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2017

A New Form of Stem-Cell Engineering Raises Ethical Questions
New York Times, March 21, 2017
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As biological research races forward, ethical quandaries are piling up. In a report published Tuesday in the journal eLife, researchers at Harvard Medical School said it was time to ponder a startling new prospect: synthetic embryos.

In recent years, scientists have moved beyond in vitro fertilization. They are starting to assemble stem cells that can organize themselves into embryolike structures.

Soon, experts predict, they will learn how to engineer these cells into new kinds of tissues and organs. Eventually, they may take on features of a mature human being.

In the report, John D. Aach and his colleagues explored the ethics of creating what they call “synthetic human entities with embryolike features” — Sheefs, for short. For now, the most advanced Sheefs are very simple assemblies of cells.

How Did Aboriginal Australians Arrive on the Continent? DNA Helps Solve a Mystery
New York Times, March 8, 2017
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Human skeletons and archaeological remains in Australia can be traced back nearly 50,000 years before the trail disappears. Before then, apparently, Australia was free of humans.

So how did people get there, and when? Where did humans first arrive on the continent, and how did they spread across the entire landmass?

Answers to some of these questions are stored in the DNA of Aboriginal Australians. A genetic study of 111 Aboriginal Australians, published on Wednesday, offers an interesting — and, in some respects, unexpected — view of their remarkable story.

All living Aboriginal Australians descend from a single founding population that arrived about 50,000 years ago, the study shows. They swept around the continent, along the coasts, in a matter of centuries. And yet, for tens of thousands of years after, those populations remained isolated, rarely mixing.

Scientists Say Canadian Bacteria Fossils May Be Earth’s Oldest
New York Times, March 1, 2017
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They are microscopic artwork: tiny tubes and long filaments, strange squiggles etched into some of the most ancient rocks known.

On Wednesday, researchers reported that these may be the oldest fossils ever discovered, the remains of bacteria thriving on Earth not long, geologically speaking, after the very birth of the planet. If so, they offer evidence that life here got off to a very early start.

But many experts in the field were skeptical of the new study — or downright unconvinced.

Martin J. Van Kranendonk, a geologist at the University of New South Wales, called the patterns in the rocks “dubiofossils” — fossil-like structures, perhaps, but without clear proof that they started out as something alive.

Disappearing Seagrass Protects Against Pathogens, Even Climate Change, Scientists Find
New York Times, February 16, 2017
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Every continent save Antarctica is ringed by vast stretches of seagrass, underwater prairies that together cover an area roughly equal to California.

Seagrass meadows, among the most endangered ecosystems on Earth, play an outsize role in the health of the oceans. They shelter important fish species, filter pollutants from seawater, and lock up huge amounts of atmosphere-warming carbon.

The plants also fight disease, it turns out. A team of scientists reported on Thursday that seagrasses can purge pathogens from the ocean that threaten humans and coral reefs alike. (The first hint came when the scientists were struck with dysentery after diving to coral reefs without neighboring seagrass.)

But the meadows are vanishing at a rate of a football field every 30 minutes. Joleah B. Lamb, a postdoctoral researcher at Cornell University and the lead author of the new study, said she hoped it would help draw attention to their plight.

The Purpose of Sleep? To Forget, Scientists Say
New York Times, February 2, 2017
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Over the years, scientists have come up with a lot of ideas about why we sleep.

Some have argued that it’s a way to save energy. Others have suggested that slumber provides an opportunity to clear away the brain’s cellular waste. Still others have proposed that sleep simply forces animals to lie still, letting them hide from predators.

A pair of papers published on Thursday in the journal Science offer evidence for another notion: We sleep to forget some of the things we learn each day.

In order to learn, we have to grow connections, or synapses, between the neurons in our brains. These connections enable neurons to send signals to one another quickly and efficiently. We store new memories in these networks.

Most Primate Species Threatened With Extinction, Scientists Find
New York Times, January 18, 2017
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Our fellow primates are in trouble.

In a study of unprecedented scope, a team of 31 primatologists has analyzed every known species of primate to judge how they are faring. The news for man’s closest animal relatives is not good.

Three-quarters of primate species are in decline, the researchers found, and about 60 percent are now threatened with extinction. From gorillas to gibbons, primates are in significantly worse shape now than in recent decades because of the devastation from agriculture, hunting and mining.

“I think we’re going to get quite a number of extinctions within next 50 years if things go on the way they are,” said Anthony B. Rylands, a senior research scientist at Conservation International and a co-author of the new study, which was published in Science Advances.

On Long Migrations, Birds Chase an Eternal Spring
New York Times, January 5, 2017
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Bird migrations have stumped the greatest minds for thousands of years. Aristotle thought that the robins living in Greece in the winter somehow turned into redstarts in the summer. In fact, robins migrate from Greece to Northern Europe around the time redstarts arrive from Africa.

Scientists have gotten a much better understanding of bird migration in recent centuries, but there’s a tremendous amount they have yet to learn. After tracking more than three dozen birds with sensors for thousands of miles, a team of researchers reported on Wednesday that their migration defied the expected course.

Instead of simply flying straight from their summer grounds in Denmark to their winter site in Africa, the birds stretched out their journey, stopping at several places along the way for weeks at a time.

“It’s more of a nomadic life,” said Kasper Thorup, a bird migration expert at the University of Copenhagen and co-author of the new study. “They hardly have a place to call home.”

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