. 20, leaving her mate on nest duty. She returned just after Super Bowl Sunday (Feb. 7) with a full belly and settled down on the nest, allowing her mate to fly off to sea in search of food, officials said.

Wildlife officials wasted no time in naming the chick, dubbing it Kūkini, which means "messenger" in Hawaiian.

In the 1960s, psychologist Stanley Milgram famously conducted experiments in a Yale University basement showing that people will apparently inflict pain on another person simply because someone in a position of authority told them to. Now, researchers have taken those classic experiments one step further, providing new evidence that might help to explain why people are so easily coerced.

According to the new work by researchers at University College London and Université Libre de Bruxelles in Belgium, when someone gives us an order, we actually feel less responsible for our actions and their painful consequences.

"Maybe some basic feeling of responsibility really is reduced when we are coerced into doing something," says Patrick Haggard of University College London. "People often claim reduced responsibility because they were 'only obeying orders.' But are they just saying that to avoid punishment, or do orders really change the basic experience of responsibility?"

Nicknamed the "Superman memory crystal," a new storage device made of nanostructured glass can archive 360 terabytes worth of information for billions of years. Created by scientists at the University of Southampton using femtosecond laser writing, the sliver of fused quartz coin can withstand temperatures up to 157 degrees Celsius (350 degrees Fahrenheit). It is an example of 5D optical data storage.

The research team from the University's Optoelectronics Research Center first experimentally tested the technology in 2013. The final iteration encodes files in five dimensions (size, orientation + 3 dimensional position of nanostructures), writing with ultrafast, intense pulses of light.

Giant canyons on Charon, one of Pluto's five known moons, suggest there was once a warm ocean underneath, NASA says. Scientists believe the ocean might be still there, frozen under the moon's surface.

Recent images from the New Horizon spacecraft suggest that Charon's peculiar tectonic landscape could have been formed by expansion from the inside.

Having frozen, the ocean might have pushed outward, causing the moon's surface to stretch and fracture on a massive scale.

This has raised the question about how such an ocean would form in the first place. Scientists believe that as the outer layer of Charon is primarily water-ice, in the moon's youth it could have been heated by internal processes and radioactive elements. Some of the melting water apparently went underneath, into the moon's deeper layers to form a massive pool of water.

Clues as to how the solar system came into existence could be hidden in a layer of meteorites just beneath the surface of Antarctica, a team of British scientists claim.

A recent study by researchers at the University of Manchester posits the theory that a "hidden reserve" of meteorites lies between 10 and 50cm beneath the icy surface.

If discoverable, these rocks - which were originally part of large planets which subsequently broke apart - could help scientists in their understanding of the formation of the solar system.

An international group of scientists have discovered a previously unknown layer in Earth's mantle, and they estimate that it contains about eight to ten times more oxygen than Earth's atmosphere.

"This discovery came as a big surprise to us and so far we don't know what is happening to these 'rivers of oxygen' in the depths of our planet," said Elena Bykova, a member of the group of scientists who made the discovery.

The human brain may be able to hold as much information in its memory as is contained on the entire Internet, new research suggests.

Researchers discovered that, unlike a classical computer that codes information as 0s and 1s, a brain cell uses 26 different ways to code its "bits." They calculated that the brain could store 1 petabyte (or a quadrillion bytes) of information.

"This is a real bombshell in the field of neuroscience," Terry Sejnowski, a biologist at the Salk Institute in La Jolla, California, said in a statement. "Our new measurements of the brain's memory capacity increase conservative estimates by a factor of 10."

Amazing computer

What's more, the human brain can store this mind-boggling amount of information while sipping just enough power to run a dim light bulb.

By contrast, a computer with the same memory and processing power would require 1 gigawatt of power, or "basically a whole nuclear power station to run one computer that does what our 'computer' does with 20 watts," said study co-author Tom Bartol, a neuroscientist at the Salk Institute.

In particular, the team wanted to take a closer look at the hippocampus, a brain region that plays a key role in learning and short-term memory.

To untangle the mysteries of the mind, the research team took a teensy slice of a rat's hippocampus, placed it in embalming fluid, then sliced it thinly with an extremely sharp diamond knife, a process akin to "slicing an orange," Bartol said. (Though a rat's brain is not identical to a human brain, the basic anatomical features and function of synapses are very similar across all mammals.) The team then embedded the thin tissue into plastic, looked at it under a microscope and created digital images.

Next, researchers spent one year tracing, with pen and paper, every type of cell they saw. After all that effort, the team had traced all the cells in the sample, a staggeringly tiny volume of tissue.

"You could fit 20 of these samples across the width of a single human hair," Bartol told Live Science.

Scientific discoveries that involve humans interfacing with machines can evoke reactions of fear and wonder. Quite often, these feelings are epitomized through works of science fiction. Think Mary Shelly's "Frankenstein," for starters; or its modern day equivalent, one of many films playing on our mixed feelings toward AI, "Ex Machina."

One British sci-fi TV series that captures the anxious mix of fear and wonder that accompanies machine-human interfaces is Black Mirror. One episode in this series, titled "The Entire History of You" features a piece of technology called "Grain".

When implanted behind a human's right ear, grain records a person's first-hand visual and auditory experience and converts it into a chronological collection of watchable videos.